According to the Speden's method, a spirally cut strip of the basilar artery of a dog was mounted in a bath filled with artificial CSF, and vasoactivity of fresh and aged serum, whole blood and blood-CSF mixture upon the isolated artery were tested. Contraction of artery produced by serum was most obvious in the fresh sample and diminished quickly as aging continued. Thus serum aged over 4 days were essentially non-vasoactive. Also it was completely abolished by adding methysergide, a serotonin antagonist. On the other hand, vasoactivity found in supernatants of the incubated whole blood and blood-CSF mixture progressively increased as incubation continued, reaching its peak after approximately 7 days of incubation. When the aged whole blood or aged blood-CSF mixture, particularly the latter, was applied, a tonic tention superimposed with phasic contraction of the isolated artery developed and lasted for several hours. Contraction was further enhanced markedly under the hypoxic condition produced by the cessation of continuous O₂-supply into the reaction medium. Supernatants of blood-CSF mixture incubated for 7 days at 37°C was passed through a column of sephadex G-100. Vasoactive substance existed specifically at the peak III which demonstrated positive ninhydrin reaction. When peak III, thus isolated, was introduced into the basal cistern of the dog marked vasospasm at the circle of Willis and basilar artery developed and lasted over 2 weeks. Further biochemical analysis of peak III using CM cellulose ion exchange resin and disc electrophoresis, demonstrated that the vasoactive property lay in the polypeptides closely allied to oxyhemoglobin or oxyhemoglobin itself. Haptoglobin, a normal constituent of serum, is known to combine with hemoglobin to form a stable hemoglobin-haptoglobin compound. Following the next series of experiments of either in vitro or in vivo conditions, it was demonstrated that the hemoglobin induced vasospasm was greatly abolished by the addition of haptoglobin. Clinical application of haptoglobin upon the spastic cerebral artery around the ruptured aneurysm were found to be very encouraging.

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It is well known that so-called vasospasm is one of the most important factors complicating the management of patients with subarachnoid hemorrhage from cerebral aneurysms. Yet, the pathogenesis or even the difinition of it remains obscure, and no satisfactory treatment has been devised to combat its adverse effects. Angiographically demonstrated arterial luminal narrowing has been noted to be reversible and has been attributed entirely to vasospasm. Is angiographic arterial narrowing merely the reduction of the lumen due to presumed change in muscle tone in the vessel wall? In an attempt to elucidate this problem, we have made a prospective and histological study of the intracranial arteries with angiographically demonstrated arterial narrowing in 6 cases. In all of them, the course of vasospasm was investigated by repeated angiographies. At autopsy, main intracranial arteries were carefully dissected free from the base of the brain and processed through graded alcohols. After dehydration the specimens were stored in Tetralin (C₁₂H¹⁰) for 2 days. The cleared specimens were examined with a dissecting microscope, comparing them with the angiographic findings. Serial sections were cut and stained for light microscopy. The arterial wall corresponding to the angiographic vasospasm showed various structural changes. We have devided so-called vasospasm into three stages according to the duration of the disease as follows. In acute stages (less than 1 day after the onset), contraction of the medial smooth muscle cells may be the main cause of luminal narrowing. In subacute stages (less than 2 weeks after the onset), the arterial wall demonstrated the reduction in its lumen size with medial thickening, marked corrugation of the internal elastic lamina, intimal edema due to endothelial injuries, and thrombus formation, corresponding with the angiographic vasospasm. In chronic stages (more than 2 weeks after the onset), most cases showed dilatation of the arterial lumen on the angiogram. It was noted that there were necrosis and reduction of the medial smooth muscle cells histologically. In a case which showed progressive angiographic arterial narrowing for more than 2 weeks, the arterial wall showed luminal narrowing with cellulofibrous thickening of the intima and the organization of the thrombus.
The presence of these structural changes following the vasospasm seems to be very important to properly understand this phenomenon. It is clear from our study that the most important thing is to prevent the arteries from spasm from the clinical point of view.

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Analysis of the various factors influencing rebleeding during the period of preoperative management has been carried out on 147 patients with intracranial aneurysms. The timing of operation in the ruptured intracranial aneurysm was discussed from the results of this study. Rebleeding occurred in 15 of 147 patients while waiting for surgery. Factors highly related with rebleeding during the period of preoperative management were as follows; grade II, major bleeding associated with loss of consciousness at the last subarachnoid hemorrhage, arteriosclerosis, acute stage within 7 days especially within the first 3 days after the last bleeding, IC-PC aneurysms, large and multilocular aneurysms, and diffuse and severe vasospasm.
The ideal time for the surgery of grade I and grade II patients in the acute stage is within 24 hours after admission, preferably within a few hours, since incidences of rebleeding after admission are very high in acute grade I and II, especially in grade II patients, with very low operative mortality.
The optimal time of the direct operations of grade III and IV patients should be as early as possible if the aneurysm has high tendency of rebleeding. It should be delayed if the patient has few factors of rebleeding, as mentioned above.
The death rate is almost 100 % in conservatively treated patients in Hunt's grade V. Although few patients in this clinical state can be restored to fair conditions by early surgical interventions, such as external or internal decompressions, ventricular drainage, or direct operation of the aneurysm, the operative mortality rate should be assessed against the natural death rate, which is close to 100 %. A very high operative mortality rate should be acceptable. For this reason, early operative procedures for intracranial lesions and aneurysms seems to be indicated even in grade V patients.

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Twelve cases of arteriovenous malformation (AVM) of the spinal cord were operated on at the Department of Neurological Surgery, Kitano Hospital, from July 1972 through August 1975. They included three cases of intramedullary spinal cord AVM and nine cases of extramedullary spinal cord AVM (Table).
Initial symptoms were due to ischemia of the spinal cord in two cases and to subarachnoid hemorrhage in the remaining 10 cases. In five out of those 10 cases, predisposing factors causing subarachnoid hemorrhage were pregnancy, upsidedown standing, massage of the neck, neck-flexion on hair washing, and twisting of the waist. Those movements increased the venous pressure of the spinal cord, then the blood pressure in spinal cord AVM, and resulted in subarachnoid hemorrhage.
For the diagnosis of spinal cord AVM myelography was done first, followed by spinal angiography. Spinal angiography was the most important diagnostic procedure preoperatively, because it gave valuable informations concerning the num bers and the location of the feeding arteries, the site and the size of spinal cord AVM, the numbers of drainage veins and the direction of blood flow.
Since most of the spinal cord AVMs were located at the dorsal surface of the spinal cord with a few feeding arteries, they could be removed relatively easily by posterior approach after laminectomy. On the contrary, spinal cord AVMs with a number of feeding arteries, particularly those which were mainly fed by the anterior spinal artery, had been considered to have no surgical indication. However, we operated on three cases of intramedullary spinal cord AVMs which were mainly supplied by anterior spinal artery. The operative procedures were as follows : After myelotomy with microsurgical techniques, the tissues surrounding the spinal cord AVM were dissected to reach the anterior spinal artery. After coagulation of the feeding artery, the spinal cord AVM was totally removed. Although these procedures were followed by a transient aggravarion of clinical symptoms, there have been no serious sequelae persistent.

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Secondary tumors of the skull, the meninges and the brain are said to be rare in children. According to the Annual of the Pathological Autopsy Cases in Japan of 1971 and 1972, there were 173 cases of these secondary tumors in children while there were 196 cases of primary brain tumors. It is, therefore, concluded that these secondary tumors are rather frequent.
Fifty-one fatal cases of secondary tumors of the skull, the meninges and the brain in children treated in the National Cancer Center Hospital (Tokyo) from 1962 to 1974 were studied and were their diagnosis and the treatment discussed, with special emphasis on the indication of surgical removal. These included 18 leukemias, 13 neuroblastomas, 9 retino-blastomas, 8 sarcomas, 2 malignant lymphomas and I embryonal carcinoma. Leukemia: The leptomeningeal infiltration existed in most cases. Diagnosis was made by the evidence of leukemic cells in the cerebrospinal fluid. The intrathecal injection of methotrexate with or without whole-brain irradiation was effective in first course, but was not effective in secound or third courses. The autopsy findings indicated that the typical pattern was the diffuse infiltration of leukemic cells in the leptomeninges and in the subarachnoid space, and multiple intracerebral hematomas accompanied by leukemic cells were occasionally observed. Neuroblastoma : Metastatic skull tumors were palpated in all cases. Autopsy findings revealed that metastatic lesions existed not only in the skull but also in the meninges. Radiotherapy was applied without sufficient effect. Retinoblastoma : The leptomeningeal infiltration with the early consciousness disturbance was characteristic. Intrathecal injection of Methotrexate was not effective. Autopsy findings indicated that tumor cells infiltrated along the optic nerve into the intracranial subarachnoid space, spread diffusely and formed solitary lesions in the hypothalamus, the cerebellum or other intracerebral regions.
Our studies suggest that indication of the neurosurgical removal of tumors is limited for most cases. Early diagnosis and the care under pediatricians and neurosurgeons will bring better prognosis by intensive treatment with chemotherapy, radiotherapy and decompressive operation.

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From our experience of more than 200 cases of verified acoustic tumors, the diagnostic problems of acoustic tumor and the choice of the surgical approach were discussed.
Hearing loss, tinnitus and dizziness are known as early signs of acoustic tumor. However, as far as tinnitus was concerned, only 57 % of our cases experienced this sympton.
Hearing loss of sudden onset is sometimes the earliest presenting symptom of acoustic tumor as MIeyer (1941)¹², Hallberg et al (1959)², Straud et al (1969)¹⁷ and Higgs (1973)³ have already pointed out. Six such cases were found in our series.
This indicates, in cases of so called sudden deafness, careful examination to rule out acoustic tumor must be carried out.
Audiometric study was important in small acoustic tumor, when hearing loss was not so marked. However, sophisticated audiometry did not always demonstrate typical retrocochlear lesion.
Hearing loss is said to progress gradually. However, some of our cases showed almost no progression over 6 years. In bilateral acoustic tumor mainly due to von Recklinghausen's disease, even though tumor was large hearing was less impaired compared with unilateral tumor.
Small tumors did not show any lateral gaze nystagmus, saccardic pursuit eye movement nor abnormal optokinetic nystagmus response, whereas these signs of the oculomotor dysfunction was demonstrated in large tumors.
The authors proposed a system to diagnose early acoustic tumor as is shown in the figure 9. The relationship between the choice of surgical approach and the results of the functional tests such as hearing loss, other cranial nerve involvements, gaze nystagmus, disturbance of induced optokinetic nystagmus and cerebellar symptoms were mentioned, which is shown in the table 1.

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For the purpose of preventing obstruction of the peritoneal catheter following ventriculoperitoneal (V-P) shunt, we have devised a method of making additional slits in the peritoneal catheter of an Ames-Dow-Corning set, extending 10 to 15 cm from the tip. Results of clinical application of this method were analyzed in comparison with other V-P shunting methods. In 31 children cases of hydrocephalus, 42 V-P shunt operations were performed, using the Ames-Dow-Corning set with additional slits, and postoperative shunt impairments were observed 19 times (45 %), where four times (10 %) were abdominal catheter obstruction. In 14 children cases, 20 V-P shunt operations were performed, using the Pudenz single lumen shunt set, and postoperative shunt impairments were observed 19 times (95 %), of which 9 times (45 %) were abdominal catheter obstruction. In 17 children cases, 28 V-P shunt operations were performed, using the Mishler double lumen shunt set, and postoperative shunt impairments were observed 21 times (75 %), of which 13 times (46 %) were abdominal catheter obstruction. Thus it has been evidenced that application of the method of additional slit formation in the peritoneal catheter is useful to reduce incidences of postoperative abdominal catheter impairment and in promoting duration of shunt patency.
In several cases in which V-P shunt had been done with the Ames-Dow-Corning set having additional slits, changes in intraventricular pressure accompanying alterations in posture were examined. Marked negativity in intraventricular pressure during maintenance of an erect posture, which indicated existence of a siphon effect, was noted, and counteracting measures were referred to.

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