Sensory integration in writer's cramp: comparison with controls and evaluation of botulinum toxin effect.
OBJECTIVE
Abnormal temporal and spatial sensory integration have been described in mixed groups of dystonic patients. We tested somatosensory integration and the effect of botulinum toxin (BoNT) in patients with writer's cramp (WC).


METHODS
Median and ulnar SEPs were recorded in 29 WC patients and in 10 controls. We performed: individual and simultaneous stimulation of median and ulnar nerves (MU) and paired stimulation of median nerve at interstimulus-interval (ISI) of 40 and 100 ms. All the trials were repeated after blinded randomized treatment with placebo or BoNT-A.


RESULTS
We found no differences between patients and controls in standard SEPs. Spatial (except for N9) and temporal suppression after ISI 40 were present in both groups for all the waves; after ISI 100, suppression was present only for N70. There were no differences between patients and controls. After BoNT-A treatment, no changes were observed.


CONCLUSIONS
In contrast with previous findings in heterogeneous dystonic groups, and although some studies suggest impairment of spatial and temporal sensory discrimination in patients with focal dystonia, in our large cohort of patients with WC we found no evidence of abnormal somatosensory integration investigated by means of SEPs and no changes in somatosensory variables after BoNT-A treatment.


CONCLUSIONS
Our findings may suggest pathophysiological differences between focal and generalized dystonia, and may also point to an inferior sensitivity of SEPs in detecting abnormalities in sensory discrimination as compared to methods based on subjective discrimination.
Contarino
M F
MF
Department of Neurology and Clinical Neurophysiology, Academic Medical Centre, University of Amsterdam, H2-222, PO Box 22660, 1100 DD Amsterdam, The Netherlands.
Kruisdijk
J J M
JJ
Koster
L
L
Ongerboer de Visser
B W
BW
Speelman
J D
JD
Koelman
J H T M
JH
D000328:Adult; D019274:Botulinum Toxins, Type A / Q000627:therapeutic use*; D015331:Cohort Studies; D004311:Double-Blind Method; D020821:Dystonic Disorders / Q000188:drug therapy* / Q000503:physiopathology*; D004599:Electric Stimulation Therapy; D004569:Electroencephalography; D005073:Evoked Potentials, Somatosensory / Q000187:drug effects / Q000502:physiology; D005260:Female; D006236:Handwriting; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000187:drug effects / Q000502:physiology; D008875:Middle Aged; D009465:Neuromuscular Agents / Q000627:therapeutic use*; D011597:Psychomotor Performance / Q000187:drug effects / Q000502:physiology; D014459:Ulnar Nerve / Q000187:drug effects / Q000502:physiology
D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A