Effects of electrical stimulation of cricothyroid and thyroarytenoid muscles
on voice fundamental frequency.
Once the needle is inside thyroarytenoid muscle
LEMG demonstrates motor unit potential, the patient is asked to phonate at this time and change in visual and voice signal due to recruitment confirms placement and botulinum toxin is injected.
Predominance of FOG and FG muscle fibers correspond to the data obtained in physiological studies of laryngeal muscles of primates, dogs and rabbits (Hall-Craggs, 1968; Hast, 1969), in which the thyroarytenoid muscle
was classified as fast.
5 units of botulinum toxin into the belly of the left thyroarytenoid muscle
58) This may prove successful in others with singer's dystonia; however, successful injection results in at least some paresis (weakness) of the thyroarytenoid muscle
which constitutes the body of the vocal fold.
The depth of injection should be such that the injection volume is deposited just lateral to the thyroarytenoid muscle
so that the presence of the injected material results in medialization of the arytenoid cartilage.
1 ml normal saline) were injected into each of two locations on each thyroarytenoid muscle
with a 25-gauge laryngeal injection needle at the time of direct laryngoscopy.
At least one pair of agonist-antagonist muscles that can change vocal-fold length is needed, such as the cricothyroid muscle paired with the thyroarytenoid muscle
, or the cricothyroid muscle paired with the lateral cricoarytenoid muscle or a strap muscle .
Findings on laryngeal EMG were essentially normal except for the detection of a few large-amplitude motor units within the left thyroarytenoid muscle
that were not consistent with a focal laryngeal mononeuropathy.
In aBducted chest, the effect of the vocal fold bulging caused by contraction of the thyroarytenoid muscle
in chest register can be counteracted by a decreasing adduction in the posterior glottis, allowing for a "breathy chest" phonation.
Flexible and rigid stroboscopy demonstrated severe atrophy and weakness of the right thyroarytenoid muscle
, incomplete adduction of the left vocal fold, bilateral vocal fold scarring, reflux laryngitis, a left vocal fold mass, supraglottic compression, and bilateral varicosities (figure).
The injection should be deep enough to reach into the substance of the thyroarytenoid muscle
at the level of the free edge of the vocal fold.