Cholesteatoma labyrinthine fistula: prevalence and impact.

INTRODUCTION: Labyrinthine fistula is one of the most common complications associated with cholesteatoma. It represents an erosive loss of the endochondral bone overlying the labyrinth. Reasons for cholesteatoma-induced labyrinthine fistula are still poorly understood.

OBJECTIVE: Evaluate patients with cholesteatoma, in order to identify possible risk factors or clinical findings associated with labyrinthine fistula. Secondary objectives were to determine the prevalence of labyrinthine fistula in the study cohort, to analyze the role of computed tomography and to describe the hearing results after surgery.

METHODS: This retrospective cohort study included patients with an acquired middle ear cholesteatoma in at least one ear with no prior surgery, who underwent audiometry and tomographic examination of the ears or surgery at our institution. Hearing results after surgery were analyzed according to the labyrinthine fistula classification and the employed technique.

RESULTS: We analyzed a total of 333 patients, of which 9 (2.7%) had labyrinthine fistula in the lateral semicircular canal. In 8 patients, the fistula was first identified on image studies and confirmed at surgery. In patients with posterior epitympanic and two-route cholesteatomas, the prevalence was 5.0%; and in cases with remaining cholesteatoma growth patterns, the prevalence was 0.6% (p=0.16). In addition, the prevalence ratio for labyrinthine fistula between patients with and without vertigo was 2.1. Of patients without sensorineural hearing loss before surgery, 80.0% remained with the same bone conduction thresholds, whereas 20.0% progressed to profound hearing loss. Of patients with sensorineural hearing loss before surgery, 33.33% remained with the same hearing impairment, whereas 33.33% showed improvement of the bone conduction thresholds' Pure Tone Average.

CONCLUSION: Labyrinthine fistula must be ruled out prior to ear surgery, particularly in cases of posterior epitympanic or two-route cholesteatoma. Computed tomography is a good diagnostic modality for lateral semicircular canal fistula. Sensorineural hearing loss can occur post-surgically, even in previously unaffected patients despite the technique employed.