[Exploration of intraspinal tumors using evoked motor potentials (EMP): correlations with data of evoked...

MEPs to transcutaneous magnetic stimulation have been recorded in 43 patients with an intraspinal tumor documented by MRI. The tumor was extramedullary in 18 patients and intramedullary In 25. MEPs were abnormal in 62.8% of patients. There were no significant differences in the rate of MEP abnormalities according to the lesion site or the histological findings, except for meningiomas which showed abnormal MEPs in all eight patients included in this series. The percentage of patients with abnormal MEPs was 9.3% despite the absence of any clinical symptom of central motor pathway dysfunction. Infraclinical MEPs abnormalities were observed in 24% of explored limbs. Median and tibial nerves somatosensory evoked potentials (SEPs) were recorded in 41 patients and showed abnormalities of central conduction or of segmental spinal responses in 65.9% of the cases. When combining data from MEP and SEPs, abnormalities were observed in 70.7% of patients (29/41). Five patients (12.2%) had abnormal MEPs, but normal SEPs, and four other patients (9.8%) had abnormal SEPs, but normal MEPs. This finding suggests that both MEPs and SEPs should be recorded for presurgical evaluation of-intraspinal tumor.