Does transcranial stimulation for motor evoked potentials (TcMEP) worsen seizures in epileptic patients following spinal deformity surgery?

Khalid M. I. Salem, Laura Goodger, Katherine Bowyer, Masood Shafafy, Michael P. Grevitt

To investigate the effect of Transcranial Motor Evoked Potentials (TcMEP) in increasing the severity or frequency of post-operative seizures in patients undergoing deformity corrective spine surgery with a known history of seizures pre-operatively. The information on all patients with history of epilepsy/seizures who underwent spinal TcMEP cord monitoring for deformity correction surgery was retrospectively collected through a review of the hospital notes. The benefits of TcMEP in the early detection of potential cord ischemia were deemed by the operating surgeon to outweigh the increased risks of seizures, tongue biting, etc. Data on age, gender, pre-operative diagnosis, curve type, intra-operative monitoring alerts, duration of hospital stay, and post-operative in-hospital seizures were collected. Additionally, the patients were contacted following discharge and data on any change in the frequency of the seizures or an alteration in seizure-related medication post-operatively was also collected. The records of 449 consecutively monitored patients were reviewed and 12 (2.7 %) patients with a history of seizures pre-operatively were identified. The mean age was 23 (9-59) years, 7 females, 11 scoliosis corrections (4 neuromuscular, 1 degenerative, 6 idiopathic adolescent), and one sagittal balance correction surgery. Intra-operatively, all patients had TcMEP monitoring, were catheterised, and had no neuromonitoring alerts or record of tongue biting or laceration. Post-operatively, the mean hospital stay was 12 (4-25) days with no recorded seizures. At a mean of 23 (12-49) months post-discharge, none of the patients reported a worsening of seizures (pattern or frequency) or required an alteration in the seizure-related medications. TcMEP does not appear to trigger intra-operative or post-operative seizures and is not associated with deterioration in the seizure control of patients suffering seizures pre-operatively.