A-BETA-FIBER MEDIATED ACTIVATION OF CINGULATE CORTEX AS CORRELATE OF CENTRAL POSTSTROKE PAIN

A patient is presented who suffered a lateral brainstem infarction whi ch selectively abolished pain and temperature sensitivity in the lower right limb. One year later central post-stroke pain had developed in the affected limb with touch and cold allodynia. P40m dipoles calculat ed from magnetoencephalographic fields after electrical stimulation of both tibial nerves were localized in SI as is seen in normal subjects . However, stimulation of the affected side caused deep pain sensation s and elicited a large N80m component, best explained by an additional ly active dipole in cingulate cortex. This early co-activation in a li mbic structure suggests peripheral AP-fiber mediation and lemniscal pr ojection. Abnormal link to the pain system may be due to sensitization and reorganization above the level of nociceptive deafferentation.