Search

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 We investigated the effects of exogenous GS on hypoxia- and GABA A receptor–induced axonal depression in neonatal rats. Methods To assess the effects of GS on spinal cord axons, CAPs were recorded. Hemicords were exposed to hypoxia by 30-minute superfusion with Ringer's solution saturated with 95% N 2 and 5% CO 2 followed by 60-minute exposure to 95% N 2 and 5% CO 2 gassing (N 2 gassing phase) and then 90 minutes of resuperfusion with oxygenated Ringer's solution (resuperfusion phase). Exogenous high GS (15 U) or low GS (1.5 U) was delivered during the N 2 gassing phase. The effects of GS on GABA A receptor–induced axonal depression were analyzed with oxygenated isolated dorsal columns. Results The high GS significantly reduced the decline in the CAP amplitudes during the N 2 gassing and resuperfusion phases ( P = .0185) compared to the hypoxia control. The low GS treatment showed a trend toward recovery during the N 2 gassing and resuperfusion phases, but the effect was not significant ( P = .3953). In isolated dorsal columns, GS significantly reduced the CAP amplitude depression induced by GABA A receptor agonist. Conclusions Our findings suggest that GS had dose-dependent protective effects on the spinal cord against hypoxia-induced axonal depression. It may inhibit the depression of CAP amplitudes by blocking GABA A receptors.

We investigated the usefulness of fluorescein cerebral angiography (FAG) and microvascular Doppler ultrasonography (MDU) for detecting the blood flow insufficiency in the perforating arteries during aneurysm surgery. FAG was performed to confirm the patency of perforating arteries located deeply in the surgical field. After aneurysm clipping, the target arteries were illuminated using a beam from the pencil-type probe with a blue light-emitting diode at its tip. After intravenous administration of 5 ml of 10% fluorescein sodium, fluorescence in the vessels was clearly observed through a microscope and recorded on videotape. The excellent image quality and spatial resolution facilitated intraoperative real-time assessment of the patency of the perforating arteries and branches such as the posterior communicating artery, anterior choroidal artery, lenticulostriate artery, recurrent artery of Heubner, hypothalamic artery or posterior thalamoperforating artery. Although MDU has generally been used in aneurysm surgery to assess the blood flow velocity before and after clipping, the complexity of keeping the MDU probe on the target vessel at the appropriate angle and degree of compression makes the detection of changes in flow velocity difficult. To overcome this problem, we continuously measured the blood flow velocity by MDU during aneurysmal clipping. The continuous MDU monitoring during aneurysm clipping enabled us to detect slight blood flow changes in real time. The findings of this study suggest that the monitoring methods introduced here are safe and reliable for detecting intraoperative blood flow insufficiency in the perforating arteries and facilitate the prevention of unexpected postoperative cerebral infarction.

We investigated the usefulness of the posterior tibial nerve somatosensory evoked potentials (PTN-SEP) for detecting the cerebral blood flow insufficiency of the anterior cerebral artery (ACA) during anterior communicating (Acom) or distal ACA aneurysm surgery. PTN-SEP monitoring was employed in 112 patients of Acom and 23 patients of distal ACA aneurysm. After dural incision, control data were recorded, and a decrease of more than 50% in the amplitude of P37-N45 was defined as significant. We evaluated the intraoperative PTN-SEP findings, causes of PTN-SEP change, and motor outcomes in the lower extremities. PTN-SEP changes were observed in 21 patients. The causes of SEP change were thought to be attributable to blood flow insufficiency with aneurysmal bleeding, with or without temporary occlusion on the ACA in 10 patients. In the other 10 patients, the cause was intensive temporary occlusion. In the last patient, inappropriate clipping on the parent artery was the cause of SEP change. No obvious difference was observed between bilateral and unilateral ACA occlusion. Following the release of the occlusion and repositioning of the clip, PTN-SEP was recovered to the control value in all but 1 patient. Of these 21 patients, 11 did not show any postoperative motor paresis of the lower extremity; transient motor paresis was recognized in 10 patients. Despite the large variability of territories of the ACA and collateral circulation via the leptomeninges, intraoperative PTN-SEP monitoring was helpful in the operative maneuver, such as ACA occlusion.

Object The authors performed fluorescein cerebral angiography in patients after aneurysm clip placement to confirm the patency of the parent artery, perforating artery, and other arteries around the aneurysm. Methods Twenty-three patients who underwent aneurysm surgery were studied. Aneurysms were located in the internal carotid artery in 12 patients, middle cerebral artery in six, anterior cerebral artery in three, basilar artery bifurcation in one, and junction of the vertebral artery (VA) and posterior inferior cerebellar artery in one. After aneurysm clip placement, the target arteries were illuminated using a beam from a blue light-emitting diode atop a 7-mm diameter pencil-type probe. In all patients, after intravenous administration of 5 ml of 10% fluorescein sodium, fluorescence in the vessels was clearly observed through a microscope and recorded on videotape. Results The excellent image quality and spatial resolution of the fluorescein angiography procedure facilitated intra-operative real-time assessment of the patency of the perforating arteries and branches near the aneurysm, including: 12 posterior communicating arteries; 12 anterior choroidal arteries; four lenticulostriate arteries; three recurrent arteries of Heubner; three hypothalamic arteries; one ophthalmic artery; one perforating artery arising from the VA; and one posterior thalamoperforating artery. All 23 patients experienced an uneventful postoperative course without clinical symptoms of perforating artery occlusion. Conclusions Because the fluorescein angiography procedure described here allows intraoperative confirmation of the patency of perforating arteries located deep inside the surgical field, it can be practically used for preventing unexpected cerebral infarction during aneurysm surgery.

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.

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 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.

The effects of N-methyl-D-aspartate (NMDA), glutamate, and glycine on the developmental axons of the neonatal rat spinal cord were investigated. Isolated dorsal column preparations from postnatal day (PN) 0 to 14 Long-Evans hooded rats (n = 119) were used in vitro. Compound action potentials (CAPs) were recorded from the cuneate and gracile fasciculi with a glass micropipette electrode. NMDA (100 microM) significantly increased CAP amplitude in PN 0-6 cords by 21.5 +/- 9.2% (mean +/- standard error of the mean, p0.001, n = 8) and in PN 7-14 cords by 6.7 +/- 6.6% (p0.001, n = 10). NMDA (10 microM) significantly increased the CAP amplitude by 6.3 +/- 2.9% in PN 0-6 cords (p0.01, n = 10). The increase of CAP amplitude induced by NMDA (100 microM) in PN 0-6 cords was significantly greater than that in PN 7-14 cords (p0.005). Glutamate (100 microM) significantly increased the CAP amplitude by 8.8 +/- 8.1% in PN 0-6 cords (p0.001, n = 29) and 6.7 +/- 7.5% in PN 7-14 cords (p0.01, n = 14), and glutamate (10 microM) significantly increased by 6.3 +/- 2.9% in PN 0-6 cords (p0.01, n = 21). The amplitudes induced by glutamate (100 microM or 10 microM) did not significantly differ between PN 0-6 and PN 7-14 cords. Application of glycine (100 microM) did not significantly alter CAP amplitudes induced by NMDA (100 microM or 10 microM) and glutamate (100 microM or 10 microM). D(-)-2-amino-5-phosphonopentanoic acid (NMDA receptor antagonist) blocked the effects of NMDA and glutamate. These results suggest that NMDA receptor is present on afferent dorsal column axons and may modulate axonal excitability, especially during the 1st week after birth.

This study investigated whether the optic nerve evoked potential (ONEP) elicited by electrical stimulation of the optic nerve can serve as a reliable intraoperative indicator of visual function. In the experimental study, two silver-ball stimulating electrodes were placed on the dog optic nerve adjacent to the apex of the orbit and one recording electrode was placed on the optic nerve near the chiasm. The nerve was stimulated with 0.1 to 10 mA rectangular pulses. Stable and reproducible ONEPs were obtained. The ONEPs were not influenced by electromyographic potentials and were recorded more clearly on the optic nerve than on the surrounding tissue. Stepwise incremental transection of the thickness of the nerve resulted in incremental amplitude reduction proportional to the transected area. No response was recorded after complete sectioning of the nerve. In the clinical study, recordings were obtained from 15 patients after craniotomy to treat parasellar tumors or cerebral aneurysms. Reproducible ONEPs were recorded intraoperatively from the electrode placed on the optic nerve near the chiasm in 14 of 15 patients. In the remaining patient, the ONEP, recorded only after tumor removal because the optic nerve was stretched and extremely thin, was remarkably small and the patient developed unilateral blindness postoperatively. These experimental and clinical results suggest the possibility of intraoperative monitoring of visual function in patients undergoing craniotomy for the treatment of lesions near the optic nerve.

Based on our experiences with medico-legal autopsies, we analyzed traumatic injury of the vertebrobasilar artery (VBA) in traffic accident victims. VBA rupture occurred in six cases with traumatic medullary lesions, but in none with cervical cord injury. A relatively small external force applied to the head or neck can induce isolated traumatic subarachnoid hemorrhage (SAH), which accounts for approximately 11% of fatal head injuries. We examined the relationship between site of impact and site of vascular injury in 16 cases of isolated traumatic SAH. The results showed that the vertebral artery (VA) on the side of impact tended to be longitudinally injured in victims experiencing an external force equivalent to that of a fist punch to the head or face. There was no clear relationship between the site of impact and the site of vascular injury in victims who had sustained an external force greater than that of a fist punch. However, our results suggest that an external force causing rotation of the head was likely to cause tearing of the artery. In cases in which an external force equivalent to that of a fist punch was applied to the head, a raised blood alcohol level was a significant risk factor for artery rupture. Furthermore, a difference in the diameters of the left and right VAs was a risk factor for artery rupture. To determine why the VA, the most frequent site of arterial dissection, is also frequently the site of injury, we histologically examined normal and dissected VBAs. We also discuss medico-legal issues of the causal relationship between external force applied and rupture or dissection of the VA.

脳動脈瘤手術症例220例に対して運動誘発電位 (MEP) を用いた脳血流不全のモニタリングを施行した. 刺激は大脳皮質の運動領野を直接電気刺激し, 刺激と対側の母指球筋から筋電図を記録した. 麻酔はプロポフォールを用いた完全静脈麻酔で, ベクロニウムを点滴静注し筋弛緩レベルを一定に保った. 術中MEPに変化を認めなかった193例では, 術後に運動麻痺は認めなかった. 25例で一過性のMEP変化を認め, このうち14例では術後に運動麻痺は認めなかったが11例で一過性の運動麻痺を認めた. 術中MEPが消失し回復しなかった2例で重度の運動麻痺が永続し, 頭部CTにて内包に梗塞巣が出現した.

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.

To detect cervical vascular lesions in 90 patients with intracranial cerebrovascular diseases, we performed three-dimensional CT angiography (3D-CTA) of the head and neck using multi-detector row CT (MD-CT) with a single- or double-bolus injection of contrast material. In the single-injection group (n=70), the head and neck were scanned in one session after continuous injection at a rate of 3 ml/s of contrast medium (total 100 ml). In the double-bolus injection group (n=20), the head was scanned first after the delivery of contrast material (3 ml/s, total 70 ml) and the neck was scanned after a boost injection (2 ml/s, total 30 ml). The single-bolus injection method was simple and suitable for screening for vascular lesions at the carotid bifurcations. The double bolus injection method yielded excellent 3D-CTA of the vertebral- and carotid arteries without interference by cervical veins and was suitable for screening the whole length of the carotid arteries, including the origin of the vertebral arteries. The head and neck 3D-CTA using MD-CT provides valuable diagnostic information regarding vascular lesions of the intracranial and cervical arteries.

Thirty-seven patients with brain tumors were studied by dynamic magnetic resonance imaging (MRI) using a field echo method. The tumors included nine pituitary adenomas, nine schwannomas, eight meningiomas, three gangliogliomas, two metastatic brain tumors, two malignant lymphomas and four other brain tumors, which were histologically diagnosed. Sequential images were acquired every 15 s for 5 min after administration of Gd-DTPA. With setting of a region of interest (ROI) in the tumors, the signal intensity (S.I.) ratios were calculated. The time intensity curves of the S.I. ratios were investigated. The dynamic curves of the S.I. ratio could be classified into four patterns: (1) rapid increase followed by gradual decrease (pituitary adenoma, meningioma and germinoma); (2) gradual increase followed by plateau (schwannoma); (3) rapid increase followed by gradual increase (metastatic brain tumor, malignant lymphoma and ganglioglioma); (4) no or faint enhancement (craniopharyngioma, epidermoid and cavernous angioma). Our study indicated that the tumors had the characteristic patterns of the dynamic curve of S.I. ratios. Dynamic MRI using a field echo provides useful information for the differential diagnosis of brain tumors.

The object of this study is to assess whether aneurysm surgery can be performed in patients with ruptured and unruptured cerebral aneurysms by using three-dimensional computerized tomography angiography (3D-CTA) alone, without conventional catheter angiography (CCA). We have operated on 153 consecutive patients with ruptured aneurysms and 89 patients with unruptured aneurysms based on 3D-CTA findings since December 1996 and February 1997, respectively. In the cases of ruptured aneurysm, 153 ruptured aneurysms including 62 associated unruptured aneurysms were detected by 3D-CTA. CCA was performed in 7 of 153 patients after they underwent 3D-CTA, which included four dissecting vertebral artery (VA) aneurysms, two basilar artery (BA) tip aneurysms, and one BA–superior cerebellar artery (SCA) aneurysm. In 89 patients with unruptured aneurysms, 101 unruptured aneurysms were detected by 3D-CTA. In 5 of 101 unruptured aneurysms, which included giant or large aneurysms and a case of an aneurysm associated with infarction, CCA was needed. All of the ruptured and unruptured aneurysms were confirmed during surgery and treated successfully. The authors stress that 3D-CTA could replace CCA in the diagnosis of saccular aneurysms and that surgery could be performed in almost all ruptured and unruptured aneurysms by using only 3D-CTA without CCA.

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.

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.

Objective We sought to confirm the effects of methylprednisolone (MP) on axonal depression induced by hypoxia, gamma-aminobutyric acid (GABA), and (+/-)-8-hydroxy-dipropylaminotetralin hydrobromide (8-OH-DPAT). Methods Compound action potentials were recorded to assess the effects of MP in neonatal rat spinal cord axons. Longitudinally hemisected spinal cords were superfused for 120 minutes in Ringer's solution saturated with 95% N2 and 5% CO2. The effect of MP on GABA- and 8-OH-DPAT-induced axonal depression was analyzed with oxygenated isolated dorsal columns. Results Hypoxia (120 min) significantly reduced the response amplitudes in hemicord preparations. MP (30 micromol/L) prevented hypoxia-induced depression of action potential amplitudes. In oxygenated dorsal column preparations, GABA (50 micromol/L) significantly reduced action potential amplitudes. At 10, 30, and 100 micromol/L, MP had no effect on axonal excitability and GABA-induced axonal depression. 8-OH-DPAT (100 micromol/L) significantly reduced the action potential amplitude. MP (10, 30, 50, and 100 micromol/L) reduced 8-OH-DPAT-induced amplitude depression in a dose-dependent manner. Conclusion At the higher concentrations, MP protected spinal cord axons against hypoxia-induced excitability loss. It had an effect on serotonin 1A-induced axonal depression but not on GABA-induced depression.

In our previous study, 60 cases of subarachnoid hemorrhage (SAH) from ruptured aneurysms were prospectively evaluated both by three-dimensional computerized tomography angiography (3D-CTA) and conventional catheter angiography (CCA), which resulted in a 100% accuracy for 3D-CTA in the diagnosis of ruptured aneurysms. Based on the results, we assessed whether the aneurysm surgery can be performed on patients with ruptured cerebral aneurysms using 3D-CTA without CCA. 3D-CTA was performed with a helical CT scanner. A total of 123 consequent patients with SAH who had undergone surgery in the acute stage on the basis of 3D-CTA findings were studied. One hundred and twenty-three ruptured aneurysms, including 49 associated unruptured aneurysms, were detected using 3D-CTA. In 7 of 123 ruptured aneurysms, 3D-CTA was followed by CCA to acquire the diagnostic confirmation or the information of the vein. All of the ruptured aneurysms were confirmed at the surgery and treated successfully. One hundred and sixteen patients who underwent the operation with the use of 3D-CTA only had no complications related to the lack of CCA information. 3D-CTA provided us with aneurysm location as well as the surgically important information on the configuration of its sac and neck, and its relationship to adjacent vessels and bone structures. 3D-CTA can replace CCA in the diagnosis of ruptured aneurysms and acute surgery can be performed in almost all acutely ruptured aneurysms by using only 3D-CTA without CCA.

Cisternal irrigation therapy with urokinase and ascorbic acid was applied in 118 cases for preventing vasospasm after aneurysmal subarachnoid hemorrhage (SAH); in other 28 cases only urokinase was used. All of the patients were in Group 3 according to the CT classification by Fisher, and the CT number (Hounsfield number) of the thickest clot was over 60. These CT findings suggested a high chance for occurrence of symptomatic vasospasm. All patients underwent surgery within 72 hours. After clipping the aneurysm, irrigation tubes were placed in the Sylvian fissure (inlet), either on one side or bilaterally, and also in the prechiasmal or prepontine cistern (outlet). Lactated-Ringer’s solution with urokinase (60, 120 IU/ml) and ascorbic acid (2, 4 mg/ml) was infused at the rate of 20–60 ml/hours for about 10 days. In the former group with urokinase and ascorbic acid, symptomatic vasospasm was observed in 3 cases (2.5%) and only one of them (0.8%) showed neurological sequelae. In the latter group with only urokinase (30–120 IU/ml), symptomatic vasospasm occurred in three cases (10.7%), transiently. We compared these results with those of 111 control cases without the irrigation therapy, which had the same degree of SAH on the preoperative CT scans. In the control group, symptomatic vaso-spasm occurred in 38 cases (34.2%).

Object. Evoked potentials elicited by electrical stimulation of the oculomotor nerve and recorded from surface electrodes placed on the skin around the eyeball reportedly originate in the eye and are represented on electrooculograms. Because evoked potentials recorded from surface electrodes are extremely similar to those of extraocular muscles, which are represented on electromyograms, the authors investigated the true origin of these potentials. Methods. Evoked potentials elicited by electrical stimulation of the canine oculomotor nerve were recorded from surface electrodes placed on the skin around the eyeball. A thread sutured to the center of the cornea was pulled and the potentials that were evoked during the resultant eye movement were recorded. These potentials were confirmed to originate in the eye and to be represented on electrooculograms because their waveforms were unaffected by the administration of muscle relaxant. To eliminate the influence of this source, the retina, a main origin of standing potentials of the eyeball, was removed. This resulted in the disappearance of electrooculography (EOG) waves elicited by eye movement. Surface potentials elicited by oculomotor nerve stimulation were the same before and after removal of the retina. Again the oculomotor nerve was electrically stimulated and electromyography (EMG) response of the extraocular muscles was recorded at the same time that potentials were recorded from the surface electrodes. In their peak latencies, amplitudes, and waveforms, the evoked potentials obtained from surface electrodes were almost identical to EMG responses of extraocular muscles. Conclusions. Evoked potentials elicited by electrical stimulation of the oculomotor nerves and obtained from surface electrodes originated from EMG responses of extraocular muscles. These evoked potentials do not derive from the eye.

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 analyzed patients who developed cerebral infarction along the distribution of the perforating artery after aneurysm surgery in order to learn how to avoid such complications in the future.Neck clipping of a cerebral aneurysm was performed on 825 patients consecutively. Cerebral infarction along the distribution of the perforating artery was evaluated by a postoperative CT scan. We investigated the incidence of cerebral infarction, its causes, clinical symptoms and prognoses.Postoperative CT scans demonstrated low-density areas in 35 patients (4.2%). We determined that the responsible arteries were the anterior choroidal artery (9 cases), posterior thalamoperforating artery (3 cases), lenticulostriate artery (7 cases), anterior thalamoperforating artery (7 cases) and recurrent artery of Heubner (9 cases).The causes were attributed to occlusion due to neck clipping (48.6%), ischemia due to intraoperative temporary occlusion of the parent artery (20.0%), ischemia due to retraction of the perforating artery (17.1%) and direct injury (14.3%). Neurological deterioration appeared in 23 patients (2.8%) and remained in 13 (1.6%).Cerebral infarction along the distribution of the anterior choroidal artery or the posterior thalamoperforating artery usually caused severe neurological deficit, resulting in a poor outcome. On the other hand, those of the lenticulostriate artery, anterior thalamoperforating artery or recurrent artery of Heubner did not have a serious effect on outcome.Cerebral infarction along the distribution of the perforating artery was caused by neck clipping as well as temporary occlusion of the parent artery and retraction or injury of the perforating artery. To improve surgical results, it is particularly important to preserve the anterior choroidal artery and posterior thalamoperforating artery.

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.

It has generally been thought that the neurogenic control of cerebral circulation is decided mainly by the autonomic nervous system. Recent studies, however, indicate that sensory nerves rich in calcitonin gene-related peptide (CGRP) are also distributed on cerebral arteries. CGRP is one of neuropeptides that has strong vasodilative effect. This indicates that sensory nerves may antidromically dilate cerebral arteries mediated by CGRP. The aim of this study is to investigate the relationship between the CGRP containing nerves and cerebral circulation. Firstly, we developed a selective denervation model of CGRP containing nerves. The denervation was performed with intrathecal administration of capsaicin in rats. Secondly, we measured the change of regional cerebral blood flow (rCBF) during the occlusion of bilateral common carotid artery or systemic hypotension. CGRP immunoreactivity around cerebral arteries disappeared after capsaicin treatment. The rCBF during the occlusion of bilateral common carotid artery decreased more in the capsaicin group than in the control group. There was no significant difference in the changes of rCBF during systemic hypotension. These results showed that CGRP containing nerves would participate in the vascular response of cerebral arteries. It is likely that sensory nerves with CGRP should have antidromic effect on cerebral circulation.

Motor evoked potentials by magnetic stimulation is less invasive and causes no pain as opposed to high current electric stimulation. However, the distribution of the magnetic field generated by the round coil has not been fully studied. In this report, we mapped the extent of the magnetic induction flux density, and then the evoked potentials from the spinal cord were investigated by transcranial magnetic stimulation. We also examined the origin of the evoked potentials obtained by the magnetic stimulation. The following results were obtained. The magnetic induction flux density was at its maximum at the edge of the coil. The potentials consisted of a first negative wave and subsequent multiphasic waves. The first negative wave was similar to a response of the subcorticospinal tract in the lower brain stem, while the subsequent multiphasic waves were similar to those of the pyramidal tract. Although magnetic stimulation has certain advantages over electric stimulation, several problems remain to be solved for the monitoring of motor functions in the clinical settings.

Background and Purpose —Cisternal irrigation therapy with urokinase (UK) was performed in multiple institutions to prevent symptomatic vasospasm. The efficacy and safety of this therapy were evaluated, and the optimal concentration of UK was estimated. Methods —This therapy was performed in 28 patients who underwent surgery within 72 hours of the onset of severe subarachnoid hemorrhage (Fisher’s group 3, CT number [Hounsfield units] >60). After the aneurysm was clipped, irrigation tubes were placed in the Sylvian fissure (inlet) unilaterally and in the prepontine or chiasmatic cistern (outlet). Lactated Ringer’s solution with UK (30, 60, or 120 IU/mL) was infused at a rate of 30 mL/h. The presence of symptomatic vasospasm was evaluated by changes in the clinical symptoms and the presence of a new low-density area on CT scan. Drained irrigation fluid and peripheral blood were examined chronologically to evaluate the fibrinolytic system. Results —Symptomatic vasospasm was observed transiently in 3 cases (10.7%) without any low-density area on CT scan. In the 120-IU/mL group, no symptomatic vasospasm occurred. Analysis of drainage fluid suggested that UK 120 IU/mL is effective. The mean values of total drained blood volume for the respective groups were as follows: 58 mL in 30 IU/mL, 106 mL in 60 IU/mL, and 143 mL in 120 IU/mL. No abnormal changes were observed in the coagulative and fibrinolytic systems after UK irrigation. Conclusions —These results suggest that cisternal irrigation therapy with UK is safe and effective for the prevention of symptomatic vasospasm after aneurysmal subarachnoid hemorrhage.

BACKGROUND Cisternal irrigation therapy with urokinase and ascorbic acid was introduced to prevent symptomatic vasospasm after aneurysmal subarachnoid hemorrhage (SAH). To dissolve and wash out the subarachnoid clot, cisternal irrigation with urokinase is used. Ascorbic acid is added to degenerate oxy-hemoglobin, one of the strongest spasmogenic substances, into verdohemelike products, which are nonspasmogenic. The efficacy and safety of this therapy were evaluated. METHODS This therapy was performed consecutively in 217 patients. The degree of SAH of the patients was classified as Fisher CT Group 3, and the highest CT number (Hounsfield number) exceeded 60 in the SAH, which suggested a significant risk for symptomatic vasospasm. All patients underwent surgery within 72 hours from the onset of SAH. After clipping the aneurysm, irrigation tubes were placed in the Sylvian fissure (inlet) unilaterally or bilaterally and in the prepontine or chiasmal cistern (outlet). Lactated Ringer’s solution with urokinase (120 IU/mL) and ascorbic acid (4 mg/mL) was infused at a rate of 30 mL/hour/side for approximately 10 days. RESULTS Of the 217 patients studied, symptomatic vasospasm was observed in 6 cases (2.8%), and two of these six cases (0.9%) demonstrated sequelae. The average total blood volume calculated from the drainage fluid was approximately 114 mL. Analysis of the absorption spectrum of the drainage fluid revealed disappearance of the oxy-hemoglobin-specific 576-nm peak. Complications occurred in eight patients during irrigation therapy; two patients experienced seizures, two patients developed meningitis, and four patients had an intracranial hemorrhage. However, all of these patients recovered without neurological deficits. CONCLUSIONS These results suggest that cisternal irrigation therapy with urokinase and ascorbic acid is effective in preventing symptomatic vasospasm after aneurysmal SAH.

Collectins, C-type (Ca2+-dependent) animal lectins with both collagenous and carbohydrate recognition domains, function as opsonins against pathogens. We previously described an N-acetylglucosamine (GlcNAc)-binding lectin (ficolin/P35) with a collagen- and a fibrinogen-like sequence present in human serum. In this report we show that ficolin/P35 can serve as an opsonin and enhance the clearance of pathogens having surface GlcNAc. Ficolin/P35 bound to an Ra chemotype strain of Salmonella typhimurium (TV119) which has an exposed GlcNAc at the non-reducing termini of the polysaccharide. On the other hand, ficolin/P35 did not bind to LT2, a smooth type strain of S. typhimurium with additional O-polysaccharides covering GlcNAc. Ficolin/P35 enhanced the uptake of TV119 by monocytes or polymorphonuclear leukocytes but had no opsonic activity towards LT2. These results suggest that, like collectins, ficolin/P35 is a collagenous lectin which has a role in innate immunity against certain pathogenic organisms by acting as an opsonin. We prepared monoclonal antibodies against ficolin/P35 and developed an enzyme-linked immunosorbent assay (ELISA) for measuring ficolin/P35 concentrations in humans. The mean serum concentration of ficolin/P35 from 130 normal individuals was estimated to be 13.7 microg/ml.

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.

✓ Olfactory evoked potentials (OEPs), obtained by electrical stimulation of the olfactory mucosa, were recorded in dogs and humans to develop an objective method for evaluating olfactory functions. In dogs, OEPs were recorded from the olfactory tract and the scalp. The latency of the first negative peak was approximately 40 msec. A response was not obtained after stimulation of the nasal mucosa and disappeared after sectioning of the olfactory nerve. With increasing frequencies of repetitive stimulation, the amplitude was reduced, suggesting that the response was synaptically mediated. These results demonstrate that evoked potentials from the olfactory tract and the scalp following electrical stimulation of the olfactory mucosa originate specifically from the olfactory system. In humans, a stimulating electrode with a soft catheter was fixed on the olfactory mucosa. The OEPs from the olfactory tract, recorded with a negative peak of approximately 27 msec, had similar characteristics to OEPs found in dogs. The OEPs from the olfactory tract in humans also originate specifically from the olfactory system. The authors postulate that OEPs obtained by electrical stimulation of the olfactory mucosa may prove useful for intraoperative monitoring of olfactory functions.

✓ The authors report a case in which anterior choroidal artery (AChA) blood flow insufficiency due to aneurysm clip rotation was detected intraoperatively by motor evoked potential (MEP) monitoring and ischemia was successfully avoided. The patient had an incidentally discovered aneurysm for which occlusion of its neck was performed through a standard frontotemporal craniotomy without changing the MEP amplitude. After it was confirmed that the surrounding arteries were not stenotic, the brain retractor on the frontal lobe was released; MEP amplitude subsequently decreased. Rotation of the clip toward the frontal base by repositioning of the frontal lobe caused the AChA stenosis at the origin of its branches. On reorienting the clip toward the frontal lobe, the AChA stenosis was released and MEP amplitude recovered. To prevent repeated clip rotation, a large amount of gelatin (Spongel) was inserted between the frontal base and the clip. The authors confirmed that clip rotation did not occur after repositioning of the frontal lobe. Motor evoked potential amplitude was maintained until dural closure. Postoperatively, the patient demonstrated no neurological deficit and there was no newly developed low-density area on computerized tomography scans.

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.

✓ Three cases of ruptured aneurysm at the basilar bifurcation accompanied by megadolichobasilar anomaly were successfully treated using a transthird ventricular approach. A translamina terminalis approach was used to enter the third ventricle. In two cases, the floor of the third ventricle had been partly destroyed by aneurysm rupture, and a small split in the third ventricular floor was necessary to gain a wide operative field. In the third case, an intact floor was opened along the midline. Clipping was accomplished in all three cases after preserving the perforating arteries. Postoperatively, no complications from splitting the floor were observed. Key surgical points and the prospective view of the transthird ventricular approach are discussed.

The lectin pathway is a novel pathway for activation of the complement cascade, which is initiated by the binding of mannose-binding protein (MBP) to its carbohydrate ligands. We investigated whether the complement system was activated in vitro by glioma cells through this pathway to the C3 level. MBP was found to bind to all six glioma cell lines tested by using flow cytometric analysis. Binding of a complex of MBP-associated serine protease and MBP was observed in two of the cell lines examined, thereby resulting in C4 consumption. Activation of C3 was hemolytically evaluated in these two lines. C3 consumption was also observed in one. Based on these results, it is likely that recognition by MBP followed by complement activation occurs in certain glioma cell lines.