Transcranial Motor Evoked Potential Monitoring in a Patient With a Deep Brain Stimulator: A Case Report.

A major complication of surgical scoliosis correction is permanent injury of the spinal cord. Intraoperative neuromonitoring continually evaluates spinal cord function through monitoring sensory and corticospinal motor tracts. There is no literature or manufacturer recommendation on whether transcranial motor evoked potential (tcMEP) monitoring can be performed safely in the presence of a deep brain stimulator (DBS) system. A 17-year-old adolescent boy with severe neuromuscular scoliosis presented for a posterior spinal fusion. The patient suffered from generalized dystonia treated with a DBS terminating in the left and right globus pallidus internus. The competing goals of monitoring motor function during the spinal fusion and preserving the integrity of the DBS system were discussed preoperatively. The DBS system was deactivated for the duration of surgery, and tcMEPs were used sparingly at the lowest suitable stimulation voltage. Intraoperative management focused on facilitating neurophysiologic monitoring through a total intravenous anesthetic of propofol, methadone, and remifentanil. The tcMEPS remained unchanged throughout the operation and the patient emerged able to move his lower extremities to command. Postoperatively, the DBS system was turned back on and showed retained settings, normal functioning, and unchanged impedance of the DBS leads. Neither the patient nor his parents reported any subjective changes in the symptoms of dystonia. The authors conclude that monitoring tcMEPs in the presence of a DBS implant may be done safely, when the clinical circumstances suggest that the added information gained from tcMEPs outweighs the theoretical risk to the DBS system and the course of the medical condition treated by the DBS.