Vocal cord paralysis/paresis (VCP), also known as vocal fold paralysis/paresis, refers to the impaired mobility of the true vocal cord or fold due to neurologic dysfunction.
Unilateral vocal cord paralysis usually presents with dysphonia (hoarseness), characterized as a breathy, weak voice due to air leaking through the glottic gap as one vocal cord is unable to adduct fully. Patients may also complain of dysphagia or choking as glottic incompetence increases the risk of aspiration.
Bilateral vocal cord paralysis may present as dyspnea if the paralyzed cords rest close to the midline, reducing the glottic area available for air movement.
The diagnosis may also be made incidentally on laryngoscopy or imaging as up to one-third of patients with impaired vocal cord impairment are asymptomatic 1.
Neurologic dysfunction resulting in vocal cord paralysis most common localizes to the recurrent laryngeal nerve, but can also be due to upstream lesions affecting the vagus nerve (from which the recurrent laryngeal nerve branches off) or the brain. Injury to the recurrent laryngeal nerve affects motor function of most of the intrinsic laryngeal muscles (posterior cricoarytenoid, lateral cricoarytenoid, transverse arytenoid, oblique arytenoid, and thyroarytenoid).
In comparison, injury to the superior laryngeal nerve, which supplies only the cricothyroid muscle, causes subtle changes in voice and is less clinically significant.
Unilateral involvement is much more common than bilateral involvement 7. The left side is most commonly affected, likely because the longer course of the left recurrent laryngeal nerve presents greater opportunity for injury.
- superior thoracic masses, e.g. lung cancer (most common 7), aortic pathologies (e.g. thoracic aortic aneurysm), thyroid cancer, laryngeal cancer 6,7
- masses affecting the vagus nerve, e.g. jugular foramen masses, carotid body tumors
- surgical iatrogenic injury, especially post thyroidectomy 6
- idiopathic 7
- blunt and penetrating trauma in the head and neck, and thorax
- congenital anomalies, e.g. meningomyelocele, Chiari malformation, hydrocephalus
The imaging features of vocal cord paralysis include:
- enlarged pyriform sinus
- medialization and thickening of the aryepiglottic fold
- enlarged laryngeal ventricle
- atrophy of the thyroarytenoid muscle, which makes up the bulk of the true cord 2
- anteromedial deviation of the arytenoid cartilage
- abducted vocal cord during breath-hold imaging with compensatory medial bowing of the contralateral cord
- atrophy of the posterior cricoarytenoid muscle 3
When vocal cord paralysis has been diagnosed, a cause should be actively sought along the course of the recurrent laryngeal nerve from origin in the brainstem, through the neck, and should always include the superior mediastinum.
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- 3. Romo LV, Curtin HD. Atrophy of the posterior cricoarytenoid muscle as an indicator of recurrent laryngeal nerve palsy. AJNR Am J Neuroradiol. 1999;20 (3): 467-71. AJNR Am J Neuroradiol (full text) - Pubmed citation
- 4. Paquette CM, Manos DC, Psooy BJ. Unilateral vocal cord paralysis: a review of CT findings, mediastinal causes, and the course of the recurrent laryngeal nerves. Radiographics. 2012;32 (3): 721-40. doi:10.1148/rg.323115129 - Pubmed citation
- 5. Kumar VA, Lewin JS, Ginsberg LE. CT assessment of vocal cord medialization. AJNR Am J Neuroradiol. 2006;27 (8): 1643-6. AJNR Am J Neuroradiol (full text) - Pubmed citation
- 6. Pearce's Surgical Companion. TFM Publishing Ltd (UK). ISBN:B00B8TTTHM. Read it at Google Books - Find it at Amazon
- 7. Seyed Toutounchi SJ, Eydi M, Golzari SE et-al. Vocal cord paralysis and its etiologies: a prospective study. J Cardiovasc Thorac Res.6 (1): 47-50. doi:10.5681/jcvtr.2014.009 - Free text at pubmed - Pubmed citation