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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.

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.

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.

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.

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.

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.

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.

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.

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.

破裂脳動脈瘤急性期における再破裂は予後不良となる大きな因子である.過去5年間に経験した破裂脳動脈瘤452例中, 来院後再破裂を来たした24例 (5.3%) を対象として, 特に再破裂直前の収縮期血圧に注目し, 3日以内の急性期症例と4日以降の慢性期症例に分けて検討した.急性期の再破裂症例は12例で, そのうち10例で降圧が不充分と思われた.収縮期血圧100mmHg未満での再破裂は認められなかった.また, 80～100mmHg程度の降圧により症状の悪化した症例も認められなかった.4日以降の症例では脳血管蛮縮の時期と重なっていることもあり, 充分な降圧は行えなかった.根治手術を施行し得たのは9例で, 手術可能なまでに状態の改善しなかった15例は全例死亡した.破裂脳動脈瘤急性期では限界はあると思われるが, 早期からの徹底的な血圧コントロールが必要であると思われた.

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.

A model of intracranial arteriovenous (AV) shunting must incorporate local hypoperfusion and simulate the hemodynamics of arteriovenous malformations. In this study, the hemodynamics of an intracranial AV shunt model in the acute stage were clarified. End-to-side anastomoses with a femoral vein graft were performed between a cortical branch of the middle cerebral artery (MCA) and the superior sagittal sinus in anesthetized dogs. Local cerebral blood flow (l-CBF) was measured by laser Doppler blood flowmetry. l-CBF decreased suddenly by 34.2% when the shunt was opened in the ipsilateral MCA territory. Upon re-occlusion, l-CBF immediately equaled or exceeded the pre-opening value and returned to the pre-opening value within the next 15 minutes. Opening the shunt produced little change in l-CBF in the territory of the ipsilateral or contralateral anterior cerebral artery. The decrease in l-CBF was correlated with shunt volume only in the MCA territory. l-CBF manifested a PaCO(2)-dependent increase before shunt opening, but CO(2) reactivity was impaired after opening the shunt only in the MCA territory. This dog model features local hypoperfusion due to intracranial AV shunting and disturbance of CO(2) reactivity in the acute stage. The hemodynamics of this model will be confirmed in the chronic stage.

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.

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 25-year-old Japanese woman had both ulcerative colitis and Takayasu's disease and was positive for HLA-A24, BW52, and DR2. She was found to have thickening of the wall of the carotid artery on contrast-enhanced computerized tomography of the neck and chest. Prednisolone, beraprost, and sulfapyridine achieved rapid remission of both diseases.(Internal Medicine 33:127-129, 1994)

Two unusual cases of partially thrombosed or fusiform type aneurysm on the cortical segment of the superior cerebellar artery (SCA) with subarachnoid hemorrhage are described. A 71-year-old female had a partially thrombosed, multi-lobular aneurysm located at the marginal branch of the SCA. This aneurysm was successfully clipped and wrapped via a subtemporal transtentorial approach in the acute stage. A 52-year-old female had an atherosclerotic fusiform aneurysm located at the distal portion of the hemispheric branch of the SCA. This aneurysm was successfully trapped using an infratentorial supracerebellar approach in the acute stage. Both patients were discharged without neurological deficits. The subtemporal transtentorial or lateral suboccipital approach for the proximal cortical segment, and the infratentorial supracerebellar approach for the distal cortical segment of the SCA are recommended for surgical treatment of these aneurysms.

Brain abscess occurred in a patient with maxillary cancer treated with radiotherapy, chemotherapy by arterial infusion and radical surgery for right maxillary cancer.Three months after the treatment, the symptoms of temporal bone necrosis which were otorrhea, preauricular fistula and swelling of the preauricular lesion and the external auditory meatus were evident. Meningitis and brain abscess developed subsequently. Right temporal craniotomy was performed to remove the brain abscess and bone necrosis. Since the operation the patient has been asymptomatic and there has been no evidence of cancer recurrence.Intracranial complications due to temporal bone necrosis after the treatment of head and neck cancer are discussed. It is especially important to diagnose osteonecrosis and intracranial complications early after the combination therapy of maxillary cancer, because there is a high risk of infection due to direct surgery of bones or to bone exposure at the site of operation, especially when radiation therapy is used.

Thirty four cases of bilateral hematoma (14%) out of 248 cases of acute traumatic intracranial hematoma are reported with regards to clinical analysis and therapeutic problems. Operative results of the bilateral hematomas were the worst among various intracranial hematomas because of severe preoperative conditions and bilateral brain damage. Bilateral hematomas had no specific clinical features in comparison with unilateral hematomas. It was difficult to diagnose them by symptoms alone. The validity of Nelson and Freimanis method of differential diagnosis between unilateral hematoma and bilateral hematoma based on the shift of anterior cerebral artery during unilateral cerebral angiography was checked. Fifteen cases out of 25 cases of bilateral hematoma angiographically showed over 51 % shifts of the anterior cerebral artery. This was quite different from the report by Nelson and Freimanis.

A 20-year-old woman was admitted in November, 1978 because of left proptosis, which had progressed slowly since September, 1977. Her eye ball movement was normal and no other neurological dificits were noted. Plain skull roentgenograms suggested an osteogenic tumor of the left medial supraorbital region. Left carotid angiography showed hypertrophied ethmoidal branches of the ophthalmic artery. Bifrontal craniotomy was performed. The left orbital bone was separated from the dura mater and removed. An encapsulated ovoid tumor (3.5×3.5×4.0 cm) appeared under the thinned and expanded orbital bone. The main mass was situated in the left ethmoidal sinus. The tumor, which was separated from the dura mater and periorbita by the membranous bone, was removed piece by piece, totally. Postoperatively, the left proptosis decreased but a slight disturbance of the left eye ball movement occurred. Typical psammomatous meningioma was noted microscopically. She was discharged in December, 1978 with slight disturbance of the left eye ball movement and mild proptosis. She had no symptoms in September 1980. A total of 60 cases of primary ectopic meningioma were reviewed from the literature.

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.