Nobuo Kiya

Monitoring of Facial Evoked EMG for Hemifacial Spasm: a Critical Analysis of its Prognostic Value

Summary Microvascular decompression (MVD) has come to stay as an effective way of treating hemifacial spasm. But it remains to be seen how much each of the electrophysiological monitoring techniques (intra-operative) are contributing to its increased efficacy. Their role as indicators for re-exploration or recurrence is to be evaluated with more studies. We have used the lateral spread response in those patients who had distinctly abnormal recording on the ipsilateral side, studied the intra-operative changes during MVD and correlated with the outcome of surgery. 38 patients operated for HFS, were selected for intra-operative monitoring of abnormal muscle responses. In 17 patients, there was persistence of abnormal muscle responses in the immediate postoperative period and only 6 of them had mild HFS. Two of 21 patients who had disappearance of abnormal responses had persistent mild HFS; but in all cases, the HFS disappeared within 3 months. So we found that the intra-operative recording was really not reliable in predicting the immediate postoperative outcome. However the outcome at 3 months suggested that waiting for some time before re-exploration is a better option, especially if the HFS had become mild.

Neuroendoscopy in microvascular decompression for trigeminal neuralgia and hemifacial spasm: technical note.

Abstract Miocrovascular decompression is an effective treatment for trigeminal neuralgia (TN) and hemifacial spasm (HFS). A complete cure cannot be obtained, and additional adjuncts for extended use of endoscopy are needed. The use of an endoscope combined with the operating microscope can enhance the surgeon’s ability to view deep structures during operation. We study the application of combined microsurgical and endoscopic techniques in 21 cases of HFS and 12 cases of TN. With these techniques the surgeon can explore the ventral aspect of the brainstem and cranial nerves without further retraction, can see the groove caused by compression of the offending artery, and can confirm the proper position of the prosthesis after attachment to the dura by fibrin glue. In HFS the most common offending vessels in 75% of cases were the posterior inferior cerebellar artery (PICA) and anterior inferior cerebellar artery (AICA) and in 25% of cases the vertebral artery (VA). In trigeminal neuralgia the offending vessel in 60% of cases was the superior cerebellar artery (SCA), and in 40% of cases the AICA. The overall success rate was 97% with minimal morbidity 3% (facial palsy) and no mortality. The aim of this work is to study advantages and disadvantages of using endoscopy during microvascular decompression for TN and HFS. [Neural Res 2000; 22: 522-526]

Synthesized surface anatomy scanning (SSAS) for surgical planning of brain metastasis at the sensorimotor region: initial experience with 5 patients.

SummarySurface anatomy scanning (SAS) is a powerful technique that uses T2-weighted magnetic resonance images (MRI) to visualize brain surface structures, and to precisely localize subcortical lesions. To overcome technical limitations of this method, synthesized SAS (SSAS) superimposes MR angiography (MRA) data on the SAS images. We describe our initial experience with surgical planning for the resection of metastases at the sensorimotor region in 5 patients using SSAS. Neurological deficits were assessed before and after surgical resection. Although 4 of 5 patients had mild to severe neurological deficits before surgery, three became symptom-free and no patient had an increased deficit after surgery. Our results undoubtedly provide palliative surgery for sensorimotor metastases. As SSAS is non-invasive and requires a short scanning time, this method could become a useful technique for the routine pre-operative simulation for surgery on brain surface lesions such as sensorimotor metastases.

Precisely Targeted Tumor Biopsy and Marking under CT-Fluoroscopy

An innovative imaging procedure, computed tomographic (CT) fluoroscopy, was recently developed by Katada and Toshiba Medical Corporation in Japan [1,2]. This procedure permits sequential display of computed tomograms in real time. CT-fluoroscopy has been found to be extremely useful for real-time monitoring, which ensures the safety and accuracy of invasive techniques such as punctures in the neurosurgical field [3]. We recently, attempted targeted needle biopsy at three points, the subcortex near the lesion and the lateral side and center of the lesion, under CT-fluoroscopy. We then attempted to precisely place a marker at the inner border of the lesion near the internal capsule. A round mini-coil was used as the marker. Two weeks later we succeeded in extensively resecting the tumor lesion without producing motor weakness because the marker’s shadow on an ultrasonic image allowed navigation to the bottom of the lesion very precisely by showing where the eloquent area was located. A neuronavigation system using preoperative images was used simultaneously. There was a difference of 10 mm between the point indicated with the navigator and the actual position of the marker. This difference is considered to reflect brain shift caused by intraoperative leakage of cerebrospinal fluid. Thus, the computer-aided neuronavigation system appears to require a feedback technique for intraoperative brain shift that would enhance precision, reliability, and safety. In this respect, CT-fluoroscopy combined with intraoperative CT is considered to play a potentially very important role.

Classification and treatment of aneurysms of the internal carotid siphon.

A series of 48 surgically treated internal carotid siphon aneurysms is presented. The projection of these aneurysms are a key factor in their surgical repair and should be included in a classification system.