Authors: Lee VS, Zhou XP, Rahn DA III, Wang EQ, Jiang JJ
Title: Perturbation and nonlinear dynamic analysis of acoustic phonatory signal in Parkinsonian patients receiving deep brain stimulation
Source: Journal of Communication Disorders 2008 41(6): 485-500
Year: 2008
Research Design: Non Randomised Controlled Trial
Rating Score: 05/10
This rating is confirmed
Eligibility specified - N
Random allocation - N
Concealed allocation - N
Baseline comparability - N
Blind subjects - Y
Blind therapists - N
Blind assessors - Y
Adequate follow-up - Y
Intention-to-treat analysis - N
Between-group comparisons - Y
Point estimates and variability - Y

Nineteen PD patients who received deep brain stimulation (DBS), 10 non-surgical (control) PD patients, and 11 non-pathologic age- and gender-matched subjects performed sustained vowel phonations. The following acoustic measures were obtained on the sustained vowel phonations: correlation dimension (D2), percent jitter, percent shimmer, SNR, F0, vF0, and vAm. The results indicated the following: The mean D2 of control PD patients was significantly higher than the mean D2 of non-pathologic subjects and patients who received deep brain stimulation. These results suggest an improvement in PD voice in treated patients. Many PD vocal samples in this study have type 2 signals containing subharmonics that may not be suitable for perturbation analysis but are suitable for nonlinear dynamic analysis, making the D2 results more reliable. These findings show that DBS may provide measurable improvement in patients with severe vocal impairment.

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