Endolymphatic Hydrops in Otologic Syphilis: A Temporal Bone Study

Otosyphilis: A Review of the Literature

The number of cases of syphilis has increased in the United States and in many high-income nations. Otosyphilis is a less recognized complication of syphilis that can lead to irreversible sensorineural hearing loss. Different pathophysiological mechanisms have been proposed to explain hearing loss in otosyphilis. We review the literature on otosyphilis in adults and propose the need for future work in this field to identify better ways to diagnose, treat, and manage this disease. Patients with syphilis should be screened routinely for hearing loss, and all patients with new, sudden, or fluctuating sensorineural hearing loss should be evaluated for syphilis.

Pediatric otosyphilis—An unusual cause of conductive hearing loss

We present the case of a 5 year old female with a unilateral conductive hearing loss which had a relapsing and remitting course over a 3 year period. An initial noncontrast CT temporal bone study was unremarkable and a diagnosis of otitis media was made in the first instance. However, a second CT temporal bone study performed 3 years later demonstrated bilateral demineralisation of the ossicles and abnormal lucency affecting both the otic capsules. A diagnosis of otosyphilis was proposed on the basis of the imaging features and a prior medical history of previously treated congenital syphilis. With the benefit of hindsight, early pericochlear lucency was identified on the initial CT temporal bone study. There has been a steady rise of syphilis cases since the millennium with resurgence in many high income countries. Otosyphilis has a highly variable clinical presentation and there is limited data to establish the pattern of hearing loss in pediatric patients with a background of congenital otosyphilis. Temporal bone and otic capsule demineralisation carries a broad differential diagnosis including osteogenesis imperfecta, otosclerosis, Paget's disease and radiation related changes. Otosyphilis is a rare but potentially treatable cause of deafness and a high index of suspicion is required to make the diagnosis. In conjunction with a positive syphilis serology, a noncontrast temporal bone CT can aid the diagnosis and expedite the treatment.

Adverse outcome pathway for aminoglycoside ototoxicity in drug-resistant tuberculosis treatment

Individuals treated for multidrug-resistant tuberculosis (MDR-TB) with aminoglycosides (AGs) in resource-limited settings often experience permanent hearing loss. However, AG ototoxicity has never been conceptually integrated or causally linked to MDR-TB patients' pre-treatment health condition. We sought to develop a framework that examines the relationships between pre-treatment conditions and AG-induced hearing loss among MDR-TB-infected individuals in sub-Saharan Africa. The adverse outcome pathway (AOP) approach was used to develop a framework linking key events (KEs) within a biological pathway that results in adverse outcomes (AO), which are associated with chemical perturbation of a molecular initiating event (MIE). This AOP describes pathways initiating from AG accumulation in hair cells, sound transducers of the inner ear immediately after AG administration. After administration, the drug catalyzes cellular oxidative stress due to overproduction of reactive oxygen species. Since oxidative stress inhibits mitochondrial protein synthesis, hair cells undergo apoptotic cell death, resulting in irreversible hearing loss (AO). We identified the following pre-treatment conditions that worsen the causal linkage between MIE and AO: HIV, malnutrition, aging, noise, smoking, and alcohol use. The KEs are: (1) nephrotoxicity, pre-existing hearing loss, and hypoalbuminemia that catalyzes AG accumulation; (2) immunodeficiency and antioxidant deficiency that trigger oxidative stress pathways; and (3) co-administration of mitochondrial toxic drugs that hinder mitochondrial protein synthesis, causing apoptosis. This AOP clearly warrants the development of personalized interventions for patients undergoing MDR-TB treatment. Such interventions (i.e., choosing less ototoxic drugs, scheduling frequent monitoring, modifying nutritional status, avoiding poly-pharmacy) will be required to limit the burden of AG ototoxicity.

Good Clinical Approach: Delphi Consensus for the Use of Betahistine in Menière's Disease

Menière's disease is a disorder of the inner ear that causes vertigo, tinnitus, fullness, and hearing loss. Several pharmacological treatments are available, but none of them has shown significant results. Betahistine has been largely used but its effect on the main symptoms of Menière's disease remains unclear. In order to improve clinical appropriateness and to reduce the heterogeneity of the therapeutic approaches for Menière's disease, we proposed a European Consensus Conference on Betahistine's prescription. A group of European experts in vestibular disorders completed a questionnaire, prepared by opinion leaders, on the use of betahistine in Menière's disease. The Delphi method was used as an iterative investigation method in order to increase and establish the consensus. While betahistine was considered useful to reduce the number of the vertigo attacks during the intercritical phase of the disease, its use during attacks was considered helpful only when associated with other drugs. Betahistine was not considered useful for preventing hearing loss. The experts support the use of betahistine during the intercritical phase of the disease to reduce the number and severity of vertigo episodes. They also defined the parameters for a good clinical approach to evaluate the efficacy of betahistine treatment for Menière's disease.

Secondary Endolymphatic Hydrops

HYPOTHESIS

A review of the most recent literature will provide clinicians with an update of secondary endolymphatic hydrops, aiding in diagnosis and treatment of affected patients.

BACKGROUND

Secondary endolymphatic hydrops is a pathologic finding of the inner ear resulting in episodic vertigo and intermittent hearing loss. It is a finding for which extensive research is being performed.

METHODS

A review of the most recent literature on secondary endolymphatic hydrops was performed using PubMed literature search.

RESULTS

Recent investigation of secondary endolymphatic hydrops has brought attention to traumatic and inflammatory insults as causes for secondary endolymphatic hydrops. Such etiologies, including postsurgical effects of cochlear implantation and endolymphatic sac ablation; otosclerosis and its operative intervention(s); acoustic and mechanical trauma; medications; and systemic inflammatory processes, have been determined as causes of secondary lymphatic hydrops. Histopathological slides for many of the etiologies of secondary endolymphatic hydrops are presented.

CONCLUSION

Through an understanding of the pathophysiology and etiologies of secondary endolymphatic hydrops, clinicians will gain a better understanding of this complex disease process, which will aid in treatment of patients with this disease process.

Stria vascularis and cochlear hair cell changes in syphilis: A human temporal bone study

OBJECTIVE

To observe any changes in stria vascularis and cochlear hair cells in patients with syphilis.

MATERIALS AND METHODS

We examined 13 human temporal bone samples from 8 patients with syphilis (our syphilis group), as well as 12 histopathologically normal samples from 9 age-matched patients without syphilis (our control group). We compared, between the two groups, the mean area of the stria vascularis (measured with conventional light microscopy connected to a personal computer) and the mean percentage of cochlear hair cell loss (obtained from cytocochleograms).

RESULTS

In our syphilis group, only 1 (7.7%) of the 13 samples had precipitate in the endolymphatic or perilymphatic spaces; 8 (61.5%) of the samples revealed the presence of endolymphatic hydrops (4 cochlear, 4 saccular). The mean area of the stria vascularis did not significantly differ, in any turn of the cochlea, between the 2 groups (P>0.1). However, we did find significant differences between the 2 groups in the mean percentage of outer hair cells in the apical turn (P<0.026) and in the mean percentage of inner hair cells in the basal (P=0.001), middle (P=0.004), and apical (P=0.018) turns. In 7 samples in our syphilis group, we observed either complete loss of the organ of Corti or a flattened organ of Corti without any cells in addition to the absence of both outer and inner hair cells.

CONCLUSION

In this study, syphilis led either to complete loss of the organ of Corti or to significant loss of cochlear hair cells, in addition to cochleosaccular hydrops. But the area of the stria vascularis did not change.

Otologic disorders causing dizziness, including surgery for vestibular disorders

This chapter will focus on vertigo/dizziness due to inner-ear malformations, labyrinthine fistula, otosclerosis, infectious processes, and autoimmune inner-ear disorders. Inner-ear malformation due to dehiscence of the superior semicircular canal is the most recently described inner-ear malformation. Vertigo/dizziness is typically induced by sound and pressure stimuli and can be associated with auditory symptoms (conductive or mixed hearing loss). Labyrinthine fistula, except after surgery for otosclerosis, in the context of trauma or chronic otitis media with cholesteatoma, still remains a challenging disorder due to multiple uncertainties regarding diagnostic and management strategies. Otosclerosis typically manifests with auditory symptoms and conductive or mixed hearing loss on audiometry. Vertigo/dizziness is rare in nonoperated otosclerosis and should draw clinical attention to an inner-ear malformation. Computed tomography scan confirms otosclerosis in most cases and should rule out an inner-ear malformation, avoiding needless middle-ear surgical exploration. Labyrinth involvement after an infectious process is unilateral when it complicates a middle-ear infection but can be bilateral after meningitis. Labyrinth involvement due to an inflammatory disease is a challenging issue, particularly when restricted to the inner ear. The diagnosis relies on the bilateral and rapid aggravation of audiovestibular symptoms that will not respond to conventional therapy but to immunosuppressive drugs.

Histopathologic ear findings of syphilis: a temporal bone study

To the best of our knowledge, histopathologic studies of syphilitic ears have generally focused on hydropic changes; so far, no such studies have investigated peripheral vestibular otopathology using differential interference contrast microscopy, in patients with syphilis. For this study, we examined 13 human temporal bone samples from 8 patients with a history of syphilis. Using conventional light microscopy, we performed qualitative histopathologic assessment. In addition, using differential interference contrast microscopy, we performed type I and type II vestibular hair cell counts on each vestibular sense organ with minimal autolysis; in which the neuroepithelium was oriented perpendicular to the plane of section. We then compared vestibular hair cell densities (cells per 0.01 mm² surface area) in the syphilis group vs. the control group. In the syphilis group, we observed precipitate in the endolymphatic or perilymphatic spaces in 1 (7.7 %) of the samples and endolymphatic hydrops in eight (61.5 %) of the samples. Hydrops involved the cochlea (four samples) and/or saccule (four samples). In addition, the syphilis group experienced a significant loss of type II vestibular hair cells in the maculae of the utricle and saccule, and in the cristae of the lateral and posterior semicircular canals, as compared with the control group (P < 0.05).

Endolymphatic hydrops in Ménière's disease: cause, consequence, or epiphenomenon?

OBJECTIVE

To determine the relationship of endolymphatic hydrops to Ménière's disease.

DATA SOURCES

Comprehensive review of articles from 1938 through 2012 via Medline and Index Medicus.

STUDY SELECTION

Articles discussing Ménière's disease and/or endolymphatic hydrops that include temporal bone autopsy data.

DATA EXTRACTION

Fifty-three case reports and series were studied containing examination of 541 hydropic temporal bones and including 276 patients with Ménière's disease. These were divided into those meeting the 1995 American Academy of Otolaryngology-Head and Neck Surgery criteria for Ménière's disease and those that failed to meet these criteria.

CONCLUSION

An individual meeting the 1995 criteria for Ménière's disease has a near certain probability of having endolymphatic hydrops in at least 1 ear. Autopsy data do not support the view that the association of MD and EH is an epiphenomenon or that MD causes EH; this leaves us with the probability that EH causes MD. If it is causative, hydrops alone is insufficient to cause Ménière's disease, indicating that there must be one or more additional cofactors that cause asymptomatic hydrops to become symptomatic Ménière's disease. Vascular risk factors should be studied as possible cofactors.