Toshihiko Miyamoto

Intracranial aneurysm due to metastatic choriocarcinoma

The case of a woman with an episode of subarachnoid hemorrhage 2 days after delivery is presented. An emergency operation was performed, and an intracerebral clot from a ruptured aneurysm was removed. Histologic examination of the resected aneurysm showed metastasis from a choriocarcinoma to the aneurysmal wall. Six cases of intracranial aneurysm due to metastasis of choriocarcinoma are reviewed.

Present Role of Stereotactic Thalamotomy for Parkinsonism

14 cases of unilateral and 5 cases of bilateral thalamotomy for parkinsonism were reviewed, with 32–144 months’ (mean 67.8) and 54–212 months’ (mean 110) follow-up, respectively, after the initial operation. Rigidity and tremor disappeared in approximately 80% of cases and was reduced in the remaining 20%. 68% improved by one or two grades in the Hoehn-Yahr scale after operation. Thalamotomy abolished dyskinesias and on-off phenomena on the operated sides. 36% of cases discontinued levodopa therapy after operation. CT study of the lesions suggested that destruction of a large part of basal Vop was most important to obtain the best results.

VL Thalamotomy for the Treatment of Tremor in Patients with Thalamic Syndrome

A 59-year-old female who underwent successful thalamotomy for tremor in thalamic syndrome was reported. Thalamic syndrome including tremor of the left limbs and slight dysesthesia over the left side of the face was thought to be due to the vascular lesion located in the right thalamus and adjacent structure by detailed radiological and electrophysiological examination. Significant alleviation of tremor was achieved by right VL thalamotomy without any complication.

Electrophysiological Study of Thalamo-Cortical Relation in Man

Single or repetitive stimulation of the thalamic nucleus has been performed during stereotaxic surgery for over 250 patients with extrapyramidal disorders or intractable pain in our service for the last 7 years, because the stimulation has been encountered as a useful tool for determination of the stereotaxic target. Aside from such direct therapeutic considerations, computer analysis of the cortical evoked responses has brought us much interesting information regarding the physiological mechanism of the thalamo-cortical relations in man. Thus, bilateral, three-negative, cortically evoked responses after single stimulation of the unilateral VL nucleus of the thalamus and differences of augmenting and recruiting responses between the human and the laboratory animal have been reported in the last symposium. In our recent study further investigation of the possible pathway from the stimulated unilateral VL nucleus to bilateral cortex and some analysis of augmenting response were carried out with 50 parkinsonism patients. The impulse which provokes the first positive wave of the contralateral side was thought to be transmitted from stimulated VL nucleus to the contralateral cortex directly via corpus callosum with a velocity of 36–43 m/sec. Repetitive stimulation of the VL nucleus showed typical augmenting or recruiting-like augmenting responses under a certain condition.