Acoustic analysis of Parkinsonian speech in the early stage after subthalamic nucleus deep brain stimulation

Abstract

Objective To investigate the early efficacy of deep brain stimulation (DBS) of subthalamic nucleus (STN) in the treatment of dysarthria in patients with Parkinson's disease (PD). Methods From May 2017 to November 2017, 10 PD patients treated with STN-DBS at Neurosurgery Department affiliated to Nanjing Medical University and 10 healthy volunteers (healthy control group) were recruited retrospectively. Ten PD patients without anti-Parkinson disease medication were recorded in a relatively quiet room at the states of 1 month after operation with stimulation-off, 1 month after operation with stimulation-on, and 3 months after stimulation-on. The speech signal was analyzed by Praat software and 3 fundamental frequency parameters were extracted which were the mean fundamental frequency, the range and standard deviation of fundamental frequency. The speech signals from the healthy control subjects were collected and analyzed at the same time. Results The speech fundamental frequency range (PD group: 15.5±4.8 St, control group: 22.5±5.6 St, t=-2.962, P=0. 008) and the standard deviation of fundamental frequency (PD group: 2.4±0.7 St, control group: 3.7±0.8 St, t=-4.017, P=0. 001) in PD group with stimulation-off 1 month post operation were significantly lower than those in healthy control group. There was no significant difference in any parameter of fundamental frequency of the PD patients between the state of 1 month after stimulation-on and the state of 1 month after operation (all P > 0.05). At 3 months after stimulation-on, the fundamental frequency range (19.23.8 St, P=0.017) and the fundamental frequency standard deviation (3.20.8 St, P=0.001) of the speech were significantly higher than those at 1 month after operation with stimulation-off, and those was not significant statistical different compared with controls (all P > 0.05). Conclusion Early stage of STN-DBS treatment could improve the phonological tone of PD patients and relieve the stiffness of laryngeal muscles and vocal cord. Key words: Parkinson disease; Dysarthria; Deep brain stimulation; Subthalamic nucleus; Acoustic analysis