Lower Limb Paralysis After Spinal Fusion Surgery

This case involves a sixty-two-year-old male patient who presented to the hospital with a displacement of a cervical intervertebral disc and was admitted to the neurosurgery service after a workup revealed cervical spinal stenosis, cervical myelomalacia, and cervical spondylosis. The patient underwent an anterior discectomy and fusion at C5/C6 and C6/C7, with SSEP and MEP monitoring in place throughout the operative procedure. The operative note described the removal of a significant amount of osteophytes and the use of plates and screws to secure the fusion. The procedure was conducted without incident and a stage two spinal stabilization procedure was scheduled for the following week. The second procedure was conducted but this time MEP monitoring was not employed. The patient awoke from surgery with a paralyzed right upper extremity. A CT scan was performed that showed no neuro laminal vertebral, foraminal, or central canal encroachment from metallic hardware. EMG and nerve conduction studies were done and conclusions were that there was electrophysiologic evidence of bilateral brachial plexopathies with widespread active denervation in all tested muscles innervated from C5 to T1. The patient had a diagnosis of bilateral brachial plexopathy with the left side being injured to a much lesser extent and is currently undergoing rehabilitation with minimal improvement.

Question(s) For Expert Witness

1. How is SEP/MEP monitoring useful in avoiding injury in a patient during surgery?

Expert Witness Response E-001705

SEP/MEP monitoring is used widely to assess the integrity of the spinal cord during surgery in which the spinal cord is manipulated. SEPs are used most often during scoliosis correction. Ischemia of ascending somatosensory pathways produces a drop in amplitude or loss of waveforms, thus warning the surgeon in time to take corrective action. Ischemic changes are usually widespread. In rare cases, however, motor function is lost when somatosensory pathways have not been affected. Other spinal procedures in which SEP monitoring is used include reduction of vertebral fractures, other vertebral injuries, and spinal cord tumor surgery. Conduction abnormalities that selectively abolish the silent periods can distinguish between hydromyelia (a physiologically dilated central canal) and space-occupying syringomyelia.