title: Reduced somatosensory hand representation in thalidomide-induced dysmelia as revealed by fMRI.
abstract: The concept of cerebral plasticity suggests that the hand representation in somatosensory cortex is abnormal in congenital malformation disorders. To investigate this issue we studied 11 subjects with different degrees of upper extremity dysmelia due to thalidomide embryopathy in comparison to 10 control subjects. In the affected subjects fingers are typically missing in radio-ulnar order beginning with the thumb. Haemodynamic responses to electrical stimulation of the radial-most and ulnar-most fingers were measured in each subject using functional magnetic resonance tomography. The size of the hand area in the primary somatosensory cortex was estimated by calculating the Euclidian distance between corresponding activation peaks on the lateral postcentral gyrus. The cortical somatosensory hand representation was found to be significantly smaller in dysmelic subjects as compared with the control subjects (P <0.001). The shrinkage of the hand area was not proportional to the number of missing fingers. Furthermore, the cortical representation of the ulnar fingers in the dysmelic subjects was shifted towards the cortical thumb representation of the control group. We suggest that the unproportional reduction of the hand area together with the observed shift may reflect use-dependent rather than malformation-induced reorganization of the somatosensory hand area.
authors.affiliation: Department of Neurology, University Hospital Düsseldorf, Moorenstr. 5, 40225 Düsseldorf, Germany. cornelia.stoeckel@uni-duesseldorf.de
authors.forename: M Cornelia
authors.initials: MC
authors.lastname: Stoeckel
authors.forename: Silke
authors.initials: S
authors.lastname: Jörgens
authors.forename: Otto W
authors.initials: OW
authors.lastname: Witte
authors.forename: Rüdiger J
authors.initials: RJ
authors.lastname: Seitz
mesh_terms: D000328:Adult; D001931:Brain Mapping; D004558:Electric Stimulation / Q000379:methods; D005260:Female; D005385:Fingers / Q000503:physiopathology; D006225:Hand / Q000503:physiopathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D010100:Oxygen / Q000097:blood; D013003:Somatosensory Cortex / Q000098:blood supply / Q000503:physiopathology* / Q000528:radiation effects; D018709:Statistics, Nonparametric; D013792:Thalidomide / Q000009:adverse effects; D038062:Upper Extremity Deformities, Congenital / Q000139:chemically induced / Q000473:pathology / Q000503:physiopathology*
chemical_list: D013792:Thalidomide; D010100:Oxygen