Botulinum Toxin (BTX) Injections in ENT

1. Laryngeal Disorders

Spasmodic Dysphonia (Laryngeal Dystonia) - PRIMARY indication

• Adductor spasmodic dysphonia (most common, ~90%): BTX is injected into the thyroarytenoid (TA) muscle bilaterally, usually under EMG guidance. It is the gold-standard treatment, with over 900 patients studied at a single institution with consistent results.
• Abductor spasmodic dysphonia: BTX injected into the posterior cricoarytenoid (PCA) muscle.
• Mixed laryngeal dystonia: Combination injections.
• Cummings Otolaryngology: "Botulinum toxin is an important treatment for spasmodic dysphonia and other dystonias."

Laryngeal Granulomas

• Bilateral vocal fold injection of BTX to the adductor muscle groups is the primary treatment. The dose is approximately 10-fold higher than for spasmodic dysphonia.

Vocal Fold / Glottic Gap (Chemical Injection for Medialization)

• BTX is listed as a chemical injection option alongside bevacizumab, saline, and cidofovir for vocal fold augmentation procedures.

2. Salivary Gland Disorders

Sialorrhea (Drooling / Excessive Salivation)

• Intraglandular injection into the parotid and/or submandibular glands - a key minimally invasive treatment, especially in neurologically impaired children (cerebral palsy, etc.).
• Chronic intraglandular BoNT-A has been shown to reduce salivary gland size ultrasonographically.
• It is part of the stepwise management alongside anticholinergics, duct ligation, and gland excision.
• Cummings: "An individualized stepwise treatment approach for sialorrhea includes... botulinum toxin injection..."

3. Post-Parotidectomy Complications

Frey's Syndrome (Auriculotemporal Syndrome / Gustatory Sweating)

• Caused by aberrant reinnervation of parasympathetic fibers to sweat glands after parotidectomy.
• Intradermal/intracutaneous injection of BTX-A into the affected preauricular skin is an effective treatment.
• KJ Lee's Essential Otolaryngology: "Frey syndrome can be treated with botulinum toxin."
• Cummings: "Intracutaneous injection of botulinum toxin A has been described as an effective treatment in severe cases of Frey syndrome."

4. Pharyngeal / Swallowing Disorders

Cricopharyngeal Dysfunction / Pharyngeal Pouch (Zenker's Diverticulum)

• BTX injected into the cricopharyngeus muscle (percutaneously or endoscopically) to relieve upper esophageal sphincter dysfunction.
• Used in dysphagia from Parkinson's disease, ALS, oculopharyngeal muscular dystrophy (OPMD), and post-laryngectomy voice rehabilitation.
• Scott-Brown's: "Botulinum toxin has been injected both percutaneously and endoscopically. Success is variable."
• In laryngectomized patients, BTX into the cricopharyngeus improves fluency of laryngeal/tracheoesophageal voice.

5. Nasal Disorders

Non-Allergic Rhinitis (NAR) / Vasomotor Rhinitis

• BTX is injected intranasally into the head of the inferior and middle turbinates via its anticholinergic effect on secretory activity of the nasal mucosa.
• Reduces rhinorrhea, but effects are temporary (up to 12 weeks) and do not address non-rhinorrhea nasal symptoms.
• Cummings: "BTX can be injected intranasally into the head of the inferior and middle turbinates safely without significant side effects."

6. Facial Nerve Disorders

Facial Synkinesis (Post-Bell's Palsy / Post-Facial Nerve Degeneration)

• BTX injected into the orbicularis oculi to reduce eyelid synkinesis.
• Lowest effective dose: 40 units into the orbicularis oculi gives the best synkinesis reduction while avoiding ptosis.

Summary Table

Note: The most classically tested/asked ENT indication in exams is spasmodic dysphonia (adductor type - into TA muscle) and Frey's syndrome post-parotidectomy. Sialorrhea and cricopharyngeal dysfunction are also high-yield.