Symptoms of patulous Eustachian Tube (PET) were first described by Jago in 1858 and reported by Schwartze in 1864, recognizing PET as a clinical entity. This review summarizes the causes, epidemiology, diagnosis, and treatment of PET, with a particular emphasis on diagnosis and treatment, detailing the diagnostic criteria and silicone plug (Kobayashi plug) surgery proposed or developed in Japan. PET is often linked to weight loss from chronic illnesses, dieting, anorexia nervosa, hemodialysis, and bariatric surgery. It is also associated with pregnancy, oral contraceptive use, nasopharyngeal and muscular atrophy or scarring, and neuromuscular diseases. Interestingly, many PET cases lack an identifiable cause. The prevalence of PET ranges from 0.3 % to 7.0 %, with a higher incidence in females and typically occurring in adolescents and adults. Diagnosis relies on a combination of clinical history, physical examination, ET function test, and imaging. The Japan Otological Society (JOS) proposed standardized diagnostic criteria, where a "definite PET" diagnosis requires all three criteria (aural symptoms, tubal obstruction procedures, and objective findings), while "possible PET" requires two. Treatment includes conservative and surgical interventions. For persistent and severe cases that do not improve with conservative treatments, surgical options are explored. These surgical procedures are classified by the type of intervention, which includes tympanic membrane manipulation (such as tympanostomy tube insertion and mass loading of the tympanic membrane), plug surgery, ET injection, shim surgery, tuboplasty, and ET closure. The Kobayashi plug, a 23 mm long silicone plug, is specifically designed for PET treatment. Indications for its use include "definite PET," a PHI-10 score of 26 or higher, and lack of improvement after six months of conservative treatment. Preoperative evaluations include CT scans to assess ET patency and confirm the bony portion. Surgery, mostly performed under local anesthesia, involves inserting the plug into the ET via a myringotomy, ensuring the correct size and position with endoscopic guidance. In conclusion, PET is a challenging condition with diverse etiologies and symptoms. Effective management requires a comprehensive diagnostic approach and tailored treatment plans, with the Kobayashi plug offering a promising solution for refractory cases. Further research and advancements in diagnostic techniques and therapeutic interventions will continue to enhance the management of PET.
