Mitsuyuki Koiwa

Intra-operative monitoring by facial electromyographic responses during microvascular decompressive surgery for hemifacial spasm

SummaryThe facial electromyographic response was monitored intraoperatively in 40 patients with hemifacial spasm who were operated on by microvascular decompression of the facial nerve. All 40 patients showed an abnormal facial electromyographic response (lateral spread response) with a latency of about 10 msec after stimulation. The abnormal response resolved before decompression in 22, resolved immediately with decompression in 16, and failed to resolve in two. Of the 38 patients in whom the abnormal response disappeared during surgery, 36 were postoperatively free from hemifacial spasm and two had mild hemifacial spasm. The two patients in whom the lateral spread response did not disappear during surgery showed persistent hemifacial spasm.In conclusion. Disappearance of the lateral spread response during surgery correlated with the absence of hemifacial spasm in the early postoperative period. The prognosis of hemifacial spasm was good in cases in whom the lateral spread response disappeared. Therefore, the authors think that intra-operative facial electromyography is very useful in assessing the efficacy of microvascular decompression and in predicting the prognosis of hemifacial spasm.

Magnetic resonance angiography (MRA) of ruptured cerebral aneurysm

SummaryThe purpose of this study was to evaluate the high resolution magnetic resonance angiography (MRA) as pre-operative angiography for the detection of ruptured cerebral aneurysms. MRA was performed on 1.5 tesla system using the 3-dimensional time of flight (3D-TOF) method. The field of view was 16 cm or 20 cm and matrix size was 192×256 or 256×512. Twenty patients with ruptured cerebral aneurysms and 35 cases of non-ruptured aneurysms (incidental aneurysm) examined by both conventional angiography and MRA were included in this study. All the ruptured aneurysms were operated on based on the information obtained from conventional angiography and MRA. Aneurysms smaller than 3 mm in size were difficult to visualize on MRA. However, most ruptured aneurysms were clearly visualized because they were generally larger than 3 mm. The image quality of MRA was satisfactory for planning surgery.Screening for non-ruptured cerebral aneurysms using MRA is controversial. However, in ruptured aneurysms larger than 3 mm in size, MRA clearly revealed the aneurysm, and MRA findings were informative enough to plan surgery. It is concluded that this noninvasive examination can be selected as a first-choice examination especially in cases of ruptured aneurysm.

Aneurysm of the Vein of Galen in an Infant: Case report

A case of an aneurysm of the vein of Galen treated by a successful direct surgical procedure during the infancy is presented together with five year’s follow-up observation.