Objective: To elucidate longitudinal changes of speech and voice functions in Parkinson’s disease (PD) patients treated with subthalamic nucleus deep brain stimulation (STN-DBS).

Background: Previously, we reported that PD patients treated with STN-DBS had five distinct phenotypes of speech and voice disorders: relatively good speech and voice function type, stuttering type, breathy voice type, strained voice type, and spastic dysarthria type and that some PD patients also had hypokinetic dysarthria (J Neurol Neurosurg Psychiatry 2015; J Neural Transm 2015). However, changes of these phenotypes over time are still unknown.

Methods: Thirty-two consecutive PD patients were assessed before and up to 1 year after surgery (PD-DBS). Eleven PD patients treated with medication were also assessed longitudinally (PD-Med). Speech and voice functions (Assessment of Motor Speech for Dysarthria and GRBAS scale), motor function (Unified Parkinson’s Disease Rating Scale III (UPDRS-III) and UPDRS-IV), cognitive function (Mini-Mental State Examination, Montreal Cognitive Assessment, and verbal fluency), activity of daily living (Schwab & England Scale), and levodopa equivalent daily dosage (LEDD) were evaluated.

Results: At baseline, speech and voice functions of the two groups were not significantly different. At 1 year after surgery, slight but significant deterioration in speech intelligibility (p = 0.001) and grade of dysphonia (p = 0.001) were observed only in PD-DBS group. Although the incidence of hypokinetic dysarthria (63% of PD-DBS vs 82% of PD-Med), stuttering (50% vs 45%), breathy voice (66% vs 73%), and strained voice (3% vs 9%) was similar at baseline, significant score deterioration associated with strained voice (28%) and spastic dysarthria (44%) were observed in only PD-DBS patients during 1 year follow-up. After stopping stimulation, most PD-DBS patients who had strained voice and spastic dysarthria showed significant improvement in these phenotypes.

Conclusions: The increasing incidence of strained voice and spastic dysarthria after DBS in this longitudinal study was consistent with the results from our previous reports. An improved understanding of the above-mentioned phenotypes may help clinicians detect DBS-induced speech and voice disorders during early phase.

References: [1] Tsuboi T, Watanabe H, Tanaka Y, Ohdake R, Yoneyama N, Hara K, et al. Distinct phenotypes of speech and voice disorders in Parkinson’s disease after subthalamic nucleus deep brain stimulation. J Neurol Neurosurg Psychiatry 2015;86:856–64.

[2] Tsuboi T, Watanabe H, Tanaka Y, Ohdake R, Yoneyama N, Hara K, et al. Characteristic laryngoscopic findings in Parkinson’s disease patients after subthalamic nucleus deep brain stimulation and its correlation with voice disorder. J Neural Transm 2015;122:1663–72.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/longitudinal-changes-in-speech-and-voice-functions-after-subthalamic-stimulation-in-parkinsons-disease-patients/