Objective: To elucidate longitudinal changes of speech and voice disorders 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). However, changes of these phenotypes over time are still unknown.

Methods: Twenty-five PD patients were assessed before STN-DBS and up to 2 years after surgery. 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), quality of life (Parkinson’s disease Questionnaire), activity of daily living (Schwab & England Scale) were assessed. Speech and voice functions were compared between the on- and off-stimulation conditions.

Results: At 1 year after surgery, UPDRS IV (p = 0.001), quality of life (P = 0.022), and ADL during off-time (p = 0.001) significantly improved from baseline. In contrast, speech intelligibility significantly deteriorated (p = 0.001). In individual analysis, hypokinetic dysarthria (8 patients), stuttering (8 patients), breathy voice (13 patients), and strained voice (1 patient) were observed before surgery. In addition, stuttering (2 patients), breathy voice (6 patients), strained voice (3 patient), and spastic dysarthria (11 patients) emerged or worsened postoperatively although the severity were relatively mild. Stuttering (1 patient, 50%), breathy voice (1 patient, 17%), strained voice (3 patients, 100%), and spastic dysarthria (8 patients, 73%) improved after stopping stimulation in varying degrees.

Conclusions: A subset of the patients had speech and voice disorders before surgery, which were considered to be due to PD itself. After surgery, several patients experienced changes in their speech and voice. Particularly, strained voice and spastic dysarthria were strongly associated with stimulation. In contrast, stuttering and breathy voice could be mainly responsible for PD itself.

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