Preservation of Nasal Valve Function in Congenital Deficiency of the Lower Lateral Cartilage: A Systematic Review and Case Series.

Introduction: Isolated congenital lower lateral cartilage (LLC) anomalies are incidental intraoperative findings that challenge surgical planning. Despite their role in external nasal valve support, variable clinical presentation suggests the existence of compensatory mechanisms that warrant further investigation. Objectives & Hypotheses: We evaluate the available evidence on isolated congenital LLC deficiency to explore reported preoperative nasal valve dysfunction and surgical outcomes, with the hypothesis that the available evidence demonstrates an association between isolated congenital LLC deficiency and nasal valve dysfunction. Study Design: PRISMA-compliant systematic review and case series. Methods: A systematic search of three databases was undertaken to identify reports of isolated congenital LLC deficiency. Studies without intraoperative confirmation and those involving pediatric populations were excluded. The validated Joanna Briggs Institute (JBI) Critical Appraisal Tools and CARE Guidelines were used to assess evidence quality. Results: Fifteen studies (n=18) were eligible, comprising 14 case reports and one case series. Unilateral involvement was most common (n=16), with the middle crus most frequently affected. Eight patients were asymptomatic. Only three studies were rated as high quality (JBI 6-7/8). In our case series, the incidence of isolated congenital LLC absence was 0.002 and lateral crus absence was asymptomatic, whereas absence of the medial and middle crura was associated with dynamic external nasal valve collapse. These observations are hypothesis-generating, suggesting a greater functional role for medial crus integrity in nasal valve competence, with lateral crus absence appearing more consistently asymptomatic across the literature. Conclusions: Potential compensatory mechanisms may help preserve nasal valve function despite isolated LLC deficiency, a rare anomaly that underscores the need for intraoperative preparedness and tailored reconstruction when encountered incidentally.