Short latency evoked potentials in response to acoustic stimulation can be recorded from the thalamus and the subthalamus during stereotactic surgery for relief of intractable pain or tremor.
The wave shape, polarity, amplitude and latencies of such responses do not change in wave I-V (wave VI and VII are exceptions) with different electrode positions from the cortical surface to the subthalamic area. Wave I-V may be generated at the midbrain stem, but wave VI-VII must be generated at the thalmic level. The amplitude of the potentials recorded at the thalamus and the subthalamic area, on the other hand, is enhanced after producing a lesion at the recording site.
The results also indicate that short latency evoked potentials to clicks recorded from electrodes in the thalamus and the subthalamic area, or from an electrode at vertex, are volume-conducted far field potentials emanating from the brain stem.

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Neuronal organizations between the labyrinth, the neck, and vestibulo-cerebellum were investigated in the cat.
Disynaptic excitatory postsynaptic potentials (EPSPs) and inhibitory postsynaptic potentials (IPSPs) were recorded in dorsal neck extensor motoneurons in response to stimulation of individual ampullary nerves. Stimulation of the saccular nerve usually evoked IPSPs in contralateral and EPSPs in ipsilateral neck motoneurons. Many potentials probably were trisynaptic. The predominant pattern produced by utricular nerve stimulation consisted of ipsilateral inhibition and contralateral excitation and many potentials were disynaptic.
Afferent volleys from the neck joint ascend ipsilaterally in the spinal cord, cross to the contralateral side in the brain stem, and project to the vestibular nuclei interacting with the vestibulo-ocular reflex activity. EPSPs or IPSPs were evoked in abducens motoneurons by stimulation of contralateral or ipsilateral neck joint, respectively.
Stimulation of neck afferents causes activity in the flocculus by a climbing fiber (CF) and also by a mossy fiber (MF) route. In the rostral half of the flocculus, field potentials were recorded in response to stimulation of the neck, vestibular and optic nerves. Neck afferents project also to the nodulus.
With regard to MF pathways, neck activity arises, at least in part, in joint receptors and the relay is located in Brodal and Pompeiano's group X.

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In order to understand the pathogenesis of increased intracranial pressure, the concept of the driving pressure (DP) from the intracranial vascular system was proposed. The DP consists of combined pressure continuously transmitted from the arterial pressure (ADP) and venous pressure (VP) systems. The theoretical equation of the intracranial pressure (ICP) is expressed as follows:
ICP = ADP + VP (1)
ADP is expressed as (2).
ADP = η (BP-VP) (2)
η is defined as ΔICP/ΔBP. The authors chose the term driving pressure rate to designate this ratio. Thus, η may be taken for a kind of transfer function which can be expressed as the pressure transmission rate from the arterial system to the cerebrospinal fluid system. Measurement of the η index is simple and allows frequent checks of the often momentary changes in a patient's condition, thus providing an important index of intracranial pressure environment. Analysis of intracranial pressure by means of the driving pressure concept facilitates understanding of both mean pressure and pulse pressure. The validity of analysis of intracranial pressure in terms of the driving pressure was shown from clinical data and animal experiments.

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Using radioimmunoassay, astroprotein (an astrocyte-specific cerebroprotein) in cerebrospinal fluid (CSF) from 81 cases with intracranial diseases (60 brain tumors and 21 miscellaneous lesions) and four cases with non-intracranial diseases was measured. Astroprotein in CSF of cases with non-intracranial disease was generally below 25 ng/ml. In contrast, 10 of 17 cases (58.8%) with glioma, 10 of 43 patients (23.3%) with brain tumors other than glioma and four of 21 patients (19.0%) with miscellaneous intracranial diseases (including seven cases of intracranial aneurysm, four of meningitis, three of hydrocephalus, three of epilepsy and two of Parkinsonism) showed elevated astroprotein (up to 500 ng/ml or more) in CSF. The cystic fluid in glioblastoma usually contained remarkably large amounts of astroprotein.

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One hundred human embryos, five foetuses and seven infants with holoprosencephaly were studied. In the embryos, diagnostic criteria consisted of: 1) disturbed diverticulation of the rostral neural canal; and 2) presence of median facial anomaly. Developmental stages of the holoprosencephalic embryos ranged from the Carnegie stage 14 to 23. For the diagnosis of holoprosencephaly in foetuses characteristic facial anomalies had to be relied on. In infants, facial anomalies were present in only three out of seven patients. The necessity to use proper diagnostic aids was emphasized. In angiograms, peculiar azygos anterior cerebral artery is diagnostic of alobar and semilobar holoprosencephaly while dysgenesis of the deep venous system is helpful for the diagnosis of lobar holoprosencephaly. Air ventriculography and CAT scan revealed broader interventricular communication, presence of the dorsal sack and/or absence of the interhemispheric fissure. The types of holoprosencephaly were diagnosed as alobar in four, semilobar in one and lobar in two cases. Apparent hydrocephalus was not found in the malformed embryos. It was present in two out of five holoprosencephalic foetuses, and six out of seven newborn patients. The hydrocephalic process seems to begin in the foetal period in most cases. From the review of 89 reported cases, hydrocephalus does not seem common in the alobar and the semilobar type, but it seems almost always present in lobar holoprosencephaly. The prognosis of lobar holoprosencephaly does not seem so desperate if hydrocephalus is successfully treated. The importance of holoprosencephaly, especially its lobar type, in neurosurgical practice was emphasized.

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The authors describe a unique case of congenital unilateral hydrocephalus associated with congenital hemihypertrophy. On computed tomograms of the head, the area of the foramen of Monro and the anterior part of the lateral ventricle were noted to be compressed by an enlarged basal ganglia on the side of hemihypertrophy. It is our opinion that the proliferation of the basal ganglia in this case can be a part of the hemihypertrophy syndrome and this mass must have disturbed the circulation of the cerebrospinal fluid of the lateral ventricle in the early period of the fetal life, producing obstructive unilateral hydrocephalus secondary to the obstruction of the foramen of Monro. Although the lateral ventricles were filled with air on pneumoventriculography, this might have been secondary to rupture of the septum pellucidum.

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For the purpose of investigating the role of the humoral agents released by platelet aggregation in the pathogenesis of transient cerebral ischemic attacks (TIA), the products of platelet suspension which was aggregated by Thrombin was infused as a bolus into the internal carotid artery in rabbits. Before injection, formed elements were filtered off by the use of a milipore filter. The injected material was supposed to contain substances released by platelet aggregation, such as serotonin, histamin, ADP and so on as well as various prostaglandins, among which the existence of thromboxane A2 (TXA₂) possessing a potent vasoconstricting effect was known.
Before and after the injection, the cortical CBF (coCBF), EEG and systemic arterial pressure (SAP) were continuously monitored under controlled respiration. According to the pattern of response of coCBF following injection of Thrombin-added PRP (T-PRP), a total of 29 rabbits were divided into three groups. In the first group (7/29), the coCBF decreased markedly immediately after the injection, which was accompanied by supression of EEG. Such an ischemic change lasted for 5-10 minutes and then gradually subsided. In two additional rabbits which exhibited the same ischemic pattern, India ink was intravenously administered when the fall of coCBF was at its maximum. This revealed considerable non-filling of the capillary networks of the cerebral cortex in the injected side. The responsible agent for this remarkable cerebral ischemia was considered to be TXA₂. In the second group (9/29), a biphasic pattern (initial brief ischemia followed by more prolonged hyperemia) was observed. In the third group (13/29), transient but prominent hyperemia was observed. In the two latter groups, there were only slight supressions of EEG as compared to the first group. India ink perfusion of the brain, carried out in the two additional rabbits exhibiting this hyperemic pattern, revealed a patent cerebral microcirculation. This transient hyperemia seen in the second and the third groups was considered to be due to the action of some unknown substance which had a potent vasodilating effect. Recently found Prostacyclin (PGI₂) was suggested as a possible agent which caused the hyperemic response. The result of the present study is considered to indicate that the dual control system of platelet aggregation and vascular tonus by TXA₂ and Prostacyclin as proposed by Moncada et al.¹⁴⁾ is also effective to the cerebral vessels.

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Seven cases of dural arteriovenous malformation are reported with analysis of the symptoms, hemodynamics, treatment and follow-up results.
The present disease is thought to be progressive and should be definitely distinguished from the intracerebral AVM and traumatic arteriovenous fistula since the hemodynamics of arteriovenous shunt showed extensive and dynamic changes with the lapse of time as observed from the results of long-term follow-up studies.
The best treatment is to primarily block arteriovenous shunt at the dura and tent as much as possible.

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The correlationship between the prognosis of the 21 adult “Moyamoya” patients and their clinical and cerebral angiographic features is reported.
Clinical and angiographical features were as follows:
1. Subarachnoideal hemorrhage was the initial symptom in 62%.
2. The prognosis was better in SAH type than in the other types.
3. The recurrence rate was 50%.
4. In SAH type, AG I type accounted for 70%, and a higher rate of AG II, III types were noted in APO and TIA types.
5. The angiographic types were much closely correlated with the prognosis than the clinical types. The cases of AG I type showed favorable prognosis and the prognosis of AG II, III types were poor. This may be attributed to the easy development of critical cerebral ischemic condition in AG III type as compared with AG I type.

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In 393 cases of cerebral aneurysm operations from 1971 to 1973, the cases in which operation was performed within the first week after SAH had the highest mortality. However a closer analysis of these cases in the first week revealed that the results of surgery were significantly different by each day. The first day showed neither poor results nor deaths. The worst day was the third. To clarify such differences, we report studies of the results of surgery within the first four days after SAH in 31 cases.

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Two cases of homonymous hemianopsia caused by chiasmal compression due to intracranial aneurysm are presented. Both cases are aneurysms of the internal carotid artery and these aneurysms developed to the median direction. Visual field defects in both cases were incongruous homonymous hemianopsia without macular sparing. It should be noted that when homonymous hemianopsia is present without any signs of an intracranial mass, the existence of a nonruptured aneurysm should be highly considered.

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In order to understand the mechanism of the cerebral vasospasm that often follows rupture of an intracranial aneurysm, an experimental study on contractile and regulatory proteins in arterial smooth muscle was performed. Ca²⁺ sensitive myosin B was extracted from a bovine carotid artery and was separated into its components: myosin A, actin, tropomyosin and troponin. Electronmicrograph of the components revealed that: 1) Myosin A had a rod-like structure; its diameter and length were 150 and 3, 000 Å, respectively. 2) F-actin showed a helical structure with a pitch of about 390 Å. 3) Myosin B in low ionic strength, showed an arrowhead structure. 4) In a clearing response, thick and thin filaments (diameter: 150 Å and 80 Å, respectively) of myosin B were separated. 5) In a state of superpercipitaion, large aggregates of thick and thin filaments were observed. 6) Tropomyosin paracrystals showed a typical band structure; its periodicity was 390 Å. 7) Fresh myosin B exhibited Ca²⁺ sensitive superpercipitation. 8) In the desensitized myosin B, however, no superpercipitation was observed neither in the presence nor absence of Ca²⁺. 9) Addition of native tropomyosin and Ca²⁺ to this system caused definite superpercipitation. It is clear that the existence of native tropomyosin and Ca²⁺ are indispensable for the contraction of vascular smooth muscle.

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Ultrastructural features of the secretory granules of human pituitary adenomas obtained at operation from 18 patients were studied in correlation with the clinical features and abilities of the tumor tissue to synthesize and release growth hormone (HGH) and prolactin. These abilities were measured quantitatively, isolating the hormones with polyacrylamide gel disc electrophoresis after in vitro labelling of the hormones with ¹⁴C-leucine. The pituitary adenomas without recognizable functional significance (8 cases), which clinically manifested hypopituitarism, showed low hormone synthesis. In the cytoplasm, small secretory granules (100-200 nm in diameter) covered with a limiting membrane and having a clear halo and dense core were sparsely distributed. In prolactin producing adenomas, which clinically manifested hyperprolactinemia with galactorrheaamenorrhea syndrome (3 cases), higher prolactin synthesis was found. In the tumor cells, round and pleomorphic secretory granules were observed. The latter, measuring up to 450 nm in diameter, were considered to be prolactin granules. Round secretory granules measuring 150-350 nm in diameter were commonly observed in the adenomas showing high HGH synthesis function and/or elevated plasma HGH concentration. This type of granules were common in HGH producing adenomas clinically manifesting acromegaly (5 cases), and, therefore, were considered as HGH granules. Though less irregularly-shaped than in prolactin producing adenomas, pleomorphic secretory granules were also found in the HGH producing adenomas together with the round granules. The high prolactin synthesis and release functions of the HGH producing adenomas would be correlated to the presence of this type of granules. There were two tumors in which, the ultrastructural appearance could not be correlated with clinical features or measured abilities of the hormone synthesis and release.

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Meningiomas are rare tumors of childhood and adolescence but one should always consider them when making a differential diagnosis. Seventy-five patients in this age group were reviewed, including 7 of our own. Several features differing from those of adulthood meningiomas are described. Some of the tumors may have unusual growth patterns, such as cyst formation, resulting in confusing angiographic appearances.

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Experimental spine and spinal cord injuries were induced in dogs by dropping a 3 kg weight through a guide tube from a two-meter height onto the surgically exposed and stabilized 3rd and 4th cervical spines of sixteen dogs. Skeletal specimens were examined, and the site and extent of fractures were compared with systemic and neurological signs of spinal cord injuries.
Five animals died immediately after injury and another one was found dead the next morning. Out of three survivals that recovered from traumatic shock, two became quadriplegic. Two other animals showed quadriparesis and paraparesis, respectively. Fractures of cervical vertebrae were found in all animals, and their sites occurred in the following frequency: cost-transverse process, spinous process, lamina, vertebral body and pedicle. The 3rd and 4th cervical vertebrae were injured with similar frequency. The fracture characteristics of cervical vertebrae by the present method are briefly discussed.
Every animal with vertebral body fracture either died immediately or developed profound neurological sequelae. Traumatic shock and vertebral body fracture were encountered more frequently in smaller animals, and neurological sequelae were less pronounced in larger animals. Neurological deficits, however, occurred in only one when fractures were limited to the cost-transverse process and spinous process. Only 25% of the animals showed neurological sequelae in the present series. More standardized studies are a prerequisite for the present method to form a reproducible and quantitative injury model of the spine and the spinal cord.

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An epidemiological study of vegetative state patients (abbreviated as VSP) in the Tohoku district was carried out. The prevalence rate of VSP in this area is estimated to be 2 to 3 per 100, 000 population. From this figure, a rough estimate of the total VSP polulation in Japan of some 2, 000 to 3, 000 may be reasonably obtained. The causative illness leading to vegetative state was most frequently cerebrovascular disorder (notably hypertensive intracerebral hemorrhage and cerebral infarction) which accounts for 58% of all VSP. Another 24% are accounted for by head injury. As to the age group, the largest proportion (25%) of entire VSP are in their sixties.
These VSP are in quite miserable condition economically as well as psychologically and they are badly in need of financial support from administrative authorities. Emphasis, therefore, must be placed on the necessity of providing for both medical expenses and very high nursing fees being charged by round-the-clock attendants, so that the patients' families can be aided from going into financial ruin.

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