ACTB-associated dystonia-deafness syndrome with good response to DBS GPi revisited

Dystonia-deafness syndrome is a rare disorder characterized by dystonia with sensorineural hearing impairment. While various genetic causes have been identified, many cases remain unexplained. Deep brain stimulation of the globus pallidus internus is an established treatment for dystonia, but outcomes vary depending on the underlying cause.

We conducted a long-term follow-up of a 31-year-old male diagnosed with DDS, initially reported in 2016.

The patient exhibited progressive generalized dystonia and sensorineural hearing loss. At the age of 19, bilateral DBS-GPi implantation was performed, resulting in sustained symptom improvement until the age of 25. However, progressive worsening of dystonia led to the initiation of adjunctive botulinum toxin therapy, which initially provided symptom relief. At the age of 26, disruption of a DBS extension wire caused acute symptom exacerbation, necessitating surgical replacement. Further clinical deterioration was exacerbated by a hardware-related infection, leading to surgical removal of the left DBS system at the age of 30, which prompted placement of a percutaneous endoscopic gastrostomy. At the age of 31, the right-sided DBS system was also removed. Bilateral reimplantation of the DBS-GPi system was performed at the age of 31. Trio exome sequencing identified a de novo heterozygous pathogenic ACTB variant, p.Arg183Trp.

This case highlights both the benefits and limitations of DBS in ACTB-associated dystonia. While this mutation may predict DBS efficacy, long-term outcomes are influenced by disease progression, hardware complications, and systemic factors. Further research is needed to establish ACTB variants as predictive markers for DBS responsiveness.