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OBJECTIVE: To evaluate the usefulness of motor evoked potential (MEP) monitoring and mapping in arteriovenous malformation surgery. METHODS: Intraoperative MEP monitoring was performed in 21 patients whose AVMs were located near the motor area or fed by arteries related to the corticospinal tract to detect blood flow insufficiency and/or direct injury to the corticospinal tract and/or to map the motor area. RESULTS: In 4 of 16 patients monitored for blood flow insufficiency, the MEP changed intraoperatively. In 2 patients, the changes were attributable to temporary occlusion of the feeding artery (anterior choroidal or lenticulostriate artery): 1 patient had a venous infarction around the internal capsule caused by thrombosis of the draining vein and the other bled intraoperatively from the nidus. In 17 patients, the MEP was monitored to rule out direct injury. In 1 patient, the MEP changed on coagulation of fragile vessels around the nidus in the precentral gyrus; it recovered after coagulation was discontinued. In 1 of 5 patients with MEP changes, the MEP did not recover; permanent hemiparesis developed in this patient because of venous infarction. In 1 of 11 patients subjected to MEP mapping of the motor area, we found translocation to the postcentral sulcus. CONCLUSION: In arteriovenous malformation surgery, MEP monitoring facilitates the detection of blood flow insufficiency and/or direct injury of the corticospinal tract and mapping of the motor area. It contributes to reducing the incidence of postoperative motor paresis.

We assessed the usefulness of the separate demonstration of the arterial- and venous phase on 3D-CT angiography (3D-CTA) using a 64-multidetector row CT (MDCT) scanner for the surgery of brain tumors. Nineteen patients with meningiomas (n=11), schwannomas, metastatic brain tumors (n=2 each), glioblastoma multiforme, malignant lymphoma, craniopharyngioma, and embryonal carcinoma (n=1 each) underwent scanning on a 64-MDCT scanner. After dynamic CT scanning to determine the scan timing for the arterial- and venous-phase, we individually scanned the arterial- and venous phase for 4 sec after injecting a nonionic contrast medium. Using the CT threshold setting and subtraction and cutting techniques, we produced individual 3D-CT images of the arteries, veins, tumors, and bones. The operators subjectively assessed the usefulness of these images in comparison with 3D-CTA. We separately demonstrated the arterial- and venous phase on 3D-CTA covering the entire head in all 19 cases. The 3D-CT arteriographs, 3D-CT venographs, and the fused 3D-CT images facilitated our understanding of the 3D anatomic relationship among the tumor, arteries, veins, and bony structures. In 14 of 19 cases our method provided the surgically valuable findings; the information on the anatomical relation between tumor and the surrounding arteries and veins (in 13 cases) the identification of anatomical course of the encased vessels (in one), and feeding arteries and draining veins (in one), and discrimination between the venous sinus and tumor (in one). The anatomical information yielded by our technique makes safer surgery possible. If more detailed information which 3D-CTA cannot provide is required, our method should be performed.

Background Although AV shunts are known to exist in the normal dura mater, their histologic appearance has not been examined in detail. Arteriovenous shunts in the normal dura mater adjacent to the transverse sinus, the most frequent site of DAVFs, were studied histologically. Methods Normal dura mater adjacent to the transverse sinus was obtained from 8 cadavers. Each specimen was cut into approximately 4- μ m-thick serial sections; these were stained by the elastic Masson method and examined under a light microscope. Results Of the 8 specimens, 5 harbored a total of 6 AV shunts; no shunts were found in the other 3 specimens. The shunts, located in the supratentorial (n = 1) and infratentorial dura mater (n = 4) and in the tentorium cerebelli (n = 1), were classified into 2 types. In direct-type shunts, the artery connected directly to the vein; the diameter of these shunts ranged from 40 to 80 μ m. In indirect-type shunts, the artery and vein were parallel and were indirectly connected by a shunt vessel, producing an H shape. The diameter of these shunt vessels ranged from 30 to 45 μ m. All 6 shunts were connected to veins or the venous lake; none connected directly to the transverse sinus. Conclusions The existence of direct- and indirect-type AV shunts in the normal dura mater was confirmed histologically. Both types exhibited the histologic features of DAVFs, suggesting that AV shunts in the normal dura mater might be involved in the etiology of DAVFs.

Objective Intraoperative monitoring of the motor-evoked potential has been widely used in patients undergoing neurosurgery. Direct stimulation of the brain with high-frequency monopolar stimulation (HFMS) is one of the most common methods to produce motor-evoked potential. We studied the influence of HFMS on the rat cerebral cortex. Methods We applied 1.5, 15, 30, 40, or 50 mA of HFMS to the rat sensorimotor cortex by a short sequence of five monopolar, monophasic, anodal rectangular 500-Hz pulses. We delivered one short five-pulse train 100 times every 5 seconds and examined pre- and post-stimulation electroencephalograms and histological changes at the stimulation site. Results We observed no spike waves after HFMS in any of the rats. There was no change in the power spectrum or frequency content in any of the rats exposed to HFMS. Histologically, there was significant swelling of the dendrites in rats sacrificed immediately after exposure to 40- and 50-mA stimulation; the 50-mA stimulation group also exhibited slight swelling of the mitochondria. These findings were not obtained in any of the rats sacrificed 30 days after stimulation. Conclusion In rats exposed to a stimulation intensity of 30-mA or less, no morphological or electrophysiological changes were observed. However, the possibility that HFMS may affect neural tissue cannot be ruled out.

In this communication, we studied whether 3D-CT angiography (3D­ CT A) gives us enough information for a safe operation without those from conven­ tional catheter angiography (CCA) in patients with ruptured aneurysms. Between December 1996 and September 2005, we treated 162 consecutive patients with ruptured aneurysms in the acute stage based on 3D-CT A findings. One hundred sixty-two ruptured aneurysms, including 64 associated unruptured aneurysms, were detected using 3D-CT A. CCA was performed in nine (5.6%) of the 162 patients after 3D-CT A. They were four dissecting vertebral artery aneurysms, two basilar tip aneurysms, one basilar artery-superior cerebellar artery (BA -SCA), one previously clipped BA-SCA and one internal carotid-posterior communicating artery aneurysm. All ruptured aneurysms confirmed at surgery were treated suc­ cessfully. The lack of information on CCA did not lead any neurological deficits or difficulties in the surgical procedure. 3D-CT A was of high diagnostic value compatible with CCA and yielded impor­ tant information such as the configuration of the aneurysmal sac and neck, calcification in the aneurysmal wall, and the aneurysms' anatomic relation with adjacent vessels and bone structures. We suggest that 3D-CTA can replace CCA in the diagnosis of ruptured aneurysms and that most of ruptured aneurysms can be operated by using only 3D-CT A without CCA.

Object. The usefulness of motor evoked potential (MEP) monitoring to detect blood flow insufficiency (BFI) in the cortical branches of the middle cerebral artery (MCA) and lenticulostriate arteries (LSAs) during MCA aneurysm surgery was investigated based on the correlation between MEP and somatosensory evoked potential (SEP) monitoring. Methods. Fifty-three patients with MCA aneurysms underwent surgery accompanied by intraoperative MEP and SEP monitoring. There was no postoperative motor paresis in 43 patients in whom MEP and SEP results remained unchanged. In the other 10 patients, nine manifested transient MEP changes; in five of these, SEP changes did not occur. The transient MEP changes were thought to be attributable to BFI of the MCA cortical branches in two patients, the LSA in three, and either the MCA branches or the LSA in four patients. Of these nine patients, six did not present with postoperative motor paresis; transient motor paresis was recognized in the other three. In the 10th patient, MEP waves disappeared and did not recover. This patient's SEPs remained at 70% of the control level, and he developed severe hemiparesis. A postoperative computerized tomography scan revealed a new low-density area in the corona radiata and putamen. Conclusions. Blood flow insufficiency in both the LSA and MCA cortical branches that perfuse the corticospinal tract can be detected by intraoperative MEP monitoring. Somatosensory evoked potential monitoring is not reliable enough to detect BFI in the MCA branches and the LSAs.

BACKGROUND The optimal management of poor-grade patients with aneurysmal subarachnoid hemorrhage (SAH) remains controversial. We evaluated therapeutic outcomes to identify appropriate treatments for SAH patients admitted with a poor grade. METHODS We retrospectively studied 136 patients admitted within 6 hours after SAH onset with a poor Hunt & Kosnik Grade (IV and V). RESULTS Of 136 poor-grade patients, 20 with massive intracerebral or subdural hematoma underwent urgent hematoma evacuation and aneurysmal neck clipping. Seven of these achieved a favorable outcome (good recovery or moderate disability). Another 7 patients with prominent hydrocephalus or massive intraventricular hematoma underwent urgent continuous ventricular drainage. Of these, 4 manifested spontaneous grade improvement and underwent neck clipping; the other 3 died resulting from rebleeding. The remaining 109 patients whose poor grade was primarily because of SAH were observed without immediate surgery. In 43 patients of 109, the grade improved within 24 hours after hospitalization and within 38 hours in the other 4 patients. Aneurysmal neck clipping was performed in these 47 patients and a favorable outcome was achieved in 25 patients. The remaining 62 patients did not improve and the outcome was unfavorable. CONCLUSIONS Poor-grade SAH patients should be treated according to the pathogenesis underlying their poor grade. Close monitoring for a grade change over the first 24 hours after hospitalization is mandatory in patients whose poor grade is primarily because of the SAH and helps to determine the appropriateness of surgery.

Object. The lack of a specified intraoperative method for monitoring anterior choroidal artery (AChA) blood flow insufficiency (BFI) led the authors to devise a method for checking the BFI in this artery during aneurysm surgery. To this end, the authors relied on the intraoperative motor evoked potentials (MEPs) elicited by electrical stimulation of the hand motor cortex. Methods. The study population consisted of 108 patients with internal carotid artery (ICA) aneurysms who underwent surgery via a standard frontotemporal craniotomy. After the dura mater had been opened, a grid electrode strip with 16 small electrodes was inserted subdurally into the hand motor cortex from the edge of the craniotomy. To check BFI in the AChA, the hand motor cortex was stimulated at an intensity level between 10 and 18 mA. The MEPs were successfully recorded from the contralateral thenar muscles in all 108 patients. There was no postoperative motor paresis in 88 patients in whom the MEPs remained unchanged during the performance of various surgical maneuvers. Among the other 20 patients, 19 manifested transient MEP changes, but 15 of those patients experienced no postoperative motor paresis. In four patients who exhibited transient MEP changes, either after aneurysm clipping or during temporary occlusion of the ICA and/or AChA, hemiparesis occurred postoperatively but disappeared within 24 hours. In one patient with an ICA—posterior communicating artery aneurysm, the MEP disappeared and did not reappear by the time of dural closure. Severe hemiplegia developed in this patient and a computerized tomography scan obtained postoperatively revealed a new low-density area in the internal capsule. Conclusions. The findings of this study suggest that the monitoring method that is introduced here is safe and reliable for detecting intraoperative BFI in the AChA.

The object of this study is to assess whether aneurysm surgery can be performed in patients with ruptured cerebral aneurysms by using three-dimensional computerized tomography angiography (3D-CTA) alone, without conventional catheter angiography (CCA). Between May 1994 and November 1996, a consecutive series of 60 cases of ruptured cerebral aneurysms was evaluated by both 3D-CTA and CCA prospectively and compared the detectability of cerebral aneurysms. Both 3D-CTA and CCA demonstrated a 100% diagnostic accuracy of ruptured cerebral aneurysms. In the associated unruptured cerebral aneurysms, the diagnostic accuracies of 3D-CTA and CCA were 96% and 92%, respectively. Based on the results, we have operated on 128 consecutive patients with ruptured aneurysms in the acute stage based on 3D-CTA findings since December 1996. One hundred twenty eight ruptured aneurysms including 50 associated unruptured aneurysms were detected by 3D-CTA. In seven of 128 ruptured aneurysms, which included four dissecting vertebral artery aneurysms, two basilar artery (BA) tip aneurysms, and one BA-superior cerebellar artery (SCA) aneurysm, 3D-CTA was followed by CCA to obtain diagnostic confirmation or information concerning the vein of Labbé, which was needed to guide the surgical approach for BA tip aneurysms. All of the ruptured aneurysms were confirmed at surgery and treated successfully. One hundred twenty one patients who underwent surgery with 3D-CTA findings only had no complications related to the lack of information of CCA. The authors considered that 3D-CTA could replace CCA in the diagnosis of ruptured aneurysms and that surgery could be performed in almost all acutely ruptured aneurysms by using only 3D-CTA without CCA.

We devised a technique to fix the temporalis muscle to the transplanted hydroxyapatite implant by using a titanium plate, which is fixed to the hydroxyapatite ceramic implant by screws and achieves good clinical results. The size, shape, and curvature of the hydroxyapatite ceramic implants were determined according to full-scale models fabricated using the laser lithographic modeling method from computed tomography data. A titanium plate was then fixed with screws on the implant before implantation, and then the temporalis muscle was refixed to the holes at both ends of the plate. The application of this technique reduced the hospitalization time and achieved good results esthetically.

Hydroxyapatite ceramic implants were used in the reconstruction of very large and complex-form cranial bone defects in nine patients. The bone defects were the result of craniectomy after infections and other complications such as severe brain edema, after neurosurgery, and as a result of trauma, subdural hemorrhage, and surgery for brain tumor. The size, shape, and curvature of the hydroxyapatite ceramic implants were determined based on high-precision, full-scale models fabricated through a laser lithographic molding method by using computed tomographic data. The use of this method allowed the fabrication of hydroxyapatite ceramic implants of shapes that accurately matched the area of bone defect, allowing for a minimum of adjustment during the operation even with a complex-form implantation. Not only were good cranial contour reconstructed and aesthetically satisfactory results obtained in the cases treated by incorporating this series of techniques, but neurologic conditions present in some cases were also improved to some extent. The postoperative course has been steady for all nine patients, with no blood transfusions required during or after the operations and no implants requiring removal because of infection or other postoperative complications. The average length of postoperative hospitalization for the nine cases was 11.7 days, remarkably short considering the clinical conditions.

Using a temporoparietal fascial flap and hydroxyapatite ceramics, we treated a patient for complications after a neurosurgical operation for glossopharyngeal neuralgia. These consisted of pneumocephalus and cerebrospinal fluid rhinorrhea resulting from fistulas of mastoid air cells associated with a subcutaneous dead space. By means of the temporoparietal fascial flap, we were able to fill the dead space and reinforce the repaired dural and mastoid lesion as well. Hydroxyapatite ceramics were also useful for closing the mastoid air cell fistulas.

A rare case of ruptured carotid-ophthalmic aneurysm splitting the optic nerve was reported. A 52-year-old man presented with a sudden severe headache and bilateral visual deterioration. His right visual acuity was hand motion and the left was 2.0. His left visual field revealed a partial defect of the temporal visual field. Three-dimensional CT angiography revealed an ophthalmic aneurysm of 9 mm projecting superior-medially, The operation was performed to preserve the visual function as much as possible. The C2 portion aneurysm splitting the right optic nerve was visible. Before aneurysm clipping, the right anterior clinoid process and optic canal were drilled out to reduce the tension of the optic nerve. Intraoperative monitoring of visual evoked potential (VEP) under propofol anesthesia was performed to prevent further visual disturbance. Electroretinogram (ERG) was introduced to ascertain the arrival of the light stimulus at the retina even when the VEP could not be recorded. The right ERG was recorded, but the right VEP was flat. Both ERG and VEP were reproducible on the left side. Six months after the operation, the right visual acuity had improved to 0.08 and the visual field revealed nasal hemianopsia. The left visual acuity was unchanged while the visual field had improved to upper temporal quadrant hemianopsia. Various attempts to preserve the visual function were discussed.

Background In the current study, as a first step to develop a monitoring method of cerebellar functions, we tried to record evoked potentials on the cerebellar cortex by electrical stimulation of the rat SCT, which is located in the Inf-CPed. Methods The experimental study was performed on rats. Unilateral muscular contractions of quadriceps femoris muscle were elicited by electrical stimulation. The evoked potentials were recorded from the surface of the ipsilateral cerebellum and the contralateral primary sensory cortex. Results The highly reproducible potentials obtained from the ipsilateral cerebellar hemisphere were named SCEP. The SCEP exhibited one negative peak with a latency of 11.7 ± 0.3 milliseconds (N 11 ). Short-latency somatosensory evoked potential was recorded from the contralateral primary sensory cortex with a latency of 19.1 ± 0.6 milliseconds. Coagulation of the ipsilateral Inf-CPed caused disappearance or marked reduction of the SCEP N 11 , but it did not change the SSEP. On the other hand, sectioning of the ipsilateral dorsal column resulted in the disappearance of the SSEP, but it did not affect the SCEP N 11 . Conclusions Reproducible SCEP was recorded from the rat cerebellar hemisphere by electrical stimulation of the quadriceps femoris muscle. We posit that the SCEP differs from the SSEP, which ascends via the dorsal column, and that it is conducted by the dorsal SCT located in the Inf-CPed. Our results suggest that it may be possible to detect the dysfunction of the Inf-CPed electrophysiologically by using SCEP.

Oxyhemoglobin (Oxy-Hb) produced a concentration-dependent contraction of monkey, dog, and bovine cerebral artery strips. Treatment of Oxy-Hb with ascorbic acid suppressed the ability of Oxy-Hb to contract the arteries, especially in the monkey arteries. The ability of intracisternally applied Oxy-Hb to constrict the basilar artery in anesthetized dogs was diminished when Oxy-Hb was treated previously with ascorbic acid (AsA-Hb). The contraction caused by Oxy-Hb was suppressed by treatment with indomethacin and aspirin in isolated bovine cerebral arteries. Endothelium-dependent relaxations elicited by substance P and relaxations induced by stimulation of the vasodilator nerves with nicotine were suppressed by treatment with Oxy-Hb and AsA-Hb; however, the inhibitory effect of AsA-Hb was markedly less. Oxy-Hb attenuated nitroglycerin-induced relaxations in a dose-dependent fashion, whereas AsA-Hb in concentrations up to 1.6 x 10-5 M did not significantly influence the relaxations. It is concluded that incubation of Oxy-Hb with ascorbic acid alters markedly the biological activity of Oxy-Hb; the vasoconstrictor activity is suppressed, and the ability to diminish vasodilator actions is minimized. These findings provide a rationale for the use of ascorbic acid in cisternal irrigation to prevent the development of cerebral vasospasm after a subarachnoid hemorrhage.

An 8-year-old boy presented with a rare cerebral medulloepithelioma manifesting as headache, nausea, and vomiting. Neuroimaging demonstrated a mass containing a cyst in the left frontal lobe. Gross total resection of the tumor with a 1-cm margin was performed under intraoperative monitoring. The histological diagnosis was medulloepithelioma. Stereotactic radiotherapy (total dose 20 Gy) was given to the brain up to 1 cm from the surgical margin. Follow-up neuroimaging 5 years later showed no signs of recurrence. He now attends junior high school, with normal mental and physiological development. Medulloepitheliomas are rare, highly malignant embryonal tumors of the central nervous system. Combined gross total tumor resection and radiotherapy are recommended to obtain the most favorable outcome.

Object The object of this study was to investigate patients with cerebral infarction in the area of the perforating arteries after aneurysm surgery. Methods The authors studied the incidence of cerebral infarction in 1043 patients using computed tomography or magnetic resonance imaging and the affected perforating arteries, clinical symptoms, prognosis, and operative maneuvers resulting in blood flow disturbance. Results Among 46 patients (4.4%) with infarction, the affected perforating arteries were the anterior choroidal artery (AChA) in nine patients, lenticulostriate artery (LSA) in nine patients, hypothalamic artery in two patients, posterior thalamoperforating artery in five patients, perforating artery of the vertebral artery (VA) in three patients, anterior thalamoperforating artery in nine patients, and recurrent artery of Heubner in nine patients. Sequelae persisted in 21 (45.7%) of the 46 patients; 13 (28.3%) had transient symptoms and 12 (26.1%) were asymptomatic. Sequelae developed in all patients with infarctions in perforating arteries in the area of the AChA, hypothalamic artery, or perforating artery of the VA; in four of five patients with posterior thalamoperforating artery involvement; and in two of nine with LSA involvement. The symptoms of anterior thalamoperforating artery infarction or recurrent artery of Heubner infarction were mild and/or transient. The operative maneuvers leading to blood flow disturbance in perforating arteries were aneurysmal neck clipping in 21 patients, temporary occlusion of the parent artery in nine patients, direct injury in seven patients, retraction in five patients, and trapping of the parent artery in four patients. Conclusions The patency of the perforating artery cannot be determined by intraoperative microscopic inspection. Intraoperative motor evoked potential monitoring contributed to the detection of blood flow disturbance in the territory of the AChA and LSA.

Object Rebleeding from ruptured intracranial aneurysms is a major cause of death and disability. With regard to the factors that precipitate the rebleeding and influence the time course after initial bleeding, previous reports differ in their results, and the number of patients investigated was not sufficient for valid conclusions. This study was thus designed to clarify the factors related to rebleeding from ruptured intracranial aneurysms in a large group of patients of the North Eastern Province of Japan. Methods We found 181 patients with rebleeding after hospitalization among 5612 cases of ruptured intracranial aneurysms from January 1997 to December 2001 in 33 major hospitals in the North Eastern Province of Japan. We analyzed the data with respect to the time course after bleeding and rebleeding, the arterial blood pressure, the situation when rebleeding occurred, the methods of neuroimaging, the level of consciousness, the treatment and the outcome. Results Of 181 patients who were hospitalized, rebleeding occurred in 65 (35.9%) within 3 h and 88 (48.6%) within 6 h after the initial subarachnoid hemorrhage (SAH). The consciousness level before the rebleeding varied widely in distribution, but belonged to the drowsiness or less [Japan coma scale (JCS) single-digit] in 83 patients (45.8%), but after rebleeding, JCS triple-digits (semicoma to coma) included 152 patients (84.0%). Systolic arterial blood pressure prior to rebleeding was most commonly between 120 and 140 mmHg. Rebleeding did occur more frequently during angiography (totally 29 patients, 20%) and much less frequently during 3D-CTA and MRA procedures (a single case). Treatment consisted of aneurysm neck clipping in 72 patients (40.0%), endovascular therapy with coils in 4 patients (2.2%) and conservative ones in 103 patients (56.9%). As to outcome, 109 patients with rebleeding (60.2%) died in 3 months following initial SAH. Conclusion Rebleeding occurs more frequently in the earlier period after the initial SAH than previously believed. Thus, more aggressive pharmacologically induced systemic arterial hypotension appears to be important for preventing rebleeding but ultimate outcome of more aggressive hypotension is yet to be determined. If feasible, in order to avoid catheter-angiography related rebleeding, evaluations solely with 3D-CTA and MRA should be in consideration and earlier surgical intervention seems essential as rebleeding does occur often within the first 3 h of onset.

Our success rate of intraoperative monitoring of visual evoked potential (VEP) had been approximately 30% in the past. In order to improve recording rate of intraoperative VEP, we developed a new stimulating device using high power light emitting diodes. Electroretinogram was simultaneously recorded to understand whether flash stimulation reached the retina. In addition, total venous anesthesia with propofol was used to avoid the adverse effect of inhalation anesthesia. We report the results after introduction of these improvements. Intraoperative monitoring of VEP was attempted in 35 cases. We evaluated success rate of VEP recording, correlation between VEP findings and postoperative visual function, and reasons why recording was not successful. Stable and reproducible waveforms were obtained in 59 sides (84%). Two cases, whose VEP deteriorated intraoperatively, developed postoperative visual disturbance: In 11 sides (16%), stable waveforms were not obtained. There were two main causes. In 8 sides out of 11, the cause was attributed to pre-existing severe visual disturbance. In these 8 sides, VEP in the awake state was not recordable or was recordable, but with very low amplitudes under 1 microV. In the other 3 sides, the cause was attributed to movement of a stimulating device by reflecting the fronto-temporal scalp flap. In conclusion, the successful recording rate was increased to 84% from approximately 30%, after introduction of various trials. We need further improvement in recording intraoperative VEP to establish a reliable intraoperative monitoring method for VEP.

Histological evaluation of dissecting aneurysms of the cerebral arteries has suggested that defects in the internal elastic lamina (IEL) induce dissection of the arterial wall. Dissecting aneurysms occur most frequently in the vertebral artery (VA). The present study examined sections of the normal VA to elucidate the mechanisms of arterial dissection. Bilateral VAs (20 vessels) were obtained from 10 patients who died of causes other than intracranial lesions. The VAs were detached from the VA union to the site 10 mm proximal from the point penetrating the dura mater. The VAs were cut at 5-mm intervals, and each segment was observed using modified Masson's trichrome staining for elastic fibers. The thickness of the media and adventitia significantly thinned after the origin of the posterior inferior cerebellar artery (PICA). IEL defects were observed at 35 sites in 11 vessels from six subjects. There was a high incidence of IEL defects in the extradural portion and near the origin of the PICA, areas frequently involved in arterial dissection. There was a high incidence of intimal thinning at areas of IEL defects (19 of 35), and thinning was particularly marked distal to the origin of the PICA. In the absence of intimal thickening, the vascular strength at the site of IEL defects may be reduced, which would promote the occurrence and progression of arterial dissection.

✓ Four years after undergoing a superficial temporal artery—middle cerebral artery bypass procedure, this patient presented with a ruptured aneurysm at the anastomosis site. The ruptured aneurysm caused subarachnoid and intracerebral hemorrhages and was treated by surgically clipping its neck. Characteristics of the aneurysm included: 1) a relatively large size (8 × 6 × 6 mm); 2) a thickened wall; 3) a location apart from the suture line; 4) a projection in a direction consistent with hemodynamic stress; and 5) a time interval from bypass surgery to rupture that lasted 4 years. These features, along with the well-known fact that hemodynamic stress can cause aneurysms, led the authors to believe that this aneurysm was a true one. The authors present a case of this unusual complication following bypass surgery and provide a brief review of the literature.

A 52-year-old man suddenly experienced headache and vomiting. Computed tomography demonstrated a small area of hemorrhage in the right cerebellar hemisphere. Angiography revealed a thalamic arteriovenous malformation (AVM) fed by the bilateral medial posterior choroidal arteries and left marginal tentorial artery, and drained into the confluence via the cerebellar veins without flow into the supratentorial venous system. The draining veins included two varices, one of which, in the right cerebellar hemisphere, was thought to be the source of bleeding. The AVM nidus was removed via the right occipital transtentorial approach. A portion of a drainer adhered to the surface of the great vein of Galen but without opening into the galenic system and all drainers from this thalamic AVM flowed into the infratentorial cerebellar venous system.

A 54-year-old man with a past history of gastric malignant lymphoma treated by the total gastrectomy and the chemotherapy, developed bilateral sudden deafness one year later. Two years after the gastrectomy he became abruptly paraplegic with sensory impairments of the lower extremities and neurogenic bladder. Serum LDH and soluble IL-2 receptor were high in titers (552 U/l and 1,090 U/l, normal range 145-519). Although the imaging studies of the spinal cord were negative, the myelopathic symptoms resolved dramatically after a course of pulse dose methylprednisolone therapy. However, he soon developed an abnormal behavior and mental deterioration in 3 weeks. The MRIs of the brain revealed abnormal signals compatible with multiple cerebral infarctions. As intravascular malignant lymphomatosis (IML) was suspected because of the laboratory and MRI findings, biopsies of the skin, the bone marrow, the muscle and the lymph node were carried out, without evidence of lymphoma. The brain biopsy ultimately confirmed the presence of IML. The patient remarkably responded to biweekly CHOP (cyclophosphamide, doxorubicin, vincristine, prednisolone) therapy in terms of regaining the mental alertness and improved hearing. However, the CHOP therapy was prematurely interrupted prior to completion because of infective arthritis. The relapse soon ensued, and he died 6 months after admission. This case was of interest because a solid gastric lymphoma appears to have transformed into the form of intravascular lymphomatosis without mass formations or leukemic changes. Although the neurological symptoms in association with IML are thought to be the results of ischemic events, this case illustrates a remarkable reversibility of the symptoms. This implies that the cerebral symptoms are not necessarily the results of typical ischemic infarction, but due to relative ischemia because of chiefly capillary-venous occlusion by lymphoma cells. The majority of the symptoms is thus attributable to the functional impairment. Therefore, the therapeutic intervention may dramatically improve the symptoms due to IML.

Objective The perinidal vascular structures of cerebral arteriovenous malformations were examined, to clarify their pathomorphological features. Methods Twenty-two resected specimens of human brain structures adjacent to the nidus were examined. The vessels surrounding the nidus were three-dimensionally reconstructed with a computer graphics system. Results In all cases, the analysis of serial sections revealed that perinidal dilated capillaries were located in brain tissue 1 to 7 mm from the nidal border. The vessels surrounding the nidus demonstrated markedly dilated capillary networks (perinidal dilated capillary network [PDCN]). The diameters of the vessels forming the PDCN were 10 to 25 times those of normal capillaries. The PDCN connected not only to the nidus, feeding arteries, and draining veins, via arterioles and venules, but also to the normal capillary network, arterioles, and venules. Conclusion Without exception, each nidus was accompanied by a PDCN, which connected not only to the nidus, feeding arteries, and draining veins, via arterioles and venules, but also to normal capillaries, arterioles, and venules. The PDCN should be considered in studies aimed at gaining an understanding of the mechanisms underlying the intraoperative and postoperative bleeding, growth, and recurrence of surgically treated cerebral arteriovenous malformations.

A 42-year-old man was admitted due to recurrent bacterial meningitis, as he had been treated here for bacterial meningitis three years prior to the current event. He had a remote history of head injury that he had almost forgotten, and his laboratory data showed no immunodeficiency state. 111In-DTPA cisternography showed an abnormal radioactive accumulation in the frontal lobe adjacent to the left frontal sinus at 23 hours after intrathecal injection, and MPR CT images revealed the left frontal sinus bone fracture. These findings indicated that he had a head injury by which a delayed CSF fistula has been formed. He was surgically treated for a CSF leakage. Although a combination therapy of ABPC and CTRX was efficacious for this patient, this regimen may not be ideal, as meningitis by PRSP has been increasing in incidence. Pneumococcal meningitis, once not a difficult infection to treat, could be a difficult one, as resistant strains to ABPC and CTRX have been more common.

Object. The aim of this study was to assess whether aneurysm surgery can be performed in patients with ruptured cerebral aneurysms by using three-dimensional computerized tomography (3D-CT) angiography alone, without conventional catheter angiography. Methods. In a previous study, 60 patients with subarachnoid hemorrhage (SAH) from ruptured aneurysms were prospectively evaluated using both 3D-CT and conventional angiography, which resulted in a 100% accuracy for 3D-CT angiography in the diagnosis of ruptured aneurysms, and a 96% accuracy in the identification of associated unruptured aneurysms. The results led the authors to consider replacing conventional angiography with 3D-CT angiography for use in diagnosing ruptured aneurysms, and to perform surgery aided by 3D-CT angiography alone without conventional angiography. Based on the results, 100 consecutive patients with SAH who had undergone surgery in the acute stage based on 3D-CT angiography findings have been studied since December 1996. One hundred ruptured aneurysms, including 41 associated unruptured lesions, were detected using 3D-CT angiography. In seven of 100 ruptured aneurysms, which included four dissecting vertebral artery aneurysms, two basilar artery (BA) tip aneurysms, and one BA—superior cerebellar artery aneurysm, 3D-CT angiography was followed by conventional angiography to acquire diagnostic confirmation or information about the vein of Labbé, which was needed to guide the surgical approach for BA tip aneurysms. All of the ruptured aneurysms were confirmed at surgery and treated successfully. Ninety-three patients who underwent operation with the aid of 3D-CT angiography only had no complications related to the lack of information gathered by conventional angiography. The 3D-CT angiography studies provided the authors with the aneurysm location as well as surgically important information on the configuration of its sac and neck, the presence of calcification in the aneurysm wall, and its relationship to the adjacent vessels and bone structures. Conclusions The authors believe that 3D-CT angiography can replace conventional angiography in the diagnosis of ruptured aneurysms and that surgery can be performed in almost all acutely ruptured aneurysms by using only 3D-CT angiography without conventional angiography.

We performed cranioplasty using hydroxyapatite ceramics and periosteal flaps in three patients with extensive cranial bone defects. These defects were left after post-brain surgery infection forced the removal of cranial bone. Hydroxyapatite ceramics made by using computer-aided design from three-dimensional computed tomographic image data were implanted in these patients. The defects were relatively large (the largest was 16.5 x 7.5 cm) and had a high degree of curvature. Three pieces were required in one patient, although one piece was sufficient in the other two patients. The surgical technique consisted of removal of the epidural granulation tissue, exposure of the cranial bone defect site, and shaping of the hydroxyapatite ceramics to fit the defect entirely, followed by the implantation of the hydroxyapatite ceramics. In anticipation of induction of the bone to hydroxyapatite, we covered the hydroxyapatite ceramics with periosteal flaps of cranial bones; however, based on only these three patients, our knowledge of the ossification-promoting effect is incomplete. More clinical cases should be investigated to evaluate further the clinical efficacy of this method for treatment. As we have reported here, the treatment of cranial bone defects by using computer-designed hydroxyapatite ceramics and a periosteal flap is safe and highly effective.

A 49-year-old man who had been suffering from disturbance of hearing for 5 years suddenly developed severe headache, nausea, and vomiting. Computed tomography (CT) scans both with and without contrast medium enhancement, performed on the day of admission, showed a nearly round high-density area in the left cerebellopontine angle. A left transaxillary vertebral angiogram showed no aneurysm or arteriovenous malformation. Hemorrhage from a tumor in the left cerebellopontine angle was suspected. CT scan without contrast medium enhancement, performed on the 17th day after onset, showed only a small, ill-defined high-density area in the cerebellopontine angle. An operation was performed on the 20th day after onset. The tumor was totally extirpated together with a clot. Histologically the tumor was an acoustic neurinoma with hemorrhage and necrosis. The postoperative course was favorable. Massive hemorrhage from primary intracranial tumors, especially acoustic neurinomas, is discussed. Radical operation on the tumor should be performed as soon as possible.

Ten patients were treated with systemic administration of mannitol followed by blood substitute (perfluorochemicals) in the acute period of cerebral infarction in order to suppress the development of infarction and progressive deterioration. This chemotherapy was followed by reconstructive vascular surgery. There were 8 patients with cerebral infarction and 2 others in whom cerebral vascular occlusion occurred during an operation. Due to this treatment, there was no case in which the patient's condition was aggravated or in which death occurred. At examination two months later, 8 of the 10 patients had returned to productive lives. We consequently believe that this therapeutic method may prove to be an effective means of treating cerebral infarction in the acute stage. It is also thought that this method is applicable in surgical cases in which long-term vascular occlusion is required.

In Cerebrovascular “Moyamoya” Disease, children and adults show different aspects of abnormal net-like vessels (called “Moyamoya”) at the base of the brain. The reason for the difference has not been clarified as yet. In order to explain the reason, this study was undertaken to investigate possibilities and morphology of the anastomosis among the perforating branches as well as the influence of their aging by means of micro-angiography and/or graphical reconstruction of serial sections. 1) Three groups of fetuses, children and adults were subjected to the study of the aging of Aa. corporis striati mediae. The number, courses, and shapes of vessels, that is, such items as diverting angle at the middle cerebral artery, smoothness or irregular changing of their courses or directions as well as diameters are carefully observed by microangiography. Changes with aging were found remarkable among all of these items. It must be noted that the younger had the more arteries, suggesting easiness of collateral formation. 2) The existence of anastomosis among the perforating branches with one another, between these vessels and Aa. medullaris were clearly verified by graphical reconstruction of serial sections. It was also observed that the pattern of the anastomosis and the caliber of each anastomosis varied with aging. This observation may well indicate that the “Moyamoya” vessels appeares as collateral pathways based on the perforating branches and also that “Moyamoya” vessels are easily formed in the younger than in the older.

✓ Five cases of moyamoya disease associated with aneurysm are reported. In three cases, the aneurysms were located at the peripheral portion of the posterior choroidal artery, and in two at the basilar artery. Based on these cases, the symptoms and mechanisms of formation of aneurysms in moyamoya disease are discussed.

The 1, 080 cases of intracranial saccular aneurysms, which were seen at our clinic during the period from June 1961 to September 1975, were subjected to the analysis on the location of the aneurysms, age distribution and sex incidence.

Two cases of homonymous hemianopsia caused by chiasmal compression due to intracranial aneurysm are presented. Both cases are aneurysms of the internal carotid artery and these aneurysms developed to the median direction. Visual field defects in both cases were incongruous homonymous hemianopsia without macular sparing. It should be noted that when homonymous hemianopsia is present without any signs of an intracranial mass, the existence of a nonruptured aneurysm should be highly considered.

5 cases of brain tumor in newborn babies under 2 months are presented. 4 of them were supratentorial teratoma and originated from the midline, and 1 was a glioma at the cerebellopontine angle. 2 cases died before surgery and 2 cases after surgery. In our 5th case a benign teratoma of 150 g was removed from the third ventricle. He was discharged and enjoyed rather good health for 2 years and 1 month before dying of recurrence of tumor. Internal hydrocephalus associated with the huge tumor was responsible for the sudden deterioration of general condition. Therefore, shunting procedures should be performed as the first aid. However, in our experiences, the conditions at admission were too critical and/or too late to be beneficial. Thus, early diagnosis is absolutely necessary for surgical treatment. A summary and discussion of the data of 103 previously reported cases are included.

The authors report the effects of radiation therapy for glioma in 61 children. Subsequent to irradiation the patients received long-term follow-up, which included computed tomographic (CT) scanning. Brain atrophy (BA) was considered to have occurred if one focus of cortical or brainstem atrophy, and/or ventricular dilatation, was identified on follow-up CT but had not been present on CT scans obtained immediately after the completion of radiation therapy. In 20 cases BA could not be evaluated. Thus, BA was found in 10 of the 41 cases (24.4%) at 33 months after radiation therapy. The mean whole brain irradiation doses in the BA (+) and BA (-) groups were 50.6 Gy and 28.7 Gy, respectively (p

Moyamoya formations at the base of the brain are not congenital vascular malformations but represent collateral pathways associated with chronic progressive stenosis of the carotid fork. The authors have studied 44 personal cases, 18 children under 15 years of age, and 26 adults. In children the Moyamoya vessels change through six stages: (1) carotid fork stenosis; (2) progressive carotid stenosis with initial Moyamoya collaterals and dilatations of cerebral arteries; (3) dilatation of Moyamoya collaterals and disappearance of anterior and middle cerebral arteries; (4) thinning of Moyamoya; (5) contraction of Moyamoya and disappearance of posterior cerebral arteries; (6) intracerebral vessels perfused from the external carotid and/or vertebrae. These six stages are not observed in adults. Bilateral cervical perivascular sympathectomy (PVS) was performed in 9 children and superior cervical ganglionectomy (SCG) was added unilaterally in 4 and bilaterally in 3 cases. Angiographic follow-up studies were carried out 1–7 years following surgery. Improvement was observed in most of the cases examined within the first 2 months after surgery. This was not the case in arteriograms performed more than 6 months postoperatively. It would seem that PVS and SCG can improve the progress of Moyamoya vessels but only for a short period of time. Clinical symptoms, however, seem to continue improving over a long period of time. Cerebral blood flow improved 5 weeks following surgery in a 13-year-old boy.