Differential diagnosis of adductor spasmodic dysphonia and muscle tension dysphonia using acoustic parameters

Objective:The study aimed at differentiating Adductor Spasmodic Dysphonia (ADSD) from Muscle Tension Dysphonia (MTD) using acoustic measurements . Method: Perceptual as well as acoustic analysis of the voice was done on 12 patients of Adductor Spasmodic dysphonics and Muscle tension dysphonics each. The age of these patients ranged between 30 to 64 years . Results: Adductor spasmodic dysphonics statistically differed from muscle tension dysphonia in the acoustic parameters of voice break, harmonic to noise ratio, and jitter. The parameters which showed maximum significance of differences were voice break which was presented only by the adductor spasmodic dysphonics and harmonic to noise ratio which was affected in muscle tension dysphonia. Conclusion: Voice breaks were found to be more sensitive in discriminating adductor spasmodic dysphonia from muscle tension dysphonia in the present study. Percentage of voice break correlated with perceptual assessment of severity. Key wordsAdductor Spasmodic Dysphonia, Muscle Tension Dysphonia, Acoustic Parameters Differential diagnosis of adductor spasmodic dysphonia and muscle tension dysphonia using acoustic parameters Spasmodic dysphonia (SD) is a voice disorder characterized by involuntary disruption of voice, the signs of which are seen during voluntary speech and are asymptomatic during coughing, crying, laughing, and yawning. There are two main types of SD, adductor spasmodic dysphonia (ADSD) and abductor spasmodic dysphonia (ABSD) [1]. ADSD is more common compared to ABSD and is characterized by hyper adduction of the vocal cords producing effortful, strained-strangled voice quality. ABSD is characterized by breathy, abrupt breaks and prolonged abduction during voiceless consonants [1] There has been considerable debate regarding the psychogenic versus neurogenic etiology for spasmodic dysphonia [1]. Muscle tension dysphonia may be confused with Adductor spasmodic dysphonia because of the similarity in symptoms. Muscle tension dysphonia is a hyperfunctional voice disorder characterized by a generalized increase in muscle tension in the larynx and paralaryngeal areas associated with vocal abuse in the absence of any organic pathology [2]. The voice in this disorder is breathy, strained and harsh and associated with vocal fatigue [3]. Laryngoscopic findings include ventricular fold activation, narrowing of the pharyngeal structures and anteroposterior squeezing of the muscles that surround the vocal folds [4] or even complete obstruction of true vocal folds [5]. There are not many studies on the differential diagnosis of ADSD from Muscle tension dysphonia using acoustic analysis. Few studies have compared ADSD with MTD like fiberoptic laryngoscopy, phonatory airflow measurement, spectrography, phonatory break analysis [6-12].