Toru Hoshida

Benefit of simultaneous recording of EEG and MEG in dipole localization

Summary:  Purpose: In this study, we tried to show that EEG and magnetoencephalography (MEG) are clinically complementary to each other and that a combination of both technologies is useful for the precise diagnosis of epileptic focus.

Management of dissecting aneurysms of the posterior circulation

SummaryWe analysed the clinical presentation, treatment and outcome of our own 36 cases of posterior circulation dissecting aneurysms (DA) and discussed the surgical indications and procedures regarding posterior fossa DA. Twenty one cases were male, 15 cases were female. Their mean age was 54±14 years. Clinical manifestations were subarachnoid haemorrhage (SAH) in 14 cases (39%) and ischaemic attacks in 22 cases (61%). Three of 14 SAH cases had rebleeding in the acute stage. Angiographic findings were aneurysmal dilatation in 16 cases, retention of contrast medium in 12 cases, string sign in 9 cases, double lumen in 4 cases, pearl and string sign in 3 cases, and occlusion of parent artery in 2 cases. Surgical treatment was performed on nineteen cases (53%). The operation was carried out in the acute stage on the SAH group; in the subacute or chronic stage on the ischaemic group. The surgical procedure was the proximal ligation, trapping and removal of DA with or without revascularization of the parent artery. 84% of the surgically managed patients and 71% of the nonsurgical cases had a favourable outcome (good recovery or moderate disability). Poor prognosis was revealed from the rebleeding and primary neurological stage. We recommend surgical treatment in the acute stage on the SAH group. On the ischaemic group surgical treatment in the subacute or chronic stage is recommended, if the DA has the risk of rupture or progression of the dissection.

Secretory meningioma with elevated serum carcinoembryonic antigen level

We recently encountered a 68-year-old woman with right sphenoid wing meningioma of the secretory type accompanied by an elevated serum carcinoembryonic antigen level. This case was neuroradiologically characterized by marked brain edema. Histologically, the lesion was rated as having meningothelial components and was rich in blood vessels and pseudopsammoma bodies. Carcinoembryonic antigen, epithelial membrane antigen, keratin, and cytokeratin were immunohistochemically detected in the pseudopsammoma bodies and the cells producing these bodies.

Rebleeding during transport of patients with a ruptured intracranial aneurysm.

Although many reports have described the rebleeding risk of the ruptured aneurysm in already hospitalized patients, there are only a few reports that have addressed the incidence of rebleeding in these patients before hospitalization. To improve the prognosis of patients with a ruptured intracranial aneurysm, it seems very important to know the incidence of rebleeding before hospitalization. We focused on changes in the computed tomographic (CT) scans and neurological findings at the primary hospital and our institution in 366 patients with ruptured aneurysms who were transferred on the day of the initial hemorrhage, and studied the rebleeding rates in these patients. In 73 (19.9%), we confirmed that rebleeding from the ruptured aneurysm had occurred during transport. The incidence of rebleeding in the prehospitalized patients with a ruptured aneurysm is supposed to by very high. Appropriate medical countermeasures for prevention of rebleeding in prehospitalized patients are crucial to decrease the overall mortality and morbidity rate of intracranial aneurysm.

Monitoring of venous blood flow velocity during interhemispheric approach for deep seated lesions

SummaryNo precise intra-operative monitoring of venous blood flow has yet been developed for neurosurgical procedures. Preservation of the bridging veins is an important issue in order to minimize complications due to disturbances of venous blood flow during an inter-hemispheric approach. In the present study, venous blood flow velocity was measured in 11 anterior circulation aneurysms. The measurement was performed before brain retraction, during brain retration and after completion of the procedure without brain retraction. In 6 cases, a bridging vein was dissected completely free from the dura up to its entry into the superior sagittal sinus (SSS group). In 5 cases, dura was cut parallel to the bridging vein so that the vein remained covered by the dura (dura group). Venous blood flow velocity was measured by microvascular Doppler sonography. The results show that venous blood flow can be better preserved during the retraction when the bridging vein remains covered with the dura than if the vein is dissected completely free from the dura.

Isoflurane in the management of status epilepticus after surgery for lesion around the motor area

SummaryWhen conventional treatment for status epilepticus fails, general anaesthesia is recommended. We present our experience with isoflurane, an inhalational anaesthetic, in the management of four patients with status epilepticus which occurred soon after surgery for motor area lesion. The seizures were controlled with relatively small concentrations of isoflurane. Hypotension, the only adverse effect of isoflurane, was managed easily with the use of dopamine in physiological saline. Although status epilepticus occurring soon after surgery is transient, it carries a risk of persistent brain damage if active treatment is not instituted promptly. Isoflurane general anaesthesia may be recommended to control it in the intensive neurosurgical care.

Effect of stimulation of the dorsal aspect of the cervical spinal cord on ’Iocal cerebral blood flow and EEG in the cat

Abstract Currently there is considerable interest in electrical stimulation of the dorsal aspect of the cervical spinal cord as a potentially effective therapy for persistent vegetative patients. The authors assessed change in the local cerebral blood flow (LCBF) and electroencephalogram (EEe) in the cat following spinal cord stimulation (SCS). In 31 adult cats under isoflurane anesthesia, an electrode for SCS was introduced epidurally to the midline of the C2-C3 segment. Stimulation was performed at 25 Hz and 0.7 msec for30 min. These animals were divided into five groups by the voltage: (1) 2V (n = 7), (2) 4V (n = 7), (3) 6V (n = 7), (4) 4V with intravenous injection of muscarinic cholinergic agents - atropine sulfate (n =5), and (5) sham-operated control (n = 5) without stimulation. LCBF was measured by laser Doppler flowmetry through bilateral small burr holes at the parietal area during and 60 min after stimulation. At 2~ LCBF increased only during SCSI then returned to the pre-stimulated level, while the increase continued until the end of the experiment at 4Vand 6V. The increase in LCBF was not affected by atropine sulfate. EEe showed spike and wave or polyspikes after SCS in two animals of the 6V group, but not in the 2V and 4V groups, and moreover a moderate increase ofthe background activity at only 4V. The present data suggested that SCS at 4Vcan provide the appropriate microcirculatory enhancement with less harmful influence which continues to increase 30 min after SCSI although the exact mechanism should be elucidated continuously. Within the limitation of animal experiments, this study could provide the logical basis for determining the condition of SCS. [Neural Res 2000; 22: 386-392]

Giant true posterior communicating artery aneurysm

The case of a giant posterior communicating artery (PCoA) aneurysm is reported in which the clinical presentation was Korsakoffs syndrome. Left carotid angiography revealed a partially thrombosed giant PCoA aneurysm. Three-dimensional computed tomography angiography showed the precise neck of aneurysm and surrounding structures from a multidirectional view. Hypoperfusion of the bilateral frontal, temporal, and medial inferior thalamus was seen on single-photon emission computed tomography. According to previous reports, giant true PCoA aneurysms are rare; in fact, there has been only one report of a giant true PCoA aneurysm. We discuss the radiological characteristics and the clinical presentation of giant true PCoA aneurysms.

Evaluating the effect of superficial temporal artery to middle cerebral artery bypass on pure motor function using motor activation single photon emission computed tomography.

OBJECTIVE We evaluated and analyzed the effect of superficial temporal artery to middle cerebral artery bypass for internal carotid artery occlusion on pure motor function using motor activation single photon emission computed tomography. METHODS Motor activation single photon emission computed tomographic (SPECT) images were obtained for nine patients who had undergone superficial temporal artery to middle cerebral artery anastomosis for symptomatic internal carotid artery occlusion. All motor activation SPECT images using the finger opposition task on the affected side were obtained before bypass surgery and at 1 week, 1 month, and 3 months after bypass surgery. The results of motor activation single photon emission computed tomography were expressed as negative or positive. RESULTS Before bypass surgery, the resting SPECT images revealed reduction of cerebral blood flow (CBF) on the affected side in all nine patients. The results of motor activation single photon emission computed tomography in three patients were positive. One week after bypass surgery, the results of the resting and motor activation CBF studies did not demonstrate any marked changes. One month after bypass surgery, the resting CBF increased in four patients. The results obtained for two of the patients revealed preoperative positive motor activation. The results of motor activation single photon emission computed tomography obtained for five patients were positive. Three months after bypass surgery, eight patients experienced improvement in the resting CBF, and the results of motor activation single photon emission computed tomography obtained for seven patients were positive. Among these, the results of preoperative motor activation single photon emission tomography obtained for four patients were negative. CONCLUSION Superficial temporal artery to middle cerebral artery bypass is useful not only for resting CBF but also for pure motor function based on motor activation SPECT images. From the preoperative motor activation study, it was concluded that patients with preoperative positive motor activation could attain the effect of bypass earlier than patients with preoperative negative motor activation.

Thoracic meningioma presenting subarachnoid haemorrhage

A 67 year-old-female developed sudden lumbago followed by headache and urinary retention. On the following day, she began to suffer from dysaesthesia affecting the left thigh. One week after the onset lumbar puncture revealed xanthochromic CSF. An extensive radiological survey on the 1 lth day disclosed an abnormal intensity area on the spinal MR image at the lower thoracic level. The patient was referred to our clinic on the 18th day after the onset. MR imaging with and without Gd-DTPA enhancement was performed on the 30th day after the onset. T1 weighted-images demonstrated an enhanced lesion at the thoracic cord level from Thl0 to Th12. Myelography on the 36th day revealed a filling defect of the contrast dye extending from Thl0 to Thl2 on the left side. CTmyelography showed a clear image of the subarachnoid space with a filling defect in the dorsolateral aspect on the left side (Fig. 1, left). Because of the persistent symptoms, we operated on this patient to remove the mass lesion on the 45th day after the onset of her illness. Hemilaminectomy from Thl0 to Thl2 was performed on the left side. When the dura was opened, a soft tumorous mass was recognized subdurally and was removed. The tumour was not attached to the dura and other structures. The surface of the spinal cord appeared yellowish due to haemosiderin pigmentation. On the basis of these findings, the tumour was thought to be granulomatous tissue with previous haemorrhage. Histological examination revealed a psammomatous meningioma (Fig. 1, right). The postoperative course was uneventful, and the urinary retention disappeared by the 10th postoperative day. The