THE CORTICAL SOMATOTOPIC MAP AND PHANTOM PHENOMENA IN SUBJECTS WITH CONGENITAL LIMB ATROPHY AND TRAUMATIC AMPUTEES WITH PHANTOM LIMB PAIN

The extent of the cortical somatotopic map and its relationship to pha ntom phenomena was tested in five subjects with congenital absence of an upper limb, four traumatic amputees with phantom limb pain and five healthy controls. Cortical maps of the first and fifth digit of the i ntact hand, the lower lip and the first toe (bilaterally) were obtaine d using neuroelectric source imaging. The subjects with congenital upp er limb atrophy showed symmetric positions of the left and right side of the lower lip and the first toe, whereas the traumatic amputees wit h pain showed a significant shift (about 2.4 cm) of the cortical repre sentation of the lower lip towards the hand region contralateral to th e amputation side but no shift for the toe representation. in healthy controls, no significant hemispheric differences between the cortical representation of the digits, lower lip or first toe were found. Phant om phenomena were absent in the congenital but extensive in the trauma tic amputees. These data confirm the assumption that congenital absenc e of a limb does not lead to cortical reorganization or phantom limbs whereas traumatic amputations that are accompanied by phantom limb pai n show shifts of the cortical areas adjacent to the amputation zone to wards the representation of the deafferented body part.