Hemilaryngeal Microsomia: An Anatomic Variant

SummaryObjectivesThis study aims to describe a congenital laryngeal structural variant, hemilaryngeal microsomia (HLM), and to correlate identification on physical examination with computerized tomography scan (CT) and laryngoscopy findings.MethodsThe study was conducted at a tertiary care center. Six patients presenting with hoarseness were admitted to a tertiary care otolaryngology office. These patients had asymmetrical thyroid cartilage prominence on palpation during physical examination. A diagnosis of HLM was made. All patients underwent laryngostroboscopy and CT scan. Four control patients with normal thyroid cartilage anatomy on physical examination, CT, and stroboscopy results were included for comparison.ResultsDisparities in thyroid cartilage angles correlated with documented physical examination findings for six out of six HLM patients. On CT scan, the average difference in left and right thyroid laminar angles was 30.2° ± 18.3° in HLM patients vs 4.00° ± 1.63° in control patients (P = 0.023). Strobosocopic findings also correlated with HLM. The arytenoid cartilage was anteriorly or medially displaced on the microsomic side in all six HLM patients. Three patients had anterior placement of the vocal process resulting in shortening of the vocal fold on the microsomic side of the larynx.ConclusionsHLM is a congenital structural anomaly of the larynx that may be palpated on physical examination. HLM found on physical examination can be correlated with asymmetries found on CT scan and endoscopy. There is no evidence that the structural features of HLM were causally related to voice symptoms, but the findings on HLM may lead to misdiagnosis. A larger study is indicated to confirm laryngeal structural differences between patients with HLM on physical examination and the general population. Whether or not HLM affects clinical or surgical outcomes remains to be studied.