RESUMO
OBJECTIVES: Excessive or disharmonious activity of internal and external laryngeal muscles causes a type of dysphonia known as muscle tension dysphonia (MTD). MTD is often diagnosed based on laryngoscopic findings and clinical history. Several diagnostic and classification systems have so far been proposed based on increased supraglottic activity to determine MTD. Various studies have shown that increased supraglottic activity may also be observed in those with normal voice. The present study aimed to precisely examine the incidence of abnormal muscle tension pattern (aMTP) in those with normal voice in comparison with those with MTD. The secondary goal of this study was comparative examination of acoustic parameters and maximum phonation time (MPT) in the group with MTD and normal individuals. MATERIAL AND METHODS: Participants were 75 people with MTD (41 women and 34 men) and 50 individuals with normal voice and no history of dysphonia (20 women and 30 men). Laryngoscopic evaluation was performed for all participants by considering four types of aMTP. Acoustic analyses, including cepstral peak prominence, jitter, shimmer and NHR, as well as MPT examination were performed. RESULTS: A significant difference between the MTD group and control group was observed in all MTPs except for MTP 2 (lateral-to-medial approximation of the false vocal folds) (P = 0.367, χ2(1) = 0.81). In other MTPs, a significant difference existed between the control and MTD groups in terms of aMTP incidence (P < 0.05). CONCLUSION: On the four aMTPs, results revealed that one must exercise caution in diagnosing MTD based on MTP 2 (medial compression of ventricular folds), and this must not be the sole criterion for diagnosis. Moreover, cepstral peak prominence and MPT analyses are of high clinical significance.
