Diagnostic possibilities for the nuchal evoked potential.

As a response to stimulation of the arm nerves an evoked potential can be recorded in the posterior neck region in man. This nuchal evoked potential (NEP) was recorded in three selected patients with A) cervical rib, B) syringomyelia, and C) prolapse of cervical intervertebral disc. Patients A and C had low-amplitudic NEPs with increased latencies when the affected side was stimulated and "normal" NEPs when the unaffected side was stimulated. Patient B had grossly abnormal, polyphasic NEPs (regardless of the side stimulated) but the simultaneously recorded somatosensory evoked potential was "normal". No systematic differences in the parameters of the NEP due to different recording locations on the neck could be observed.