Potential role of Intraoperative neurophysiological evaluation of central motor conduction time : case series

Objective: We demonstrate the case series in which the intra-operative central motor conduction time (CMCT) was measured during untethering surgery to provide additional information about spinal cord function, distinct from peripheral nervous system.

Methods: We retrospectively reviewed the cases that CMCT was measured during surgery performed at a single tertiary hospital. Total of 21 patients were included. Informations regarding spine MRI, Urodynamic study, EMG/NCS study were also collected. F-wave and M-wave latencies were evaluated to measure CMCT, from bilateral abductor hallucis muscles by stimulating the tibial nerve at medial malleolus.

Results: CMCT were measured in all participants. The values were 34.2±8.0(ms) in the right side, while 34.4±9.9(ms) in the left side. Groups were divided by presence of low-lying conus medullaris, syrinx, abnormal electrodiagnostic test finding, urodynamic study findings (bladder neck incompetence, underactive bladder, detrusor-sphincter dyssynergia, and low bladder compliance). Among compared variables, low lying conus medullaris was significantly associated with delay in CMCT.

Conclusion: Significant spinal cord dysfunction could be detected intra-operatively, especially in those with low lying conus medullaris. Further studies for reliability, validity are required.