Effects of Deep Brain Stimulation on Adductor Laryngeal Dystonia

OBJECTIVE: To examine the effects of globus pallidus interna (GPi) and ventral intermediate nucleus of the thalamus (VIM) deep brain stimulation (DBS) on patients with adductor laryngeal dystonia (ADLD). METHODS: Seven patients with ADLD underwent DBS (GPi = 4; VIM = 3) surgery. Postoperative voice testing was performed after stable DBS programming. Primary outcome measures included tremor rate, extent of fundamental frequency/intensity modulation, percentage of voicing, duration/number of voice breaks, and cepstral peak prominence. Linear mixed effects models tested voice improvement after GPi and VIM surgery, with significance determined after controlling for multiple comparisons. RESULTS: GPi-DBS showed trends for improved percentage of voicing, duration of voice breaks, number of voice breaks, and extent of intensity modulation pre-post within-group with large effect size. VIM-DBS showed trends for improved tremor rate within-group with large effect size. Between-group comparison showed greater improvement in percentage voicing and extent of intensity modulation in patients with GPi-DBS compared to VIM-DBS, whereas tremor rate showed greater improvement after VIM-DBS compared to GPi-DBS. Duration of voice breaks showed more improvement in GPi than VIM but it did not achieve statistical significance after multiple comparison adjustments. CONCLUSIONS: Objective acoustic voice analyses provide preliminary, target-specific patterns that warrant confirmation of bilateral GPi-DBS for patients with ADLD and bilateral VIM-DBS for those with both ADLD and vocal tremor. Future research with larger sample sizes, along with investigations into the neuronal mechanisms underlying laryngeal neuromodulation, is needed to further evaluate the role of DBS in treating ADLD.