Variant petrotympanic fissure as possible cause of an otologic complication during TMJ arthroscopy. A case report.

In this reported case, a variant petrotympanic fissure--opening at the height of the orifice of the Eustachian tube into the hypotympanon--was identified by high resolution computed tomography (CT) as the possible cause of a tympanic membrane perforation. Inner ear function was preserved by an otosclerotic stapes which prevented destruction of the labyrinth. The perforation was closed by a myringoplasty and was to be followed by a stapedectomy after six months to restore normal hearing. Surgeons performing temporomandibular joint arthroscopy should be aware that in a small percentage of patients a variant anatomy of the tympanic plate exists and, therefore, great care must be exercised in the manipulation of instruments near this structure. A preoperative high resolution CT with thin slices of the temporal bone might allow identification of these high risk patients.