Search

BACKGROUND: The use of a digital three-dimensional (3D) exoscope system in neurosurgery is increasing as an alternative to the operative microscope. The objective of this study was to compare a digital 3D exoscope system with a standard operating microscope as a neurosurgical visualization tool in a highly challenging experimental setting. METHODS: End-to-side bypass procedures, each at a depth of 9 cm, were performed in a simulation setting. The quality of the task and the depth effect, visualization, magnification, illumination, and ergonomics were evaluated. RESULTS: No major differences were noted between the microscope and the 3D exoscope in terms of the quality of the work. Working with the 3D exoscope was more time-consuming than working with the microscope. Changing the depth and focus was faster using the operative microscope. The 3D exoscope enabled higher magnification and offered better ergonomic features. CONCLUSIONS: In a highly challenging experimental setting, comparable procedural quality was found for the microscope and the 3D exoscope. Each visualization tool had advantages and disadvantages. Over time and with technologic advances, the digital 3D exoscope may become the main operative visualization system in microneurosurgery.

BACKGROUND: Mirror distal anterior cerebral artery aneurysms (DACAAs) are a rare finding in patients with subarachnoid hemorrhage, with only a few cases reported. CASE DESCRIPTION: A 40-year-old man was admitted for sudden-onset headache, nausea and vomiting, and transient right arm hypoesthesia. Computed tomography scan showed a subarachnoid hemorrhage with intracerebral hemorrhage within the interhemispheric fissure, but computed tomography angiography failed to identify any aneurysms. Subsequent digital subtraction angiography with three-dimensional reconstructions revealed 1.5-mm-diameter mirror DACAAs on the A3 segments. However, the definite rupture site remained unidentifiable. After interdisciplinary consultation, endovascular treatment was favored, and complete occlusion of both DACAAs was achieved by coiling without stent placement. During coiling of the right DACAA, a thrombus in the right callosomarginal artery formed, and treatment with abciximab (ReoPro) was initiated to dissolve the thrombus. After treatment, the patient presented with right leg paresis; however, computed tomography did not show any ischemia, intracerebral hemorrhage increase, or vasospasm. Over the following days, the leg paresis improved, and the patient achieved increased mobilization. He was transferred for further rehabilitation 16 days after hemorrhage. The leg paresis had recovered to a grade 3/5. CONCLUSIONS: Rapid identification of the rupture site in patients with subarachnoid hemorrhage and multiple aneurysms is crucial for initiating optimal treatment. In patients with mirror aneurysms in close proximity to each other, this is not easily accomplished, complicating treatment decisions. Although clipping has been the standard for DACAA occlusion, coiling should be taken into consideration as a viable alternative.

Neurosurgeons are vulnerable to additional noise in their natural operating environment. Noise exposure is associated with reduced cognitive function, inability to concentrate, and nervousness. Mediation music provides an opportunity to create a calmer environment which may reduce stress during surgery. A pilot study was performed to find a suitable task, meditation music of surgeon’s choice, and operation noise and to reach a certain level of training. For the main experiment, two neurosurgeons with different microsurgical experience used real operation noise and meditation music with delta waves as mediating music. Each surgeon performed 10 training bypasses (five with noise and five with music) with 16 stitches in each bypass. The total time to complete 16 stitches, a number of unachieved movements (N.U.Ms), length of thread consumed, and distribution of the stitches were quantified from the recorded videos and compared in both groups. A N.U.Ms were significantly reduced from 109 ± 38 with operation room (OR) noise to 38 ± 13 (p

Background The microscope is the standard tool for microneurosurgery worldwide. However, the reduced illumination of the surgical field with the use of a conventional microscope during surgeries of deeply located pathologies remains unaddressed. Accordingly, different exoscope systems have recently been introduced in clinical practice. Here, we report our initial experience with the digital 2-dimensional Synaptive Modus V exoscope system in spinal and cranial surgery. Methods During a 2-week period between 27 September to 11 October 2018, we used the Synaptive Modus V exoscope system and performed eight neurosurgical procedures including spine (n = 4) and cranial procedures (n = 4). Visual quality, depth perception, complications, switching to microscope comfort level of the surgeon, and learning curve during surgery were evaluated. Results A total of eight procedures were performed, namely, vestibular schwannoma (n = 1), skull base meningioma (n = 1), olfactory groove meningioma (n = 1), tentorial meningioma (n = 1), anterior cervical discectomy (n = 1), cervical laminectomy (n = 1), and lumbar disc herniation (n = 2). The overall results were comparable to the operative microscope with better visual quality and greater comfort for the surgeon. Conclusion The Synaptive Modus V system is a safe tool to perform common spinal surgeries and intracranial tumor resection. Image quality is better than a microscope but with slightly less depth perception. Vigorous training in the laboratory may be helpful before clinical use. Electronic supplementary material The online version of this article (10.1007/s00701-019-03953-x) contains supplementary material, which is available to authorized users.

Outcome and treatment-associated morbidity analysis of trigone meningioma surgery. We retrospectively assessed 27 neurosurgically treated patients (median age 63 years, range 15–84) between 1999 and 2019. The median preoperative Karnofsky Performance Scale (KPS) was 80 (range 20–100), and the majority (78%) suffered from tumour-specific symptoms. The most frequent symptoms were aphasia (n = 6), visual field deficits (n = 5), and increased intracranial pressure (n = 5). The median tumour volume was 11.2 cm3 (range 3.9–220.5). The most common approaches were the transtemporal (n = 17) and transparietal routes (n = 5). At last follow-up (median follow-up 35 months, range 3–127), the median KPS was 90 (range 30–100); eleven (42%) patients had improved, nine (35%) were unchanged, six (23%) had worsened, and one was lost to follow-up. One year after surgery, 18/21 (86%) patients had retained an activity level similar or improved compared with preoperatively. No surgery-related mortality was recorded. Postoperative new neurological deficits were seen in 13 (48%) patients; eight suffered from permanent, most commonly motor deficits (n = 4), and five of transient deficits. Permanent new motor deficits improved in the majority of affected patients (3/4) over time. New deficits were more often seen for transtemporal (8/17) than transparietal approaches (1/5). Patients with postoperative permanent new deficits had a significantly worse KPS at last follow-up (p < 0.001). The transtemporal and transparietal approaches provide good access, but the latter might provide for a better risk profile. Patients show favourable outcome, but there is a considerable risk for new neurological deficits. This must be taken into consideration for oligosymptomatic patients.

Background Previous studies have consistently demonstrated gaze behaviour differences related to expertise during various surgical procedures. In micro-neurosurgery, however, there is a lack of evidence of empirically demonstrated individual differences associated with visual attention. It is unknown exactly how neurosurgeons see a stereoscopic magnified view in the context of micro-neurosurgery and what this implies for medical training. Method We report on an investigation of the eye movement patterns in micro-neurosurgery using a state-of-the-art eye tracker. We studied the eye movements of nine neurosurgeons while performing cutting and suturing tasks under a surgical microscope. Eye-movement characteristics, such as fixation (focus level) and saccade (visual search pattern), were analysed. Results The results show a strong relationship between the level of microsurgical skill and the gaze pattern, whereas more expertise is associated with greater eye control, stability, and focusing in eye behaviour. For example, in the cutting task, well-trained surgeons increased their fixation durations on the operating field twice as much as the novices (expert, 848 ms; novice, 402 ms). Conclusions Maintaining steady visual attention on the target (fixation), as well as being able to quickly make eye jumps from one target to another (saccades) are two important elements for the success of neurosurgery. The captured gaze patterns can be used to improve medical education, as part of an assessment system or in a gaze-training application.

Recently, the use of digital exoscopes has been increasingly promoted as an alternative to microscopes. The aim of this study is to compare experimental bypass quality in both visualization methods.This study used two hundred 1-mm chicken wing vessels, which were used for either exoscopic or microscopic (100 samples each) bypass procedures. All procedures were recorded between July 2018 and September 2018. The bypass quality was evaluated according to our published practical scale (time, stitch distribution, intima-intima attachment, and orifice size).Both methods are effective in doing bypass suturing (practical scale score was good, 86% vs. 85%; P = 0.84). There were no significant differences regarding intima-intima attachment (P = 0.26) and orifice size (P = 0.25). However, suturing time (P0.001) was less using the microscope, whereas stitch distribution (P = 0.001) was better using the exoscope. Different suturing techniques (interrupted vs. continuous) had overall comparable results (P = 0.55).Both methods produced equally satisfactory results in experimental bypass procedures. The exoscope has the potential for better 3-dimensional visualization and sharing the surgeon's view with others for teaching purposes.

Resection of brain arteriovenous malformation (AVM) is challenging, particularly if the feeder arteries and draining vein are not directly visible on the surface. Indocyanine green video angiography can assist in detection of the connecting point of the draining vein with the superficial vein and can thus localize the cortical entry point for AVM resection. Here, we present a case of a 27-year-old man with headache. Computed tomography scan showed right occipital atypical bleeding. Computed tomography angiography and digital subtraction angiography confirmed the cortical AVM fed by the posterior cerebral artery branches. We decided on surgical treatment because the small posterior cerebral artery feeders were not easily accessible for endovascular treatment. We used an OPMI PENTERO 900 microscope to perform microsurgical resection of AVM. We present an illustrative video showing the surgical approach, microsurgical anatomy, and technical aspects of the utility of video indocyanine angiography (video-ICG) in deep cortical small AVM surgery. Video-ICG assisted detection of the cortical arterialized draining vein that was anastomosed with a sprawled superficial vein. This enabled a customized approach for the AVM resection ( Video 1 ). Postsurgical video-ICG showed normalized flow in the superficial vein supporting the complete resection of AVM. ICG is potentially helpful for detecting the cortical entry point of a deep draining vein with a sprawled superficial vein. ICG should be used as an adjunct to better understand the microvascular anatomy that may aid decision making during AVM surgery.

Objective Flow diversion is a popular technique used to treat ordinary small, as well as complex internal carotid artery (ICA) aneurysms. We describe aneurysm occlusion rates, complications and patient outcomes in patients with ICA aneurysms treated with flow diverter stents. Patients and methods We identified all consecutive patients with ICA aneurysms that were treated with flow diverter stents between 2014 and 2019 at our institution. We divided the aneurysms into two anatomic subgroups (cavernous and supraclinoid segments). All the imaging studies and medical records were reviewed for relevant features in relation to aneurysms, complications and patient outcomes. Results A total of 62 patients with 76 ICA aneurysms (72 unruptured; 4 ruptured) were treated with 70 flow diversion procedures, including six re-treatments. Complete aneurysm occlusion was achieved in 61 % of patients at 6-month follow-up (cavernous 69 %, supraclinoid 58 %), and in 69 % at the latest follow-up (mean of 18 months). Postprocedural intracranial ischemia or hemorrhage was seen in 24 % of patients, including two aneurysm ruptures after flow diversion, and related major long-term functional decline or mortality was seen in 6% of patients. Preprocedural dysfunction of extraocular muscles or vision disturbance improved moderately at best (40–60 %). At the latest follow-up, 54 patients (87 %) were functionally independent (mRS ≤2). Conclusion Flow diversion for cavernous and supraclinoid ICA aneurysms demonstrated acceptable results, but complex aneurysm features cause uncertainty in predicting aneurysm occlusion probability. Patients should be informed of the non-negligible rate of complications, and of only moderate improvement rate of cranial nerve dysfunctions.

Aneurysmal subarachnoid hemorrhage (aSAH) is a complex and potentially deadly disease. Neurosurgical clipping or endovascular coiling can successfully obliterate ruptured aneurysms in almost every case. However, despite successful interventions, the clinical outcomes of aSAH patients are often poor. The reasons for poor outcomes are numerous, including cerebral vasospasm (CVS), post-hemorrhagic hydrocephalus, systemic infections and delayed cerebral ischemia. Although CVS with subsequent cerebral ischemia is one of the main contributors to brain damage after aSAH, little is known about the underlying molecular mechanisms of brain damage. This review emphasizes the importance of pharmacological interventions targeting high mobility group box 1 (HMGB1)-mediated brain damage after subarachnoid hemorrhage (SAH) and CVS. We searched Pubmed, Ovid medline and Scopus for “subarachnoid hemorrhage” in combination with “HMGB1”. Based on these criteria, a total of 31 articles were retrieved. After excluding duplicates and selecting the relevant references from the retrieved articles, eight publications were selected for the review of the pharmacological interventions targeting HMGB1 in SAH. Damaged central nervous system cells release damage-associated molecular pattern molecules (DAMPs) that are important for initiating, driving and sustaining the inflammatory response following an aSAH. The discussed evidence suggested that HMGB1, an important DAMP, contributes to brain damage during early brain injury and also to the development of CVS during the late phase. Different pharmacological interventions employing natural compounds with HMGB1-antagonizing activity, antibody targeting of HMGB1 or scavenging HMGB1 by soluble receptors for advanced glycation end products (sRAGE), have been shown to dampen the inflammation mediated brain damage and protect against CVS. The experimental data suggest that HMGB1 inhibition is a promising strategy to reduce aSAH-related brain damage and CVS. Clinical studies are needed to validate these findings that may lead to the development of potential treatment options that are much needed in aSAH.

Posterior communicating artery (PcomA) aneurysms are frequently encountered, but there are few publications on their morphology. A growing number of aneurysms are incidental findings, which makes evaluation of rupture risk important. Our goal was to identify morphological features and anatomical variants associated with PComA aneurysms and to assess parameters related to rupture. We studied CT angiographies of 391 consecutive patients treated between 2000 and 2014 at a single institution. We determined clinically important morphological parameters and performed univariate and multivariate analysis. There were a total of 413 PComA aneurysms: 258 (62%) were ruptured and 155 (38%) unruptured. Ruptured PComA aneurysms had the potential to cause severe bleeding with IVH and/or temporal ICH (n = 170, 66% of ruptured). The main types of PComA origin were classified as follows: (1) separate (32%), (2) side by side (21%) and (3) a joint neck with the aneurysm (6%). After the multivariate logistic regression, the morphological parameters related to PComA aneurysm rupture were an irregular aneurysm dome, neck diameter, and aspect ratio > 1.5. The most marked morphological features of the PComA aneurysms were: saccular nature (99%), infero-posterior dome orientation (42%), infrequency of large or giant aneurysms (4%), narrow neck compared to the aneurysm size, PComA originating directly from the aneurysm neck or the dome (28%), and fetal or dominant PComA on the side of the aneurysm (35%). There were location-related parameters that were more strongly associated with PComA aneurysm rupture than aneurysm size: an irregular aneurysm dome, larger diameter of the aneurysm neck and aspect ratio > 1.5.

The retrosigmoid approach for vestibular schwannoma surgery has remained the standard approach by most neurosurgeons. Drilling the posterior wall of the internal auditory meatus (IAM) is an essential step in removing the intrameatal tumor. During IAM drilling, three anatomical structures can be encountered, including the posterior semicircular canal, vestibular aqueduct, and jugular bulb. Any of these can be injured during drilling, especially if the jugular bulb lies above the inferior edge of the IAM. Although IAM drilling is performed in most vestibular schwannoma surgeries, information on how to manage complications such as jugular bulb injury is lacking. Here we use an intraoperative video to demonstrate how to manage the inadvertent injury to the jugular bulb in order to avoid massive blood loss. We present a case of a 39-year-old woman with hearing loss, diagnosed with a cerebellopontine angle mass extending into the IAM. Surgery was required due to tumor progression. We used the retrosigmoid approach to access the tumor. During IAM drilling, the jugular bulb was injured. A thin layer of bone wax was applied under continuous suction. The margins of the wax were then gently compressed with a dissector; great care was taken to avoid pushing the wax into the jugular bulb. Excess bone wax was removed (video 1). A small diamond drill (2 mm) was used for further drilling. Our instructional video shows the surgical approach, microsurgical anatomy, and technical aspects of managing massive bleeding from jugular bulb injury. It should therefore be helpful for young neurosurgeons.

Background Classification of middle cerebral artery (MCA) aneurysms is sometimes difficult because the identification of the main MCA bifurcation, the key for accurate classification of MCA aneurysms, is inconsistent and somewhat subjective. Objective To use the meeting point of the M1 and M2 trunks as an objective, generally accepted, and angiographically evident hallmark for identification of MCA bifurcation and more accurate classification of MCA aneurysms. Methods We reviewed the computed tomographic angiography data of 1009 consecutive patients with 1309 MCA aneurysms. The M2 trunks were followed proximally until their meeting with the M1 trunk at the main MCA bifurcation. The aneurysms were classified according to their relative location: proximal, at, or distal to the MCA bifurcation. The M1 aneurysms were further subgrouped into M1 early cortical branch aneurysms and M1 lenticulostriate artery aneurysms, extending the classic 3-group classification of MCA aneurysms into a 4-group classification. Results The main MCA bifurcation was the most common location for MCA aneurysms, harboring 829 aneurysms (63%). The 406 M1 aneurysms comprised 242 M1 early cortical branch aneurysms (60%) and 164 M1 lenticulostriate artery aneurysms (40%). We found 106 MCA aneurysms (8%) at the origin of large early frontal branches simulating M2 trunks liable to be misclassified as MCA bifurcation aneurysms. Even though 51% of the 407 ruptured MCA aneurysms were associated with an intracerebral hematoma, this did not affect the classification. Conclusion Studying MCA angioarchitecture and applying the 4-group classification of MCA aneurysms is practical and facilitates the accurate classification of MCA aneurysms, helping to improve surgical outcome.

Aneurysms of the posterior cerebral artery (PCA) are uncommon. Because of their low incidence, only 5 series with more than 30 patient cases have been reported. The treatment of PCA aneurysms is challenging because of the high frequency of fusiform aneurysms and closeness to important neuroanatomic structures.A total of 121 patients with 135 PCA aneurysms were reviewed. The clinical and radiologic data, treatment strategies, and 1-year outcomes were analyzed. Patients with giant aneurysms, associated aneurysms, and aneurysms on arteriovenous malformation-feeding PCAs were considered as complex cases. Outcomes were categorized into 3 groups: good (modified Rankin Scale [mRS], score 0-1), moderate (mRS score, 2-4), and poor (mRS score, 5-6).There were 52 ruptured (39%) and 83 unruptured (61%) PCA aneurysms in 121 patients, with the following distribution: P1 (n = 53), P1/2 (n = 39), P2 (n = 28), and P3 (n = 15). The incidence of fusiform PCA aneurysms was high (24%). Microsurgical treatment was applied to 63 aneurysms and endovascular treatment to 19 aneurysms; 55 aneurysms were treated conservatively. The following treatment results were achieved: for patients with unruptured PCA aneurysms, n = 19; 12 good outcomes, 63%; 6 moderate, 31%; 1 poor, 1%; for patients with ruptured PCA aneurysms, n = 27; 10 good, 37%; 9 moderate, 33%; 8 poor, 30%; and for patients with complex neurovascular diseases and PCA aneurysms, n = 96; 42 good, 43%; 40 moderate, 42%; 14 poor, 15%.Aneurysms of the PCA are infrequent and often associated with other vascular diseases. Microsurgery and endovascular treatment are effective for the occlusion of PCA aneurysms. The preservation or reconstruction of the parent vessel is crucial for favorable treatment outcomes.

Background Anterior clinoidal meningiomas (ACMs) are a subgroup of meningiomas accounting for less than 10% of supratentorial meningiomas. Objective To assess the reliability and safeness of the lateral supraorbital approach (LSO) to remove ACMs. Methods Between September 1997 and October 2009, a total of 73 ACM patients were operated on at the Department of Neurosurgery, Helsinki University Central Hospital, by the senior author (J.H.). We retrospectively analyzed the clinical data, radiological findings, surgical treatment, histology, and outcome of patients, and discuss the operative technique. Results Seventy-three patients were operated on by applying the LSO approach. Apparently complete removal was achieved in 57 patients (78%). Anterior clinoidectomy was performed in 21 cases. Preexisting visual deficit improved in 11 of 39 patients and worsened in 4; 3 had de novo visual deficit. At 3 months after discharge, 60 (82%) patients had a good recovery, 9 (12%) patients were moderately disabled, 1 presented with severe disability, and 3 (4%) patients died of surgery-related causes. Sixteen (22%) patients had residual tumors, 6 of which required reoperation. During the median follow-up of 36 months (range, 3-146), tumor recurred in 3 patients: 2 were followed-up and 1 was reoperated on. Conclusion ACMs can be removed via the LSO approach with relatively low morbidity and mortality. Anterior clinoidectomy is required only in selected cases, and we prefer the intradural approach during the LSO approach. High-power coagulation should be avoided in proximity of the optic nerve.

Cavernomas of the temporal lobe occur in 10–20% of patients with cerebral cavernomas. They frequently cause epileptic seizures, some of which tend to become refractory to medical therapy. Surgical removal of safely achievable symptomatic lesions has been frequently consistent with good long-term outcome. In the present study, a postoperative outcome is assessed. Of our 360 consecutive patients with cerebral cavernomas, 53 (15%) had a single cavernoma in the temporal lobe. Forty-nine patients were treated surgically and were included in the study. All data were analyzed retrospectively. The cavernomas were allocated into three groups based on the temporal lobe site: medial, anterolateral, and posterolateral. To collect follow-up data, all available patients were interviewed by phone. Seizure outcome was assessed using the Engel classification and general outcome using the Glasgow Outcome Scale (GOS). Patients’ median age at presentation was 37 (range, 7–64) years, with a female/male ratio of 2.5:1. Epileptic seizures occurred in 40 patients (82%). Median duration of seizures preoperatively was 3 (range, 0.1–23) years. In addition, four patients (10%) had memory disorder. Three patients without history of seizures (6%) complained of headache and two (4%) had memory problems. Three patients (6%) had an incidental cavernoma. Hemorrhage occurred in nine patients (18%) preoperatively. Median postoperative follow-up time was 6 (range, 0.2–26) years. Favorable seizure outcome (Engel class I and II) was registered in 35 patients (90%). Ten patients (25%) who had only a single seizure before surgery were seizure free during postoperative follow-up. Good general outcome (GOS, 4.5) was detected in 46 patients (96%). Two patients (4%) developed a new mild memory deficit after surgery, and in two patients existing memory deficits worsened. Microsurgical removal of temporal lobe cavernomas is a safe and effective method to improve seizure outcome in patients with medically intractable epilepsy and to prevent deterioration caused by hemorrhage.

Objective Anterior choroid artery aneurysms (AChAAs) constitute 2%-5% of all intracranial aneurysms. They are usually small, thin walled with one or several arteries originating at their base, and often associated with multiple aneurysms. In this article, we review the practical microsurgical anatomy, the preoperative imaging, surgical planning, and the microneurosurgical steps in the dissection and the clipping of AChAAs. Methods This review, and the whole series on intracranial aneurysms (IAs), are mainly based on the personal microneurosurgical experience of the senior author (J.H.) in two Finnish centers (Helsinki and Kuopio) that serve, without patient selection, the catchment area in Southern and Eastern Finland. Results These two centers have treated more than 10,000 patients with IAs since 1951. In the Kuopio Cerebral Aneurysm Database of 3005 patients with 4253 IAs, 831 patients (28%) had altogether 980 internal carotid artery (ICA) aneurysms, of whom 95 patients had 99 (2%) AChAAs. Ruptured AChAAs, found in 39 patients (41%), with median size of 6 mm (range = 2-19 mm), were associated with intracerebral hematoma (ICH) in only 1 (3%) patient. Multiple aneurysms were seen in 58 (61%) patients. Conclusions The main difficulty in microneurosurgical management of AChAAs is to preserve flow in the anterior choroid artery originating at the base and often attached to the aneurysm dome. This necessitates perfect surgical strategy based on preoperative knowledge of 3 dimensional angioarchitecture and proper orientation during the microsurgical dissection.

We report two cases of operative intervention that was beneficial in the treatment of delayed symptomatic radionecrotic masses that had developed following stereotactic radiosurgery (SRS) using the gamma knife (GK) for the treatment of cerebral arteriovenous malformations (AVM). Case 1 involved a small craniotomy for decompression of a large cerebral multiloculated cyst, which had become symptomatic 84 months following gamma knife treatment for a left frontal lobe AVM. Case 2 involved surgical excision of an occipital radionecrotic mass 72 months following GK treatment for an occipital AVM. This patient had suffered from longstanding symptomatic cerebral oedema, which on occasions had become life threatening. Case 2 is also the first report of a radionecrotic mass occurring post-SRS for an AVM, which conversely appeared to demonstrate increased uptake on single photon emission computed tomography (SPECT) scan. The first literature review of such delayed symptomatic radionecrotic lesions is presented. There appears to be a late onset of symptoms (average 55 months, range 12–111 months) associated with such radionecrosis. Drainage of such cysts or excision of the mass lesion appears to be consistently beneficial to the patients and appears to be uncomplicated. We recommend early surgical intervention for such delayed symptomatic radionecrotic masses that do not resolve following non-operative management. We also recommend caution in interpretation of SPECT scan results when attempting to differentiate radionecrosis from neoplasia.

Background Aneurysms originating from the A2 segment of ACA and its frontobasal branches are rare, forming less than 1% of all IAs. There are only few reports on management of A2As. In this article, we review the practical anatomy, preoperative planning, and avoidance of complications in the microsurgical dissection and clipping of A2As. Methods This review, and the whole series on IAs, is mainly based on the personal microneurosurgical experience of the senior author (JH) in two Finnish centers (Helsinki and Kuopio), which serve, without patient selection, the catchment area in Southern and Eastern Finland. Results These two centers have treated more than 10000 patients with IAs since 1951. In the Kuopio Cerebral Aneurysm Database of 3005 patients and 4253 IAs, there were 35 patients carrying 35 A2As, forming 1% of all patients with IAs, 0.8% of all IAs, and 3% of all ACA aneurysms. Twenty-one (60%) patients presented with ruptured A2As with ICH in 11 (52%) and IVH in 7 (33%). Nineteen patients (54%) had multiple aneurysms. Conclusions A2As are often small, even when ruptured, with relatively wide base, and they are frequently associated with ICHs of IVHs. Our data suggest that A2As rupture at smaller size than IAs in general. The challenge is to select appropriate approach, locate the aneurysm deep inside the interhemispheric fissure, and to clip the neck adequately without obstructing branching arteries at the base. Unruptured A2As also need microneurosurgical clipping even when they are small.

Background Aneurysms originating from the A3 segment of anterior cerebral artery (A3A) form about 5% of all IAs. They are the most common among distal anterior cerebral artery aneurysms. There are relatively few reports on management of A3As. In this article, we review the practical anatomy, preoperative planning, and avoidance of complications in the microsurgical dissection and clipping of A3As. Methods This review, and the whole series on IAs, is mainly based on the personal microneurosurgical experience of the senior author (JH) in 2 Finnish centers (Helsinki and Kuopio), which serve, without patient selection, the catchment area in Southern and Eastern Finland. Results These 2 centers have treated more than 10000 patients with IAs since 1951. In the Kuopio Cerebral Aneurysm Database of 3005 patients and 4253 IAs, there were 163 patients carrying 174 A3As, forming 5% of all patients with IAs, 4% of all IAs, and 15% of all ACA aneurysms. Ninety-seven (60%) patients presented with ruptured A3As with ICH in 27 (28%) and IVH in 26 (27%). Ninety-four (58%) patients had multiple aneurysms. Conclusions Aneurysms of A3 segment of ACA are often small, even when ruptured, with relatively wide base, and they are frequently associated with ICHs of IVHs. Our data suggest that A3As rupture at smaller size than IAs in general. The challenge is to select appropriate approach, to locate the aneurysm deep inside the interhemispheric fissure, and to clip the neck adequately without obstructing branching arteries at the base. Unruptured A3As also need microneurosurgical clipping even when they are small.

OBJECTIVE: Distal anterior cerebral artery (DACA) aneurysms have special anatomic features such as small size, broad base with originating branches, association with anterior cerebral artery (ACA) anomalies, and multiple aneurysms. Our aim is to evaluate incidences of these findings from pretreatment angiograms to help both microsurgical and endovascular treatment planning. METHODS: We performed detailed angiographic analysis of 101 consecutive patients diagnosed with DACA aneurysms from 1998 to 2007 in the Department of Neurosurgery at the Helsinki University Central Hospital in Helsinki, Finland. All patients underwent either digital subtraction angiography (n = 39) or computed tomographic angiography (n = 62). RESULTS: Of the 101 patients, 50 patients (50%) had multiple aneurysms, 7 patients (7%) had multiple DACA aneurysms, and 1 patient (1%) had an associated arteriovenous malformation. The 108 DACA aneurysms were found in seven different locations: frontobasal branches (n = 2); A2 segment (n = 5); A3 segment inferior to genu of corpus callosum (n = 19), anterior to genu of corpus callosum (n = 70), and superior to genu of corpus callosum (n = 1); A4 or A5 segments (n = 7); and distal branches (n = 4). Mean sizes were 7.4 mm (range, 2-35 mm) and 4.2 mm (range, 1-9 mm) for the 67 ruptured and 41 unruptured aneurysms, respectively. A broad base, wider than the parent artery, was seen in 68% of patients, and 94% of patients had a branch origin at the base. The neck-to-dome ratio was 1:1 in 25% of patients. Anomalies of the ACA were seen in 23 patients (23%): azygos ACA in 4 patients (4%), bihemispheric ACA in 15 patients (15%), and triplication of ACA in 4 patients (4%). CONCLUSION: The special neurovascular features and frequent ACA anomalies, best identified from computed tomographic angiography or rotational digital subtraction angiography, must be taken into account when planning occlusive treatment of DACA aneurysms.

Background Anterior communicating artery complex is the most frequent site of intracranial aneurysms in most reported series. Anterior communicating artery aneurysms are the most complex aneurysms of the anterior circulation due to the angioarchitecture and flow dynamics of the ACoA region, frequent anatomical variations, deep interhemispheric location, and danger of severing the perforators with ensuing neurologic deficits. The authors review the practical microsurgical anatomy, importance of preoperative imaging in surgical planning, and microneurosurgical steps in dissection and clipping of ACoAAs. Methods This review, and the whole series on intracranial aneurysms, are mainly based on the personal microneurosurgical experience of the senior author (JH) in 2 Finnish centers (Helsinki and Kuopio), which serve, without patient selection, the catchment area in Southern and Eastern Finland. Results These 2 centers have treated more than 10 000 patients with aneurysm since 1951. In the Kuopio Cerebral Aneurysm Database of 3005 patients with 4253 aneurysms, 1145 patients (38%) had altogether 1179 ACA aneurysms; of them, 898 patients harbored 921 (78%) ACoAAs. In this series, 715 patients (80%) presented with ruptured ACoAAs with the median diameter of 7 mm. Giant ACoAAs were present in 15 (2%), whereas only 3 (0.3%) were classified as fusiform. Conclusions Anterior communicating artery aneurysms present frequently with SAH at small size. Furthermore, unruptured ACoAAs may have increased risk of rupture regardless of size, also as an associated aneurysm, and require treatment. The aim in microneurosurgical management of an ACoAA is total occlusion of the aneurysm sac with preservation of flow in all branching and perforating arteries. This demanding task necessitates perfect surgical strategy based on review of the 3D angioarchitecture and abnormalities of the patient's ACoA complex with its ACoAA and to orientate accordingly during the microsurgical dissection. The surgical trajectory should provide optimal visualization of the ACoA complex without massive brain retraction. Precise dissection in the 3D anatomy of the ACoA complex and perforators requires not only experience and skill but patience to work the dome and base under repeated protection of temporary clips and pilot clips. This is particularly important with the complex, large, and giant aneurysms.

Objective This study presents the combined experience of two Finnish neurosurgical centers in the treatment of 501 consecutive patients with distal anterior cerebral artery (DACA) aneurysms. Our aim was to compare treatment outcomes of these lesions with intracranial aneurysms in general and to identify factors predicting the outcome. Methods We analyzed the clinical and radiological data of all 501 patients and focused on the 427 patients treated between 1980 and 2005, the era of microsurgery and computed tomographic imaging. No patients were lost to follow-up. We compared treatment and outcome of ruptured DACA aneurysms (n = 277) with all consecutive ruptured aneurysms from the Kuopio Cerebral Aneurysm Database (n = 2243) and used multivariate analysis to identify factors predicting 1-year outcome. Results DACA aneurysms accounted for 6% of all intracranial aneurysms. They were smaller (median, 6 versus 8 mm), more frequently associated with multiple aneurysms (35 versus 18%), and presented more often with intracerebral hematomas (53 versus 26%) than ruptured aneurysms in general. Their microsurgical treatment showed the same complication rates (treatment morbidity, 15%; treatment mortality, 0.4%) as for other ruptured aneurysms. At 1 year after subarachnoid hemorrhage, they had similar favorable outcome (Glasgow Coma Scale score >or=4) as other ruptured aneurysms (74 versus 69%), but their mortality rate was lower (13 versus 24%). Factors predicting unfavorable outcome for ruptured DACA aneurysms were advanced age, Hunt and Hess grade greater than or equal to III, rebleeding before treatment, intracerebral hematoma, intraventricular hemorrhage, and severe preoperative hydrocephalus. Conclusion Despite their specific features, with modern treatment methods, ruptured DACA aneurysms have the same favorable outcome and lower mortality at 1 year as ruptured aneurysms in general.

Background Distal middle cerebral artery aneurysms originate from branches of MCA distal to its main bifurcation or the peripheral branches. Distal middle cerebral artery aneurysms are the least frequently seen among the middle cerebral artery aneurysms. The purpose of this article is to review the practical anatomy, preoperative planning, and avoidance of complications in the microsurgical dissection and clipping of MdistAs. Methods This review, and the whole series on intracranial aneurysms, are mainly based on the personal microneurosurgical experience of the senior author (JH) in 2 Finnish centers (Helsinki and Kuopio), which serve without patient selection the catchment area in Southern and Eastern Finland. Results These 2 centers have treated more than 10 000 aneurysm patients since 1951. In the Kuopio Cerebral Aneurysm Database of 3005 patients with 4253 aneurysms, 69 patients carrying altogether 78 MdistAs formed 5% of all MCA aneurysms. Among the 18 patients with ruptured MdistAs (23%), an ICH occurred in 9 (50%). Conclusions Distal middle cerebral artery aneurysms are rare. The microneurosurgical treatment of MdistAs is challenging. They are often difficult to localize during the operation, and lack of collateral circulation makes their occlusion more demanding. High rate of ICH and high tendency of rebleeding urge acute or emergency surgery in most of ruptured cases. Microneurosurgical clipping is the most effective treatment of MdistAs.

Background The M1As are located in the main trunk (M1) of the MCA, between the bifurcation of the ICA and the main bifurcation of M1. Proximal MCA aneurysms are often small and thin-walled, which makes their proper clipping tedious. There are few reports on their microsurgery. Methods This review, and the whole series on intracranial aneurysms, is mainly based on the personal microneurosurgical experience of the senior author (JH) in 2 Finnish centers (Helsinki and Kuopio), which serve, without selection, the catchment area in the southern and eastern Finland. Results These 2 centers have treated more than 10 000 patients with aneurysm since 1953. We review the practical anatomy, preoperative planning, and avoidance of complications in the microsurgical dissection and clipping of M1As which form 7.4% of all intracranial and 14% of all MCA aneurysms in our patients. Conclusions Proximal MCA aneurysms are often wide-necked and intimately connected to an M1 branch at its origin on M1, features that favor exosurgery rather than endosurgery. The direction and course of the parent and branching arteries and the orientation of the fundus are the most important factors affecting the efficacy and safety of clipping.

BACKGROUND: Giant intracranial aneurysms (GIAs), which are defined as intracranial aneurysms (IAs) with a diameter of ≥25 mm, are most likely associated with the highest treatment costs of all IAs. However, the treatment costs of unruptured GIAs have so far not been reported. OBJECTIVE: To examine direct costs of endovascular and surgical treatment of unruptured GIAs. METHODS: We retrospectively examined 55 patients with unruptured GIAs treated surgically (37 patients) or endovascularly (18 patients) between April 2004 and March 2014. We analyzed the costs of all hospital stays, interventions, and imaging with a median follow-up of 46 months. RESULTS: There was no difference in the costs of hospital stay between surgical and endovascular treatment groups ($10,565 vs. $14,992; P = .37). Imaging costs were significantly higher in the surgical group than in the endovascular treatment group ($2890 vs. $1612; P < .01), as were the costs of the intervention room and personnel involved in the intervention ($5566 vs. $1520; P < .01). Implants used per patient were more expensive in the endovascular group than in the surgical treatment group ($20,885 vs. $167). The total direct treatment costs were higher in the endovascular group ($52,325) than in the surgical treatment group ($20,619; P < .01). Treatment costs were associated with the type of treatment and GIA location but not with patient age, sex, or GIA size. CONCLUSION: Endovascular GIA treatment produced higher direct costs than surgical GIA treatment mainly due to higher implant costs. Reducing endovascular implant costs may be the most effective tool to decrease direct costs of GIA treatment.

BACKGROUND: The Giant Intracranial Aneurysm Registry is a multicenter observational trial exclusively focusing on giant intracranial aneurysms (GIA). As no data exist on the interobserver variability in the radiological description of GIA, there is some uncertainty concerning the reliability of the GIA characteristics included in the registry. We have therefore designed a study to test the interobserver variability in the description of the specific GIA characteristics that are examined in the GIA registry. METHODS: Six different raters analyzed imaging of five GIA concerning GIA location, GIA size, GIA shape, GIA thrombosis, and the presence of perianeurysmal edema. Interobserver variability was examined using intraclass correlation and Fleiss' kappa analysis. RESULTS: The intraclass correlation coefficient was 0.99 (95 % CI 0.97-1.0) for the largest GIA diameter and 0.98 (95 % CI 0.94-1.0) for the largest GIA diameter in an axial imaging slice. We found perfect interobserver agreement (Fleiss' kappa 1.00)in the characterization of GIA location and the presence of perianeurysmal edema and almost perfect interobserver agreement for GIA thrombosis (Fleiss' kappa 0.86, 95 % CI 0.63-1.00). Only moderate interobserver agreement was found in the description of GIA shape (Fleiss' kappa 0.50, 95 % CI 0.27-0.73). CONCLUSIONS: While GIA size, location, thrombosis, and the presence of perianeurysmal edema showed excellent interobserver agreement, the description of GIA shape was achieved with only moderate agreement. Data on GIA shape in multicenter studies, like the GIA registry, should therefore be discussed with caution and potentially reassessed in a centralized fashion.

Background and Purpose— There is high case-fatality rate and loss of productive life-years related to aneurysmal subarachnoid hemorrhage (aSAH) but data on long-term survival of patients with aSAH are scarce. We aim to evaluate long-term excess mortality and related risk factors after an aSAH event. Methods— Survivors (n=3078) of aSAH who had survived for ≥1 year were reviewed for this retrospective follow-up study, which was conducted in the Department of Neurosurgery in Helsinki between 1980 and 2007. Follow-up started 1 year after the aSAH and continued until death or the end of 2012 (48 918 patient-years). Mortality and relative survival ratios were derived using a matched general population. Results— Survivors of aSAH after 20 years showed 17% excess mortality compared with the general population. Even young patients and patients with good recovery showed excess mortality. The highest excess mortality was among patients with multiple aneurysms, old age, poor preoperative clinical condition, conservative aneurysm treatment, and unfavorable clinical outcome at 1 year. Conclusions— Even after initially favorable recovery from an aSAH, survivors experience excess mortality in the long run in comparison to a matched general population. Cardiovascular disease at younger age and cerebrovascular events were overrepresented as causes of death, which indicates the importance of treatment of vascular risk factors. Young patients and patients with multiple aneurysms who are recovering from an aSAH should be followed-up and treated most actively.

Saccular aneurysms are frequently associated with arteriovenous malformations (AVMs) probably due to hemodynamic stresses exerted on an arterial wall. The incidence of such an association has been reported between 5.5% and 12% [1,2]. Most of these aneurysms are small or medium sized, giant aneurysms are very rare with only few cases published. Some of the associated aneurysms located on the arterial feeders of the AVM may decrease in size or even disappear completely after the AVM treatment [3]. However, intranidal aneurysms usually venous in origin, require treatment and when treated microsurgically, they should be removed together with the AVM nidus. If the intranidal aneurysm is giant, the complete removal of the AVM becomes even more challenging. Microscope integrated nearinfrared indocyanine green videoangiography (ICG) can be useful in such a situation mainly for intraoperative orientation. Here we present a case report of an AVM associated with giant intranidal aneurysm, which was treated successfully with the aid of intraoperative ICG.

Objective Aneurysms of the posterior cerebral artery (PCA) are rare, and therefore the individual and institutional experience of their microsurgical management is usually limited. In the present article, we describe our experience with the subtemporal approach to aneurysms arising from the PCA. Methods We reviewed 34 patients diagnosed with 37 PCA aneurysms, all microsurgically managed using the subtemporal approach between 1980 and 2012 at 2 Finnish neurosurgical centers (Helsinki and Kuopio). The following procedures were applied using the subtemporal approach: neck clipping (n = 24); proximal occlusion (n = 7); trapping (n = 2); wrapping (n = 1); aneurysmoraphy (n = 1); bypass bridging/trapping (n = 1); and a complex excimer laser-assisted nonocclusive anastomosis procedure (n = 1). Results Of these 34 patients, 16 presented with acute subarachnoid hemorrhage as a result of PCA aneurysm rupture, and 11 of the 16 had good outcome (modified Rankin scale 0–2) at 3 months The remaining 18 patients were treated microsurgically for incidentally diagnosed unruptured aneurysms, and 14 of the 18 had a good outcome. The most common serious complication in this series was an ipsilateral PCA infarction (12/34; 35%), mostly after proximal occlusion (n = 7) and/or trapping (n = 2). Conclusions The subtemporal approach is a suitable approach to aneurysms of the segments P1, P1–P2 junction, and P2, as well as the anterior P3 segment of the PCA. Using the subtemporal approach, the cerebrospinal fluid is released before retraction is necessary to prevent temporal lobe injury. The subtemporal approach can provide enough space for revascularization procedures. The most encountered complications were not related to the subtemporal approach but to the specific nature of PCA aneurysms.

Background Posterior cerebral artery (PCA) aneurysms are rare lesions. Because of their low incidence, the individual or institutional experience is usually limited. Objective To identify specific anatomic features related to PCA aneurysms based on the analyses of pretreatment angiograms. Methods We performed a detailed angiographic study of 81 patients with a diagnosis of 93 PCA aneurysms. Fifty-three patients underwent computed tomography angiography, 49 underwent digital subtraction angiography, and 6 underwent magnetic resonance angiography. Between 1980 and 2012, a total of 120 patients with 136 PCA aneurysms and 11 352 patients with 16 444 intracranial aneurysms were treated at our institutions. Results There were 29 ruptured and 64 unruptured PCA aneurysms. The distribution of the aneurysms along the PCA segments was P1 (n = 39; 9 ruptured), P1/P2 junction (n = 25; 9 ruptured), P2 (n = 21; 5 ruptured), and P3 (n = 8; 6 ruptured). The median aneurysm size was 7 mm for the ruptured and 4 mm for the unruptured aneurysms. Saccular aneurysms (n = 69, 74%) had a typical projection for each location: P1 segment, upward (67%); P1/P2 junction, anterior/upward (80%); P2 segment, lateral (67%); and P3 segment, posterior (50%). Multiple aneurysms were seen in 43 patients. PCA aneurysms related to arteriovenous malformations were observed in 10 patients. Conclusion PCA aneurysms are infrequent lesions, often associated with multiple aneurysms and arteriovenous malformations and are fusiform in shape. Most ruptured PCA aneurysms are smaller than 10 mm and usually distally located. At each PCA segment, saccular PCA aneurysms have a typical dome orientation.

The object of this study was to describe the authors' institutional experience in the treatment of complex middle cerebral artery (MCA) aneurysms necessitating bypass and vessel sacrifice.Cases in which patients with MCA aneurysms were treated with a combination of bypass and parent artery sacrifice were reviewed retrospectively.The authors identified 24 patients (mean age 46 years) who were treated with bypass and parent artery sacrifice. The aneurysms were located in the M1 segment in 7 patients, MCA bifurcation in 8, and more distally in 9. The mean aneurysm diameter was 30 mm (range 7-60 mm, median 26 mm). There were 8 saccular and 16 fusiform aneurysms. Twenty-one extracranial-intracranial and 4 intracranial-intracranial bypasses were performed. Partial or total trapping (only) of the parent artery was performed in 17 cases, trapping with resection of aneurysm in 3, and aneurysm clipping with sacrifice of an M2 branch in 4. The mean follow-up period was 27 months. The aneurysm obliteration rate was 100%. No recanalization of the aneurysms was detected during follow-up. There was 1 perioperative death (4% mortality rate) and 6 cerebrovascular accidents, causing permanent morbidity in 5 patients. The median modified Rankin Scale score of patients with an M1 aneurysm increased from 0 preoperatively to 2 at latest follow-up, while the score was unchanged in other patients. Most of the permanent deficits were associated with M1 aneurysms. Twenty-one patients (88%) had good outcome as defined by a Glasgow Outcome Scale score of 4 or 5.Bypass in combination with parent vessel occlusion is a useful technique with acceptable frequencies of morbidity and mortality for complex MCA aneurysms when conventional surgical or endovascular techniques are not feasible. The location of the aneurysm should be considered when planning the type of bypass and the site of vessel occlusion. Flow alteration by partial trapping may be preferable to total trapping for the M1 aneurysms.

A wide sylvian opening, with either a proximal or distal start, has been standard for microsurgical management of middle cerebral artery (MCA) aneurysms. However, extensive sylvian dissection is potentially associated with increased incidence of iatrogenic injury to the brain and neurovascular structures. The aim of the present study was to describe the technique of focused opening of the sylvian fissure for microsurgical management of MCA aneurysms with additional tips on handling difficulties which may be encountered with this technique.A 3D image-based anatomic orientation, clipping field-focused surgical planning, slack brain, and high magnification are the basic requirements for this approach. A 10-15 mm sylvian opening is placed so that it allows safe access and a good surgical view of the MCA aneurysm clipping field. Under proximal control of the MCA, the aneurysm neck can be dissected and clipped effectively and safely, in this small surgical field.The presented technique has been developed and refined by the senior author during the surgery of 1,097 aneurysms over the last 13 years. It has proved to be safe, and effective for clipping of both ruptured and unruptured MCA aneurysms. Its greatest advantages are a shorter operative time and less brain and vessel manipulation compared to more extensive approaches.The focused sylvian opening is a less-invasive alternative to the classical wide sylvian opening for the microsurgical management of most MCA aneurysms.

Giant intracranial aneurysms are rare and heterogeneous lesions with complex vascular anatomy. The aim of this retrospective study was to provide a comprehensive description of the anatomical features of giant aneurysms. We identified 125 patients with 129 giant aneurysms (≥25 mm) who were treated between 1987 and 2007 at the Department of Neurosurgery of Helsinki University Central Hospital (HUCH). All the imaging studies and medical records were reviewed for relevant information. The distribution of the giant aneurysms among regions was as follows: internal carotid artery (ICA) 39 %, middle cerebral artery (MCA) 32 %, vertebrobasilar and posterior cerebral artery (VB-PCA) region 25 %, and anterior cerebral artery (ACA) including the anterior communicating artery 5 %. The cavernous ICA segment (n = 21, 16 %) and the MCA bifurcation (n = 25, 19 %) were the most frequent specific locations. Half (n = 11) of all fusiform aneurysms were found in the VB-PCA region. As many as 41 % of the giant MCA aneurysms were ruptured. Major anatomic variations were found in three (2 %) and multiple giant aneurysms in three (2 %) patients. Wall calcification was noted in 24 % and intraluminal thrombosis in 33 % of ruptured giant aneurysms (n = 42). The majority of giant aneurysms are located in the ICA and MCA regions, while the ACA region is an exceptional site. The MCA region is the most common site for ruptured giant aneurysms. Associated anatomic variations and the multiplicity of giant aneurysms are a rare finding.

Objective Finnish saccular intracranial aneurysm (sIA) disease associates to 2q33, 8q11, and 9p21 loci and links to 19q13, Xp22, and kallikrein cluster in sIA families. Detailed phenotyping of familial and sporadic sIA disease is required for fine mapping of the Finnish sIA disease. Methods Eastern Finland, which is particularly isolated genetically, is served by Kuopio University Hospital's Department of Neurosurgery. We studied the site and size distribution of unruptured and ruptured sIAs in correlation to age and sex in 316 familial and 1454 sporadic sIA patients on first admission from 1993 to 2007. Results The familial and sporadic aneurysmic subarachnoid hemorrhage patients had slightly different median ages (46 vs 51 years in men; 50 vs 57 years in women), different proportion of males (50% vs 42%), equal median diameter of ruptured sIAs (7 mm vs 7 mm) with no correlation to age, and equally unruptured sIAs (30% vs 28%). The unruptured sIAs were most frequent at the middle cerebral artery (MCA) bifurcation (44% vs 39%) and the anterior communicating artery (12% vs 13%), in contrast to the ruptured sIAs at the anterior communicating artery (37% vs 29%) and MCA bifurcation (29% vs 29%). The size of unruptured sIAs increased by age in the sporadic group. Conclusion The MCA bifurcation was most prone to develop unruptured sIAs, suggesting that MCA branching during the embryonic period might be involved. The different site distribution of ruptured and unruptured sIAs suggests different etiologies for sIA formation and rupture. The lack of correlation of size and age at rupture (exposure to risk factors) suggests that the size at rupture is more dependent on hemodynamic stress.

Microneurosurgical excision is known to be the definitive treatment for brain arteriovenous malformation (AVMs). The most important factors governing the operability of an AVM are location, size, age of the patient, and the neurosurgeon's and team's experience. We present in this review the surgical experience of the senior author (JH) in microneurosurgical treatment of brain AVMs. This consists of the following steps: (1) accurate preoperative embolization; (2) optimal selection of the surgical approach; (3) accurate definition and preservation of the normal arterial vessels of passage; (4) temporary clipping of the feeding arteries; (5) a special method of coagulation called "dirty coagulation" of the deep small difficult vessels inside apparently normal brain around the AVM; (6) removal of all AVM; (7) meticulous hemostasis; (8) intra- and postoperative digital subtraction angiography (DSA); (9) clinical and radiological follow-up. These steps are not possible in AVMs lying entirely within central eloquent areas. Nine out of ten small- and medium-sized arteriovenous malformations (AVMs) are suitable for direct surgery, but surgical complications increase drastically with the size of the AVM. Nevertheless, the actual results of combined treatment with preoperative Onyx embolization followed by microsurgery have decreased these risks.

Distal anterior cerebral artery (DACA) aneurysms, also known as pericallosal artery aneurysms, represent about 6% of all intracranial aneurysms. They are located on the A2-A5 segments of the anterior cerebral artery and on its distal branches.This paper summarizes present knowledge on radiological features, treatment options, treatment results, and long-term follow-up of DACA aneurysms.Typical features of DACA aneurysms are small size, broad base, and branches originating from the base. When ruptured, they cause intracerebral hematoma in nearly half of the cases. DACA aneurysms are nowadays more often treated with microsurgical clipping than endovascular coiling due to their distal location and morphologic features. With clipping the results are same or slightly better than for aneurysms at other locations, coiling is often associated with more complications than in other aneurysms.Clipping is a long-lasting treatment with very small recurrence rate, there is no long-term data available on efficacy of coiling yet. For ruptured DACA aneurysms the most important factors affecting outcome is the severity of initial bleeding and patient's age.

Microneurosurgical techniques introduced by Prof. Yaşargil have been modified by the senior author (JH) when treating more than 4,000 patients with aneurysms at two of the Departments of Neurosurgery in Finland, Kuopio and Helsinki, with a total catchment area of close to three million people. This experience is reviewed, and the treatment of anterior circulation aneurysms by simple, fast, normal anatomy preserving strategy is presented.Most of the aneurysms of the anterior circulation are treated by using the lateral supraorbital approach, a less invasive, more frontally located modification of the pterional approach. To avoid extensive skull base surgery, a slack brain is needed and achieved by experienced neuroanesthesia and by surgical tricks for removal of CSF.Diagnosis of cerebral aneurysm before rupture improves treatment results more than any technical advances. Until this is realized, we continue to treat cerebral aneurysms by simple, fast, preserving normal anatomy-strategy, which has served our patients well.Patients with cerebral aneurysms should be treated at specialized neurovascular centers.

Objective The lateral supraorbital approach for safely and completely removing olfactory groove meningiomas was assessed. Methods Between September 1997 and June 2008, a total of 656 meningiomas were operated on by the senior author (JH) at the Department of Neurosurgery, Helsinki University Central Hospital; 66 were olfactory meningiomas. We retrospectively analyze the clinical data, radiological findings, surgical treatment, histology, and outcome of all the olfactory groove meningioma patients and discuss the operative techniques used. Results Sixty-six patients were operated on by the lateral supraorbital approach. The median preoperative Karnofsky Performance Scale score was 80 (range, 40-100). Three patients were redo cases in which the primary operation had been performed elsewhere. Seemingly complete tumor removal was achieved in 60 patients (91%); there was no surgical mortality. Postoperatively, 6 patients (9%) had cerebrospinal fluid leakage, 5 (8%) had new visual deficits, 4 (6%) had wound infections, 4 (6%) had cotton granulomas, and 1 (2%) had a postoperative hematoma. The median Karnofsky score at discharge was 80 (range, 40-100). Six patients had recurrent tumors; 3 underwent reoperations after an average of 21 months (range, 1-41 months); 1 was treated with radiosurgery, and 2 were only followed. During the median follow-up time of 45 months (range, 2-128 months), there were 4 recurrences (6%) diagnosed on average 32 months (range, 17-59 months) after surgery. Conclusion The lateral supraorbital approach can be used safely for olfactory groove meningiomas of all sizes with no mortality and relatively low morbidity. Surgical results and tumor recurrence with this fast and simple approach are similar to those obtained with more extensive, complex, and time-consuming approaches.

OBJECTIVE The prognosis of giant aneurysms remains poor despite recent advances in microneurosurgery. Thick-walled and partially calcified giant aneurysms with an atheromatic base are difficult to clip safely. Special techniques allowing reshaping of the base and ensuring the stability of clips are often needed. We present our experience with direct clipping of thick-walled giant aneurysms with the aid of the DeBakey cardiovascular clamp (Aesculap, Tuttlingen, Germany). METHODS Eighty-two patients with a giant aneurysm (>/=25 mm) were treated actively at the Department of Neurosurgery, Helsinki University Central Hospital, Helsinki, Finland, between 1997 and 2007. The vascular clamp technique was used in 8 of 50 patients in whom direct clipping was performed. The remaining patients were treated with bypass and trapping, trapping only, proximal occlusion, coiling, or explorative surgery. RESULTS The vascular clamp (DeBakey in 5 cases, Crile forceps [Medicon Medizin-Technik, Tuttlingen, Germany] in 2 cases, and Halsted-Mosquito forceps [Medicon Medizin-Technik, Tuttlingen, Germany] in 1 case) was used in 7 saccular middle cerebral artery aneurysms and 1 fusiform basilar bifurcation aneurysm. Two patients had postoperative infarctions, 1 attributable to occlusion of perforators by a clip and the other caused by clips sliding down the calcified base, occluding a major branch. Six patients had no neurological sequelae, 1 patient had transient upper limb paresis, and the patient with the occluded major branch died. CONCLUSION The DeBakey vascular clamp is helpful in assisting direct clipping of thick-walled giant aneurysms with a partially calcified atheromatic base. Some practical features of this instrument require further refinement.

Internal carotid artery bifurcation aneurysms form 2% to 9% of all IAs. They are more frequent in younger patients than other IAs. In this article, we review the practical microsurgical anatomy, the preoperative imaging, surgical planning, and the microneurosurgical steps in the dissection and the clipping of ICAbifAs.This review and the whole series on IAs are mainly based on the personal microneurosurgical experience of the senior author (JH) in 2 Finnish centers (Helsinki and Kuopio), which serve, without patient selection, the catchment area in Southern and Eastern Finland.These 2 centers have treated more than 11 000 patients with IAs since 1951. In the Kuopio Cerebral Aneurysm Database of 3005 patients with 4253 IAs, 831 (28%) patients had altogether 980 ICA aneurysms, of whom 137 patients had 149 (4%) ICAbifAs. Ruptured ICAbifAs, found in 78 (52%) patients, with median size of 8 mm (range, 2-60 mm), were associated with ICH in 15 (19%) patients. Ten (7%) ICAbifAs were giant (or = 25 mm). Multiple aneurysms were seen in 59 (43%) patients. The ICAbifAs represented 18% of all IAs ruptured before the age of 30 years.The main difficulty in microneurosurgical management of ICAbifAs is to preserve flow in all the perforators surrounding or adherent to the aneurysm dome. This necessitates perfect surgical strategy based on preoperative knowledge of 3D angioarchitecture and proper orientation during the microsurgical dissection.

Background Aneurysms originating distal to the A3 segment of the ACA, located on the A4 and the A5 segments or the distal cortical branches of the ACA (AdistAs) are rare, forming about 0.5% of all IAs. There are only few reports on management of AdistAs. In this article, we review the practical anatomy, preoperative planning, and avoidance of complications in the microsurgical dissection and clipping of AdistAs. Methods This review, and the whole series on IAs, is mainly based on the personal microneurosurgical experience of the senior author (J. H.) in 2 Finnish centers (Helsinki and Kuopio), which serve without patient selection the catchment area in Southern and Eastern Finland. Results These 2 centers have treated more than 10000 patients with IAs since 1951. In the Kuopio Cerebral Aneurysm Database of 3005 patients and 4253 IAs, there were 26 patients carrying 26 AdistAs, forming 0.9% of all patients with IAs, 0.6% of all IAs, and 2% of all ACA aneurysms. A total of 10 (38%) patients presented with ruptured AdistAs, with ICH in 4 (40%) and IVH in 2 (20%); 16 patients (62%) had multiple aneurysms. Conclusions AdistAs are small, even when ruptured, with relatively wide base, and they are frequently associated with ICHs. Our data suggest that AdistAs rupture at smaller size than IAs in general. The challenge is to locate the aneurysm inside the interhemispheric fissure and to clip the neck adequately without obstructing branching arteries at the base. Unruptured AdistAs also need microneurosurgical clipping even when they are small.

Background Aneurysms originating from the proximal segment of anterior cerebral artery (A1As) are rare, forming less than 1% of all IAs. There are only few reports on microneurosurgical management of A1As. In this article, the authors review the practical anatomy, preoperative planning, and avoidance of complications in the microsurgical dissection and clipping of A1As. Methods This review, and the whole series on IAs, is mainly based on the personal microneurosurgical experience of the senior author (JH) in 2 Finnish centers (Helsinki and Kuopio), which serve without patient selection the catchment area in Southern and Eastern Finland. Results These 2 centers have treated more than 10 000 patients with aneurysm since 1951. In the Kuopio Cerebral Aneurysm Database of 3005 patients with 4253 aneurysms, there were 23 patients carrying 23 A1As, forming 0.8% of all patients with aneurysm, 0.5% of all aneurysms, and 2% of all ACA aneurysms. Twelve (52%) patients presented with ruptured A1As with ICH in 3 (25%) and IVH in 2 (17%). Seventy percent of patients had at least 1 associated aneurysm. Conclusions Aneurysms arising from A1 are usually small, with a fragile wall. Our data suggest that A1As rupture at smaller size than IAs in general. Because of their small size and involvement of perforating arteries at their base, microneurosurgical clipping is the method of choice in treatment of ruptured A1As. Unruptured A1As also need microneurosurgical clipping even when they are small.

Objective The aim of this study was to assess the long-term excess mortality after the rupture of distal anterior cerebral artery (DACA) aneurysms compared with that of a matched general Finnish population in an unselected, population-based series. Methods We identified 280 consecutive patients (119 men, 161 women) treated for ruptured DACA aneurysms (clipped, 262; coiled, 10; no intervention, 8) at two neurosurgical centers serving solely the southern and eastern parts of Finland from 1976 to 2003. All patients were followed from subarachnoid hemorrhage until death or the end of 2004. No patients were lost to follow-up. Long-term excess mortality was estimated using the annual relative survival ratio compared with the general Finnish population matched by age, sex, and calendar time. Results The median follow-up period was 9.6 years (range, 0.1-29 yr). The 3-year cumulative relative survival ratio was 0.84 (95% confidence interval, 0.78-0.88), implying 16% excess mortality in the patient group during the first 3 years after subarachnoid hemorrhage. The annual relative survival ratio attained 1.0 at the fourth year of follow-up, indicating no excess mortality thereafter. There were four episodes of recurrent subarachnoid hemorrhage and only one from a treated DACA aneurysm, with a 10-year cumulative risk of 1.4% (95% confidence interval, 0.0-3.0). Cardiovascular disease and cancer were the leading causes of death after 10 years of follow-up. Conclusion After surviving 3 years after the rupture of a DACA aneurysm, the patients' long-term survival became similar to that of the matched general population. Rebleeding of treated DACA aneurysm was rare.

Background Of the MCA aneurysms, those located at the main bifurcation of the MCA (MbifA) are by far the most frequent. The purpose of this article is to review the practical anatomy, preoperative planning, and avoidance of complications in the microsurgical dissection and clipping of MbifAs. Methods This review, and the whole series on intracranial aneurysms, is mainly based on the personal microneurosurgical experience of the senior author (JH) in 2 Finnish centers (Helsinki and Kuopio), which serve without patient selection the catchment area in southern and eastern Finland. Results These 2 centers have treated more than 10 000 patients with intracranial aneurysm's since 1951. In the Kuopio Cerebral Aneurysm Data Base of 3005 patients with 4253 aneurysms, MbifAs formed 30% of all ruptured aneurysms, 36% of all unruptured aneurysms, 35% of all giant aneurysms, and 89% of all MCA aneurysms. Importantly, in 45%, rupture of MbifA caused an ICH. Conclusions Middle cerebral artery bifurcation aneurysms are often broad necked and may involve one or both branches of the bifurcation (M2s). The anatomical and hemodynamic features of MbifAs make them usually more favorable for microneurosurgical treatment. In population-based services, MbifAs are frequent targets of elective surgery (unruptured), acute surgery (ruptured), and emergency surgery (large ICH), even advanced approaches (giant). The challenge is to clip the neck adequately, without neck remnants, while preserving the bifurcational flow.

Microneurosurgical techniques introduced by Prof Yasargil in the 1960s have increased the neurosurgeon's ability to operate in small and often very narrow and deep gaps. Microneurosurgical techniques-ensuring an almost bloodless field and mostly obviating need for transfusion-should be atraumatic and noninvasive to the already lesioned central nervous system tissues and structures. Instruments in microneurosurgery range from very short to very long and from sturdy to delicate, depending on the working depth, characteristics of tissues, and the microneurosurgical anatomy. However, to keep it simple and fast, and to appreciate normal anatomy, it is preferable to use only a limited array of instruments. Besides the use of instruments and the operating microscope, everything else in the neurosurgical arena should be optimized and professional, such as the positioning of the patient and the conduct of neuroanesthesia. This review of the very basics is distilled from the Helsinki and Kuopio neurosurgery practices in Finland and from the senior author's (JH) experience of close to 10,000 operations, and this is to encourage young neurosurgeons of the world-most of them working with limited resources-to continue to improve their microneurosurgical skills to serve their patients best.

Activation of peripheral mixed and cutaneous nerves activates a distributed cortical network including the second somatosensory cortex (SII) in the parietal operculum. SII activation has not been previously reported in the stimulation of the dorsal penile nerve (DPN). We recorded somatosensory evoked fields (SEFs) to DPN stimulation from 7 healthy adults with a 122‐channel whole‐scalp neuromagnetometer. Electrical pulses were applied once every 0.5 or 1.5 sec to the left and right DPN. For comparison, left and right median and tibial nerves were stimulated alternatingly at 1.5‐sec intervals. DPN stimuli elicited weak, early responses in the vicinity of responses to tibial nerve stimulation in the primary somatosensory cortex. Strong later responses, peaking at 107–126 msec were evoked in the SII cortices of both hemispheres, with left‐hemisphere dominance. In addition to tactile processing, SII could also contribute to mediating emotional effects of DPN stimuli. Hum. Brain Mapping 18:90–99, 2003. © 2002 Wiley‐Liss, Inc.

During recent decades extra-intracranial and intra-intracranial bypasses have deserved high interest among neurosurgeon, especially in management of giant cerebral aneurysms. Development of microsurgery and neuroanesthesiological techniques, advances in neuroradiology and neurophysiology prerequisite improvement of revascularization surgery. Evolution of competitive endovascular methods pushes the surgeons to improve microneurosurgical technique of revascularization and elaboration of new approaches to management of intracranial aneurysms. In this review we discuss principles of surgery of cerebrovascular bypasses in management of giant aneurysms applied in our clinic.