[Can EC-IC bypass prevent brain ischemia from recurring?].

The effectiveness of extracranial-intracranial arterial bypass (EC-IC bypass) surgery for patients with hemodynamic compromise still remains controversial. In the present study, we evaluated the correlation between the pre- and post-surgical cerebral hemodynamics and long-term prognosis. 28 patients and a subsequent 21 patients (41 men, eight women: mean age 59.9 [S.D. 8.6] years) with reduced cerebrovascular reserve due to steno-occlusive disease of the cerebral major arteries formed the study groups 1 and 2, respectively. Measurement of the mean hemispheric cerebral blood flow (mCBF) and the cerebral vasoreactivity (%mCVR) with an intravenous acetazolamide injection were performed by a 133Xe inhalation method and SPECT. Patients were treated with EC-IC bypass surgery and measurement of mCBF and %mCVR were made again about one month after surgery. The patients were observed for a long period (mean 44.3 months). During the follow-up period, 6 patients experienced recurrent ischemic strokes. The annual incidence of recurrent ischemic stroke was 4.4%. The patients with significantly reduced pre- and post-surgical resting mCBF of the affected hemisphere were at significantly higher risk of recurrent ischemic stroke than the patients with normal mCBF (p < 0.01). The %mCVR of the affected hemisphere rose after surgery.

[A case of posttraumatic delayed cerebral arterial spasm; case report and review of the literature on the pathogenesis].

A case of posttraumatic delayed cerebral arterial spasm is presented. A 71-year-old man was admitted to our hospital with head injury. Neurological examination on admission only revealed consciousness disturbance (Japan Coma Scale 30). CT scan 19 hours after the injury demonstrated a contusional hematoma in the right frontal lobe, faint subarachnoid hemorrhage in the left sylvian fissure and subdural hematoma in the interhemispheric fissure. His consciousness was disturbed on the 14th day. CT scan demonstrated a left subdural effusion, which was surgically evacuated. However, from the next day the patient developed left hemiparesis. Right carotid angiogram on the 17th day after the injury revealed multiple segmental arterial narrowing in the right anterior cerebral artery (ACA) and middle cerebral artery (MCA). We diagnosed a posttraumatic delayed cerebral arterial spasm. CT scan revealed low density areas in the right ACA and MCA territory. The pathogenesis of posttraumatic delayed arterial spasm is not yet well known. Now, four theories have been suggested as follows: (1) Subarachnoid hemorrhage, (2) Direct mechanical injury to the arterial wall, (3) Hypothalamus dysfunction, and (4) Disturbed autoregulation. In our case, three important factors are suggested. The first is direct injury to the artery, the second is cerebral contusion, and the third is subdural effusion.

[Transcallosal approach to para-ventricular tumors].

Our experience with the transcallosal approach to para-ventricular tumors is reviewed and our operative technique is described. A group of 7 patients with a variety of tumors affecting the lateral ventricle, 3rd ventricle and basal ganglia have been treated using an anterior transcallosal approach. Using a posterior transcallosal approach, we operated upon 2 patients with thalamic tumors. The anterior part of the body of the corpus callosum is divided in the anterior transcallosal approach and the posterior part of the body of the corpus callosum is divided with preservation of the splenium in the posterior transcallosal approach. The division amounting to approximately 2-3 cm is sufficient exposure. With the exception of tumors affecting the basal ganglia, thalamus and anterior 3rd ventricle, complete excision of each lesion was effected. There were no operative deaths. The complications in this group of patients were primarily related to the nature and location of the primary tumor, but four complications were directly related to the transcallosal approach. Venous infarctions occurred in 2 patients and subdural fluid collections occurred in 2 patients. Therefore, planning of the flap placement and the extent of brain retraction must be based on preoperative angiographic assessment of parasagittal venous tributaries. We performed some detailed studies of the interhemispheric transfer of somesthetic and perceptual motor tasks, as well as psychometric testing post-operatively in 2 patients. No significant clinical deficit subsequent to dividing the anterior part of the body of the corpus callosum could be demonstrated. The results and clinical material indicate that transcallosal approach is a safe, feasible alternative in the management of the tumors in these regions.

[Primary intracranial germ cell tumor with abnormal high value of alpha-fetoprotein after the radiation therapy].

A 7-year-old boy was admitted to Hokkaido University Hospital complaining of headache and vomiting. On admission he was slightly confused and presented Parinaud's sign. CT scan revealed abnormal high density mass with contrast enhancement effect at the pineal region and obstructive hydrocephalus. Laboratory studies showed the normal value of human chorionic gonadotropin and no trace of alpha-fetoprotein. Germinoma was most suspected based on the findings of CT scan and laboratory studies. The radiation therapy was carried out for a month and CT scan taken after the radiation therapy revealed marked reduction of the size of the tumor at the pineal region, and he was discharged. But he was re-admitted 3 months after the discharge complaining of headache and vomitting again. CT scan showed the recurrence of the tumor and laboratory studies showed abnormal high value of A.F.P. After the ventriculo-peritoneal shunt, the sub-occipital craniectomy was performed by the Stein's approach, and the tumor was removed. Pathologically the tumor was a typical yolk sac tumor. This case is a very interesting case because it suggests an alternation of the element of the germ cell tumor by the radiation therapy. At first admission, germinoma was the main element of the tumor judging from the effectiveness of the radiation therapy and laboratory studies. But the main element of the tumor seemed to have changed to yolk sac tumor after the radiation therapy. The relation between the tumor markers and the types of the germ cell tumor and histopathological characters of the intracranial germ cell tumor were discussed.