Effect of Pallidal Deep Brain Stimulation on Psychiatric Symptoms in Myoclonus-Dystonia due to ε-Sarcoglycan Mutations—Reply

In reply

Contarino et al describe the effect of bilateral DBS of the GPi in 5 patients with M-D due to SGCE mutations and point out the frequent occurrence of psychiatric worsening after surgery. Their results confirm the strong motor improvement for both myoclonus and dystonia in GPi-DBS–treated patients. The 5 patients had been evaluated by a trained neuropsychologist using a structured clinical interview that allowed comprehensive psychiatric monitoring before surgery and throughout follow-up. Unfortunately, use of a psychiatric structured interview was not part of the systematic assessment in our study, given the absence of behavioral adverse effects of GPi-DBS in our experience^1- 2 and according to the literature.³ This is because the psychiatric vulnerability of patients with M-D due to SGCE mutations had been previously recognized⁴ and, according to our clinical routine for DBS, these 5 patients were examined by a trained psychiatrist before surgery at the 9- to 12-months assessment and more frequently if necessary. At baseline, all of the patients had mild generalized anxiety and only 1 had a major depressive episode. No clinically meaningful psychiatric adverse effect was identified during the 18-month follow-up. According to patients' self-evaluation, anxiety was improved. There is no univocal explanation for such a discrepancy. It may be related to different psychiatric characteristics of the patients included in the 2 studies or with GPi-DBS–related effects. Modification of the pharmacological treatment after surgery might also have played a role in the psychiatric worsening observed in the patients reported by Contarino et al.