Neuromodulation for Laryngeal Dystonia: A Systematic Review.

OBJECTIVE

The aim of this study was to systematically review and evaluate neuromodulation therapies that are currently being explored/used in the treatment of laryngeal dystonia (LD).

METHODS

A systematic review of the literature was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines searching Embase, Medline, and Cochrane with the cover period January 1960-August 2024. The search strategy used was (("Laryngeal Dystonia" OR "Spasmodic Dysphonia") AND ("Neuromodulation" OR "Deep Brain Stimulation")). Articles were reviewed and screened based on the set inclusion and exclusion criteria. The Joanna Briggs Institute Critical Appraisal Checklists were used to assess the risk of bias in the included studies. Patient demographics and diagnosis, neuromodulation therapy used and its details, voice outcomes, and complications were extracted from each of the studies. A narrative review was subsequently synthesized.

RESULTS

Twelve studies met the selection criteria and were included. In total, 130 LD patients were identified with the following neuromodulation therapies being evaluated for their use in LD: vibro-tactile stimulation, laryngeal electrical stimulation, pharmacologic (sodium oxybate), repetitive transcranial magnetic stimulation, and deep brain stimulation (DBS). All included studies reported various degrees of improvement in patients' voice symptoms with the neuromodulation therapy used. No definitive conclusion could be drawn for their efficacy within the included studies consisting of six case reports, three proof-of-concept/pilot studies, and three phase I clinical trials that used a number of different voice outcome measures used to report treatment effects, and a general lack of long-term follow-up. No significant complications were reported for any of the neuromodulation therapies.

CONCLUSION

Most neuromodulation therapies being explored for LD are at a very early exploratory stage. Although more clinical trials are required, from the available evidence, sodium oxybate and DBS currently appear to have the most potential for translation into clinical practice.