Tina Islam, Presenter: Nothing to Disclose

Andreas Kupsch, Abstract Co-Author: Nothing to Disclose

Harald Bruhn MD, Abstract Co-Author: Nothing to Disclose

Sein Schmidt, Abstract Co-Author: Nothing to Disclose

Lutz Ludemann, Abstract Co-Author: Nothing to Disclose

Karl-Titus Hoffmann MD, Abstract Co-Author: Nothing to Disclose

To characterize the cortical representation patterns in patients with focal dystonia (writer’s cramp) using functional MRI (fMRI) of the primary motor and somatosensory cortices, the supplementary motor area, and the secondary somatosensory cortex.

FMRI at 3.0 T was used to examine 17 right-handed untreated patients and 17 age- and gender-matched, right-handed healthy control subjects during finger-tapping, index finger flexion and electrical median nerve stimulation of both dystonic and unaffected hands. The experiments were conducted randomly in a block design. Dystonic movements were excluded by simultaneous EMG monitoring. Statistical parametric mapping (SPM2) was used to evaluate Brodmann areas (BA) 1-3, 4, 6, and 40. Brunner multivariate analysis and Wilcoxon test for paired samples were performed using SPSS and SAS.

A comparison within the groups revealed an absence of hemispheric dominance in patients. Compared to control subjects, patients had decreased activation in the left BA 4 with motor stimulation of both hands. Patients showed decreased activation in the left BA1-3 with right finger-tapping, in the left BA 3 with right index finger flexion and left finger-tapping, and in the right BA 2 with left finger-tapping. Patients also showed decreased activation in the bilateral BA 6 with motor stimulation of the left hand and in the left BA 6 with right finger-tapping. Patients had decreased activation in bilateral BA 40 with both right and left finger-tapping. No intergroup differences were seen with electrical median nerve stimulation.

The findings suggest a decreased baseline activity and/or an impaired reactivity to motor tasks in the primary motor and somatosensory cortex, supplementary motor area, and secondary somatosensory cortex in patients with task-specific focal dystonia for both dystonic and clinically unaffected hands.The increased cortical activation seen in previous studies is likely attributed to pathologic excitation triggered by dystonic movements.

FMRI identifies patterns of deficient neuronal activation and inhibition in the motor corticonuclear circuit in focal dystonia and assigns them to anatomical structures.

Islam, T, Kupsch, A, Bruhn, H, Schmidt, S, Ludemann, L, Hoffmann, K, Characterization of Cortical Representation Patterns in Focal Dystonia by Functional Magnetic Resonance Imaging at 3.0 Tesla.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5000971.html