title: Cutaneous pain threshold changes after sympathetic block in reflex dystrophies.
abstract: In a group of 30 subjects suffering from sympathetic reflex dystrophies of the limbs, the sympathetic ganglia of the affected side were blocked with a local anesthetic. Using an original method, we measured the cutaneous pain threshold before the block and at prefixed intervals after the block during a period of 2 days. In all subjects the cutaneous pain threshold showed damped oscillations both in the limb ipsilateral to the block and in the contralateral one. The analysis of these oscillations showed: (a) that the sympathetic control of the cutaneous pain threshold may be exerted through a negative feedback loop (skin-afferent input-CNS-sympathetic output-skin); (b) that the afferent discharge of a limb controls the contralateral sympathetic output through central mechanisms.
mesh_terms: D000328:Adult; D000368:Aged; D001340:Autonomic Nerve Block; D004056:Differential Threshold; D005260:Female; D007839:Functional Laterality; D006801:Humans; D007866:Leg / Q000294:innervation; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000503:physiopathology*; D012019:Reflex Sympathetic Dystrophy / Q000503:physiopathology* / Q000628:therapy; D012867:Skin / Q000294:innervation*; D013997:Time Factors