The purpose of this study was to evaluate the characteristics of pain(s) and their relationship to somatosensory abnormalities, and magnetic resonance imaging (MRI) spinal cord findings, in 27 patients with long-standing painful syringomyelia. Detailed histories, pain drawings, and physical examination data were collected. MRIs were reviewed by an experienced neuroradiologist. Average symptom duration was 14 years. Pain was the sole symptom at onset in 59% of the patients, cited as the primary cause of disability in 67% of the subjects. It was reported as spontaneous in 93% of the cases, paroxysmal in 70%, and touch/pressure-evoked in 22% and rated as moderate in 70% and severe in 11%. Pain and somatosensory abnormalities primarily involved the upper/lower torso and back, but all other body areas were affected. Primarily, hypoesthetic sensory abnormalities to ,touch, pinprick, and cold were found, only partially matching the areas of pain in most patients. MRIs revealed large cervicothoracic syrinx in most patients with cord atrophy and arachnoiditis in several. Blinded infusions of sodium amytal (SA) dramatically modified hypoesthesia in 2 patients. The temporary modification of negative sensory abnormalities under SA suggests that some sensory deficits are dynamically maintained as a result of central nervous system (CNS) plasticity, superimposed on phenomena arising from structural neural tissue damage.