Early diagnosis of cerebral ischemia in cerebral vasospasm by oxygen-pulse near-infrared optical topography.

PURPOSE: Early diagnosis of vasospasm is a key factor in the choice of treatment after subarachnoid hemorrhage (SAH). However, a noninvasive method of diagnosing delayed ischemic neurological deficit (DIND) has not been established. We therefore propose a new method of diagnosing cerebral ischemia using near-infrared optical topography (OT) with oxygen inhalation. MATERIALS AND METHODS: We used a 44-channel OT system that covers the bilateral front otemporoparietal areas to assess 29 patients who underwent surgery within 72 h of the onset of SAH. The patients inhaled room air followed by oxygen for 2 min, and then peripheral oxygen saturation (SpO2) was continuously monitored at the index fingertip. The patients were assessed by N-isopropyl-p-[¹²³I]iodoamphetamine (IMP)-SPECT and OT on the same day. Ischemic findings were confirmed using principal component analysis with reference to the systemic SpO2value. RESULTS: Seven of 29 patients developed DIND. Evidence of ischemia was identified by OT in all seven of these patients before the onset of DIND. The OT and SPECT findings agreed in 27 (93 %) of the 29 patients. DISCUSSION AND CONCLUSIONS: Our method might detect cerebral ischemia before the onset of DIND and thus be clinically useful for assessing cerebral ischemia with vasospasm.

Late onset cerebrospinal fluid leakage associated with past head injury.

Late onset cerebrospinal fluid (CSF) leakage, such as rhinorrhea or otorrhea, is a rare complication of closed head injury. We encountered two cases of delayed CSF leakage more than 10 years after head injury. In both cases, surgical treatments were performed using intradural approaches, and the dural defects were closed with viable pedicled flaps. After surgery, the CSF leakage was completely cured and no remarkable complication was observed in either case. The present two cases of late onset CSF leakage suggest that surgical repair procedures should be performed as soon as the leaks are discovered. A bifrontal intracranial approach is recommended to treat frontal cranial base leakage. Temporal craniotomy is recommended to treat temporal base leakage. All cases should be treated using an intradural approach, and the dural defect is best repaired with viable pedicled flaps.

Intraoperative monitoring during surgery for hypoglossal schwannoma.

A 54-year-old man presented with an intracranial schwannoma of the hypoglossal nerve between the medulla and the left hypoglossal canal. The condylar fossa approach was used with intra-operative electromyography (EMG) monitoring of the lower cranial nerves. The tumor was then removed carefully without decreasing the tongue EMG responses. EMG monitoring enabled us to remove the tumor while maintaining the function of the hypoglossal nerve. Tongue EMG was easily recorded by stimulating the hypoglossal nerve fibers, which was useful in identifying the hypoglossal nerve and evaluating its function. This suggests that tongue EMG is a useful monitoring tool to enhance neurological outcome following removal of tumors in this region.

Clipping of a vertebral artery aneurysm behind the hypoglossal nerve under the monitoring of lower cranial nerves.

Under an operative view, an aneurysm of the vertebral artery is located behind the lower cranial nerves. To prevent neurological deficits we employed electrophysiological monitoring while clipping an aneurysm of the vertebral artery. A 64-year-old woman had suffered a sudden severe headache in the morning. Computed tomography (CT) revealed a subarachnoid hemorrhage (SAH) and CT angiography revealed an aneurysm at a branching point of the left vertebral artery. The condylar fossa approach was taken while recording electromyography (EMG) of the lower cranial nerves. The aneurysm was located just behind the hypoglossal nerve and could not be clipped without strong traction of the hypoglossal nerve. Therefore, the hypoglossal nerve was divided to separate the lower two bundles of the hypoglossal nerve from the other bundles, and the clip was applied to the aneurysm between the nerve bundles without any change of the tongue EMG. The patient went home 10 days after operation with no neurological deficit. In conclusion, we report a case of a ruptured aneurysm of a vertebral artery, which was clipped while monitoring the lower cranial nerves. Tongue EMG monitoring enabled us to clip the aneurysm without nerve injury and revealed that the hypoglossal nerve near the hypoglossal canal can be divided into several bands without neurological deficit.

Treatment with botulinum toxin improves the hyperexcitability of the facial motoneuron in patients with hemifacial spasm.

Botulinum toxin type A (BTX) injection into the orbicularis oculi muscle is an effective treatment for patients with hemifacial spasm (HFS). The objectives of this study were to investigate the effect of this treatment on HFS, in particular the associated hyperexcitability of the facial motor nucleus, and to discuss the potential mechanism of HFS. F waves in the mentalis muscle were examined before, 2 and 6 weeks after the BTX treatment of only the orbicularis oculi muscle in ten patients with HFS. F/M ratio, duration of F waves and frequency of F waves decreased significantly after the BTX treatment compared with those before the BTX treatment. These findings demonstrate that the excitability of the facial motonucleus decreases after BTX treatment of the orbicularis oculi muscle. From these results, we hypothesize that the trigeminal afferent input and the cortical control contribute to the hyperexcitability of the facial motor nucleus in patients with HFS. This warrants further investigation into the pathophysiology of HFS.