Objective: To assess whether the thalamic pain syndrome of Dejerine-Roussy is produced preferentially by right diencephalic lesions and to elucidate its clinical features.
Background: Several experimental paradigms suggest that the right hemisphere is specialized for monitoring somatic states, including mediating pain. However, clinical studies of pain laterality have been inconclusive, possibly due to pathophysiologic diversity among analyzed patients. We collected reports of central pain laterality in a single, well-demarcated disorder, the Déjerine-Roussy syndrome.
Design/methods: Reports from English, French, and German literature were identified through Medline search and bibliography-guided retrieval. Inclusion criteria were (1) thalamic lesion documented by CT, MRI, or postmortem examination and (2) contralateral pain. Exclusion criteria were (1) tumoral/nonvascular etiology (to optimize anatomic localization), (2) symptoms consisting solely of evoked dysesthesia without spontaneous pain, or (3) sidedness of lesion not clearly indicated. Cases were analyzed for laterality as well as secondary anatomic and clinical variables.
Results: Literature search identified 274 cases. After exclusions, 180 remained. A total of 114 had a right-sided thalamic lesion, 66 left-sided (p < 0.001). Laterality predominance was greater among men than women. The frequency of other components of the Dejerine-Roussy syndrome--sensory impairment, hemiparesis, ataxia, and choreoathetosis--did not significantly differ between right and left groups. Pain onset was within the first week poststroke in 36%. Frequency of spontaneous pain was 14% after any thalamic stroke and 24% after geniculothalamic artery territory stroke.
Conclusion: Right-sided lesions predominate among reported cases of the thalamic pain syndrome. This preferential involvement of the nondominant thalamus in pain processing is supportive evidence of a nondominant hemisphere specialization in monitoring somatic states.