Laryngeal Muscle Activity in Unilateral Vocal Fold Paralysis Patients Using Electromyography and Coronal Reconstructed Images

Abstract

Objectives:

Assess laryngeal muscle activity in patients with unilateral vocal fold paralysis (UVFP) using laryngeal electromyography (LEMG) and coronal multi-planar reconstructed images (coronal images).

Methods:

Twenty-one patients suffering from paralytic dysphonia, who had had onset of UVFP more than 6 months previously, underwent LEMG, phonatory function, and coronal images. For LEMG analysis, a four-point scale was employed to grade motor unit (MU) recruitment; 4+: absent, 3+: greatly decreased, 2+: moderately decreased, and 1+: mildly decreased (less than full interference). Maximum phonation time (MPT) and mean airflow rate (MFR) were employed. Coronal images during phonation and inhalation were assessed focusing on differences in thickness and vertical position between the vocal folds during phonation.

Results:

MU recruitment results were three patients for 1+, five for 2+, six for 3+, and seven for 4+. MPT was positively correlated with the MU recruitments (P = 0.011). The thinning of the affected fold was evident during phonation in 20 of the 21 subjects. All 8 subjects with MU recruitments 1+ and 2+ showed the affected fold located at an equal level to the healthy fold. Twelve of 13 subjects with MU recruitments 3+ and 4+ showed the affected fold located at a higher level than the healthy fold. There was a significant difference between MU recruitment and vertical position of the affected fold (P = 0.001).

Conclusions:

MU recruitments in patients with UVFP may be related to phonatory function and the vertical position of the affected fold. Synkinetic reinnervation may occur in some cases with UVFP.