Labyrinthine Fistula-Our Experience at a Tertiary Hospital.

This study has aimed to determine the anatomical site of labyrinthine fistula in patients of chronic suppurative otitis media at our centre. Labyrinthine fistulae (LF) are caused by abnormal communications between the inner ear and surrounding structures resulting in perilymph leakage and hearing loss. Labyrinthine fistula represents as erosive loss of the enchondral bone overlying the semicircular canals without loss of perilymph. The manifestations of fistula like vertigo, hearing loss vary in severity and complexity, commonly ranging from very mild to incapacitating. Cholesteatoma induced fistula most commonly involves lateral semicircular canal probably because of its close proximity to the middle ear, but can involve other semicircular canals and rarely cochlea. This is a retrospective analysis of 36 patients of chronic suppurative otitis media with history of vertigo undergoing tympanomastoid surgery in whom there was an evidence of labyrinthine fistula on HRCT scan of temporal bone. The incidence of patients with labyrinthine fistula presenting with vertigo, nystagmus, sensorineural hearing loss, history of vertigo were analysed. The anatomical location of the fistula was supported by Radiological evidence. Patients underwent either canal wall down mastoidectomy or cortical mastoidectomy. The anatomical site and length of the labyrinthine fistula were analysed. Amongst the 36 patients of chronic suppurative otitis media with labyrinthine fistula 22 (61.1%) patients had atticoantral disease, 4 (11.1%) patients had chronic otitis media with extensive granulation, 2 (5.5%) patients had Tubotympanic disease with polyps, 4 (11.1%) patients had Tuberculous otitis media, 1 (2.77%) patient had Tubotympanic disease with extensive tympanosclerosis eroding the dome of lateral semicircular canal, 1 (2.77%) patient had extensive cholesteatoma with cerebellar abscess, 1 (2.77%) patient had fistula in the promontory following trauma, 1 (2.77%) patient had extensive tympanosclerosis with erosion of promontory. It was noticed that, in 14 (38.88%) patients the fistula was at the centre, in 17 (47.22%) patients the fistula is towards the ampullary end of horizontal semicircular canal and in 5 (13.88%) patients the fistula was towards the non ampullary end of lateral semicircular canal. The maximum length of fistula noticed was 6 mm and the minimum length of the fistula noticed was 2 mm. Labyrinthine fistula are most commonly noticed in the ampullary end of the lateral semicircular canal. The average length of the fistula was found to be 4 mm. Careful elevation of the cholesteatoma matrix over the endosteal membrane and immediate placement of temporal fascia over the exposed fistula is important to avoid injury to the inner ear. Maximum number of fistula were seen in the atticoantral type of Chronic suppurative otitis media. Prior knowledge of anatomical location of the fistulous tract in HRCT temporal bone is important to address the fistula.