Evaluation of cervical spine inflammatory arthritis with somatosensory evoked potentials

Bilateral independent median nerve somatosensory evoked potentials (SEP) were obtained in 15 patients with inflammatory arthritis of the cervical spine. Limitation of neck motion, neck pain, abnormal neurologic findings, and atlantoaxial subluxation were evaluated. Ten of 15 patients had abnormal SEP associated with subluxation in 9. Neurological signs specifically localizable to the central nervous system (CNS) were present in only 2 of the 10 patients. SEP were normal in the remaining 5 patients despite the presence of nonspecific neurological signs including atrophy of the intrinsic muscles of the hands and atlantoaxial subluxation determined by radiographic evaluation in 3 of 5 patients. Our study demonstrates the value of SEP in the evaluation of CNS function when findings on examination and radiographs may not conclusively document spinal cord impairment.