Deep brain stimulation for primary generalized dystonia: long-term outcomes.

BACKGROUND

Pallidal deep brain stimulation (DBS) is the best therapeutic option for patients with disabling primary generalized dystonia (PGD) that is refractory to medications. However, little is known about its long-term effects.

OBJECTIVE

To describe long-term clinical outcomes in patients with PGD who underwent pallidal DBS.

DESIGN

Case series.

SETTING

University hospital.

PATIENTS: Thirty consecutive patients with at least 2 years' follow-up after pallidal DBS for intractable PGD.

INTERVENTIONS: Pallidal DBS and annual follow-up examinations up to 8 years after DBS implantation.

MAIN OUTCOME MEASURES: Clinical outcome as measured by changes in the Burke-Fahn-Marsden dystonia scale, incidence and prevalence of adverse events, total electrical energy delivered, and implantable pulse generator longevity.

RESULTS

Twenty-three patients were followed for 3 years, 13 for 4 years, 9 for 5 years, 5 for 6 years, 5 for 7 years, and 1 for 8 years after DBS. Overall improvement at 1 year was maintained in all at successive yearly examinations. There were no intraoperative complications; hardware-related adverse events were infrequent. Rare stimulation-related adverse events primarily affected speech. Implantable pulse generators were replaced every 24 months on average in patients who received initial stimulation at 130-Hz frequency. No battery was replaced, for up to 48 months, in 20 patients initially stimulated using 60 Hz. Clinical outcome did not depend on high energies of stimulation.

CONCLUSIONS

Pallidal DBS is a safe and effective treatment for PGD, with improvement sustained for up to 8 years in 1 patient. Low energies of stimulation, although they did not affect clinical outcome, were associated with longer battery life.