Central poststroke pain: correlation of MRI with clinical pain characteristics and sensory abnormalities.

OBJECTIVE: To correlate MRI and sensory changes in patients with spontaneous lesions in the cerebral "pain pathway."
METHODS: The authors used MRI and quantitative somatosensory testing in 73 patients with central poststroke pain (CPSP) and in 13 patients with pain-free stroke with sensory deficit.
RESULTS: Lesions in any part of the discriminatory somatosensory pathway may or may not produce CPSP. Most CPSP patients have multiple lesions, many probably unrelated to pain. Ventroposterior thalamic nuclear lesions are more likely to produce half-body pain than lesions elsewhere (including the brainstem). In supratentorial lesions, the greatest pain is more likely to be in an extremity, and in infratentorial lesions, the greatest pain is likely to be in the face. Supratentorial CPSP patients have a deficit of sharpness and cold (peripherally mediated by A delta fibers) than pain-free stroke patients, whereas patients with infratentorial CPSP additionally have a deficit of C-fiber-mediated warmth and hot pain. Burning pain is more common than nonburning pain in younger patients. Warmth and cold, but not hot pain, exhibiting central convergence (spatial summation) are more affected in CPSP patients with burning than nonburning pain. Allodynic CPSP patients had a significantly greater deficit for warmth than patients without allodynia.
CONCLUSIONS: Different stroke sites produce different patterns of sensory deficit. The progression from painless sensory deficit to CPSP is not purely quantitative.