Low-frequency sound pressure and transtympanic endoscopy of the middle ear in assessment of "spontaneous" perilymphatic fistula.

This study was designed to verify an eventual perilymphatic fistula (PLF) in 264 patients with sensorineural hearing loss (SNHL) and/or vertigo. The patients were exposed to a low-frequency sound stimulation (LFS) on posturography to objectively test Tullio's phenomenon and Hennebert's sign. Endoscopes with 5 degree and 25 degree of visual angle and an outer diameter of 1.7 mm were used. The round window niche, with its foldings, oval window with stapes superstructure, a part of the facial recess and the area in the fissula ante fenestram were examined and video recorded. In one patient, we endoscopically verified a fistula in the round window membrane (resulting from a diving accident) that was covered with a fibrinous layer. In 4 cases, there was abnormal mucosal shining in the round window but without PLF. In 7 cases, the tympanic cavity could not be visualized because of the adhesive middle ear process, the abnormal anatomy, or the prominent exostoses of the ear canal prohibited vision. In 34 patients, LFS provoked unsteadiness on posturography without PLF. In 6 cases, a postoperative middle ear infection was recorded. No permanent tympanic membrane perforation occurred. It is unlikely that disease entity of "spontaneous PLF" exists. Tympanoscopy should be regarded as the first choice when a PLF is suspected.