Hideyuki Ohnishi

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.

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. (Anesth Analg 1996;82:593-9)

Surgical reconstruction of failed indirect anastomosis in childhood Moyamoya disease.

Thirty-one patients with moyamoya disease, who had been treated for encephaloduroarteriosynangiosis (EDAS), encephalomyosynangiosis (EMS) or EMS with encephaloarteriosynangiosis (EAS) in other hospitals, were admitted to Osaka Neurological Institute from January 1985 to September 1991. Twenty-seven of 57 sides treated by indirect anastomosis showed good filling of the middle cerebral artery (MCA) territory via the anastomosis, whereas 16 and 14 showed fair and poor collaterals via the anastomosis, respectively. Twenty-eight cerebral hemispheres treated by indirect anastomosis underwent further surgery and received superficial temporal artery-MCA anastomosis with or without EMS for still-existent recurrent transient ischemic attacks or completed stroke even after the indirect anastomosis. One patient still had recurrent transient ischemic attacks with quadriparesis after bilateral encephaloduroarteriosynangiosis, which had produced no effective collaterals in the MCA territory; the patient then underwent omental transplantation to the bilateral anterior cerebral artery and MCA territories, resulting in the cessation of the transient ischemic attacks. Clinical improvement after superficial temporal artery-MCA anastomosis with or without EMS was noted in all patients, except on one side, where a completed stroke had resulted in fixed neurological deficits. We do not know the reasons for the uncertainty of the development of collaterals via the indirect anastomosis, but there are many patients who still need direct reconstruction of the indirect anastomosis.

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.

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.

Classification of the Superior Petrosal Veins and Sinus Based on Drainage Pattern

BACKGROUND: The increasing number of reports of complications after sacrificing the superior petrosal veins, the largest veins in the posterior fossa, has led to a need for an increased understanding of the anatomy of these veins and the superior petrosal sinus into which they empty. OBJECTIVE: To examine the anatomy of the superior petrosal veins and their size, draining area, and tributaries, as well as the anatomic variations of the superior petrosal sinus. METHOD: Injected cadaveric cerebellopontine angles and 3-dimensional multifusion angiography images were examined. RESULTS: The 4 groups of the superior petrosal veins based on their tributaries, course, and draining areas are the petrosal, posterior mesencephalic, anterior pontomesencephalic, and tentorial groups. The largest group was the petrosal group. Its largest tributary, the vein of the cerebellopontine fissure, was usually identifiable in the suprafloccular cistern located above the flocculus on the lateral surface of the middle cerebellar peduncle. The medial or lateral segment of the superior petrosal sinus was absent in 40% of cerebellopontine angles studied with venography. CONCLUSION: The superior petrosal veins and their largest tributaries, especially the vein of the cerebellopontine fissure, should be preserved if possible. Obliteration of superior petrosal sinuses in which either the lateral or medial portion is absent may result in loss of the drainage pathway of the superior petrosal veins. Preoperative assessment of the superior petrosal sinus should be considered before transpetrosal surgery in which the superior petrosal sinus may be obliterated. ABBREVIATION: CPA, cerebellopontine angle

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=to2.5 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. (Anesth Analg 1996;83:731-4)

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.

Cortical blood flow response to hypercapnia during anaesthesia in Moyamoya disease

Cortical blood flow (CoBF) was measured continuously by the laser-Doppler method to evaluate the effect of hypercapnia on cortical blood flow during ten surgical procedures in ten young patients (mean ± SD 9.3 ± 6.4 yr) with Moyamoya disease. The CoBF was 42.8 ± 13.4 (ml·100 g−1. min−1) during normocapnia (PaCO2 = 39.0 ± 2.4 mmHg), and 38.7 ± 14.4 during hypercapnia (PaCO2 = 47.1 ± 2.5 mmHg). There was a decrease in CoBF with hypercapnia (P < 0.05) so that the normal CoBF response to hypercapnia was impaired during surgery in the patients with Moyamoya disease. He concluded that patients with Moyamoya disease have a precarious cerebral circulation and hypercapnia may be detrimental to the cortical circulation. This suggests that normocapnia is preferable to hypercapnia in patients with Moyamoya disease during anaesthesia.RésuméPendant dix interventions chirurgicales pratiquées chez dix jeunes patients (âge moyen 9,3 ± 6,4 ans) souffrant de la maladie de Moyamoya, le débit sanguin cortical (DSCo) est mesuré continuellement par la méthode Laser-Doppler dans le but d’évaluer les effets de l’hypercapnie sur le débit sanguin cortical. Le DSCo (ml·100 g−1· min−1) est de 42,8 ± 13,4 pendant la normocapnie (PaCO2 = 39,0 ± 2,4 mmHg) et de 38,7 ± 14,4 pendant l’hypercapnie (PaCO2 = 47,1 ± 2,5 mmHg). La baisse du débit pendant hypercapnie est significative (P < 0,05). Ce qui démontre que la réponse du débit sanguin cérébral est perturbée pendant la chirurgie de la maladie de Moyamoya. On conclut que cette maladie a une influence néfaste sur la circulation cérébrale pendant l’hypercapnie. Ceci suggère que dans la maladie de Moyamoya, la normocapnie est préférable à l’hypercapnie.

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.