Affiliation:
1. Department of Neurological Surgery, University of California, San Francisco, San Francisco, California
2. Departments of Neurological Surgery and Neurophysiology, University of California, San Francisco, San Francisco, California
Abstract
Abstract
OBJECTIVE
Microsurgical clipping of basilar artery aneurysms carries a risk of neurological compromise resulting from midbrain or thalamic ischemia. Somatosensory evoked potential (SSEP) monitoring and electroencephalography are the standard techniques for assessing the level of cerebroprotective anesthesia and monitoring ischemia during temporary occlusion or after permanent clipping. Transcranial motor evoked potential (TcMEP) monitoring was added to determine whether this modality improved intraoperative monitoring.
METHODS
Combined SSEP/electroencephalographic/TcMEP monitoring was used for 30 consecutive patients with basilar artery apex aneurysms in the past 1.5 years. Voltage thresholds were recorded before, during, and after aneurysm treatment for the last 10 patients.
RESULTS
All 30 patients underwent an orbitozygomatic craniotomy for clipping (28 patients), wrapping (1 patient), or superficial temporal artery-superior cerebellar artery bypass (1 patient). Electrophysiological changes occurred for 10 patients (33%), elicited by temporary clipping (6 patients), permanent clipping (3 patients), or retraction (1 patient). Isolated SSEP changes were observed for one patient, isolated TcMEP changes for five patients, and changes in both TcMEPs and SSEPs for four patients. Among patients with simultaneous changes, TcMEP abnormalities were more robust and occurred earlier than SSEP abnormalities. Impaired motor conduction was detected first with an increase in the voltage threshold (from 206 ± 22 to 410 ± 49 V, P < 0.05, n = 3) and then with loss of TcMEP responses. SSEP and TcMEP signals returned to baseline values for all patients after corrective measures were taken.
CONCLUSION
TcMEP monitoring can be safely and easily added to traditional neurophysiological monitoring during basilar artery aneurysm surgery. These results suggest that TcMEPs may be more sensitive than SSEPs to basilar artery and perforating artery ischemia. This additional intraoperative information might minimize the incidence of ischemic complications attributable to prolonged temporary occlusion or inadvertent perforator occlusion.
Publisher
Ovid Technologies (Wolters Kluwer Health)
Subject
Neurology (clinical),Surgery
Reference32 articles.
1. Corticospinal volleys and compound muscle action potentials produced by repetitive transcranial stimulation during spinal surgery;Bartley;Clin Neurophysiol,2002
2. Comparison of the effects of ischaemia on early components of the somatosensory evoked potential in brainstem, thalamus, and cerebral cortex;Branston;J Cereb Blood Flow Metab,1984
3. Somatosensory evoked potentials in experimental brain ischemia;Branston;Prog Brain Res,1984
4. Somatosensory evoked potentials in cerebral aneurysm surgery;Buchthal;Eur J Anaesthesiol,1992
5. Threshold-level repetitive transcranial electrical stimulation for intraoperative monitoring of central motor conduction;Calancie;J Neurosurg,2001
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