Involvement of glutamatergic and GABAergic transmission in MK-801-increased gamma band oscillation power in rat cortical electroencephalograms

Hypofunction of the N-methyl-D-aspartic acid receptor (NMDAr) has been considered to play a crucial role in the pathophysiology of schizophrenia. In rodent electroencephalogram (EEG) studies, non-competitive NMDAr antagonists have been reported to produce aberrant basal gamma band oscillation (GBO), as observed in schizophrenia. Aberrations in GBO power have attracted attention as a translational biomarker for the development of novel antipsychotic drugs. However, the neuronal mechanisms as well as the pharmacological significance of NMDAr antagonist-induced aberrant GBO power have not been fully investigated. In the present study, to address the above questions, we examined the pharmacological properties of MK-801 (0.1 mg/kg)-increased basal GBO power in rat cortical EEG. Riluzole (3-10 mg/kg), a glutamate release inhibitor, reduced the MK-801-increased basal GBO power. In contrast, L-838,417 (1-3 mg/kg), an α2/3/5 subunit-selective GABAA receptor-positive allosteric modulator, enhanced the GBO increase. Antipsychotics such as haloperidol (0.05-0.3 mg/kg) and clozapine (1-10 mg/kg) dose-dependently attenuated the MK-801-increased GBO power. Likewise, LY379268 (0.3-3 mg/kg), an metabotropic glutamate 2/3 receptor (mGlu2/3 receptor) agonist, reduced the GBO increase in a dose-dependent manner, which was antagonized by an mGlu2/3 receptor antagonist LY341495. These results suggest that an increase in cortical GBO power induced by NMDAr hypofunction can be attributed to the aberrant activities of both excitatory pyramidal neurons and inhibitory interneurons in local circuits. The aberrant cortical GBO power reflecting cortical network dysfunction observed in schizophrenia might be a useful biomarker for the discovery of novel antipsychotic drugs.

Intraoperative electrophysiologic monitoring of ocular motor nerves under conditions of partial neuromuscular blockade during skull base surgery

The feasibility and usefulness of intraoperative electromyographic monitoring of the oculomotor nerve (CN III), trochlear nerve (CN IV), and abducens nerve (CN IV) were evaluated under conditions of partial neuromuscular blockade in 21 patients undergoing skill base surgery. Intracranial electrical stimulation of each nerve was performed, and compound muscle action potentials (CMAPs) were reconded from the inferior or superior rectus muscle, the superior oblique muscle, and the lateral rectus muscle for monitoring of CN III, IV, and VI, respectively. Partial neuromuscular blockade was achieved by controlled infusion of vecuronium titrated to eliminate about 90% of the twitch response of the abductor pollicis brevis to electrical stimulation of the median nerve. A total of 30 cranial nerves were stimulated intraoperatively. Of these, 29 were successfully monitored (19 CN III, 6 CN IV, 4 CN VI). A relationship was found between intraoperative findings of cranial nerve monitoring, such as disappearance of response and increase in latency and stimulus threshold during manipulation of a lesion, and the presence of postoperative nerve deficits. We conclude that intraoperative electromyographic monitoring of ocular motor nerves is feasible during partial neuromuscular blockade, and that partial neuromuscular blockade does not affect the relationship between findings of intraoperative monitoring and postoperative nerve function.

Multiple pathways of sigma(1) receptor ligand uptakes into primary cultured neuronal cells

Although many antipsychotics have affinities for sigma receptors, the transportation pathway of exogenous sigma(1) receptor ligands to intracellular type-1 sigma receptors are not fully understood. In this study, sigma(1) receptor ligand uptakes were studied using primary cultured neuronal cells. [(3)H](+)-pentazocine and [(3)H](R)-(+)-1-(4-chlorophenyl)-3-[4-(2-methoxyethyl)piperazin-1-yl]methyl-2-pyrrolidinone L-tartrate (MS-377), used as a selective sigma(1) receptor ligands, were taken up in a time-, energy- and temperature-dependent manner, suggesting that active transport mechanisms were involved in their uptakes. sigma(1) receptor ligands taken up into primary cultured neuronal cells were not restricted to agonists, but also concerned antagonists. The uptakes of these ligands were mainly Na(+)-independent. Kinetic analysis of [(3)H](+)-pentazocine and [(3)H]MS-377 uptake showed K(m) values (microM) of 0.27 and 0.32, and V(max) values (pmol/mg protein/min) of 17.4 and 9.4, respectively. Although both ligands were incorporated, the pharmacological properties of these two ligands were different. Uptake of [(3)H](+)-pentazocine was inhibited in the range 0.4-7.1 microM by all the sigma(1) receptor ligands used, including N,N-dipropyl-2-[4-methoxy-3-(2-phenylethoxy)phenyl]ethylamine monohydrochloride (NE-100), a selective sigma(1) receptor ligand. In contrast, the inhibition of [(3)H]MS-377 uptake was potently inhibited by haloperidol, characterized by supersensitivity (IC(50), approximately 2 nM) and was inhibited by NE-100 with low sensitivity (IC(50), 4.5 microM). Moreover, kinetic analysis revealed that NE-100 inhibited [(3)H]MS-377 uptake in a noncompetitive manner, suggesting that NE-100 acted at a site different from the uptake sites of [(3)H]MS-377. These findings suggest that there are at least two uptake pathways for sigma(1) receptor ligands in primary cultured neuronal cells (i.e. a haloperidol-sensitive pathway and another, unclear, pathway). In addition, pretreatment of cells with a calmodulin antagonist, N-(6-aminohexyl)-5-chloro-1-naphthalene sulfonamide (W-7), a myosin light chain kinase inhibitor, 1-(5-chloronaphthalene-1-sulfonyl)homopiperazine (ML-9), or microsomal Ca(2+)-ATPase inhibitors resulted in a reduction of the amount of sigma receptor ligand uptake. These findings suggest that the Ca(2+) pump on the endoplasmic reticulum and/or calmodulin-related events might be involved in the regulation of the uptake of sigma receptor ligands into primary neuronal cells.

Binding properties of [3H]MS-377, a novel sigma receptor ligand, to rat brain membranes

MS-377 ((R)-(+)-1-(4-chlorophenyl)-3-[4-(2-methoxyethyl)piperazin-1-yl]++ +methy l-2-pyrrolidinone L-tartrate) is a novel selective sigma receptor ligand, currently being developed for the treatment of schizophrenia. MS-377 showed anti-phencyclidine (PCP), anti-dopaminergic and anti-serotonergic activities, and we anticipated that the anti-psychotic activities of MS-377 were associated with sigma(1) receptors. However, its pharmacological profile is partly distinct from those of selective sigma(1) receptor ligands. Thus, one of the possible speculations is that MS-377 has another site of action. In the present study, we examined the binding properties of radiolabeled MS-377 ([3H]MS-377) to rat brain membranes. [3H]MS-377 showed saturable and reversible binding to rat brain membranes. Scatchard plot and Hill plot from saturation studies were linear, with K(d) of 15.2+/-6.6 nM, B(max) of 599.4+/-58.6 fmol/mg protein and Hill coefficient of 1.01+/-0.01, indicating that [3H]MS-377 bound to a single high-affinity site in rat brain membranes. Displacement studies revealed that the other sigma reference compounds with different structures inhibited the specific binding of [3H]MS-377 in a competitive manner. Stereoselectivity was observed for the inhibition of [3H]MS-377 binding, (+)-isomers were more potent than (-)-isomers. Non-sigma receptor ligand PCP showed weak inhibition of [3H]MS-377 binding. The rank order of potency for the sigma reference compounds to displace [3H]MS-377 binding were as following: haloperidol>MS-377=(+)-pentazocine>DTG (1, 3-Ditolylguanidine)=(-)-pentazocine>BMY14802 (alpha-(4-fluorophenyl)-4-(5-fluoro-2-pyramidinyl)-1-piperazine butanol)>(+)-SKF-10,047>(-)-SKF-10,047=PCP. These results suggested that the MS-377 selectively binds to sigma binding site with high affinity in rat brain membranes. Therefore, the anti-psychotic activities of MS-377 are attributable to association with sigma(1) receptors.

Long-term follow-up study of unruptured vertebral artery dissection: clinical outcomes and serial angiographic findings

OBJECT

Although the spontaneous occurrence of an unruptured vertebral artery (VA) dissection has increasingly been recognized as a relatively common cause of stroke, and the clinical aspects of this lesion have gradually been determined, its natural course remains obscure. The main goal of this study was to clarify the management protocol for this condition by examining serial angiographic changes in patients with unruptured VA dissections.

METHODS

Seventeen patients with unruptured VA dissections, including 13 men and four women, were clinically and angiographically examined between 1993 and 1998. All patients were observed using serial angiography studies. The initial angiography examinations most frequently revealed stenotic lesions (appearance of a pearl-and-string sign or string sign) in eight (47.1%) of 17 cases. In 15 cases (88.2%), changes in the lesions were evident on follow-up angiography studies. Stenotic lesions resulted in occlusion in four cases, normalization in three, and subsequent formation of an aneurysm in one case, which was treated successfully by proximal occlusion of the affected vessel performed using a detachable balloon. Occluded lesions, which were initially observed in three patients, recanalized in two patients and remained unchanged in one patient. Fusiform dilation alone was demonstrated in three patients during the initial angiography session; these lesions became normalized or were unchanged on follow-up studies. Saccular aneurysms were observed in two patients. In one of these cases, proximal ligation of the parent artery was successfully performed because of subsequent aneurysm enlargement. A double lumen, which appeared in one patient with an extradural VA dissection, became occluded. Magnetic resonance T2-weighted imaging studies revealed infarction corresponding to the posterior circulation in seven cases. During long-term observation in this series, good or excellent recovery was obtained in 14 (87.5%) of 16 patients, and moderate or severe disability in two (12.5%); one patient was lost to follow up after the second angiography study.

CONCLUSIONS

A follow-up angiography study must be performed during the early stage (within approximately 3 weeks after onset of symptoms) to confirm the formation or enlargement of an aneurysm, because such conditions may be amenable to surgical treatment. Unruptured VA dissection could otherwise be treated and followed conservatively. Although the majority of dissected lesions seem likely to stabilize within a few months, as evidenced on angiography, in some cases a longer observation period is required.

Falx meningioma presenting as acute subdural hematoma: case report

BACKGROUND

Acute subdural hematomas caused by meningiomas have been rarely encountered. Pathophysiologic mechanisms and clinical considerations in these patients have not been sufficiently explored. We addressed the possible mechanism of spontaneous hemorrhage in our case and briefly discuss the optimal treatment.

CASE DESCRIPTION

This case of falx meningioma presenting as an acute subdural hematoma in a 78-year-old woman is described. On initial computed tomography (CT), an enhancing tumor of the falx appeared to be the cause of hemorrhage. Only faint contrast staining in the periphery of the tumor was seen on right external carotid arteriograms, with no evidence of other vascular supply. Extravasation of contrast material during the procedure occurred suddenly and was successfully treated by endovascular embolization using a microcatheter. The hematoma was emergently evacuated with gross total removal of the tumor. Pathologic examination confirmed a transitional meningioma with abundant hyalinized structures. Disruption of a thin-walled vessel adjacent to the tumor capsule was assumed to be the site of hemorrhage.

CONCLUSIONS

The longstanding ischemia of the tumor was considered to have produced the deposition of hyalin in the tissue, which changed the hemodynamics within the tumor, producing vascular stress leading to rupture. The prognosis of patients with meningiomas complicated by acute subdural hematoma is generally poor, with mortality reported in approximately one-half of such patients. Surgical exploration is the most effective treatment and should be conducted before irreversible brain damage has occurred.

Embolectomy for acute embolic occlusion of the internal carotid artery bifurcation

BACKGROUND

Acute occlusion of the distal intracranial segment of the internal carotid artery (ICA) causes sudden severe hemispheric ischemia. A low rate of recanalization and a high mortality rate for this condition have been noted, even with endovascular treatment.

METHODS

We report the results of emergency embolectomy in six patients with acute embolic occlusion of the internal carotid artery (ICA) bifurcation. All six patients were admitted to our institute within 2 h of the onset of symptoms. Computed tomography (CT) scans on admission revealed no low-density or high-density regions in any patients. The time between onset of symptoms and completion of angiography ranged from 2 to 4 h (2.8 +/- 0.7 h).

RESULTS

Emergency embolectomy was performed for each patient. Recanalization was confirmed angiographically in four of the patients. In the remaining two patients, massive infarction in the territory of the ICA was detected on the CT scans obtained the day of the operation, and postoperative angiography was not performed in these two cases. These two patients died of uncal herniation 6 days after onset. Two of the six patients were able to walk with a cane 2 months after surgery. The remaining two patients were unable to walk or attend to their own bodily needs without assistance. The time elapsed between onset of symptoms to reopening of the occluded vessel was within 6 h in the four surviving patients. The recanalization rate was 66.7% (4/6) for the embolectomy procedure, significantly higher than that (12.5%) of the thrombolytic therapy reported in a previous study.

CONCLUSIONS

In summary, open embolectomy can be performed when the time after onset of symptoms is less than 6 h.

Cervical infarction associated with vertebral artery occlusion due to spondylotic degeneration: case report

Cases of cervical infarction with clearly documented evidence of the underlying aetiology and associated neuroradiological abnormalities have not been frequently reported. A rare case of cervical infarction caused by midvertebral artery occlusion due to spondylotic degeneration of the spine is described. The most probable aetiological factor affecting this disease entity, and the usefulness of magnetic resonance imaging in the detection of this rare lesion, are briefly discussed.

Long-term outcome after STA-MCA anastomosis for moyamoya disease

A long-term assessment was performed to determine the posttreatment clinical course of 113 patients with moyamoya disease. All patients sustained cerebral ischemic attacks and underwent superficial temporal artery-middle cerebral artery anastomosis with or without temporal muscle grafting. The follow-up duration was 3 to 24 years (mean 14.4 ± 5.8 [standard deviation]). Complete cessation of the ischemic episodes was obtained in 110 of 113 patients. One hundred patients were able to return to independent acitvities of daily living. Intellectual delays prevented 24 patients from engaging in an independent social life. Although intracranial bleeding is one of the common manifestations in moyamoya disease, hemorrhage was not detected in the 113 patients who underwent cerebral revascularization.

Hemodynamic evaluation of the effect of percutaneous transluminal angioplasty for atherosclerotic disease of the vertebrobasilar arterial system

The relationship between clinical improvement after percutaneous transluminal angioplasty (PTA) and hemodynamic condition in vertebrobasilar insufficiency was evaluated in 43 patients between 45 and 86 years of age with clinically symptomatic atherosclerotic stenotic lesions in the posterior circulation. The 43 patients had a total of 51 stenotic lesions, including 17 in the first segment of the vertebral artery, 32 in the fourth segment of the vertebral artery, and two in the basilar artery. Angiography was performed and cerebral perfusion was measured with technetium-99m-hexamethyl-propyleneamine oxime single photon emission computed tomography before and after administration of 10 mg/kg acetazolamide prior to and more than 7 months after PTA. Mean stenosis was 81.3 +/- 7.4% before PTA, but only 41.5 +/- 17.4% at follow-up. Eighteen of the 24 patients with improved neurological condition after PTA had subnormal (< mean - 2 SDs) cerebral perfusion before PTA. Twenty of these 24 patients had subnormal vasodilatory response to administration of acetazolamide before PTA. Clinical improvement following PTA was noted in only one of the 12 patients with a single stenotic lesion of the first segment, but in 23 of the 31 patients with intracranial stenotic or multiple stenotic lesions. PTA in the posterior circulation is indicated for patients with atherosclerotic stenotic intracranial lesion or multiple stenotic lesions who have subnormal cerebral perfusion and low vasodilatory response to administration of acetazolamide.

Postoperative neurological deterioration following the revascularization surgery in children with moyamoya disease

We describe four children with moyamoya disease who developed neurologic deterioration following revascularization surgery. In all cases, anesthesia was smoothly induced and the intraoperative course was uneventful. Emergence from anesthesia was prompt and no new neurological deficit was observed. However, the children suffered strokes on 2, 4, 5, and 10 days, postoperatively, respectively. Dehydration and crying were thought to be closely associated with the stroke in each case. This report suggests that attention should be paid during entire the perioperative period to avoid stroke in patients with moyamoya disease.

Risk factors for neurologic deterioration after revascularization surgery in patients with moyamoya disease

To investigate the risk factors for postoperative neurological deterioration in patients with moyamoya disease, we retrospectively reviewed the perioperative course of 368 cases of revascularization surgery in 216 patients with this disease. Risk factors anecdotally associated with postoperative ischemic events were analyzed by comparing groups with or without a history of such events on the operative day. Ischemic events were noted in 14 cases (3.8%), 4 of which were defined as strokes and the others as transient ischemic attack (TIA). Postoperative neurological deterioration more often developed in patients who suffered from frequent TIAs, had precipitating factors for TIA, and underwent indirect nonanastomotic revascularization. The authors conclude that the incidence of postoperative ischemic events were related more to the severity of moyamoya disease and the type of surgical procedure than to other factors, including anesthetic management.

IMPLICATIONS

Although preventing stroke is the major concern for patients with moyamoya disease, risk factors for perioperative cerebral ischemia have not been clarified. We retrospectively analyzed the perioperative course in 368 cases with this disease and found that the severity of the disease and type of surgical procedure were major determinants of postoperative cerebral ischemia.

[Regional cerebral hypoperfusion reduces the effect of rectal midazolam in children with Moyamoya disease]

To investigate the effect of regional cerebral blood flow on the effect of midazolam, we evaluated 99mTc-hexamethylpropylene-amine-oxime-single photon emission computed tomography (SPECT) in 37 cases of childhood moyamoya disease. They were divided into two groups according to the findings of SPECT; one group showed hypoperfusion in the bifrontal regions (n = 20), and the other did not (n = 17). Both groups received 1 mg.kg-1 of midazolam transrectally 30 min before the anesthesia induction and level of sedation was measured with six point scales. Significantly lower level of sedation score was recognized in the group that showed hypoperfusion in bifrontal regions (P < 0.05). Our finding may suggest that regional cerebral hypoperfusion may modify the sedative effect of midazolam in children with moyamoya disease.

[Anesthetic management of patients undergoing irrigation and drainage of chronic subdural hematoma--retrospective analysis of analgesia and sedation under locoregional anesthesia]

We retrospectively investigated the relationship between intraoperative hemodynamic variability and variables including patient background, anesthetic profile, and operative profile in 108 patients undergoing irrigation and drainage of chronic subdural hematoma under locoregional anesthesia. Patients were divided into two groups according to the degree of changes in mean arterial blood pressure (MAP) and heart rate (HR) during operation. Group A (n = 66) had MAP and HR changes < 20%, and Group B (n = 42) had MAP or HR changes > or = 20% of preoperative baseline values. Age was significantly higher in group B than Group A (mean +/- SD; 70 +/- 12 vs. 62 +/- 14 years, P < 0.01). In respect to additional anesthetic agents used (none; no additional anesthetic agents, enough; pentazocine > or = 0.3 mg.kg-1 and droperidol > or = 0.05 mg.kg-1, pentazocine > or = 0.5 mg.kg-1 or droperidol > or = 0.15 mg.kg-1, little; less than "enough"), ratio of "little" administered in Group B was significantly higher than that in Group A (64.3% vs. 37.9%, P < 0.05). These findings suggest that intraoperative hemodynamic variability under locoregional anesthesia in patients with chronic subdural hematoma is associated with age and insufficient use of hypnotic and/or analgesic agents.

Distribution of intraarterially administered papaverine in endovascular treatment of delayed cerebral vasospasm

The distribution of selectively administered papaverine was determined in nine patients with delayed cerebral vasospasm in the territories of the anterior (ACA) and/or middle cerebral arteries (MCA) secondary to aneurysmal subarachnoid hemorrhage by simultaneous infusion with technetium-99m-hexamethyl-propyleneamine oxime (99mTc-HMPAO). Four of the nine patients had a ruptured anterior communicating artery aneurysm, four had an internal carotid artery aneurysm, and the remaining one had a MCA aneurysm. Trapping of anterior communicating artery was carried out in one case and clipping of aneurysms in other eight cases. Neurological deterioration with hemiparesis, paraparesis, and/or somnolence appeared between postsurgical Days 8 and 13 due to delayed cerebral vasospasm in all patients. Intraarterial infusion of 40 mg of papaverine containing 37 MBq of 99mTc-HMPAO was performed from the C1 segment in seven of the nine patients and from the C4 segment in the other two patients. 99mTc-HMPAO was distributed in the territories of the ACA and MCA in the two patients who were treated with intraarterial infusion of papaverine from the C4 segment, but was distributed only to the territory of the ACA in four patients who were treated with intraarterial infusion of papaverine from the C1 segment at 1 ml/min. In contrast, 99mTc-HMPAO was distributed in the territories of the ACA and MCA in the three patients who were treated with papaverine from the C1 segment at 2 ml/min, although most 99mTc-HMPAO was distributed in the territory of the ACA. Vasospasm of the ACA can be treated by intraarterial infusion of papaverine from the C1 segment at 1 ml/min when selective catheterization to the ACA is difficult to perform.

Rete mirabile in humans--case report

Carotid rete mirabile is a physiological vascular network between the external carotid and internal carotid systems present in some vertebrate species, but rarely observed in humans. We describe a 17-year-old girl with rete mirabile who presented with subarachnoid hemorrhage. Angiography disclosed the bilateral internal carotid arteries (ICAs) ended at the cavernous portion, and abnormal arterial networks visualized via the ICAs and the external carotid arteries in the paracavernous region. The distal ICAs were visualized via the abnormal arterial networks. After 18 years of follow-up she is leading a normal life without neurological problems. Rete mirabile in humans may present with hemorrhage or ischemic symptoms, but the prognosis appears to be good.

Effect of isoflurane on motor-evoked potentials induced by direct electrical stimulation of the exposed motor cortex with single, double, and triple stimuli in rats

BACKGROUND

The clinical application of intraoperative motor-evoked potentials (MEPs) has been hampered by their sensitivity to anesthetics. Recently, to overcome anesthetic-induced depression of myogenic MEPs, multiple stimulus setups with a paired or a train of pulses for stimulation of the motor cortex were reported. However, the effects of anesthetics on MEPs induced by these stimulation techniques are unknown.

METHODS

Bipolar electrical stimulation of the left motor cortex was carried out in 15 rats anesthetized with thiopental while the compound muscle action potentials were recorded from the contralateral hind limb. After recording of the MEP in response to the single-shock stimulation of the motor cortex, paired pulses (double pulses) or a train of three pulses (triple pulses) with an interstimulus interval of each pulse at 0.3, 0.5, 1.0, 1.5, and 2.0 ms were applied. After control MEP recording, isoflurane was administered at a concentration of 0.25 minimum alveolar anesthetic concentration (MAC), 0.5 MAC, 0.75 MAC, and 1.0 MAC, and the effects of isoflurane on the MEPs induced by single, double, and triple pulses were evaluated.

RESULTS

In all animals, distinct baseline MEPs were recorded. During the administration of 0.25 MAC and 0.5 MAC isoflurane, MEPs induced by stimulation with a single pulse could be recorded in 87% and 33% of animals, respectively, and MEP amplitude was significantly reduced in a dose-dependent manner. During the administration of 0.75 MAC isoflurane, MEPs after single-pulse stimulation could not be recorded in any animals. By stimulating with paired or triple pulses, the success rate of MEP recording and MEP amplitude significantly increased compared with those after single pulse before and during the administration of isoflurane. Both the success rate of MEP recording and MEP amplitude after double- and triple-pulse stimulation decreased significantly in a dose-dependent manner during the administration of isoflurane.

CONCLUSIONS

Application of double or triple stimulation of the motor cortex increases the success rate of MEP recording and its amplitude during isoflurane anesthesia in rats. However, these responses are suppressed by isoflurane in a dose-dependent manner.

Pseudoankylosis of the mandible after supratentorial craniotomy

After temporal craniotomy, pseudoankylosis of the mandible can cause difficult airway management during subsequent anesthesia. However, postcraniotomy changes in maximal mouth opening and the incidence of limited mouth opening have not been characterized. Ninety-two adult patients who underwent elective craniotomy were divided into three groups: Group A (n = 28) included patients who underwent parietal, occipital, or frontal craniotomy without incision of the temporalis muscles; Group B (n = 25) included patients who underwent temporal craniotomy; and Group C (n = 39) included patients who underwent frontotemporal craniotomy. Maximal mouth opening (interincisor gap) and the frequency of limited mouth opening (maximum mouth opening < or = 2.5 cm) were evaluated before operation and 3 days, 1 wk, 2 wk, 1 mo, and 3 mo after operation. The three groups did not differ with respect to age, sex, body weight, height, operative time, anesthetic time, or maximum mouth opening before operation. The postoperative reduction in maximal mouth opening was significantly greater in Group C than in Group B. In Group C, the incidence of limited mouth opening was 33.3% and 20.5% 2 wk and 1 mo after operation, respectively; however, limited mouth opening resolved within 3 mo in most patients. Supratentorial craniotomies separated by short intervals can increase the risk of limiting the mandibular opening, which may result in a difficult intubation. Careful preoperative assessment of the airway is mandatory if patients have previously undergone temporal or frontotemporal craniotomy.

Evaluation of time-dependent thresholds of cerebral blood flow and transit time during the acute stage of cerebral embolism: a retrospective study

BACKGROUND

Neurons within the ischemic penumbra are thought to be in a potentially reversible state of ischemic challenge. One therapeutic approach that is being actively explored is the recovery of function of cells within the ischemic penumbra through endovascular recanalization of cerebral arteries occluded with embolus. The purpose of this study was to determine the time-dependent hemodynamic threshold for the prevention of irreversible ischemia in patients with acutely symptomatic internal and middle cerebral artery (MCA) embolism.

METHODS

Thirty-six patients admitted within 6 hours of the onset of symptoms of acute cerebral ischemia, due to embolic occlusion of the major trunk of one of the arteries of the anterior cerebral circulation, were studied. On admission, both cerebral blood flow (CBF) and mean transit time (MTT) measurements were obtained following plain computed tomography (CT). All patients were treated by intraarterial administration of urokinase. MTT in the territory of the affected MCA divided by that in the territory of the unaffected MCA was defined as %MTT.

RESULTS

A significant negative correlation was found between MTT and CBF. In patients with at least 19 mL/100 g/minute CBF and a maximum of 1.6 %MTT, no cortical infarction occurred whether or not recanalization was obtained. Cortical infarction did not appear in patients with 9 mL/100 g/minute residual CBF and infinite %MTT in whom recanalization was achieved within 2 hours of onset, in patients with 13 mL/100 g/minute residual CBF and 3.7 %MTT in whom recanalization was achieved within 2.5 hours of onset, and in patients with 14 mL/100 g/minute residual CBF and 2.8 %MTT in whom recanalization could be achieved within 3.5 hours of onset.

CONCLUSIONS

CBF and MTT thresholds for conversion of reversible to irreversible ischemia can be rapidly determined by CT-based technologies. This type of information should be clinically relevant to guiding the management of patients with cerebral embolism.

Selective angiography of the vertebral artery in the rabbit: technical note

BACKGROUND

Selective angiography of the vertebral arteries has not been performed in rabbit models. We used a tracker-10 microcatheter for selective vertebral artery angiography.

METHODS

Five Japanese male rabbits weighing 2.0 to 2.5 kg were used. The right femoral artery was identified and an 18-gauge Teflon catheter was introduced into the iliac artery. A Tracker-10 microcatheter was introduced through the 18-gauge Teflon catheter into the right vertebral artery under fluoroscopic guidance.

RESULTS

Selective angiograms of the right vertebral artery were obtained using a bolus injection of 0.1 mL of iopamidol in all five rabbits.

CONCLUSIONS

Selective vertebral artery angiograms could be obtained via the transfemoral route with the use of Tracker-10, and intraarterial selective administration of vasodilators will be achieved using our technique.

Omental transplantation using a superficial temporal artery previously used for encephaloduroarteriosynangiosis

BACKGROUND

Childhood moyamoya disease is a chronically progressive cerebrovascular occlusive disease affecting the territories of the anterior, middle, and posterior cerebral arteries. Surgery used in treatment of moyamoya disease to vascularize the brain include direct and indirect anastomoses.

METHODS

Intracranial omental transplantation (OMT) was performed using a branch of the superficial temporal artery (STA) that had been used previously for encephaloduroarteriosynangiosis (EDAS) in five children with moyamoya disease. All five children continued to have paraparetic transient ischemic attacks (TIAs), urinary incontinence, and/or progressive mental retardation even after EDAS and/or STA-middle cerebral artery (MCA) anastomosis and encephalomyosynangiosis (EMS) to the territory of the MCA. Previously performed EDAS gave insufficient collaterals to the territory of the MCA in four of the five patients and sufficient collaterals to the territory of the MCA in the remaining patient. OMT was performed after stripping of a branch of the STA used in EDAS that gave insufficient collaterals to the brain in the former four patients; and the latter patient was performed using a parietal branch of the STA distal to the distal burr hole drilled in the previous EDAS.

RESULTS

OMT resulted in marked improvement in neurologic conditions in all five patients. Four of the five patients suffered no TIAs postoperatively, while the remaining patient still had TIAs but at a markedly decreased frequency.

CONCLUSIONS

In summary, OMT using a branch of the STA used in previously performed EDAS is required for patients with moyamoya disease who continue to manifest paraparesis, urinary incontinence, and/or progressive mental retardation even after multiple EDAS.

Preoperative predictors of reduction in arterial blood pressure following dural opening during surgical evacuation of acute subdural hematoma

To determine preoperative predictors of blood pressure reduction following dural opening during surgical evacuation of hematoma, we retrospectively assessed preoperative variables including clinical profile, hemodynamic parameters, neurological findings, and computed tomography (CT) scan results in 56 patients with traumatic acute subdural hematoma (ASDH). Patients were divided into two groups according to the degree of changes in mean arterial pressure (MAP) in response to dural opening. Group A (n = 18) had a MAP reduction > 20%, and group B (n = 38) had a MAP change within +/- 20% of baseline values (5 min before opening the dura). Significant relationships were found between MAP reductions > 20% and Glasgow coma scale (GCS) scores, abnormalities of the mesencephalic cistern on CT scan, pupillary abnormalities, and degree of midline shift. Low GCS score, absence of the mesencephalic cistern on CT scan, and bilaterally dilated pupils were particularly strong predictors of this amount of blood pressure reduction. The clinical outcomes of patients with MAP reduction > 20% following dural opening during surgery were significantly poorer than those of patients without this amount of blood pressure reduction. Our findings suggest that blood pressure reduction following opening of the dura in patients undergoing surgical evacuation of hematoma for traumatic ASDH may be predicted by careful preoperative assessment of neurological and CT scan findings.

Intraoperative myogenic motor evoked potentials induced by direct electrical stimulation of the exposed motor cortex under isoflurane and sevoflurane

We monitored myogenic motor evoked potentials (MEPS) during intracranial surgery in 21 patients anesthetized with nitrous oxide in oxygen, fentanyl, and 0.75-1.5 minimum alveolar anesthetic concentration (MAC) isoflurane (n = 11) or sevoflurane (n = 10). The exposed motor cortex was stimulated with a single or train-of-five rectangular pulses at a high frequency (500 Hz), while the compound muscle action potentials (CMAPS) were recorded from the abductor pollicis brevis muscle. Neuromuscular block was monitored by recording the CMAPs from the abductor pollicis brevis muscle in response to electrical stimulation of the median nerve at the wrist (M-response). Stimulation of the motor cortex with a single pulse elicited MEPs in none of the patients, while stimulation with a train-of-five rectangular pulses at high frequency elicited MEPs in all patients. The relationship between MEP amplitude and the level of neuromuscular block induced by vecuronium infusion was evaluated in seven patients. For comparison of the individual measurements, the MEP amplitude at a M-response amplitude of 100% was calculated by means of the individual regression curve as 100% of MEP amplitude. There was a linear correlation between percent MEP amplitude and percent M-response amplitude (r = 0.81; P < 0.01). Intraoperative monitoring of MEP could be performed at a M-response amplitude above 90 % of the baseline value in 10 patients and at a M-response amplitude of 20%-50% of the baseline value in 11 patients. During monitoring of the 21 patients, MEPs did not change in 18 patients and disappeared in two patients. In the remaining patient, MEP amplitudes were attenuated to approximately 10% of the baseline value and recovered after cessation of surgical manipulation. In the two patients in whom MEPs disappeared, motor paresis developed postoperatively. We conclude that 1) intraoperative myogenic MEP monitoring is feasible during isoflurane or sevoflurane anesthesia if stimulation is performed with a short train of rectangular pulses, and 2) that electromyographic monitoring of neuromuscular block is useful to assess intraoperative MEP changes under partial neuromuscular block.

Preoperative and postoperative evaluation of cerebral perfusion and vasodilatory capacity with 99mTc-HMPAO SPECT and acetazolamide in childhood Moyamoya disease

BACKGROUND AND PURPOSE

The results of long-term follow-up studies of cerebral perfusion and vasodilatory capacity following administration of acetazolamide after serial vascular reconstructions in 25 patients with childhood moyamoya disease are reported.

METHODS

Cerebral perfusion was measured with 99mTc-hexamethylpropyleneamine oxime single-photon emission CT before and after IV administration of 10 mg/kg acetazolamide, which was performed both before and after vascular reconstruction by superficial temporal artery-middle cerebral artery anastomosis and encephalomyosynangiosis (first and second operations) and/or omental transplantation to the brain (third operation).

RESULTS

Follow-up periods ranged between 12 and 24 months (mean +/- SD, 18.5 +/- 3.2 months) after the first operation. Repetitive transient ischemic attacks disappeared completely after serial vascular reconstructions in all patients. Before the first operation, cerebral perfusion in the territory of the middle cerebral artery on the side of initial operation was 83.9 +/- 4.7% and was significantly lower than that in the contralateral side (88.3 +/- 4.9%, n = 25; P < .0001, paired t test). Vasodilatory capacity on the side of the first operation was -18.4 +/- 2.5% and that on the contralateral side -14.4 +/- 2.1%. The former value was significantly lower than the latter value (n = 25; P < .0001, paired t test). After the first operation, cerebral perfusion and vasodilatory capacity on the side of initial operation were markedly improved, to 87.8 +/- 4.5% and -14.7 +/- 2.7%, respectively (n = 25; P < .0001, both cases, paired t test). Before the second operation, cerebral perfusion and vasodilatory capacity on the side of the second operation were 76.6 +/- 4.1% and -20.1 +/- 1.9%, respectively, and significantly lower than those before the first operation (n = 25; P < .0001, both cases, paired t test). Eight patients subsequently required bifrontal omental transplantation for repetitive paraparetic transient ischemic attacks after the second operation; they had low cerebral perfusion and vasodilatory capacity bilaterally in the territories of the anterior cerebral arteries (72.4 +/- 2.7% and -18.6 +/- 1.7%, respectively). After omental transplantation, both were significantly increased, to 81.9 +/- 3.4% and -11.8 +/- 1.9%, respectively (n = 25; P < .0001, both cases, paired t test).

CONCLUSIONS

Hemodynamic compromise existed in patients with childhood moyamoya disease and was a major cause of development of ischemic symptoms. Regions in which hemodynamic compromise was present could be determined by measuring regional cerebral perfusion and vasodilatory capacity.

Endovascular treatment with an ultra-thin 4-French guiding catheter via the transfemoral and transbrachial routes--technical note

An ultra-thin-walled 4-French catheter was used for angiography and as a guiding catheter for the Tracker-18 microcatheter in patients with intracranial dural arteriovenous fistulas (AVFs), spinal dural AVFs, spinal epidural AVF, meningioma, and acute embolic occlusion of major cerebral vessels. The 4-French guiding catheter was introduced through the transfemoral or transbrachial route. The guiding catheter and the guidewire were advanced to the aortic arch and then turned over just above the aortic valves, and finally the catheter was introduced into the external carotid artery or vertebral artery when the transbrachial approach was selected. Images of the intracranial vessels and spinal dural branches obtained were excellent in all cases. The Tracker-18 could smoothly be advanced to the target artery through the 4-French catheter in all patients. Endovascular treatment with the Tracker-18 can be performed using an ultra-thin 4-French guiding catheter, and safely via the transbrachial route.

Assessment of delayed cerebral vasospasm using intracisternal echography--technical note

BACKGROUND

A new technique using intravascular ultrasound has been used for diagnosis of coronary artery in order to obtain intravascular echo images. In this study, an intracisternally positioned ultrasound catheter was introduced obtaining serial echo images of the first segment (MI) of the middle cerebral artery in order to detect cerebral vasospasm following subarachnoid hemorrhage (SAH).

METHODS

Thirteen patients were admitted to Osaka Neurological Institute with SAH due to ruptured intracranial aneurysm. All patients underwent surgical neck clipping on the day of admission. In each patient, an 8 Fr. ultrasound imaging catheter (Cardiovascular Imaging Systems, Inc. (CVIS), Sunnyvale, CA) was detained intracisternally adjacent to the M1 segment following neck clipping of the aneurysm and placement of cisternal drainage(s) in the prepontine and/or distal portion of the Sylvian fissure. In order to detain the mirro device near the M1 segment, the tip of a 2.0 cm cisternal drainage tube (SILASCON, E-3L-12, Kaneka Medix Co, Osaka, Japan) was attached to the tip of the intravascular ultrasound catheter with 3-0 silk suture. The tip was placed in the prechiasmal cistern.

RESULTS

Angiographic evidence of delayed vasospasm was obtained for three (23.1%) of the 13 patients. In one (33.3%) of the three patients who had angiographic evidence of vasospasm (25% stenosis), decrease in the inner diameter of the M1 segment was detected on the echo images, but in the other two (66.7%), no such decrease was noted on echo images. Angiographically identified vasospasm in the latter patients was associated with only 10% stenosis.

CONCLUSIONS

Intracisternally positioned ultrasound catheter can be used for intermittent measurement of the diameter of a target artery for detection of cerebral vasospasm after SAH.

Anastomosis of occipital artery to posterior cerebral artery with interposition of superficial temporal artery using occipital interhemispheric transtentorial approach: case report

BACKGROUND

Superficial temporal artery (STA)-superior cerebellar artery (SCA) anastomosis, and STA-posterior cerebral artery (PCA) anastomosis are considered suitable as surgical procedures for the treatment of patients with significant stenosis or occlusion in the rostral portion of the basilar artery and patients with significant stenosis or occlusion of the posterior cerebral artery, respectively. However, several authors have reported frequent and serious complications of these surgical procedures, including temporal lobe retraction edema and hematoma. In this study, we introduce a new surgical revascularization using an occipital interhemispheric transtentorial approach for the treatment of severe stenosis of the rostral portion of the basilar artery.

CASE REPORT

A 47-year-old man with hypertension noted the sudden onset of nuchal pain followed by vertigo, diplopia, drunken gait, and motor weakness on his right side. Angiography performed on the day of the onset disclosed severe stenosis of the basilar artery. The stenotic portion extended just distal to the anterior-inferior cerebellar artery (AICA) to just proximal to the SCA, and in addition, a pseudolumen was visualized just distal to the left AICA. The patient underwent right occipital artery (OA) to left PCA anastomosis with interposition of the STA using an occipital interhemispheric transtentorial approach. Marked improvement in dysarthria, diplopia, ataxia gait, and visual disturbance were noted and he was able to walk without aid 3 days after operation. A postoperative angiogram of the right OA obtained 25 days after operation demonstrated visualization of the left PCA via the anastomosed OA and STA graft.

CONCLUSIONS

OA-PCA anastomosis with interposition of STA graft using an occipital interhemispheric transtentorial approach can be substituted for STA-SCA anastomosis and STA-PCA anastomosis for treatment of stenosis/occlusion of the rostral portion of the basilar artery.

Do recently developed techniques for skull base surgery increase the risk of difficult airway management? Assessment of pseudoankylosis of the mandible following surgical manipulation of the temporalis muscle

We report our experience with anesthetic care for six patients with pseudoankylosis of the mandible following neurosurgical procedures, four of whom required fiberoptically guided intubation for anesthesia. We suggest that the development of operative approaches and reconstruction techniques in skull base surgery may increase the risk of difficult airway due to limitation of mouth opening.

Hemodynamic evaluation of spinal arteriovenous malformations before and after embolization--preliminary report

This preliminary study investigated local hemodynamic changes in intramedullary spinal arteriovenous malformation (AVM) before and after embolization. 99mTcO4- was injected into the anterior spinal artery feeding the AVM via a Tracker-10 or MAGIC microcatheter. Time-dependent radioisotope images were sequentially obtained in the anteroposterior plane every 0.2 sec before and just after embolization. Local mean transit time (MTT) was then calculated for both the nidus and draining vein and compared before and after embolization. Prior to embolization, MTTs in the nidus and in the draining vein were 1.84 +/- 0.62 (mean +/- SD) and 2.80 +/- 0.69 sec for the five patients, respectively. MTTs in both the nidus and the draining vein were significantly prolonged after embolization to 3.32 +/- 1.14 and 4.90 +/- 0.93 sec, respectively (p < 0.02 and p < 0.005, respectively). In vivo measurements of local hemodynamic changes in the spinal cord during the treatment of spinal AVMs could be achieved. This method may allow investigation of the hemodynamic mechanisms which induce ischemic symptoms in patients with spinal AVM.

Haemodynamic evaluation of paraparetic transient ischaemic attacks in childhood moyamoya disease

The haemodynamic mechanisms responsible for the appearance of paraparetic transient ischaemic attacks in ten patients with childhood moyamoya disease who subsequently underwent bifrontal omental transplantation were investigated. Cerebral perfusion (CP) was measured with 99mTc-hexamethylene-propyleneamine oxime single photon computed tomography prior to and after administration of acetazolamide. Cerebral perfusion was obtained by dividing radioisotope uptake per pixel in regions of interest by that in cerebellum. Haemodynamic reserve was defined as [CP after acetazolamide--CP before acetazolamide]/CP before acetazolamide x 100. Amounts of CP in the anterior portion of the frontal lobe and in the paracentral lobule were 0.70 +/- 0.04 and 0.74 +/- 0.03, respectively, before appearance of the transient ischaemic attacks. The latter was significantly higher than the former (p < 0.0001). Haemodynamic reserves were -11.1 +/- 2.8 and -9.6 +/- 3.0, respectively, at that time. These two parameters were significantly decreased just after paraparetic transient ischaemic attacks and two parameters in the paracentral lobule were more decreased than those in the anterior portion of the frontal lobe. But these increased again after bifrontal omental transplantation in these two regions. In summary, the watershed region was located anterior to the paracentral lobule before appearance of the transient ischaemic attacks, and widened and moved backward to include the paracentral lobule just before their appearance.

Treatment of type II perimedullary arteriovenous fistulas by intraoperative transvenous embolization: case report

BACKGROUND Perimedullary arteriovenous fistulas (AVFs) are abnormal vascular connections between medullary arteries and veins without an intervening nidus. It is thought to be difficult to treat Type II AVFs which have multiple feeding branches. We performed intraoperative transvenous embolization to treat Type II AVFs. CASE REPORT A 30-year-old man with Type II perimedullary arteriovenous fistulas (AVFs), present at the level of the L-1 vertebral body, underwent surgical and endovascular treatment. The patient displayed slight motor weakness (4/5) and slight hypesthesia in the right lower extremity. Angiograms demonstrated that an anterior spinal artery and posterior spinal arteries were feeding arteries for the perimedullary AVFs. The patient underwent surgical occlusion of the fistulas three times. Fistulas present on the dorsal surface of the spinal cord were occluded with hemoclips, while those located on the ventral and ventolateral aspect of the spinal cord were occluded transvenously with isobuthyl-2-cyanoacrylate (IBCA) during surgery. Total occlusion of the perimedullary AVFs was achieved with these procedures, and no change was noted postsurgically in the patient's symptoms. CONCLUSIONS In summary, Type II perimedullary AVFs are sometimes difficult to treat using either embolization or open surgery. In such cases, both open surgery and intraoperative transvenous embolization should be performed in order to obtain occlusion of multiple fistulas.

Preoperative evaluation for risk of venous air embolism in the sitting position

We report a patient with meningioma and radiological findings of erosive bony change, who developed venous air embolism via the diploic vein in the eroded inner table of the skull during craniotomy in the sitting position. The findings in our case suggest that preoperative radiological imaging evaluation can increase an awareness of the possibility of venous air embolism.

An intra-arterial electrode for intracranial electro-encephalogram recordings

A new method for intracranial monitoring of brain electrical activity by means of an intra-arterial guide wire as electrode is described. We carried out intracranial electro-encephalography (EEG) using an insulated Seeker Lite-10 guide wire 18 times in 14 patients: ten times in 6 patients with cerebral arteriovenous malformation (AVM) before embolization, and another 8 times in 8 patients with epilepsy. In all cases, a 2-5 times stronger high voltage potential EEG compared with scalp EEG could be recorded. In 3 patients with complex partial epilepsy, intra-arterial (IA) EEG was recorded under subdural strip electrode monitoring, and IAEEG at the sphenoidal portion of the middle cerebral artery was compared with subdural electrode recordings. Frequent interictal spike discharges recorded with subdural electrodes in the lesional medial temporal lobe were simultaneously visible on IAEEG recording. This method is equivalent to that using a semi-invasive electrode, but ECoG recording can be performed at angiography. IAEEG is a method of electrode recording that has the possibility of clinical application.

Cerebral revascularization using gracilis muscle transplantation for childhood moyamoya disease

BACKGROUND

Omental transplantation is effective in the management of ischemia in the territories of the anterior and posterior cerebral arteries in childhood moyamoya disease. We introduced a surgical revascularization using gracilis muscle transplantation to these territories.

METHODS

Between January 1991 and May 1993, six children with moyamoya disease, between the age of 3 and 13 years, underwent gracilis muscle transplantation to the territory of either the anterior or the posterior cerebral artery. The mean period of follow-up after surgery was 15.2 months, with a range of 5 to 32 months. Three of the six patients had suffered from frequent transient visual disturbance and were treated with unilateral or bilateral gracilis muscle transplantation to the territory of the posterior cerebral artery. The other three patients had suffered from frequent transient paraparesis, mental retardation, and/or rectal and urinary incontinence, and were treated with gracilis muscle transplantation bilaterally to the territories of the anterior cerebral arteries.

RESULTS

All three patients with gracilis muscle transplantation unilaterally or bilaterally to the occipital lobes manifested complete disappearance of their symptoms. Two of the three patients with gracilis muscle transplantation bilaterally to the frontal lobes also manifested complete disappearance of their symptoms. The remaining patient who underwent the transplantation bilaterally to the frontal lobes, continued to have episodes of transient paraparesis, postsurgically, but the frequency of symptoms was markedly decreased.

CONCLUSIONS

Ischemia in the territories of the anterior and/or posterior cerebral arteries could be overcome with the use of gracilis muscle transplantation in childhood moyamoya disease.

Intraoperative electrophysiologic monitoring of cranial motor nerves in skull base surgery

BACKGROUND

Intraoperative cranial nerve monitoring has been applied for the preservation of nerve function during skull base surgery. However, its usefulness is controversial because clinical results reported are limited.

METHODS

We evaluated the usefulness of intraoperative electrophysiologic monitoring of the third to seventh cranial motor nerves in 15 patients undergoing skull base surgery. Intracranial bipolar electrical stimulation of each nerve was performed, and compound muscle action potentials (CMAP) were recorded from the innervated muscles.

RESULTS

CMAPs were successfully recorded from 23 of the innervated muscles. The loss of the CMAP response during the manipulation of lesions or high stimulus intensity at the end of manipulation seem to be related to the postoperative deficits of nerve function.

CONCLUSIONS

The results suggest that intraoperative electrophysiologic monitoring of cranial motor nerves is useful for prediction of postoperative nerve function.

Percutaneous transluminal angioplasty for severe stenosis of the posterior cerebral artery: case report

The Stealth dilation catheter was used for the intravascular treatment of a patient who had hemodynamically significant stenosis of the posterior cerebral artery and had a history of recurrent transient ischemic attacks associated with right hemiparesis and ipsilateral hemianopia dating from March 1993. Cerebral perfusion studies prior to and after the intravenous administration of acetazolamide demonstrated regions of moderately low perfusion and low hemodynamic reserve in the territories of the left middle and posterior cerebral arteries. Cerebral angiograms demonstrated severe stenosis of the left posterior cerebral artery and occlusions of both middle cerebral arteries, which had leptomeningeal anastomoses with the posterior cerebral arteries. Percutaneous transluminal angioplasty (PTA) was performed using the Stealth catheter on the stenotic segment of the left posterior cerebral artery after left superficial temporal artery-middle cerebral artery anastomosis. The patient manifested marked improvement in her neurologic condition just after PTA, in association with marked increase in cerebral perfusion and hemodynamic reserve in the territories of the left middle and posterior cerebral arteries. We have presented evidence that PTA can be used to treat patients with stenosis of the first segment of the posterior cerebral artery and hemodynamic compromise in the territory that artery supplies.

Traumatic arteriovenous fistula treated by superselective embolisation with microcoils: case report

A 27-year-old man with a traumatic direct dural arteriovenous fistula (DAVF) was treated using embolisation microcoils. He had suffered blunt trauma to the head while drunk and was aware of no neurological deficit. A few days after the accident, however, he noticed a bruit in the right temple. Angiography demonstrated a direct DAVF fed by the right middle meningeal artery and draining into a right temporal dural vein and the ipsilateral cavernous sinus. A Tracker-18 catheter was passed without difficulty through the fistula and the draining vein was then embolised from distal to proximal with microcoils, and finally the fistula was occluded with microcoils, resulting in total obliteration of the fistula. Immediately after the embolisation, the patient could no longer hear the bruit. Thus, when a microcatheter can be introduced into the draining vein, microcoils can be used as emboli in the treatment of direct DAVF.

Total excision of a thalamic arteriovenous malformation using an orbito-fronto-malar approach: case report

A 37-year-old woman was admitted to Osaka Neurological Institute after the sudden onset of left hemiplegia, hemihypesthesia, and ipsilateral hemianopia on February 4, 1992. Computed tomography (CT) disclosed the presence of hemorrhage in the right thalamus extending to the ipsilateral internal capsule. Cerebral angiography after CT scanning disclosed the presence of a cerebral arteriovenous malformation (AVM) fed by copsulothalamic and lateral geniculate body arteries originating from the right anterior choroidal artery. She was operated on with removal of the AVM using a right orbito-fronto-malar approach (OFM approach), which did not require transection of the cerebral parenchyma. The anterior choroidal artery could be followed distally from its origin and small feeding branches originating from the parent artery were easily identified, and the cerebral base could be examined in greater detail than with the conventional frontotemporal approach. The nidus could be excised in its entirety without difficulty. Postoperative angiography confirmed total excision of the AVM. She was transferred to another hospital for rehabilitation on April 13, 1992. Motor strength on the left side had improved to 3/5 by that time. The OFM approach appears to be potentially useful for the resection of inferolateral thalamic AVMs, because it does not require corticotomy and feeding branches can be identified and dealt with prior to other surgical manipulations.

Pituitary adenoma invading the skull base--a strategy for skull base surgery

A strategy for surgical management, including the approach and preoperative evaluation, of pituitary adenoma invading the skull base is described. Preoperative evaluation requires a balloon occlusion test of the internal carotid artery (ICA) to determine tolerance to occlusion. Failure to tolerate occlusion indicates administration of brain protective agents and/or a bypass procedure before tumor removal. The transsphenoidal, pterional, orbitofrontomalar, and infratemporal fossa approaches are all suitable for various tumor locations. A combined orbitofrontomalar and extended frontal approach allows removal of tumor with extensive invasion and is suitable for bypass procedures. Preoperative evaluation of ICA occlusion can prevent development of hemodynamic stroke. We treated five patients with pituitary adenoma invading the skull base, including two primary and three recurrent cases. All symptoms improved, but temporary oculomotor nerve disturbance occurred in three patients and anosmia in one. Reoperations for recurrent pituitary adenomas were effective in reversing the symptoms. No hemodynamic stroke was seen postoperatively. These tumors, except for drug-responsive cases, are indicated for skull base surgery.

Vasculopathy of the anterior choroidal artery following intra-arterial chemotherapy--case report

A 40-year-old male, treated with radiotherapy and supraophthalmic intracarotid artery (ICA) ACNU infusion for glioblastoma in the right occipital lobe, developed cerebral infarction secondary to vasculopathy manifesting as hemiparesis 3 months after a second ICA injection. The initial diagnosis was focal neurotoxicity, but angiography revealed severe vasospasm of the anterior choroidal artery. The symptoms improved gradually with therapy for the vasospasm. Angiography is required to discriminate vasospasm and focal neurotoxicity as a complication of ICA injection of antineoplastic agents.

Cerebellar primary germ-cell tumor in a young boy

Germ cell tumors originating in the posterior fossa are very rare. Described herein is a case of primary germ cell tumor (yolk sac tumor) found in the cerebellar vermis. A 5-year-old boy who complained of headache was admitted. CT and MRI revealed a tumor with diffuse enhancement by contrast medium in the right cerebellar vermis. Total removal was performed and a diagnosis of medulloblastoma or ependymoma was suspected. However, the tumor proved to be a yolk sac tumor with embryonal carcinomatous components from histological findings. Abnormally high levels of alpha-fetoprotein were found in blood and cerebrospinal fluid. Extensive examination indicated that the intracranial lesion had not metastasized from a primary extracranial tumor.

Lateral approach for anterior thoracic spinal lesions

A lateral approach, consisting of a modified transversectomy, hemilaminectomy, and adequate transversectomy with costectomy of 7-8 cm, was used to treat four cases of anterior or anterolateral thoracic lesions, including two cases of thoracic disc herniations, one of thoracic meningioma, and one of hypertrophic pachymeningitis. All patients presented with gait disturbance, but recovered well postoperatively except for one who needed rehabilitation of the lower extremities. This approach provides a greater access to the anterior thoracic canal, and can achieve effective anterior decompression, and a good outcome for thoracic spinal disease if recognized early.

Dural arteriovenous fistula caused by sinus thrombosis--case report

A 58-year-old male with a history of idiopathic sinus thrombosis presented with gradual onset of gait disturbance, dementia, and involuntary movement in the upper extremities. Cerebral angiography demonstrated a dural arteriovenous fistula fed by a falx cerebelli branch originating from the left vertebral artery and draining into the inferior vermian vein, the straight sinus, a cortical vein lying on the inferolateral surface of the left cerebellar hemisphere, the ipsilateral superior petrosal sinus, the sigmoid sinus, and the internal jugular vein. Endovascular embolization under fluoroscopic control resulted in complete disappearance of the involuntary movement. Sinus thrombosis may result in development of dural arteriovenous fistula which can cause life-threatening complications, so aggressive therapy should be considered.

Intravascular treatment of spinal arteriovenous malformations using a microcatheter--with special reference to serial xylocaine tests and intravascular pressure monitoring

Spinal arteriovenous malformations (spinal AVMs) are now treated using microcatheters and various embolic materials. Interventional techniques of this type are thought to be the first choice for treatment of spinal AVMs. In this study, we used the Tracker vascular access system and MAGIC catheter for intravascular treatment of spinal AVMs in order to avoid proximal occlusion. Notably, serial provocation tests using xylocaine (20 mg in bolus) and intermittent intravascular pressure monitoring in the anterior spinal artery were conducted during embolizations of five intramedullary AVMs. We used 150-350 microns polyvinyl alcohol particles (Ivalon) and/or polyvinyl alcohol (PVA) solutions as embolic materials for occlusion of these AVMs. Vital signs and neurologic functions were carefully monitored during and after the procedure. We were able totally to obliterate the nidus or markedly to reduce its size while preserving the anterior spinal artery in each of the patients. The xylocaine test was conducted an average of 2.6 times (2-4 times) during embolization. For the two patients who were treated with Ivalon and PVA solutions, the final provocation test became positive, and the embolization procedure was terminated. On the other hand, the remaining patients had a positive result on first xylocaine test and were treated with Ivalon alone. At the same time, intravascular pressure monitoring was performed via the microcatheter, which was located in the anterior spinal artery. The value of the intravascular systolic pressure prior to embolization was 71.6 +/- 14.1 mm Hg and it gradually increased during the procedure, and reached 99.6 +/- 12.6 mm Hg (90% of the systemic systolic blood pressure) by the conclusion of embolization. Serial xylocaine tests and intravascular pressure monitoring may be useful for the treatment of spinal AVMs fed mainly by the anterior spinal artery, and embolization with liquid embolic material should be terminated when the provocation test becomes positive and intravascular pressure increased to 90% of the systemic blood pressure.

Successful intra-arterial fibrinolysis of the anterior choroidal artery in the acute stage of internal carotid artery occlusion: case report

A 27-year-old man was admitted to our institution with the sudden development of right hemiparesis and dysarthria beginning an hour after the onset of symptoms on August 9, 1992. The patient was found on admission to have right hemiparesis (2/5), hemihypesthesia, hemianopia, dysarthria; he had transient atrial fibrillation. No abnormalities were detected on computed tomography (CT) scans, and cerebral blood flow studies undertaken following conventional CT scans revealed no low flow regions in the left cerebral hemisphere. But cerebral angiography disclosed an occlusion of the left internal carotid artery with well-developed cross-circulation via the anterior communicating artery and embolus lodged at the level of the anterior choroidal artery. Superselective fibrinolysis using Tracker-18 and 420,000 units of urokinase resulting in complete recanalization of the left anterior choroidal artery without distal migration of the embolus. Immediately after the procedure, his neurologic disturbance underwent complete resolution. In summary, fibrinolysis could be performed but limited to anterior choroidal artery in a case with an occlusion of the internal carotid artery with well-developed cross-flow via the anterior communicating artery; the patient's neurologic condition may deteriorate suddenly if fibrinolysis is incomplete and the embolus migrates to the internal carotid artery.

Percutaneous transluminal angioplasty of stenotic primitive hypoglossal artery--case report

A 76-year-old female presented with vertebrobasilar insufficiency due to a severe stenosis of the right primitive hypoglossal artery (an unusual carotid-basilar anastomosis) manifesting as recurrent transient ischemic attacks (TIA) associated with quadriparesis and cerebellar ataxia with vertigo, nausea, and vomiting. She had been treated with 100 mg of aspirin per day, but TIA associated with the same symptoms persisted. Cerebral blood flow (CBF) studies disclosed a region of moderately low flow in the posterior fossa. Cerebral angiography demonstrated that the posterior fossa was supplied via the right primitive hypoglossal artery, which was severely stenotic at its origin. Percutaneous transluminal angioplasty using a Stealth catheter, 3.0-mm diameter and 10-mm long, successfully dilated the stenosis. No TIA occurred postoperatively, and a marked increase in CBF was demonstrated in the posterior fossa.

Percutaneous transluminal angioplasty for acute stroke due to stenosis of major cerebral vessels: report of two cases

The Stealth dilation catheter was introduced for the intravascular treatment of two patients with acute and unstable ischemic stroke due to hemodynamically significant stenosis in the one case of the middle cerebral artery and in the other of the vertebral artery. Cerebral perfusion study on the two cases showed a moderately low flow area in the right cerebral hemisphere and in the left cerebellar hemisphere, respectively. Percutaneous transluminal angioplasty (PTA) using the Stealth catheter was conducted. The two cases showed marked improvement in their neurologic state just after PTA with marked increase in cerebral perfusion in the relevant regions.

[Intraoperative monitoring in patients undergoing surgery of lesions involving the cavernous sinus]

We reviewed the intraoperative monitoring and anesthesia in 45 patients, who had undergone operation of lesions involving the cavernous sinus between September, 1990, and May, 1993. The patient was placed in a 30 degree of head-up position to reduce the bleeding from the cavernous venous plexus. However, air embolism during the operation has not been noted in any patients. In 13 of 45 patients, a transient or permanent internal carotid artery (ICA) occlusion was performed intraoperatively under the brain protection by thiopental and the monitoring of electroencephalograph, somatosensory evoked potentials, local cerebral blood flow, and oxygen saturation of internal jugular vein. There has been no complications related to the ICA occlusion. In 7 patients, intraoperative recordings of evoked extraocular muscle activities were undertaken to monitor ocular motor nerve function. Responses from the inferior rectus muscle to the oculomotor nerve stimulation, and from the lateral rectus muscle to the abducens nerve stimulation, were obtained in 5 patients and 1 patient, respectively. Intraoperative neurophysiological monitoring in the surgery of lesions involving the cavernous sinus is crucial to reduce the surgical complications, and a team approach, including neurosurgeons, anesthesiologists, and medical engineers, is important for the future progress.