Case History—An 81 yr old man presenting with difficulty walking, paraesthiesiae in his feet, and urinary symptoms. The spinal cord is subject to numerous pathological processes that can arise within (intramedullary) and/or extrinsic to the cord (extramedullary lesions). Symptoms and signs suggestive of spinal cord disease include (1) motor—weakness and alteration in tone; acute cord lesions produce flaccidity (‘spinal shock’) and chronic processes spasticity, with hyper-reflexia, clonus, and upgoing plantar responses; pathological processes targeting lower motor neurons in the anterior horns typically produce early muscle wasting and fasciculation; (2) sensory—including numbness, loss of sensation, tingling, sensory ataxia; the demonstration of a sensory level and analysis of specific sensory deficit patterns are of particular importance in localizing the site, and therefore the likely cause, of any lesion; and (3) autonomic—sphincter dysfunction, most commonly affecting bladder function....