Cellular voids in the pathogenesis of otosclerosis.

BACKGROUND: Otosclerosis is a common ear disease that causes fixation of the stapes and conductive hearing impairment. However, the pathogenesis of otosclerosis is still unknown. Otosclerosis could be associated with the unique bony environment found in the otic capsule. Normal bone remodelling is almost completely absent around the inner ear after birth allowing degenerative changes and dead osteocytes to accumulate. High levels of inner ear anti resorptive osteoprotegerin (OPG) is most likely responsible for this capsular configuration. Studies have demonstrated how osteocyte lifespan variation creates occasional clusters of dead osteocytes, so-called cellular voids, at otosclerotic predilection sites in the human otic capsule. These cellular voids have been suggested as possible starting points of otosclerosis. AIM: To describe the cellular viability in otosclerotic lesions and compare it to that of cellular voids. MATERIALS AND METHODS: The study was based on unbiased stereological quantifications in undecalcified human temporal bones with otosclerosis. RESULTS: Osteocyte viability was found to vary within the otosclerotic lesions. Furthermore, the results presented here illustrate that inactive otosclerotic lesions consist of mainly dead interstitial bone, much like cellular voids. CONCLUSIONS AND SIGNIFICANCE: Focal degeneration in the otic capsule may play an important role in the pathogenesis of otosclerosis.

Neurotransmitter and neurotransmitter receptor expression in the saccule of the human vestibular system.

The saccule is one of the vestibular sensory organs of the inner ear. It detects head movements and provides information to maintain balance and orient in space. Despite its critical role, very little is known about its neurotransmission and regulation. Multiple disease entities and medications affect balance, which is why information on neurotransmission in the vestibular end organs including the saccule could have important pharmacological implications. To the best of our knowledge, this is the first paper to describe immunohistochemical expression of a large panel of neurotransmitters and receptors in the human saccule. Saccular tissue was sampled freshly during surgery. Based partly on previous findings in non-humans and partly on potential biological relevance, the neurotransmitters cholecystokinin, dopamine, GABA, glutamate, histamine and serotonin as well as receptors for these were selected for the tested panel. The neuroepithelium expressed glutamate receptor 1 (GluR1), metabotropic glutamate receptor (mGluR), GABA A receptor α (GABAARα), GABA B receptor 2 and cholecystokinin receptor B (CCKBR), whereas l-glutamate, GluR1, CCKBR, GABAARα, dopamine and serotonin receptor 1D were expressed in the subepithelial stroma. The non-sensory epithelium expressed GluR1, mGluR, histamine receptor 3, CCKAR and dopamine transporter. These findings provide a basis for pharmacological research and potential drug development.

Validating the 7-item Eustachian Tube Dysfunction Questionnaire in Danish.

INTRODUCTION: Eustachian tube dysfunction (ETD) may result in hearing loss, chronic otitis and cholesteatoma. With advances in treatment options, the identification of patients with obstructive ETD is becoming increasingly important. The objective of this study was to validate a Danish translation of the 7-item Eustachian Tube Dysfunction Questionnaire (ETDQ-7). METHODS: All participants underwent tympanometry, otomicroscopy and completed the ETDQ-7. We included 34 ears from patients with obstructive ETD who had abnormal tympanometry curves but no history of cholesteatoma or adhesive otitis. As a control group, 48 otherwise healthy ears with a normal tympanometry curve were included from patients with known sensorineural hearing loss or normal hearing. RESULTS: A Cronbach's alpha of 0.77 indicated a good internal consistency reliability of the questionnaire. The mean ETDQ-7 score in the obstructive ETD group was 31 versus 13.5 in the control group (p = 0.00). A receiver operating characteristics analysis produced an area under the curve of 94%, showing excellent discriminatory abilities between the groups. CONCLUSIONS: The ETDQ-7 has previously been validated in English, German, Dutch and Portuguese, demonstrating good clinical relevance. The Danish translation of the ETDQ-7 has produced similar results and may be valuable in diagnosing obstructive ETD and in monitoring the effect of balloon dilation of the Eustachian tube. FUNDING: none. The study was approved by the Danish Data Protection Agency (VD-2018-33, I-Suite 6229).