목적: Understanding the distinct subtypes of adhesive otitis media (AdOM) is crucial for appropriate treatment such as balloon Eustachian tuboplasty, particularly in distinguishing between patulous and obstructive Eustachian tube function. Nevertheless, AdOM caused by patulous Eustachian tube dysfunction remains underexplored. This study aim to describe the detailed characteristics and define the patulous type of AdOM associated with patulous Eustachian tube dysfunction. 방법:A total of 62 ears of patients diagnosed with AdOM, patulous Eustachian tube dysfunction, and traumatic perforation were included from a tertiary referral center (university hospital). Obstructive–AdOM, patulous–AdOM, patulous Eustachian tube dysfunction, and a control group with traumatic perforation patients underwent endoscopic examinations, completed symptom questionnaires, and had passive Eustachian tube opening pressure evaluated using a modified inflation-deflation test following tympanostomy tube insertion. 결과:Patulous–AdOM was identified in 43% of the patients and was characterized by significantly lower median opening pressures (222 daPa) than those in patients with obstructive–AdOM (400 daPa) and patulous Eustachian tube dysfunction (below 100 daPa). Habitual sniffing was reported in 92.3% of patients with patulous–AdOM patients, and reduced mastoid pneumatization was observed in both the patulous and obstructive subtypes. 결론:Accurate differentiation between patulous and obstructive–AdOM is essential because balloon Eustachian tuboplasty may exacerbate symptoms in patients with patulous characteristics. A comprehensive evaluation of Eustachian tube function is critical before initiating treatment, underscoring the need for tailored approaches to manage AdOM.