Electrical activity of extrinsic laryngeal muscles in subjects with and without dysphonia.

OBJECTIVE

To compare dysphonic individuals to nondysphonic with regards to electrical activity of extrinsic laryngeal muscles related to perceptual and acoustic vocal parameters.

HYPOTHESIS: Dysphonic individuals have higher electrical activity in the supra and infrahyoid muscles than those nondysphonic.

STUDY

DESIGN

Prospective, cross-sectional, case series study.

METHODS

Forty-one subjects, divided into two groups according to the presence of dysphonia, underwent evaluation of surface electromyography, auditory-perceptual, and acoustic evaluations of voice during the vocal rest and sustained emissions of the vowel /ε/ and count of 20 to 30 at usual and strong intensities.

RESULTS

The dysphonic group differed significantly from the nondysphonic by (1) lower electrical activity normalized by the maximum sustained voluntary activity evaluated in all tasks of phonation in the suprahyoid group; (2) lower recruitment of electrical activity in emissions of strong intensity compared with those of usual intensity in the suprahyoid muscles to emit the vowel /ε/ (13.66 ± 5.17 in dysphonic group and 35.20 ± 7.60 in the nondysphonic group, P = 0.029) and in the infrahyoid muscles in the count of 20 to 30 (14.90 ± 4.69 vs. 42.01 ± 6.15; P < 0.001) and to emit the vowel /ε/ (11.47 ± 6.52 vs. 22.66 ± 9.05, P < 0.001); (3) lower vocal intensity to produce the vowel /ε/ in usual and strong intensities and count in strong intensity. The electrical activities of the maximum sustained voluntary activity were reduced with increasing degree of dysphonia.

CONCLUSIONS

There was lower electrical activity of the extrinsic laryngeal muscles in dysphonic individuals compared with nondysphonic, and related to the degree of dysphonia.