Yutaka Honma

Morphological Changes in Human Cerebral Arteries after Percutaneous Transluminal Angioplasty for Vasospasm Caused by Subarachnoid Hemorrhage

Light and electron microscopy were used to study morphological changes in cerebral arteries after percutaneous transluminal angioplasty (PTA) for vasospasm in two patients with aneurysmal subarachnoid hemorrhage. One patient died of gastric bleeding 5 days after PTA. Postmortem examination of the inflated middle cerebral arteries revealed heterogeneously extended walls and dilated lumina. Throughout the vessel walls, the extracellular matrix, which was composed of nonmuscle components such as increased collagen, was stretched in conjunction with the medial muscle component. Also, torn and thinned areas of the wall and intramural hemorrhages were caused by overinflation. The second patient died of massive cerebral infarction caused by diffuse vasospasm 5 days after PTA. Prominent stretching of the walls at the atheromatous plaque margin in the dilated vessel was found in addition to the morphological changes observed in the first patient. These observations suggest that characteristic pathological alterations might be present in the vessel wall at the site of angioplasty. The major mechanism of the long-lasting effects of PTA seems to be the stretching and disruption of both the degenerative muscle and the proliferative nonmuscle components, mainly in the media of the vasospastic vessels.

Monitoring of Cortical Blood Flow during Temporary Arterial Occlusion in Aneurysm Surgery by the Thermal Diffusion Method

During aneurysm surgery, regional cortical blood flow (CoBF) was continuously monitored in 12 patients with a thermal diffusion flow probe in an attempt to assess the effects of temporary major arterial occlusion on blood flow and outcome. When the CoBF was above 30 ml/100 g/min, the safe period for temporary clipping applied distal to the perforators was 15 minutes. The occlusion time should be shortened when the CoBF is below 30 ml/100 g/min. Two patients suffered basal infarction, which was not detected by CoBF monitoring. Attention should be paid to the blood flow in the deep structures when a temporary clip is applied at a site proximal to the perforating branches. Direct measurement of CoBF may be of value in estimating the time that temporary occlusion of a major vessel can be tolerated.

Exposure of the intracavernous carotid artery in aneurysm surgery.

The pterional intradural approach was used in five cases of large and giant carotid-ophthalmic aneurysms and in two cases of intracavernous aneurysms that arose from the anterior siphon knee in the cavernous sinus (CS) and extended into the carotid cistern. In four cases of large carotid-ophthalmic aneurysms removal of the anterior clinoid process and the roof of the optic canal gave easy access to the pericarotid ring. The anteromedial part of the pericarotid ring was dissected to expose the extradural portion of the internal carotid artery (ICA) proximal to the neck and to make enough room between the wall of the CS and the extradural portion of the ICA, thus allowing easy clipping of the neck. In one case of a giant carotid-ophthalmic aneurysm extending into the CS with an extradural origin of the ophthalmic artery and in two cases of an intracavernous aneurysm arising from the siphon knee, neck clipping was performed by opening the lateral wall and roof of the CS after removal of the optic strut. The opening of the lateral wall anterior to the 3rd nerve facilitated wide exposure of the anterior siphon knee. The horizontal portion of the intracavernous ICA as well as the whole aspect of the aneurysm could be exposed as a result of the extended opening of the cavernous roof anterior to the posterior clinoid process. Successful operative results were obtained in all seven patients. A visual field detect as an operative complication was noted in one patient. No disturbance of ocular movements was noted.

Intraoperative radiotherapy for gliomas

SummaryIntraoperative radiotherapy (IORT) was performed in 20 of 36 patients with glioma; 11 glioblastomas, 7 malignant astrocytomas, 2 benign astrocytomas. Twenty or 25 Gy of irradiation was delivered in a single fraction intraoperatively, followed by external beam irradiation. The electron beam energy was selected so that the 80% isodose line fell at 2 or 3 cm below the residual tumor surface. Median survival time of IORT group was 14 months and that of the control group was 10 months. Difference of survival curve was significant. There were 6 incidences of complication caused by IORT; 1 radionecrosis, 1 convulsion, 1 abscess, and 3 severe brain edemas. IORT is suited for the treatment of malignant gliomas.

Serial observations of brain stem function by auditory brain stem responses in central transtentorial herniation

Changes in auditory brain stem responses were serially investigated in a patient with downward transtentorial herniation due to acute obstructive hydrocephalus to correlate the neurological signs with the results of computerized tomography. Neurological deterioration correlated highly with disruption of auditory brain stem responses, especially with that of the components of waves V to VII. A noninvasive technique, the measurement of auditory brain stem responses is thought to be useful in detecting the severity of downward transtentorial herniation and in estimating the recovery of brain stem function after surgical treatment of intracranial hypertension.

Monitoring of cortical blood flow during excision of arteriovenous malformation by thermal diffusion method

The cortical blood flow adjacent to arteriovenous malformations was monitored in six patients before, during, and after excision of arteriovenous malformations using a thermal diffusion probe. In a large arteriovenous malformation, a progressive increase in cortical blood flow up to two times the preexcision value was noted with occlusion of the feeding arteries. Lowering arterial pressure to keep normal cortical blood flow during and after operation resulted in minimum brain edema and an excellent result. Direct measurement of cortical blood flow is of value in determining the precise level of hypotension to prevent brain edema and ischemia that may occur with excision of a large arteriovenous malformation.

Prediction and evaluation of brainstem function by auditory brainstem responses in patients with uncal herniation

Serial measurements of auditory brainstem-evoked responses (BERs) were conducted in 15 patients with supratentorial mass lesions. Significant prolongation of the latency of wave V BERs, which originates in the inferior colliculus, occurred when the intracranial pressure (ICP) approached 30 mmHg. In four of five patients whose BERs were measured before pupillary changes, a significant lengthening of wave V latency was observed prior to clinical manifestation of uncal herniation. These results suggest that immediate medical or surgical decompression of ICP should be performed when ICP approaches 30 mmHg with significant prolongation of wave V latency.

Treatment of vasogenic brain edema with arginine vasopressin receptor antagonist--an experimental study.

We determined the effect of a centrally administered V1 receptor antagonist of arginine vasopressin on the brain water content in an animal model of vasogenic brain edema. Using adult rats, a cold injury was induced in the left hemisphere of the brain by applying a frozen copper rod. 50 ng of V1 receptor antagonist was administered into the left lateral ventricle 10 minutes prior to and/or 1 hour after injury. Twenty four hours after the cold injury, the brain water and sodium contents and plasma osmolality were measured. The V1 receptor antagonist significantly suppressed the increase of the brain water and sodium contents in the cortical structure adjacent to the lesion without any changes in plasma osmolality. Our results demonstrate the effectiveness of a V1 receptor antagonist of vasopressin on vasogenic brain edema.

A comparison of intraarterial carboplatin and ACNU for the treatment of gliomas

BACKGROUND Intraarterial chemotherapy with carboplatin for malignant gliomas has been tried recently, but its therapeutic efficacy and toxicity have not yet been elucidated. METHODS We treated patients with malignant glioma by intraarterial chemotherapy using carboplatin, and compared the efficacy as well as the side effects with intraarterial ACNU. RESULTS Twenty patients were treated with carboplatin (300 mg/m2) and 22 patients were treated with ACNU (80-200 mg/m2). Response (complete remission+partial response) rate for carboplatin was 12.5% compared to 45% for ACNU. Despite higher response rate for ACNU, the difference in the survival curves of the two groups was not significant. Three patients who were treated with high dose (150-200 mg/m2) of ACNU developed hemiparesis and aphasia. Seven patients treated with carboplatin developed 10 incidences of neurotoxicities; two hemiparesis, one aphasia, one blindness, one visual field disturbance, three convulsions, and two developed incidences of disturbances of consciousness. CONCLUSIONS Intraarterial carboplatin was not superior to intraarterial ACNU in achieving remissions, and showed much greater tendency to produce neurotoxicities.

Serial Observations of Brain Stem Function in Acute Intracranial Hypertension by Auditory Brain Stem Responses — A Clinical Study

Recently, multimodality evoked potentials have been used for the evaluation of brain function in patients with severe head injury and acute intracranial hypertension. We have studied the changes in brain stem function in patients with acute intracranial hypertension without any pressure difference between the supra- and infratentorial space and with central and uncal herniation, by measuring the auditory brain stem responses (BERs) that reflect the functional and structural integrity of the brain stem auditory pathway.