The basiparallel cut, which is a tomography parallel to the base of the posterior fossa, gives some additive value to the diagnosis of an extraaxial mass by pneumoencephalography. The view is considerably similar to the operation view through the suboccipital approach.
The anteroposterior extension and involvement of the jugular foramen by an acoustic neurinoma are clearly demonstrated by this view. Also, consistency of a mass can be estimated to a certain degree.

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The effect of the osmotic gradient between plasma and CSF on the rate of CSF formation was studied in rabbits using the ventriculo-cisternal perfusion technique. The rate of formation of CSF in the control animals with isosmolar perfusion was found to be 10.9 ± 0.5 μl/min.
In order to raise the plasma osmolality, 20% mannitol was intravenously administered as a bolus after a steady-state condition of perfusion was attained. Rapid readjustment of plasma osmolality was observed after the mannitol injection, though the osmotic gradient was reversed for CSF formation throughout the 3-hour period of perfusion. In spite of such an adverse osmotic gradient, the rate of the bulk formation of CSF was still maintained by more than 50% of the control value.
Hypertonic perfusion was performed by adding NaCl or monosaccharides into the perfusion fluid. A remarkable increase in the rate of formation of CSF was observed in the NaCI perfusion, after a steady state was achieved in the perfusion system, while in the monosaccharide perfusion, the increase in the rate of formation of CSF was not only less marked but also of shorter duration, despite the increased osmolality of the perfusate.
In face of the experimentally imposed osmotic gradient between both sides of the choroidal epithelium, the osmotic flow of water across the ependyma may take part in the mechanism of CSF production. However, when such an osmotic gradient is produced by nonelectrolytes, homeostatic regulation of CSF formation may take place. In such a mechanism, Na⁺ ion is likely to play a role as a regulatory factor.

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Ultrastructural findings of the ventricular wall and choroid plexus in experimentally-induced hydrocephalic dogs were observed with transmission and scanning electron microscopes. These findings were compared with intraventricular opening pressure, ventricular enlargement and ventricular permeability of tracers.
Morphological change of the ependyma was slight at early stages, however, ependymal degeneration and enlargement of intercellular space were recognized at late stages. At this late stage, phenol-sulfon-phthalein (tracer) penetrates deeper into the ventricular wall and lanthanum (tracer) revealed development of an absorption pathway through extracellular space.
Ultrastructural study in choroid plexus revealed dilatation of the extracellular space and significant deformity in degenerated epithelial cell. Tracer (lanthanum) study might suggest that the CSF absorption through the choroid plexus was not increased, but CSF secretion from the chroid plexus was disturbed in late hydrocephalus.
Even in the late hydrocephalic dog, which showed no rapid ventricular enlargement, the development of CSF pathway induced destruction of neuron tissues including neuron.
These facts indicate that the development of extracellular CSF pathway is harmful to the central nervous system, therefore, CSF drainage from ventricle is required to avoid destruction of the nervous tissue.

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Many investigators differ in opinion regarding the clinical concept and accurate criteria for the definition of surgically arrested hydrocephalus. We have studied the diagnostic criteria and various conditions of arrested hydrocephalus through the investigation of a series of 67 patients treated by shunting operation for progressive hydrocephalus. Of these, shunts were removed in 14 cases and these patients had no need for further treatment. We made investigations using neurological, morphological, neuroradiological and psychological methods, CSF dynamic studies including radioisotope cisternography and intraventricular CSF pressure measurements, and biochemical study of fatty acid in CSF.
On neurological examination, squint, poor vision and motor weakness were noted in the arrested stage in a few cases. Six patients were educable but slightly retarded, while two were imbeciles. Seven patients (50 %) presented no obvious physical handicaps, however, five were slightly handicapped. Intelligence developed and the degree of physical disability gradually diminished with increasing age. Physical handicaps and residual neurological signs were correlated with the etiology of hydrocephalus.
After the shunting operation head circumference remained unchanged for a period and then gradually increased within normal developmental range. Thickness of the cerebral mantle increased from 8 to 30 mm in six cases of congenital hydrocephalus. Usually, cases where thickness of the cerebral mantle were less than 14 mm within 3 months after birth, the subject had a tendency to show poor prognosis. In the arrested stage, the CSF pulse waves consisted of multiphasic components, mean intraventricular CSF pressure was found to be constant by long-term monitoring, and various RI-cisternographic patterns were observed. Three cases showed transient ventricular reflux with early clearance and convexity flow. However, in another 11 cases changes in RI-cisternographic patterns were inconsistent. Examination of fatty acid metabolism in CSF revealed that the total value of fatty acid was closest to normal range after the operation.
Arrested hydrocephalus proved to exist in varying degrees as the causes of hydrocephalus vary. Studies from various points of view provided valuable data as to the analysis of arrested hydrocephalus. Diagnosis of arrested hydrocephalus cannot be made on the basis of only simple examination, but should be made by collective judgement from the results of various examinations.

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Chromosomal constitution of 7 rat glial tumors induced by methylnitrosourea (MNU) and ethylnitrosourea (ENU) was investigated. Cells from rat glial tumors showed preferentially complete monosomy for # 3 chromosomes and partial monosomy for # 2 chromosomes. Numerical and morphological changes in # 11 and # 12 chromosomes were also observed. These chromosome aberrations have no relation with histological classification of experimental rat gial tumors. One # 3 chromosome missing in neolplastic glial tumors was constantly observed through a long term culture and had no relation with the appearance of marker chromosome. These chromosome changes were compared with the preferential involvement of # 1 and 2 chromosomes in fetal brain cells of rats shortly after a transplacental administration of ENU.

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In 38 patients with brain tumor and 17 controls, the blood levels of polyamines were measured, and studies were made on the relationship between these levels and varieties of tumors. In the group of 21 patients with glioma, these levels were significantly higher than those in the control (p<0.01), and in 14 out of 21 patients (67%) the levels exceeded the upper limit of normal range. In one patient with reticulum cell sarcoma, these levels were remarkably high. In the group of 4 patients with metastatic brain tumor, these levels were significantly higher than those in the control (p<0.05), and in 2 of 4 patients the levels exceeded the upper limit of normal range. The levels were all within normal range in 4 patients with neurinoma, 3 patients with meningioma, 2 patients with pituitary adenoma, 1 patient with pinealoma, and 1 patient with cerebellar hemangioblastoma.
In 18 patients with glioma, studies were also made on the relationship between the blood levels of polyamines and the degree of histological malignancy and of extension of tumor. There was no significant difference in these levels between the control and the group of astrocytoma localized within a lobe, but the levels were significantly higher in the group of astrocytoma extending more widely and in the groups of anaplastic glioma or glioblastoma multiforme regardless of their size.
In patients with glioma, the blood levels of polyamines before and after treatment were compared. In 3 patients subjected to surgical excision, irradiation and chemotherapy these levels were all within normal range after treatment, but in a case treated by irradiation and chemotherapy the values increased immediately after treatment.

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There are few studies dealing with the pathophysiology in the central mechanism of water and electrolytes control. The osmoreceptors have been concerned in the region of the supraoptic and paraventricular nuclei (SON, PVN) which are also the area where ADH is formed. Investigations were made on the role of osmoreceptors in ADH-releasing disorder and in experimentally induced diabetes insipidus in the cat and on the involvement of the lateral hypothalamus in these disorders as well as in hypernatremia resulting from disorders of osmoreceptors and the drinking or thirst centers. Daily intake and output, pre and postoperative electrolytes and osmolarity in the serum and urine, plasma ADH and aldosterone were measured in three groups (normal, diabetes insipidus and hypernatremia cats).
Experimental diabetes insipidus was induced by the SON lesion on one side, while mild diabetes insipidus with concurrent development of hypernatremia was produced by the SON lesion and an injury to the lateral hypothalamus.

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Clinical and endocrinological studies in 30 patients with functioning pituitary adenoma were conducted with special reference rendered to the endocrinological results of treatment.
Twenty-one patients were with acromegaly, 5 with Cushing's syndrome and 4 with Forbes-Albright syndrome.
In the treatment of patients with acromegaly, early diagnosis (microadenoma) and transsphenoidal removal was emphasized in order to obtain endocrinological cure. In the treatment of advanced tumor or adenoma with marked fibrosis, radical hypophysectomy was recommended to patients with advanced hypertension and/or diabetes mellitus and to patients after climacterium.
In patients with pituitary-dependent Cushing's syndrome, even without sellar change and without evidence of pituitary tumor other than endocrinological evidences of pituitary dependency transsphenoidal surgical procedure should be the initial treatment of choice.
Forbes-Albright syndrome with or without sellar change or even without visual impairment should also be treated surgically as selective removal of microadenoma may result in cure with restoration of the normal pituitary function.
A brief comment was made on the etiology of the pituitary adenoma. The results were ambivalent as to whether hypothalamic or pituitary but, from the clinical point of view, the hypothalamic origin should not be overestimated. In the treatment of the functioning pituitary adenoma transsphenoidal surgical removal should be performed as an initial treatment.
Because of its benign and selective nature, endocrinological cure with preservation of normal pituitary function is promised in the cases with microadenoma.

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Translational acceleration head injury experiment was performed on 12 Japanese monkeys and one baboon using a HYGE sled and a slider-impactor system. All the monkeys became concussed by force ranging 241 to 366G in slider average acceleration and two of them died of concussion (fatal or irreversible concussion). The fatal concussion animals as well as the delayed death ones showed almost unexceptionally rib and clavicle fractures and mediastinal hemorrhage. Subarachnoid hemorrhage seen in six animals were not correlated with the outcome. We were unable to produce visible brain lesions, such as brain contusion, subdural hematoma, or intracerebral hematoma, by using pure translational acceleration impacts to the head. It should be misleading to draw a human or primate head injury tolerance limit from the fatal concussion level.
Interestingly seven monkeys showed spontaneous eyelid blinking and four showed pupillary light reaction immediately post-impact and at least six animals showed “normal” EEG activity ten seconds after the impact. The cause of concussion was discussed and the role of cardiorespiratory supression by the primary shock is suggested.

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Streptkinase euglobulin lysis time (SK-ELT), fibrin and fibrinogen degradation products (FDP) and fibrinogen in blood were measured to determine the proper dosage of tAMCHA which would not cause ischemic complications but yet would suffice to prevent rebleeding in ruptured intracranial aneurysm. SK-ELT was almost doubled (130 sec) by the administration of 6-8 g/day of t-AMCHA within 24 h in normal control. On the other hand, SK-ELT in SAH patients fluctuated markedly during ten days after first bleeding. FDP demonstrated high value soon after first bleeding in Grade IV and V patients. Increase in FDP was also observed following rebleeding, severe vasospasm, and progressive neurological deterioration. Usually the increase in FDP was most obvious between 4-14 days after SAH. Fibrinogen showed the tendency to increase gradually by the administration of t-AMCHA, and this increased fibrinogen would be one of the alarm signs to indicate development of ischemic complications. From these results, it was suggested that doses of t-AMCHA should be determined precisely according to the result of repeated monitoring, and doses should be as such that it could keep SK-ELT constant between 130-150 sec.

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There is no doubt that radical surgery has been successful in preserving the lives of patients with ruptured aneurysms. On the other hand, no matter how successful we have been we cannot and must not forget the patients who died without undergoing surgery. Therefore, we investigated from clinical course, laboratory work, including angiography and autopsy, 37 cases who died during hospitalization in order to elucidate the causes of death in the natural course and to find the possibilities of minimizing the number of nonoperative fatalities. We classified the causes of death into 3 groups: intracranial hematomas, brain ischemia due to vasospasm, and aggravation of the general condition.
From the study, it was concluded that most of the lives could have been saved, if appropriate diagnosis and treatment had been made as soon as possible after the initial hemorrhage.

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A case of a giant aneurysm arising from the junction of the right posterior cerebral artery and the top of the basilar artery is reported. The aneurysm showed a bizarre arteriographic appearance like a loop which would be due to laminated intramural thrombosis. Follow-up angiograms, taken 16 months after subarachnoid hemorrhage, revealed the spontaneous disappearance of the aneurysm. In this case, the loss of buoyance following pneumoencephalography could have possibly caused the aneurysm neck to bend and induced obliteration of the aneurysm.

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A follow-up study to assess the results of surgery was carried out in 94 patients with supratentorial hypertensive intracerebral hemorrhage. The patients were operated on at the Iwate Medical University Hospital from 1970 to 1974. The operative procedure was craniotomy and total evacuation of the hematoma. Out of 94 patients 22 died within one month after surgery. The ADL of the patients was checked six months and one year after surgery. The type of hematoma, state of consciousness, severity of motor disturbances, grade of our neurological classification before surgery, and timing of operation were reviewed in each patient.
In comparing ADL of the patients 6 months after surgery with that one year after surgery, it was found that there was some possibility of improvement between 6 months and one year after surgery but further improvement could not be expected beyond one year. From the data obtained, the most suitable time to assess the results of surgery was seen to be one year after surgery.
Evaluation of the 72 patients one year after surgery showed that 30 (41.7 %) were well, 18 (25.0 %) were partially disabled, and 8 (11.0 %) were totally disabled.
Our present study leads to the conclusion that the preoperative conditions of the patients which will be well are as follows: under 55 years, somnolence or stupor, lateral type of hematoma, hemiparesis, grade I or II in our neurological classification, and early operation within 24 hours.

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The authors report a series of 63 cases of hypertensive intracerebral hematoma. Seventeen cases were operated on by conventional procedures, viz., transtemporal and frontal approaches. The number of deaths during hospitalization of this group was five. Death resulted in all of the 11 cases which were not subjected to surgery as their consciousness levels were too poor. On the other hand, in all 35 cases which were operated on by the trans-sylvian approach, only one death occurred during hospitalization. Followup studies were carried out in 34 cases for a period of 6 months to 4 and a half years. Techniques applied, indication, and the most appropriate time for surgery are described in detail.

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The purpose of this paper is to present a new method by which the functional reversibility of the ischemic brain can be evaluated by changes of somatosensory evoked potentials (SEP) in induced-hypertension.
The method (called functional SEP test) was useful in selecting appropriate candidates of completed stroke for superficial temporal artery (STA)—middle cerebral artery (MCA) anastomosis.
To evaluate the grade of reversible hypofunction of ischemic brain, cerebral blood flow (CBF) dynamics and SEPs during induced-hypertension were measured before, during and after operation in 19 completed stroke patients with main trunk occlusion of MCA.
As control studies, cerebral angiographies and CBF studies were performed in 29 conservatively treated cases.
Furthermore, preoperative angiographical findings, STA-MCA shunt flow and blood pressure of STA and MCA were examined respectively in surgically treated cases.
From these studies, our present criteria for bypass operation evolved as follows: 1) Mean CBF value is in 25 to 32 ml/ 100g/min without global loss of autoregulation and CO₂-reactivity; 2) Amplitude of initial component of SEP is augmented 2 times or more during induced-hypertension than at rest state; 3) The N₁-amplitude ratio of the normal side to the affected side is above 0.5 at rest state and increased approximately to normal value, i.e., 1.0 by induced-hypertension; and 4) The STA-MCA shunt flow through STA is in 40 to 90 ml/min and the MCA blood pressure is in 40 to 60 mmHg.

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Cerebral paragonimiasis caused by the lung fluke, Paragonimus westermani, is still existent in Japan. Human infections with Paragonimus westermani usually result from eating raw or improperly cooked crabs or crayfish. In Japan, a big crab, Eriocheir japonicus serves as the main source of this infection.
The author succeeded in producing experimental cerebral paragonimiasis in dogs and cats by direct introduction of adult flukes into the subdural space. On the other hand, he proved many Paragonimus ova in the brains of the dogs which had been orally infected with Paragonimus, but could not find any demonstrable gross lesions in all the brains. From these experimental studies, he concluded that egg embolism may have produced microscopic lesions, but gross lesions seen in human cerebral paragonimiasis resulted from a direct migration of the fluke into the cranial cavity.
The onset of cerebral paragonimiasis is usually insidious and the clinical manifestations vary, resembling suppurative meningitis, brain abscess, brain tumor, and other neurologic disorders. Other parasitic infections in the central nervous system also should be differentiated from cerebral paragonimiasis.
The principal treatment for cerebral paragonimiasis is chemotherapy and surgery. Bithionol, [2, 2'-thiobis (4, 6-dichlorphenol)] is effective for cerebral paragonimiasis in clinical use. Surgical removal of the lesion should be reserved for a single or localized lesion complicated by increased intracranial pressure, and should not be done if the lesion is multiple and extensive. Occasionally, no abscess can be found and a puncture encounters no resistance, even if repeated. In such patients, an aspiration biopsy should be done, and chemotherapy with bithionol should be started as soon as possible. For nonprogressive forms, only supportive treatment is required unless the conditions become active.

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One hundred cases of intractable pain treated with various neurosurgical procedures were reported. These 100 cases consisted of 30 cases of percutaneous cordotomy, 21 cases of posteromedial hypothalamotomy, 2 cases of rostral mesencephalic reticulotomy and 47 cases of centromedian-parafascicular (CM-Pt) thalamotomy. Clinical results of pain relief by these procedures were discussed with reference to present limits and clinical indications. Based on these clinical data, a proposal was made for new concept of pain perception.

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It is now possible for the vegetative state patients after brain damage to survive for a long period, due to the progress of modern medical science. Their long survival, however, causes various social problems. For instance, they are increasingly occupying the beds for emergency cases and many of their families have been led to financial and household difficulties.
We intended to make those problems clear by collecting statistics of these patients in the main neurosurgical clinics in Japan. Results of our three years' follow-up of these patients, including economical aids in some prefectures and medical ethics surrounding these cases are reported in this paper.

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