Otological symptoms and audiometric findings in patients with temporomandibular disorders: Costen's syndrome revisited

Objective:Otological symptoms (otalgia, subjective hearing loss, blocked ear sensation, tinnitus and vertigo) associated with temporomandibular disorders are documented features of Costen's syndrome. However, the origin of these symptoms and the causes of hearing loss are unknown. This study aimed to characterise hearing loss in a large number of patients with temporomandibular disorders. The causes of these symptoms were explored in patients with otological symptoms and normal audiometric findings.Methods:A prospective case study and literature review were performed. The audiometric features of 104 temporomandibular disorder patients were compared with those of 110 control participants.Results:A large proportion of temporomandibular disorder patients had several otological symptoms. Twenty-five per cent of unilateral or bilateral temporomandibular disorder patients had either unilateral (ipsilateral) or bilateral hearing loss; respectively, which was usually mild (p = 0.001). Hearing loss was predominantly sensorineural.Conclusion:The main cause of otological symptoms (apart from otalgia) and of audiometric findings in temporomandibular disorder patients is postulated to be an altered middle-ear to inner-ear pressure equilibrium.

Intracochlear Drug Injections through the Round Window Membrane: Measures to Improve Drug Retention

The goal of this study was to develop an appropriate methodology to apply drugs quantitatively to the perilymph of the ear. Intratympanic applications of drugs to the inner ear often result in variable drug levels in the perilymph and can only be used for molecules that readily permeate the round window (RW) membrane. Direct intracochlear and intralabyrinthine application procedures for drugs, genes or cell-based therapies bypass the tight boundaries at the RW, oval window, otic capsule and the blood-labyrinth barrier. However, perforations can release inner ear pressure, allowing cerebrospinal fluid (CSF) to enter through the cochlear aqueduct, displacing the injected drug solution into the middle ear. Two markers, fluorescein or fluorescein isothiocyanate-labeled dextran, were used to quantify how much of an injected substance was retained in the cochlear perilymph following an intracochlear injection. We evaluated whether procedures to mitigate fluid leaks improved marker retention in perilymph. Almost all procedures to reduce volume efflux, including the use of gel for internal sealing and glue for external sealing of the injection site, resulted in improved retention of the marker in perilymph. Adhesive on the RW membrane effectively prevented leaks but also influenced fluid exchange between CSF and perilymph. We conclude that drugs can be delivered to the ear in a consistent, quantitative manner using intracochlear injections if care is taken to control the fluid leaks that result from cochlear perforation.