Abnormal motor cortex organization contralateral to early upper limb amputation in humans

We performed both a functional magnetic resonance imaging (fMRI) study usin g single slice FLASH technique and an investigation with transcranial magne tic stimulation (TMS) in a 21-year-old patient. He had suffered a left uppe r extremity amputation at age 7. Anteflexion of the amputation stump produc ed an unusual, broad activation contralateral to the movement. TMS revealed an enlarged cortical motor output area of the deltoid muscle at the amputa tion stump. Application of paired magnetic stimulation demonstrated decreas ed intracortical inhibition (ICI). A T1-weighted image indicated a lack of the characteristic shape of the central sulcus contralateral to the amputat ion. In addition to previous functional studies, these new structural data suggest that maturation of the central sulcus develops in response to daily practice of the contralateral hand, possibly until adolescence. (C) 1999 E lsevier Science Ireland Ltd. All rights reserved.