Radiological Features and Pathognomonic Sign of Stapes Footplate Fistula in Inner Ear Malformations

Abstract

Objective: Some inner ear malformations may cause recurrent meningitis, which may be fatal. The etiology is usually a stapes footplate fistula which enables microorganisms to pass into the inner ear containing cerebrospinal fluid (CSF), causing repeated attacks of meningitis. Radiological signs of the fistula are not obvious and are not reported in detail in the literature. The aim of the study is to investigate the radiological features of stapes footplate fistula in inner ear malformations. Methods: Radiological findings were analyzed for seventeen patients with inner ear malformations (IEMs) operated on because of recurrent meningitis. Using this information, images of 1,010 patients with IEMs were retrospectively reviewed to investigate the radiological findings of stapes footplate fistula and their relationship to IEMs. They were classified according to the Sennaroglu classification system, and according to different stages of stapes footplate fistula. Results: In the case of a stapes footplate cyst, computerized tomography shows an opacity at the oval window. On magnetic resonance imaging, a fluid filled cystic structure continuous with and having similar signal characteristics to the CSF in the inner ear is a pathognomonic finding of a stapes footplate cyst. It is most commonly found in common cavity anomaly (18.2%); the second most frequent finding is incomplete partition type I (15%). And it can even be seen in cases of cochlear aplasia where only the vestibule is present. Conclusion: If the history reveals recurrent meningitis, particular attention should be given to the oval window area, where an opacity, cyst or a leaking lesion should be looked for on the imaging. It is the responsibility of the otolaryngologist to notice these findings, and to operate on the patient to prevent further attacks of meningitis.

Cerebellar Abscess Induced by Cochlear Fistula due to Chronic Suppurative Otitis Media

“…In addition to autism – as in the present case – patients with dementia or severe developmental disorders are also considered to be at risk for the development of otogenic intracranial complications when they refuse treatment for otitis media. It is reported certain types of inner ear malformations (e.g., stapes footplate fistula) can cause recurrent meningitis [2]. However, the present patient had no inner ear malformation or fistula of the stapes footplate.…”

“…In addition to this review article, there have been a few reports on labyrinthine fistulas without cholesteatoma. Regarding intracranial complications due to cochlear fistulae, Sennaroglu [2] reported that stapes footplate fistula can cause meningitis in cases with congenital inner ear malformations. However, no cases of acquired cochlear fistula with intracranial complications (e.g., meningitis or cerebral abscess) have been reported.…”

“…In contrast, cochlear fistula is less common [1]. Labyrinthine fistulas, including cochlear fistulas, can be congenital or acquired, with congenital fistulas associated with inner ear malformations [2] and acquired fistulas reported to be caused by cholesteatoma, inflammation, or adhesive otitis media. We herein report a case of cochlear fistula due to chronic otitis media that was diagnosed after the onset of a cerebellar abscess.…”

Endoscopic Repair of Round Window Cochleocele

“…Most commonly, these lesions are described with IP1 or common cavity anomalies (2,3). The nomenclature of lesions causing the bulging oval window sign on CT (3,4) has been discussed by Sennaroglu (2), who recognized that stapes footplate cyst is an inaccurate term, given that the contents of the lesion are not encapsulated but are in continuity with the perilymph space through the stapes footplate fistula. Although we have found no previous description of a round window cochleocele, a previous report of tympanotomy findings in a child with recurrent meningitis is suggestive of an earlier finding of this anomaly (5).…”

“…A fistula in the footplate may allow a fluid-filled pouch of endosteum to bulge into the middle ear space, referred to as a cochleocele, or, if open, allow leakage of CSF into the ear (1). Most commonly, these lesions are described with IP1 or common cavity anomalies (2,3). The nomenclature of lesions causing the bulging oval window sign on CT (3,4) has been discussed by Sennaroglu (2), who recognized that stapes footplate cyst is an inaccurate term, given that the contents of the lesion are not encapsulated but are in continuity with the perilymph space through the stapes footplate fistula.…”