Mucosal bridges (MB): a 9-year retrospective study of their incidence with a third variant proposed.

BACKGROUND: Mucosal bridges (MBs) are rare laryngeal lesions that may cause dysphonia of varying degrees. We propose the existence of a third variant of MB besides thin and thick MBs, and have termed this as an incomplete mucosal bridge (IMB). The concept of an IMB has not been previously discussed in literature. Thin and thick MBs are attached anteriorly and posteriorly on the membranous vocal fold and may cause dysphonia because of their separate vibratory characteristics from the main vocal fold. We propose the presence of an entity named as IMB, which is typically identified by palpation of a slit on the superior surface of the membranous vocal fold.

AIM: To propose and describe the existence of IMBs. Furthermore, to study the percentage of various types of MBs found while performing microlaryngeal surgeries (MLS) for benign glottic lesions, over a 9-year period at our Voice Clinic.

METHOD: An IMB may be described as a MB that does not open at its medial edge. Thus it appears as an epithelial slit on the surface of the vocal fold. On palpating this slit with a microflap elevator, a flat pocket lying just below and parallel to the vocal fold epithelium is identified. These pockets are always directed medially (never laterally) and just stop short of opening up at the medial edge. These IMBs differ from sulci and focal pit as sulci and focal pits are not covered with a hood of epithelium. Our operative records of all MLS performed for benign glottic lesions were audited from 2009 to 2017 for cases of MBs.

RESULTS: A total of 1728 MLS for benign glottic lesions were performed from 2009 to 2017 and 27 MBs were identified in 23 patients, 16 being male. A total of 11 IMBs were identified in 10 patients, with 1 case revealing a bilateral IMB. Other associated lesions were cysts, sulci, and polyps. A total of 14 thin MBs were identified in 11 patients with 3 cases revealing these bilaterally. Two thick MBs were identified in two separate cases, with one case having a bilobed hemorrhagic polyp attached to the thick MB.

CONCLUSION: Our study found MBs in 1.33% of patients being operated for benign glottic lesions. The incidence of MBs in this group was 1.56% with IMBs accounting for 0.63%, thin MBs accounting for 0.81% and thick MBs in 0.11%. We recommend all patients undergoing MLS be actively palpated for the presence of mucosal bridges including IMBs especially if a small slit is found on the surface of the vocal fold. This is vital for accurate identification and documentation of all the lesions responsible for the patients voice quality. Ours is an ongoing study and we propose to analyze the vocal outcomes associated with surgical management of these IMBs.