Duration is 6 weeks to several months. Resorption leaves little scarring. Must test for hypersensitivity reaction. Need to overcorrect as some resorption does occur. Advantage is that collagen is natural component of vocal fold.
Disadvantage is that resorption does occur.
Botulinum toxin - used to treat adductor spasmodic dysphonia. 25-30 U are injected through the cricothyroid membrane angled laterally and superiorly. Confirmation is made by EMG recording in the thyroarytenoid muscle. Effects can endure for up to four months. Best in patients with a tremor component to dysphonia.