On the Nature of Hearing Loss in Méniere's Disease.

OBJECTIVE: To explain the pathophysiology of the hearing loss in Ménière's disease (MD). BACKGROUND: In a previous report, we described a dramatic recovery of hearing in 12/31 patients with MD using antiviral (AV) drugs. The hearing loss in the remaining 19 patients with a longer history of MD remained unchanged or else worsened. Vertigo control was complete in the group with improved hearing but poorer in the group with greater hearing loss (and a longer MD history). Since achieving the recovery of hearing and control of the vertigo using AV drugs in these patients with a shorter history (≤2 years) of MD, we have continued to record dramatic hearing recovery in MD when patients have a shorter history of symptoms. We describe this here in 5 representative MD patients. We feel that the most likely explanation for the outcome is the removal of viral nucleic acids (NA) from the organ of Corti. SUMMARY: A likely explanation for the sensorineural hearing loss in MD is paralysis of the cochlear amplifier function of the outer hair cells due to the toxicity ofNA. These NA are released from neurotropic viruses located in the vestibular nerve ganglion. Key Messages: (1) Viruses (Herpes family) are the cause of the symptoms in MD. (2) Hearing loss is the result of viral NA in the organ of Corti. (3) A short history of MD symptoms (<2 years) favors hearing recovery.

Recovery of Hearing in Meniere's Disease after Antiviral Treatment.

OBJECTIVE: Determine the outcome of hearing in Meniere's Disease (MD) after antiviral treatment. STUDY DESIGN: Prospective study. SETTING: University Hospital. METHODS: Thirty one new patients with a diagnosis of MD were treated with antiviral drugs during 2012. Acyclovir or valacyclovir was used depending on insurance coverage and cost. A standard dose of 800 mg (acyclovir) or 1g (valacyclovir) 3 times a day for 3 weeks was used. The dose was decreased to twice daily for three weeks, and finally once daily for a year or longer. Hearing test including pure tone average (PTA) and speech discrimination (SD) was performed prior to treatment and 1-2 months, 6 months and 1 year after the initiation of treatment. Effect on dizziness was recorded at each evaluation, hearing was judged to be improved if PTA was lowered by at least 15 db and/or an increase in SD of 20% or greater. RESULTS: Hearing was improved in twelve and not improved in nineteen patients. Complete control of vertigo was achieved in those patients with improved hearing. The nineteen patients with no improvement in hearing were divided into 2 groups based on the level of hearing at diagnosis. Nine patients presenting with a PTA of 50 db and SD of 50% or better experienced good control of vertigo (6 out of 7; 2 with no follow-up). Ten patients with PTA of 60 db or more and SD below 50% exhibited poor control of vertigo with antivirals (3 out of 10). The duration of MD in the group with hearing improvement was shorter (2.4 years) than the group with no improvement (5.5 years). CONCLUSION: Significant hearing and balance control in patients with MD can be achieved with orally administered antiviral drugs.

A perspective on recurrent vertigo.

The recurrent nature of the 3 most common vestibulopathies suggests a recurrent cause. Histopathology in temporal bones from patients with these syndromes - vestibular neuronitis (VN, n = 7), Ménière's disease (MD, n = 8) and benign paroxysmal positional vertigo (BPPV, n = 5) - shows focal degeneration of vestibular nerve axons and degenerated nearby facial nerve meatal ganglion cells. Transmission electron microscopic confirmation of intracytoplasmic viral particles in surgically excised vestibular nerves from patients with VN and MD support a viral etiology in these vestibulopathies. Antiviral treatment of these syndromes in a series of 211 patients with a 3- to 8-year follow-up resulted in complete control of vertigo in VN (88%), MD (90%) and BPPV (60%).

Clustering is a feature of the spiral ganglion in the basal turn.

OBJECTIVE: To demonstrate the organization of the spiral ganglion in the mammalian species. METHODS: Temporal bone (TB) specimens from man (n = 2), monkey (n = 2), lion (n = 2) and cat (n = 20) were stained, decalcified and dissected according to the Sudan black B method of Rasmussen. These TB specimens were examined under a Zeiss operating microscope and photographed with a Canon 100 camera interfaced with the microscope. RESULTS: Spiral ganglion cells occurred in clusters within Rosenthal's canal in all four species. The location of the clusters was marked by the interface between axon and dendritic bundles as well as groups of ganglion cells. In monkey and man the clusters were more separated than in lion and cat. CONCLUSIONS: These observations indicate that the spiral ganglion forms clusters of neurons within Rosenthal's canal at the basal cochlear turn in the mammals investigated here. The formation of clusters may be related to the principles of neurogenesis.

Fusion as an evolutionary principle of the vertebrate labyrinth.

OBJECTIVES: This study was undertaken to demonstrate changes in the innervation of vestibular and auditory sense organs with the evolutionary ascent of the vertebrate labyrinth. METHODS: Dissected labyrinths and their nerve supply prepared by the Sudan black B technique of Rasmussen were examined and photographed with a Canon A100 camera interfaced with a Zeiss operating microscope. RESULTS: In lizards and alligators, the utricular sense organ is represented by 2 small maculae, each with a separate nerve branching off the ampullary nerves to the anterior and lateral canal cristae. These 2 maculae fuse into a bilobed macula with ascent in frogs and pigeons, eventually becoming a single large macula with its nerve supply from the superior vestibular division in guinea pigs, cats, lions, monkeys, and humans. Along with these changes, there is a fusion of the lateral and anterior canal ampullary nerves and of the bifurcating branches of the vertical canal ampullary nerves. The saccular macula is single, but receives a dual innervation from the superior division (anterior ramus) and the inferior division (posterior ramus) of the eighth nerve in alligators, pigeons, guinea pigs, cats, lions, monkeys, and humans. The main innervation is usually from the inferior division; however, saccular innervation is from the inferior division in lizards and from the superior division in frogs. The auditory sense organ is represented by a curved tube with a low-frequency receptor (lagena) at its distal end in lizards, alligators, and pigeons. In mammals, in which there is a coiled cochlea with a variable number of turns, low frequencies are recorded at the apical turn. This configuration may represent fusion of the lagena into the apical end of the auditory sense organ. CONCLUSIONS: Fusion of sense organs and of their nerve supply appears to be an evolutionary principle in the vertebrate labyrinth.

Ménière's disease is a viral neuropathy.

Morphological and clinical evidence supports a viral neuropathy in Ménière's disease (MD). Quantitative examination of 11 sectioned temporal bones (TBs) from 8 patients with a history of MD revealed a significant loss of vestibular ganglion cells in both the endolymph hydropic (EH) and non-EH ears. Transmission electron microscopy of vestibular ganglion cells excised from a patient with MD revealed viral particles enclosed in transport vesicles. Antiviral treatment controlled vertigo in 73 of 86 patients with vestibular neuronitis (85%) and 32 of 35 patients with MD (91%).

Evidence for a viral neuropathy in recurrent vertigo.

The concept that reactivation of latent neurotropic viruses (i.e. Herpesviridae group) in the vestibular ganglion is responsible for recurrent vestibulopathies is presented. A similar histopathologic degeneration of vestibular ganglion cells in vestibular neuronitis (VN), Ménière's disease and benign paroxysmal positional vertigo is presented to support this concept. The clinical response (relief of vertigo) to the administration of antiviral medication in these syndromes provides practical evidence of a viral neuropathy in patients with recurrent vertigo. Relief of vertigo after this treatment was 90% in VN, Ménière's disease and VN. The relief of positional vertigo (benign paroxysmal positional vertigo) was 66%.

A place principle for vertigo.

OBJECTIVE: To provide a road map of the vestibular labyrinth and its innervation leading to a place principle for different forms of vertigo. METHOD: The literature describing the anatomy and physiology of the vestibular system was reviewed. RESULTS: Different forms of vertigo may be determined by the type of sense organ, type of ganglion cell and location in the vestibular nerve. CONCLUSION: Partial lesions (viral) of the vestibular ganglion are manifested as various forms of vertigo.

Pathology of benign paroxysmal positional vertigo revisited.

The pathophysiology of benign paroxysmal positional vertigo (BPPV) is not completely understood. Although the concept of degenerated otoconia transforming the posterior canal (PC) crista into a gravity-sensitive sense organ has gained popular support, several temporal bone (TB) series have revealed similar deposits in normal TBs, suggesting they are a normal change in the aging labyrinth. Furthermore, some TBs from patients with BPPV do not contain particles in the posterior canal. Five TBs from patients with BPPV were studied quantitatively and qualitatively. A small PC cupular deposit was found in 1 TB, while none was seen in the other 4 TBs. The major pathological changes were 1) a 50% loss of ganglion cells in the superior vestibular division of all 5 TBs and 2) a 50% loss of neurons in the inferior division of 3 TBs, and a 30% loss in 2 TBs that contained abnormal saccular ganglion cells. These observations support a concept in the pathophysiology of BPPV that includes loss of the inhibitory effect of otolith organs on canal sense organs.

Efferent system degeneration in the human temporal bone.

Sense organ deposits have been described in temporal bones from patients with vestibular neuronitis, Meniere's disease, and benign paroxysmal positional vertigo that are not found in a comparable series of temporal bones without vestibulopathy. Because the recurrent vestibulopathies are caused by vestibular ganglionitis and the vestibulocochlear anastomosis was degenerated in these temporal bones, the deposits may represent the end buds of regenerating efferent axons injured in passage through the vestibular ganglion. Such neural buds have been described with transmission electron microscopy in animals after vestibular nerve transection and in a human temporal bone with endolymphatic hydrops. The buds may be visible by light microscopy, because their size is comparable to that of hair cell nuclei and they stain blue with hematoxylin because of their nucleic acid content. The variable location and size of these deposits (buds) in the labyrinthine sense organs is described to aid in the recognition of efferent system injury in human temporal bones.

The three faces of vestibular ganglionitis.

We present temporal bone and clinical evidence that common syndromes of recurrent vertigo are caused by a viral infection of the vestibular ganglion. In the present series, histopathologic and radiologic changes in the vestibular ganglion and meatal ganglion were consistent with a viral inflammation of ganglion cells in cases of Meniere's disease, benign paroxysmal positional vertigo, and vestibular neuronitis. Clinical observations of multiple neuropathies involving cranial nerves V, VII, and VIII on the same side in patients with recurrent vertigo are best explained by a cranial polyganglionitis caused by a neurotrophic virus, which is reactivated by a stressful event later in life. The reactivation of the latent virus may manifest as one of the above vertigo syndromes, depending on the part of the vestibular ganglion that is inflamed, the type and strain of the virus, and host resistance.

Aneurysmal bone cyst of the temporal bone associated with reversible hemifacial paralysis.

Aneurysmal bone cyst (ABC) is an uncommon lesion of the temporal bone (TB), with only 20 cases reported. Facial paralysis is a rare complication (2 cases); however, no cases have been reported with preoperative reversal of paralysis. We report a 60-year-old man with a history of remote head trauma, who presented with serious otitis media and right hemifacial paralysis, which resolved with nonsurgical therapeutic measures. Magnetic resonance imaging and computed tomography showed a destructive and expansile lesion of the TB. The lesion was surgically removed, and ABC was diagnosed histologically. The patient had an uneventful recovery and demonstrated no recurrence at 1 year of follow-up. This report presents an unusual presentation of ABC in the TB, with a review of the clinical, radiological, pathological, and therapeutic features of this entity.

Results of singular neurectomy in the posterior ampullary recess.

OBJECTIVE: To determine the effect on hearing and balance symptoms following singular neurectomy (SN) for benign paroxysmal positional vertigo (BPPV) in the ampullary recess of the posterior semicircular canal. RESEARCH DESIGN: The charts of 242 patients with chronic disabling BPPV who were treated with SN over a 29-year period (1972-2001) were reviewed. The results on relief of BPPV and hearing function were recorded. A subset of 16 patients where the posterior ampullary recess was entered to expose the SN is described in detail with regard to an effect on hearing and balance. RESULTS: A total of 252 SN were performed in 242 patients. Ten patients underwent bilateral SN sequentially; the remaining 232 patients had unilateral SN. The ages of the patients ranged from 21 to 86 years, with a mean at 57 years. The female:male ratio was 174:68. Complete relief of BPPV was achieved in 244 patients (96.8%), incomplete relief in 3 (1%), and no relief in 5 (2%). Sensorineural hearing loss (SNHL) occurred in 9 patients (3.7%). A subset of 16 patients in whom the ampullary recess was opened during SN ranged in age from 21 to 79 years, with a mean at 56 years. The female:male ratio was 12:4, with right and left sides divided almost equally. Relief of BPPV was achieved in all 16 patients with no loss of hearing function. Five patients complained of a fistula response postoperatively (31%). The fistula response resolved by 6 months postoperatively in all 5 patients. CONCLUSIONS: SN is effective in relief of BPPV with little risk of SNHL (3.7%). The risk of SNHL is not increased when the posterior ampullary recess must be entered in order to transect the singular nerve. A positive fistula response may be present temporarily in almost one third of these patients.