Occlusion of both common carotid arteries of the Mongolian gerbil results consistently in bilateral ischemia of the cerebral cortex permitting investigation of the effects of short-term ischemia of cerebral energy reserves. Biochemical evidence in the present study confirms cerebral ischemia in all gerbils subjected to bilateral carotid occlusion. The changes in metabolites during recirculation may reflect the intensity of the ischemic insult more accurately than alterations which occur during ischemia. To ensure the assessment of short periods of ischemia without ambiguity, the metabolites and cyclic nucleotides were measured after 1, 5, 20, 30 and 60 min of ischemia; and 1, 5, 30, 60 and 360 min after circulation was reestablished. The major part of changes in metabolites and cyclic nucleotides due to ischemia occurred during the first minute, ischemia of longer duration had little further effect. However, the restoration of the metabolic profile was altered by the duration of the ischemic period. In general, the longer the period of ischemia, the slower the replenishment of high-energy phosphate compounds and energy sources. Cyclic AMP increased 5 to 13 times during ischemia; cyclic GMP decreased to as little as 1/5 of control values 60 min after occlusion. During recirculation, cyclic AMP increased as much as 100-fold, while cyclic GMP increased up to 6-fold. The temporal derangements in cyclic nucleotide concentrations coincide with the loss and restoration of cortical activity; a possible mechanism has been suggested.

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Whether a patient who has had unfortunate subarachnoid hemorrhage can lead a useful life or even survive is greatly influenced by cerebral vasospasm. We have conducted studies on vasoconstrictive substances developing after subarachnoid hemorrhage and also the possibilities of inactivating drugs as a treatment for vasospasm.
Fresh blood and a supernate of the blood-CSF mixture incubated for 1 to 16 days were applied to the basilar artery of adult cats which were exposed by transcervical-transclival approach. After each application, the diameter of the artery was observed and the degree of constriction was measured using a surgical microscope.
Constriction due to the application of fresh blood was about 30%, and recovery was observed shortly after. It seems that serotonin isolated from platelet participates greatly in the transient vasoconstriction induced by fresh blood, and that the early spasm clinically is caused by serotonin and mechanical stimulation.
Supernate of blood-CSF mixture, incubated for 3 days, has weak activity compared to the powerful (50%) and long lasting activity of those incubated for 7 days. Furthermore, same mixture incubated for 15 days has little or no activity.
This change in the vasoconstrictive activity is similar and coincides chronologically with the appearance of late spasm as reported in clinical studies by Suzuki in 1975⁴⁾.
Vasogenic substance in 7th day mixtures were investigated. Heat coagulation and ultrafiltration indicates that the vasogenic substance is a protein with a molecular weight exceeding 10, 000. Sephadex G-100 gel chromatography and disc electrophoresis indicates that the substance is hemoglobin. Spectrophotography ensures that this Hb is oxyHb.
On the other hand, in 15th day mixtures, oxyHb is converted to metHb. Experimentally, pure metHb has no vasoconstrictive activity.
From the result of the present study, it is possible that bleeding from ruptured aneurysm stops spontaneously due to immediate coagulation and early spasm induced by serotonin and mechanical stimulation. Gradually oxyHb is excreted following the hemolysis. The oxyHb volume reaches its peak near or on the 7th day following the bleeding. During this progression, vasospasm is provoked when the oxyHb reaches a responsible volume. From the 7th day following the hemorrhage, oxyHb gradually changes into metHb. By the 15th day all oxyHb had been converted. Subsequently, the metHb is broken into heroin and globin and is absorbed into the blood.
We have succeeded in oxidizing oxyHb into metHb with sodium nitrite, thus preventing experimental vasospasm. In the future we intend to continue work with sodium nitrite and other drugs to seek methods to prevent clinical vasospasm.

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Aneurysms of the distal anterior cerebral artery are relatively uncommon. In this paper a series of 26 patients with such aneurysms are reviewed.
Seventeen cases were men and 9 were women. All aneurysms were found to arise at the knee of the pericallosal artery (11: left; 14: right). In one case the aneurysm was found with azygos anterior cerebral artery. Twenty-two out of 26 cases were operated directly with the interhemispheric fissure approach in chronic phase more than 3 weeks from the last subarachnoid hemorrhage. The aneurysmal neck was clipped or ligated in 17 cases, coated with EDH-adhesive in 3 cases and pericallosal artery was trapped in 2 cases.
Clinical features were examined in 21 cases with ruptured aneurysm of the distal anterior cerebral artery before operation and in 22 operated cases after the surgery.
Of these cases, 11 cases showed prolonged impairment of consciousness of more than 7 days.
Various degrees of motor disturbances were found and motor disturbances were dominant on the lower limbs. After subarachnoid hemorrhage there were 3 cases with monoparesis of a leg, 4 with hemiparesis, 3 with hemiparesis and paresis of a contralateral leg, and 2 with tetraparesis. In 7 cases the paretic side was on the same side as the aneurysm and 5 out of these cases showed contralateral projection of the aneurysmal dome in carotid angiography and in operative findings. These findings suggested that the direction of the projection of the aneurysmal dome plays a significant role in the occurence of the paresis.
Psychic changes were recognized in 10 out of 19 cases prior to operation and 4 out of 20 cases after the operation except cases with disturbance of consciousness. Therefore, the over-all psychic morbidity rate was 63% which was almost the same as the rate of anterior communicating aneurysms. There were 12 cases with amnestic syndrome (2 with typical Korsakoff's syndrome), 5 with personality changes and 2 with akinetic mutism.
Urinary incontinence without impairment of consciousness was found in 3 cases.
Long-term follow-up results for more than 8 months after the operation revealed that 16 cases had no neurological deficits, 4 had minimal deficits and one was totally disabled.
From data obtained, it is concluded that the location of aneurysms was considered responsible in producing various neurological and psychiatric changes. The favorite location of this aneurysm was at the knee of the pericallosal artery where bilateral anterior cerebral arteries and cingulate gyri are not separated from each other. Therefore, the rupture of the aneurysm and surgical procedures easily give rise to the damage of bilateral cingulate gyri and corpus callosum and the vasospasm of bilateral anterior cerebral arteries. According to these conditions, various neurological and psychiatric changes appeared in cases with the aneurysm of the distal anterior cerebral artery.

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Seven patients who had expired due to rebleeding of ruptured intracranial aneurysm during hospitalization were studied clinically and pathologically to evaluate the risk factors and the warning signs of rebleeding, and to evaluate therapeutic methods in acute stages of ruptured intracranial aneurysm.
It was evident from clinical observations that rebleeding was preceded by increase or fluctuation in blood pressure lasting from several hours to several days. And also this instability of blood pressure, which was followed by rebleeding, was caused by several psychological and physical factors, such as transportation to the neurosurgical ward, defecation and voiding, angiography and brain scan, ventricular drainage and deterioration of the neurological state. There were 20 episodes of rebleeding in these 7 cases; 15 of which occurred within 14 days after the previous attack. Among the risk factors concerning the clinical feature, all factors mentioned above which resulted from the increase or instability of blood pressure, prolonged headache and nuchal rigidity suggesting minor leakage from aneurysm and acute stage after bleeding were considered to be of great importance. Age and sex had no significance. Both hypertension in the past and upon admission were of less significance as risk factors. The grade of the patient upon admission was also not meaningful because five patients were in good condition, Grade I or II. In the risk factors examined angiographically, aneurysm over 10 mm in size, aneurysm with loculi and vasospasm were all significant, but there was no special localization to suggest the tendency of rebleeding. As warning sign of rebleeding, increase or instability of blood pressure, deterioration of the neurological state and worsening of the headache and nuchal rigidity seemed to have great significance.
Postmortum study was performed on 4 cases. Extensive brain edema was seen in all of them and cerebral herniation in three (Cases 2, 3 and 4) ; Case 2 had a small hematoma in the insule, Case 3 showed large cerebral infarction in the contralateral hemisphere to the ruptured aneurysm and Case 4 had intraventricular hemorrhage. The cause of death in Case 1 seemed that the vital center suddenly ceased to function because of severe ischemia.
Ruptured intracranial aneurysm should be treated surgically beofre rebleeding. However, if an early operation was impossible due to the patient's poor condition or some other reasons, conservative treatment is inevitable under high risk of rebleeding. Rebleeding of aneurysm depends upon two major factors; the first is the intensity of the ruptured aneurysmal wall, i.e. thrombus and adhesion around the aneurysm vs. fibrinolytic process; the second is the intensity of the power acting on the wall, i.e. blood pressure. Therefore, antifibrinolytic therapy and control of the blood pressure are essential in nonsurgical treatment of ruptured aneurysm, and control of increased intracranial pressure due to brain edema and/or hemorrhage is important.
Close observation of the patient's condition, especially of the blood pressure and of the neurological state, is of great importance in the prediction of rebleeding.

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Using the HITACHI craniocervical CT scanner, we devised a method to take direct coronal head scans with the patient in a sitting position. The scanner takes two simultaneous adjacent slices, 0.5 or 1.0 cm thick, in a scanning time of 3min 40 sec. The image is reconstructed on a 256×256 matrix, displayed on black-and-white and color TV monitors, and recorded by polaroid film. The X-ray generator is operated at 120 kV and 30 mA.
The scanner has a large and accessible scanning region. The accessibility of the scanner permits the patient to be scanned easily in a coronal plane while in a sitting position. In patients able to sit, coronal scans are easier to obtain with the patient seated rather than in a prone or supine position. No excessive flexion or extension of the head and neck is necessary. Coronal sections can be readily obtained at any anterior or posterior cranial levels by this method.
The level of the coronal slice is measured and decided through the observation window which is located at the lateral side of the scanner. The standard point and the standard line are the external auditory meatus (the upper edge = 0 point)and the Reid's base line. Coronal sections through the clivus and the parietooccipital region can be readily obtained at the position of 0 ?? 1.5 cm anterior and 0 ?? 0.5 cm posterior from the external auditory meatus, and75 ?? 90 degrees from the Reid's base line. Coronal sections through the foramen magnum and occipital region can be readily obtained at the position of 0.5 ?? 4.5 cm posterior from the external auditory meatus, and 60 ?? 75 degrees from the Reid's base line.
As a result, coronal sections give not only vertical planes of the lesions, but also provide precise relationships to the tentorium, tentorial notch, clivus, petrous pyramid, foramen magnum and upper cervical regions. They are very important in determining the attachment of the tumor, their location, extent and the relationship with neighboring structures of lesions. The addition of contrast-enhanced coronal CT often demonstrated the lesion to a better advantage. Furthermore, three dimensional orientation method by transverse and coronal CT (biplane CT) has proven to be the most important technique in neurosurgical planning of posterior fossa tumors.

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A case of a 65-year-old woman with lipoma at the callosal agenesis is reported. The patient suffered from a sudden onset of consciousness disturbance as well as left hemiparesis and was admitted into our hospital on March 11, 1976. Radiological examination revealed practically all evidences of lipoma at the callosal agenesis. In addition the right carotid arteriogram demonstrated a mass lesion of the right capsular region. From these findings, the case was diagnosed as a lipoma at the callosal accompanied by hypertensive intracerebral hematoma. Exploratory craniotomy and histological findings confirmed the lipoma at the callosal agenesis.
One year later, CT scanning displayed the lipoma, the extremely low density area (EMI: 36.29 ± 11.145, n=48), surrounded by calcification, the high density zone.
Radiological findings, especially computed tomography, are discussed in detail.

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Computed tomography (CT) findings were analyzed in 17 cases of putaminal hemorrhage accompanied by hemiplegia which had subsided almost completely by conservative therapy within one month after the onset of the disease.
The results obtained are as follows : 1) In cases of putaminal hemorrhage, it was difficult to determine from CT findings whether or not the hemorrhage had reached the posterior limb of the internal capsule, since the limb was usually shifted medially by the hematoma; 2) In such putaminal hemorrhage cases where high density area was not seen at the level showing bodies of the lateral ventricles on CT scan, disturbance of consciousness was slight and hemiplegia improved with conservative therapy; 3) In order to interpret the reason for this, a triangle on the coronary section passing through the posterior part of the posterior limb of the internal capsule was supposed.That is, the triangle is formed by three margins;the base of the triangle marked by a line from the stria terminalis(A-point) to the insula of the same level (B-point), the lateral margin by a line running down from B-point to the upper end of the putamen (C-point) and the medial margin by a line from A-point to C-point. Thus, the relationship between the triangle and the extent of hematoma was investigated; 4) In putaminal hemorrhage, destruction of the pyramidal tract due to hematoma starts from this triangle because the triangle corresponds to the foot of the corona radiata and is most vulnerable to hematoma. Therefore, we call it the “vulnerable triangle.” This triangle is destroyed first and when the hematoma advances further, the posterior limb of the internal capsule is then destroyed; and 5) In cases showing findings of high density area on the CT scan at the level of bodies of the lateral ventricles, the vulnerable triangle may have been damaged and this is an ominous sign for prognosis.

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