Significant positive effect of chronic globus pallidus internus stimulation on dystonic dysphonia accompanying torticollis

Objective: In dystonic dysphonia – which may accompany and aggravate facial and cervical dystonia –, abnormal or dystonic muscle contractions can affect the muscles that close (adduction) or open (abduction) the laryngeal mechanism causing the voice to break or to have a tight, strained or strangled quality. Treatment usually consists of local Botolinum-Toxin-A (BTX-A) injections. We here present the immediate post-operative results and clinical follow for 2 adult patients undergoing Globus pallidus internus (Gpi) – deep brain stimulation (DBS) for cervical dystonia who also suffered from severely disabling dystonic dysphonia.

Methods: Both patients (I female, 56yrs.; II male, 52yrs.) were suffering from intractable cervical dystonia accompanied by severe spasmodic dysphonia that been treated with moderate success by local BTX-A injections over an extended period of time. Electrode-implantation (DBS 3387, Medtronic) was performed under propofol anaesthesia with MRI-guided stereotaxy using a modified Leksell/Lerch system. Electrode position was verified by magnetic resonance imaging (MRI) and clinical outcome was assessed using the Tsui-score and phonetic analysis including videolaryngostroboscopy.

Results: Post-op MRI confirmed the correct electrode position in both patients, with the lowest contact just above the optic tract (20mm mm and 18mm lateral of the mid-commisure line, respectively). There was a significant improvement of the Tsui-score in both patients (reduction of 70 and 80%, respectively). Along with the improvement of the torticollis, the speech-/vocal-abilities returned to near normal values without further BTX-A injections post-operatively: Both patients are able to speak for extended periods of time without exhaustion and patient II has even been able to return to his profession as a high-school teacher without any limitations. Follow-up was 14 (pat. I) and 26 (pat. II) months, respectively.

Conclusion: GPI deep brain stimulation has been shown to offer a very effective and safe therapy in patients suffering from facial and cervical dystonia. Despite contrarian reports in literature, there also seems to be a significant positive effect on dystonic dysphonia in selected patients.