A double-blind, placebo-controlled study on the effectiveness of a Chinese herbal medicine decoction in treating chronic laryngitis

Abstract

Herbal medicine is often employed as either a primary, an alternative or adjunctive therapy in treating voice disorders in China. The principles of traditional Chinese medicine (TCM) lie in the equilibrium of yin (water) and yang (fire) concept and the removal of phlegm and stagnant blood in the body. A number of Chinese herbal medicine decoctions or formulae have been reported to be effective in treating dysphonia. Yang Yin Qing Fei (nourishment of fluid to clear dryness and heat in the lung) decoction is a popular formula used to treat chronic pharyngeal and laryngeal inflammatory diseases. It consists of eight individual herbs, Rehmannia glutinosa, Ophiopogon japonicus, Scrophularia ningpoensis, Paeonia suffruticosa, Fritillariae Cirrhosae, Glycyrrhiza uralensis, Mentha haplocalyx and Paeonia lactiflora. There is however relatively little specific information on how the decoction brings about the improvement. Indeed, there exists virtually no study that employed a randomized control design with objective outcome measures to investigate efficacy of this decoction in treating chronic laryngeal inflammatory diseases. This study employed a randomized-control style to investigate the effectiveness of Yang Yin Qing Fei decoction in treating dysphonia in chronic laryngitis. Subjects with chronic laryngitis were randomly allocated into one of the two groups: (a) herbal medicine and vocal hygiene and (b) placebo treatment and vocal hygiene. The outcome measures used included (a) voice range profile (phonetogram), (b) voice activity and participation profile (VAPP, Ma & Yiu, 2001) (c) sentence recording for perceptual voice evaluation, (d) stroboscopy, and (e) subjective evaluation of symptoms. Preliminary results showed that the group that received both the Chinese herbal medicine decoction and the vocal hygiene improved better in their vocal function than the placebo group of subjects.