[Studies of labyrinthine cholesteatoma-related fistulas: report of 22 cases]. / Prise en charge des fistules labyrinthiques cholestéatomateuses: a propos de 22 cas.

OBJECTIVE: To study the incidence, location, pre- and postoperative symptoms (hearing loss, tinnitus, vertigo, facial palsy), preoperative diagnostic imaging, and surgical treatment of labyrinthine fistulae (LF). DESIGN: Retrospective case review. PATIENTS: Twenty-two cases of LF over 382 mastoid operations performed in a 168-month period. MAIN OUTCOME MEASURES: Clinical, imaging, and surgical correlation of extensive fistulae and bone fistulae. RESULTS: LF prevalence was 5.8%. The main primary symptoms were otorrhea and hypoacusis. Only four patients presented vertigo as their main complaint. All patients underwent preoperative computed tomographic (CT) scans and preoperative audiometry. LF diagnosis was made before surgery for 100% of patients on the basis of CT scan. A second fistula was, however, misdiagnosed by imaging in two patients. With respect to surgical technique, a canal wall down procedure was performed in 77% and a conservative procedure was performed in 23%. Fistula was located in the horizontal semicircular canal in 100% of cases, and in 9%, a second fistula was operatively diagnosed. In 91% of cases, the matrix was removed, whereas it was left in the course of a canal down procedure in 9%. With a follow-up of 5.7 years, hearing remained unchanged in 80% of patients. CONCLUSIONS: Surgery with removal of the cholesteatoma matrix and sealing of the fistula with temporalis fascia is a safe procedure that can help preserve cochlear function. The choice of a canal down procedure would be influenced by cholesteatoma characteristics rather than by the finding of an LF.

Experimental model for investigating trans-mucosal gas exchanges in the middle ear of the rat.

OBJECTIVE: The total pressure in the middle ear depends on the air composition of this gas pocket, i.e. on gas exchanges occurring through either the Eustachian tube (ET) or mucosa. The aim of this study was to develop an experimental model to investigate the exclusive role of trans-mucosal gas exchanges in the middle ear (ME). MATERIAL AND METHODS: Both tympanic membranes of 20 Sprague-Dawley rats were punctured under general anesthesia. Rats were divided into two equal groups. Group 1 had no ET obstruction. In Group 2, the ET was blocked, after velar incision, by cauterization and application of cyanoacrylate glue into the lumen. One open transparent glass tube containing a droplet of colored water was placed horizontally and connected hermetically to each ear canal. The ME was then flushed with room air through the tube. Variations in ME gas volume were measured by reading the displacement of the liquid droplet in the horizontal tube. The kinetics of variations in gas volume between groups were displayed and statistically compared using a two-sided t-test. RESULTS: The pattern of variations in ME gas volume with time was similar in the two groups. Both were characterized by a decrease with three phases and an elimination rate of approximately 0.152 +/- 0.026 microl/min. There was no significant difference in the mean rate of ME volume changes between the two groups. CONCLUSION: This experimental model allows investigation of trans-mucosal gas exchanges. These exchanges exhibit an absorptive function resulting in a negative pressure that must be compensated, under physiological conditions, by air flow through the ET.

Spontaneous intracranial hypotension: a rare cause of labyrinthine hydrops.

Spontaneous intracranial hypotension should be considered as a possible cause of cochlear hydrops. We report a case of unilateral hearing loss attributed to spontaneous intracranial hypotension on the basis of characteristic abnormalities seen on magnetic resonance imaging. The diagnostic gold standards for intracranial hypotension are lumbar measurement of cerebrospinal fluid pressure and magnetic resonance imaging. The usual treatment is an autologous blood injection into the peridural spaces. The mechanism of hearing loss is thought to involve secondary perilymph depression due to a patent cochlear aqueduct. This perilymph depression would induce a compensatory expansion of the endolymphatic compartment, with a subsequent decrease in basilar or Reissner's membrane compliance. Endolymphatic hydrops can occur in the course of intracranial hypotension, and not only because of abnormal endolymph production or resorption. Hydrops can thus be classified into 1) syndromes of endolymphatic origin and 2) syndromes of perilymphatic origin, in which loss of perilymph induces compensatory expansion of the endolymphatic space.

A rare clival and sellar fracture with pneumatocephalus.

We present a case of clival and sellar complex fracture produced by an indirect mechanism. This previously healthy patient had an occipital trauma followed by epistaxis. CT showed a clival and sellar fracture with pneumatocephalus. The probable fracture mechanism was contre-coup injury, linked to cerebral shock-wave transmission. This type of fracture is generally observed in the anterior part of the skull base, in a low resistance area. Severe osteoporosis probably accounted for the unusual fracture site in this patient. A mechanism of direct clival transmission is discussed, together with the usual complications of sphenoid injuries.