Pallidal stimulation for cervical dystonia does not correct abnormal temporal discrimination

Sadnicka A¹, Kimmich O², Pisarek O¹, Ruge D¹, Galea J¹, Kassavetis P¹, Parees I¹, Saifee TA¹, Molloy A², Bradley D¹, O’Riordan S², Zrinzo L¹, Hariz M¹, Bhatia KP¹, Limousin P¹, Foltynie T¹, Rothwell JC¹, Hutchinson M², Edwards MJ¹

Mov Disord. 2013 Nov;28(13):1874-7. doi: 10.1002/mds.25581. Epub 2013 Jul 12.

Author affiliations:

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1	Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, University College London, London, United Kingdom.
2	Department of Neurology, St. Vincent’s University Hospital, Dublin, Ireland.

ABSTRACT:

BACKGROUND:

We investigated whether clinical improvement observed after deep brain stimulation (DBS) of the globus pallidus internus (GPi) in cervical dystonia (CD) is paralleled by the normalisation of temporal discrimination thresholds (TDTs), a marker of abnormal sensory processing in CD.

METHODS:

TDT was tested in 11 patients with CD after they received DBS and was compared with TDT scores from 24 patients with CD and a group of 61 controls.

RESULTS:

A clear clinical response to GPi-DBS was demonstrated (total Toronto Western Spasmodic Torticollis Rating Scale scores fell from 50 to 18; P < 0.001). In contrast, TDT remained abnormal in the CD-DBS group (P < 0.001) and was not significantly different from the abnormal TDT range observed in CD.

CONCLUSIONS:

Underlying sensory abnormalities in temporal discrimination observed in dystonia do not seem to be corrected by successful GPi-DBS. This adds further data to the ongoing debate regarding which pathophysiological abnormalities observed in dystonia are likely to be causal in the genesis of the disease rather than epiphenomena observed secondary to abnormal motor activity.

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