Patterns of reoccurrence of segmental dystonia after discontinuation of deep brain stimulation

The pattern of reoccurrence of symptoms after discontinuation of deep brain stimulation (DBS) has not been systematically studied in dystonia. Eight patients (mean age (SD) 53.8 (14.4) years) with segmental dystonia at a mean follow-up of 11.3 (4.2) months were studied after implantation of bilateral DBS electrodes in the internal globus pallidus using a standard video protocol and clinical rating scales, immediately and at 2 and 4 h after switching off DBS. Dystonic signs returned sequentially, with a rapid worsening of phasic and a slower worsening of tonic dystonic components. In all patients, phasic dystonic features appeared within a few minutes, whereas the tonic elements of dystonia reoccurred with a more variable delay. Differential clinical effects when withdrawing DBS might reflect its influence on different pathophysiological mechanisms in dystonia.