Alar clefts most commonly occur in association with cleft lip and/or other craniofacial anomalies. The basic embryonic mechanism in alar clefts involves failure of fusion between the medial and the lateral nasal processes during the sixth to tenth ... Alar clefts most commonly occur in association with cleft lip and/or other craniofacial anomalies. The basic embryonic mechanism in alar clefts involves failure of fusion between the medial and the lateral nasal processes during the sixth to tenth weeks. The medial process gives rise to one-half of the nasal septum and the medial crus of the lower lateral alar cartilage, and the lateral process gives rise to the external wall of the nose, nasal bones, upper lateral cartilage, alae, and lateral crus of the lower lateral cartilage. The dorsum and apex of the nose, which are derived from the frontonasal process, are usually well preserved in patients with isolated alar cleft (summary by Richieri-Costa and Guion-Almeida, 2009).
Richieri-Costa and Guion-Almeida (2009) reported 5 sporadic cases of isolated alar cleft and reviewed 12 previously published cases. There was no evidence of sex ratio deviation or effect of racial background. The left side was involved more than ... Richieri-Costa and Guion-Almeida (2009) reported 5 sporadic cases of isolated alar cleft and reviewed 12 previously published cases. There was no evidence of sex ratio deviation or effect of racial background. The left side was involved more than twice as often as the right. Neuropsychological development was normal.