Subdural air limits the elicitation of compound muscle action potentials by high-frequency transcranial electrical stimulation

• Published in: British journal of neurosurgery Vol. 14; no. 3; pp. 240 - 243
• Main Author: Kombos, O. Suess, T. Pietila, M. Brock, Th
• Format: Journal Article
• Language: English
• Published: Abingdon Informa UK Ltd 01.06.2000; Taylor & Francis; Taylor & Francis Ltd
• Subjects: Adult; Biological and medical sciences; Brain; Brain Neoplasms - physiopathology; Brain Neoplasms - surgery; Compound Muscle Action Potentials High-FREQUENCY Repetitive Stimulation Intraoperative Monitoring Transcranial Electrical Stimulation; Electric Stimulation; Electrodiagnosis. Electric activity recording; Evoked Potentials; Humans; Investigative techniques, diagnostic techniques (general aspects); Male; Medical procedures; Medical sciences; Monitoring, Intraoperative - methods; Muscle, Skeletal - physiopathology; Nervous system; Neurology; Pneumocephalus - diagnostic imaging; Pneumocephalus - physiopathology; Posture; Radiography; Subdural Space - diagnostic imaging; Surgery; Human; Subdural; Electric; Exploration; Intraoperative; Action potential; Stimulation; Air; Striated muscle; Transcranial route; Electrodiagnosis; Seated position; Posterior fossa; High frequency
• ISSN: 0268-8697; 1360-046X
• DOI: 10.1080/026886900408432

High-frequency transcranial electrical stimulation was performed in 8 patients undergoing surgery in the sitting position. Following the opening of the dura of the posterior fossa changes in compound muscle action potentials were observed. These changes were not attributable to surgical manoeuvres at the brain stem or spinal cord, or to anaesthetic changes. In all these cases intraoperative fluoroscopy of the skull revealed a subdural air collection underneath the stimulation electrodes. Such a subdural air collection, not infrequent in patients operated on in the sitting position, limits the application of highfrequency transcranial electrical stimulation as a monitoring technique. It remains unclear if this effect is due to the increasing distance between scalp and cortex and the insulating effect of subdural air, or due to displacement of the motor cortex. The practical importance of this report is derived from the increasing application of intraoperative motor pathway monitoring.