Brain : a journal of neurology
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It has been postulated that sensorimotor integration is abnormal in dystonia. We investigated changes in motor cortical excitability induced by peripheral stimulation in patients with focal hand dystonia (12 patients with hand cramps) and with cervical dystonia (nine with spasmodic torticollis) compared with 16 age-matched normal controls. Motor evoked potentials (MEP) to focal (figure-of-eight coil) transcranial magnetic stimulation of the hand area were recorded from the right abductor pollicis brevis (APB), first dorsal interosseus (FDI), flexor carpi radialis and extensor carpi radialis muscles. ⋯ On the contrary, hand cramp patients showed a significant facilitation of test MEP size. This study suggests that MEP suppression following peripheral stimulation is defective in patients with focal hand dystonia. Central processing of sensory input is abnormal in dystonia and may contribute to increased motor cortical excitability.
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Complex regional pain syndrome type I (CRPS I, formerly known as reflex sympathetic dystrophy) is a painful neuropathic disorder that develops after trauma affecting the limbs without overt nerve injury. Clinical features are spontaneous pain, hyperalgesia, impairment of motor function, swelling, changes in sweating, and vascular abnormalities. In this study, the pathophysiological mechanisms of vascular abnormalities were investigated. ⋯ Secondary changes in neurovascular transmission may lead to vasoconstriction and cold skin in chronic CRPS I, whereas sympathetic activity is still depressed. Vascular abnormalities are dynamic. The maximal skin temperature difference that occurs during the thermoregulatory cycle distinguishes CRPS I from other extremity pain syndromes with high sensitivity and specificity.