The possible role of the cerebral cortex adjacent to the central sulcus for the genesis of central (thalamic) pain--a metabolic study.

In nine patients with central (thalamic) pain after stroke, X-CT, MRI, PET scan and intraoperative thalamic microrecordings were performed. The PET studies made use of Sokoloff's method with 18FDG and a steady-state method with C15O2-15O2. CT scan and MRI revealed definite thalamic damage (Th) in 3 cases, putaminal damage (Put) in 3 cases, combined damage (Th + Put) in one case, and cortical (parietal) damage in 2 cases. In patients with a subcortical lesion, the greater the severity of superficial pain, the higher was the relative value of regional cerebral glucose metabolism (rCMRGlu) as compared to oxygen metabolism (rCMRO2) in the cerebral cortex around the central sulcus on the damaged side. Also, in a case with combined (Th + Put) lesion, regional oxygen extraction ratio (rOEF) was increased in this area. Moreover, in another case, central pain disappeared after a small subcortical haemorrhage in the same structure. In all patients including those with a cortical lesion, rCMRGlu was decreased in the postero-lateral (sensory) thalamus on the invalued side. The possible role of the cerebral cortex around the central sulcus for the genesis of central pain is discussed.