[The clinical investigation of labyrinthine fistula associated with chronic otitis media].

OBJECTIVE

To investigate CT, the clinical features and the management strategy of labyrinthine fistula (LF) caused by chronic otitis media (COM).

METHOD

A retrospective review were investigated in 1068 patients with COM and 89 patients (8.33%) with LF. The positive fistula test was 22 (42.3%) in 52 patients. The clinical symptoms includes 34 patients (38.2%) with vertigo, 17 patients with headache, 7 patients with tinnitus or facial palsy and anacusis preoperatively. According to the extent of LF, the patients were classified into three groups. Group 1: intact labyrinth (blue line) 37 patients. Group 2: bony erosions (bony fistula) 48 patients. Group 3: complete erosions (perilymphatic fistula) 4 patients. With respect to surgical technique, the canal-wall-down procedure was performed in 86.5%, and the modified mastoidectomy performed in 13.5%. The site of LFs were 83 ears (93.3%) on lateral semicircle canal, 4 ears on superior semicircle cannal, 2 ears on posterior semicircle cannal, and 4 ears on cochlear respectively.

RESULT

90% patients underwent preoperative CT scans. The fistula was detected radiologically in 51 of 80 patients. Preoperative coronal computed tomography is sensitive for diagnosing LF. There were 65 patients underwent coronal CT and 48 patients (73.8%) detected with LF, and 15 patients underwent horizontal CT and 3 patients (20.0%) with LF. Hearing improved in 50 patients postoperatively. The air-bone gap was 20dB in 28 patients and 21-40 dB in 22 patients. There were 11 patients bone conduction improved and 8 patients bone conduction descend. There were 32 patients experienced hearing threshold deteriorate and 4 patients with anacusis postoperatively. Generally we attempted to completely remove the matrix with operative microscope, to graft the fistulous area with temporalis fascia and bone dust promptly, and to reconstruct the middle ear mechanism in single stage. Long-term follow up revealed the vertigo of all patients eliminated or alleviated.

CONCLUSION

We must emphasis on the possibility of labyrinthine fistula in all COM patients. Even though the preoperative diagnosis is now more easily accessible with the HRCT, the surgeon should always remain aware that a fistula could be present in spite of a negative CT examination. The matrix on the fistula areas must be removed completely in the latest stage of operations. The coronal CT scan is a significant method in show of LSC fistula.