Effects of temporary functional deafferentation on the brain, sensation, and behavior of stroke patients.
الكلمات الدالة
نبذة مختصرة
Following stroke, many patients suffer from chronic motor impairment and reduced somatosensation in the stroke-affected body parts. Recent experimental studies suggest that temporary functional deafferentation (TFD) of parts of the stroke-affected upper limb or of the less-affected contralateral limb might improve the sensorimotor capacity of the stroke-affected hand. The present study sought evidence of cortical reorganization and related sensory and motor improvements following pharmacologically induced TFD of the stroke-affected forearm. Examination was performed during 2 d of Constraint-Induced Movement Therapy. Thirty-six human patients were deafferented on the stroke-affected forearm by an anesthetic cream (containing lidocaine and prilocaine) on one of the 2 d, and a placebo cream was applied on the other. The order of TFD and placebo treatment was counterbalanced across patients. Somatosensory and motor performance were assessed using a Grating orienting task and a Shape-sorter-drum task, and with somatosensory-evoked magnetic fields. Evoked magnetic fields showed significant pre- to postevaluation magnitude increases in response to tactile stimulation of the thumb of the stroke-affected hand during TFD but not following placebo treatment. We also observed a rapid extension of the distance between cortical representations of the stroke-affected thumb and little finger following TFD but not following placebo treatment. Moreover, somatosensory and motor performance of the stroke-affected hand was significantly enhanced during TFD but not during placebo treatment. Thus, pharmacologically induced TFD of a stroke-affected forearm might improve the somatosensory and motor functions of the stroke-affected upper limb, accompanied by cortical plasticity.