Hand somatosensory cortex activity following selective dorsal rhizotomy: report of three cases with fMRI.
BACKGROUND
Selective dorsal rhizotomy (SDR) is an effective treatment for lower extremity spasticity in cerebral palsy. Cortical organization in sensory cortex may be abnormal in cerebral palsy, and deafferentation is known to lead to cortical reorganization in many situations.


METHODS
We used functional magnetic resonance imaging (fMRI) of hand sensory stimulation to determine if the partial deafferentation of the lower extremity sensory system, associated with SDR, led to any alterations in the cortical somatosensory representation for the upper limbs. Three patients with spastic diplegia were studied with blood oxygen level-dependent (BOLD)-fMRI before and after SDR. fMRI during tactile stimulation of the digits of the right hand was used to map hand somatosensory cortex. Comparison of the cortical maps devoted to the hand before and after SDR assessed for cortical reorganization following partial deafferentation of the lower extremity.


RESULTS
In the one patient with upper extremity involvement, the hand sensory representation was markedly enhanced following SDR. In the other two patients, a normal pattern, but with diminished activity, was seen compared with preoperative findings. SDR for lower limb spastic diplegia does not lead to extensive reorganization of cortex dedicated to the representation of the upper limb. An essentially normal pattern of activation was seen both before and after SDR.


CONCLUSIONS
The relief of attention demands associated with spasticity may explain the modulation in intensity seen after SDR in the patients who exhibited no upper extremity involvement despite lower limb spasticity.
Ojemann
Jeffrey G
JG
Department of Neurological Surgery, St. Louis Children's Hospital, Washington University School of Medicine, St. Louis, MO 63110, USA. jojemann@u.washington.edu
McKinstry
Robert C
RC
Mukherjee
Pratik
P
Park
T S
TS
Burton
Harold
H
D000293:Adolescent; D000328:Adult; D001931:Brain Mapping; D002547:Cerebral Palsy / Q000503:physiopathology / Q000601:surgery*; D005260:Female; D006225:Hand; D006801:Humans; D007091:Image Processing, Computer-Assisted; D016014:Linear Models; D008279:Magnetic Resonance Imaging; D008297:Male; D010100:Oxygen / Q000097:blood; D019051:Rhizotomy / Q000379:methods*; D013003:Somatosensory Cortex / Q000098:blood supply / Q000503:physiopathology / Q000601:surgery*
D010100:Oxygen