Preventing position-related brachial plexus injury with intraoperative somatosensory evoked potentials and transcranial electrical motor evoked potentials during anterior cervical spine surgery.

The use of somatosensory evoked potentials (SSEPs) to monitor upper extremity nerves during surgery is becoming more accepted as a valid and useful technique to minimize intraoperative nerve injuries. We present a case illustrating the benefit of utilizing both SSEPs and transcranial electrical motor evoked potentials (TCeMEPs) for preventing position-related injury during surgery. The patient was a 43-year-old male with a history of neck pain, along with numbness and tingling of the upper extremities. While the patient was being draped, upper extremity SSEPs diminished significantly TCeMEP responses in the hands (abductor pollicus brevis-abductor digiti minimi; APB-ADM) vanished shortly after that, followed by the biceps and left deltoid. The surgeons were notified, and the tape on the shoulders was loosened. No improvements were noted in SSEPs nor TCeMEPs due to this intervention, so all tape was removed and the patient's arms were allowed to rest naturally upon the arm boards. Upper extremity TCeMEP responses could then be elicited and SSEPs improved shortly afterward. Surgery was completed with the arms on the arm boards. All signals remained stable for the remaining three hours of the procedure. At two months follow-up, the patient was well with total pain relief and normal upper extremity function when neurological examination was performed. This report demonstrates a case in which intraoperative neurophysiological monitoring was useful in identifying and reversing impending nerve injury during cervical spine surgery. Significant changes were seen in SSEPs as well as TCeMEPs, so we recommend that TCeMEP monitoring be considered as an adjunct to SSEPs for prevention of injury to the brachial plexus.

Protecting the genitofemoral nerve during direct/extreme lateral interbody fusion (DLIF/XLIF) procedures.

A 77-year-old male presented with a history of severe lower back pain for 10 years with radiculopathy, positive claudication type symptoms in his calf with walking, and severe "burning" in his legs bilaterally with walking. Magnetic resonance imaging (MRI) revealed lumbar stenosis at the L3-L4 and L4-L5 levels. During the direct or extreme lateral interbody fusion (DLIF/XLIF) procedure, bilateral posterior tibial, femoral, and ulnar nerve somatosensory evoked potentials (SSEPs) were recorded with good morphology of waveforms observed. Spontaneous electromyography (S-EMG) and triggered electromyography (T-EMG) were recorded from cremaster and ipsilateral leg muscles. A left lateral retroperitoneal transpsoas approach was used to access the anterior disc space for complete discectomy, distraction, and interbody fusion. T-EMG ranging from 0.05 to 55.0 mA with duration of 200 microsec was used for identification of the genitofemoral nerve using a monopolar stimulator during the approach. The genitofemoral nerve (L1-L2) was identified, and the guidewire was redirected away from the nerve. Post-operatively, the patient reported complete pain relief and displayed no complications from the procedure. Intraoperative SSEPs, S-EMG, and T-EMG were utilized effectively to guide the surgeon's approach in this DLIF thereby preventing any post-operative neurological deficits such as damage to the genitofemoral nerve that could lead to groin pain.