Isolated posterior column dysfunction: an unusual presentation of spondylotic myelopathy.

Two patients with previously unreported clinically evident myelopathy caused by herniated intervertebral disks are described. These patients had isolated posterior column dysfunction in the lower extremities without motor deficits, abnormal reflexes, spinothalamic sensory abnormalities, or sphincter changes. The level of cord compression was significantly more cranial than suggested by clinical localization, and the results of initial radiographic studies were unremarkable. Study of posterior column dysfunction using somatosensory evoked potentials was helpful in localizing the lesions and guiding appropriate neuroradiologic studies.