Photoglottographic measures in Parkinson's disease

This study examines the usefulness of photoglottographic measures in reflecting the phonatory effect of Parkinson's disease. In the first experiment, data obtained by photoglottography were compared between 15 male patients with Parkinson's disease and 15 normal male speakers of similar age. Six photoglottographic parameters, mean open quotient (OQ), mean speed quotient (SQ), perturbation of open quotient (POQ), perturbation of speed quotient (PSQ), frequency perturbation ratio (FPR), and amplitude perturbation ratio (APR), in sustained vowel phonation were investigated. Increased SQ (t = -2.731, df = 28, P = 0.011) and POQ (t = -2.584, df = 28, P = 0.015) were significantly associated with data from patients in comparison to normal speakers. The FPR, APR, and OQ were not significantly different between normal subjects and patients. A follow-up experiment, including 12 female and 19 male patients with Parkinson's disease, was designed to evaluate the sensitivity of SQ and POQ in detecting vocal dysfunction. The sensitivity of SQ was found to be relatively high (93.5%), while that of POQ was low (45.2%). Methodological issues regarding the effects of gender, age, stage of the disease, and treatment on photoglottographic measures in Parkinson's disease were discussed.