You are in: eMedicine Specialties > Otolaryngology and Facial Plastic Surgery > INNER EAR Inner Ear, LabyrinthitisArticle Last Updated: Mar 6, 2008AUTHOR AND EDITOR INFORMATIONSection 1 of 10
  Author: Mark E Boston, MD, Chairman, Department of Otolaryngology-Head and Neck Surgery, Wilford Hall Medical Center, Lackland Air Force Base Mark E Boston is a member of the following medical societies: American Academy of Otolaryngology-Head and Neck Surgery, American Academy of Pediatrics, and American Medical Association Coauthor(s): Barry Strasnick, MD, FACS, Chairman, Professor, Department of Otolaryngology - Head and Neck Surgery, Eastern Virginia Medical School Editors: Michael E Hoffer, MD, Director, Spatial Orientation Center, Department of Otolaryngology, Naval Medical Center of San Diego; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; Gerard J Gianoli, MD, Clinical Associate Professor, Department of Otolaryngology-Head and Neck Surgery, Tulane University School of Medicine; Vice President, The Ear and Balance Institute; Chief Executive Officer, Ponchartrain Surgery Center; Christopher L Slack, MD, Otolaryngology-Facial Plastic Surgery, Private Practice, Associated Coastal ENT; Medical Director, Treasure Coast Sleep Disorders; Arlen D Meyers, MD, MBA, Professor, Department of Otolaryngology-Head and Neck Surgery, University of Colorado School of Medicine Author and Editor Disclosure Synonyms and related keywords: labyrinthitis of the inner ear, labyrinthitis, viral labyrinthitis, serous labyrinthitis, bacterial labyrinthitis, suppurative labyrinthitis, sudden sensorineural hearing loss, neurolabyrinthitis, vestibulocochleitis, vestibulocochlearis, sudden hearing loss, ear infection, inner ear infection, ear labyrinth infection, hearing disorder, hearing disturbance, balance disorder, balance disturbance, vertigo, dysequilibrium, hearing loss, vestibular neuritis, herpes zoster oticus, Ramsay-Hunt syndrome, varicella-zoster virus, varicella reactivation, zoster reactivation, rubella, cytomegalovirus, CMV, mumps, measles, SNHL, herpes oticus, labyrinthine inflammation, labyrinthine disease, labyrinthine disorder, labyrinthine infection INTRODUCTIONSection 2 of 10
  BackgroundLabyrinthitis is an inflammatory disorder of the inner ear or labyrinth. Clinically, this condition produces disturbances of balance and hearing to varying degrees and may affect one or both ears. Bacteria or viruses can cause acute inflammation of the labyrinth in conjunction with either local or systemic infection. PathophysiologyThe anatomic relationships of the labyrinth, middle ear, mastoid, and subarachnoid space are essential to understanding the pathophysiology of labyrinthitis. The labyrinth is composed of an outer osseous framework surrounding a delicate membranous network that contains the peripheral sensory organs for balance and hearing. These sensory organs include the utricle, saccule, semicircular canals, and cochlea. Symptoms of labyrinthitis occur when infectious microorganisms or inflammatory mediators invade the membranous labyrinth and damage the vestibular and auditory end organs. The labyrinth lies within the petrous portion of the temporal bone adjacent to the mastoid cavity and connects with the middle ear at the oval and round windows. The labyrinth maintains connections with the central nervous system and subarachnoid space by way of the internal auditory canal and cochlear aqueduct. Bacteria may gain access to the membranous labyrinth by these pathways or through congenital or acquired defects of the bony labyrinth. Viruses typically spread to labyrinthine structures hematogenously or by way of the aforementioned preformed pathways. Viral and bacterial labyrinthitis are sufficiently different to warrant discussing them as separate disease processes. Viral labyrinthitis is characterized by a sudden unilateral loss of vestibular function and hearing. The acute onset of severe, often incapacitating, vertigo, frequently associated with nausea and vomiting, is characteristic of this disorder. The patient is often bedridden while the symptoms gradually subside. Vertigo eventually resolves after several days to weeks; however, unsteadiness and positional vertigo may persist for several months. Hearing loss is also present and may be the primary presenting symptom in many patients. Physical examination findings include spontaneous nystagmus towards the unaffected side with diminished or absent caloric responses in the affected ear. The hearing loss is usually mild to moderate and typically evident in the higher frequencies (>2000 Hz), although any degree or type of hearing loss may be present. An upper respiratory tract infection precedes the onset of symptoms in up to 50% of cases. Recurrent attacks are reported but are rare and may be confused with Ménière disease. Resolution of the vertigo and dysequilibrium is common and is due to partial recovery of vestibular function with concurrent central compensation of the remaining unilateral vestibular deficit. Return of hearing usually mirrors the return of vestibular function. Viral labyrinthitis is often confused with vestibular neuritis, and the terms are occasionally used interchangeably in the literature. However, most authors agree that vestibular neuritis is a disorder of the vestibular nerve and is not associated with hearing loss. Because the cochlea is affected in labyrinthine inflammation, hearing loss is always present in persons with viral labyrinthitis. Vestibular neuritis typically manifests as sudden acute vertigo without hearing loss in an otherwise healthy patient. The condition is more common in the fourth and fifth decades of life and affects men and women equally. An upper respiratory tract infection often precedes the condition, and the disorder is more common in the spring and early summer. Histopathological nerve studies of patients with vestibular neuritis demonstrate axonal loss, endoneurial fibrosis, and atrophy. These findings are consistent with a viral inflammatory etiology. The treatment of vestibular neuritis and viral labyrinthitis is similar. A unique form of viral labyrinthitis is herpes zoster oticus, or Ramsay-Hunt syndrome. The cause of this disorder is reactivation of a latent varicella-zoster virus infection occurring years after the primary infection. The initial symptoms are deep, burning, auricular pain followed a few days later by the eruption of a vesicular rash in the external auditory canal and concha. Vertigo, hearing loss, and facial weakness may follow singly or collectively. Symptoms typically improve over a few weeks; however, patients often suffer permanent hearing loss and persistent reduction of caloric responses. Viral infections can cause both congenital and acquired hearing loss. Rubella and cytomegalovirus are the best-recognized viral causes of prenatal hearing loss. Virally induced hearing loss in the postnatal period is usually due to mumps or measles. Viral infections are also implicated in idiopathic sudden sensorineural hearing loss (SNHL). These topics are covered in other articles (eg, see in the Pediatrics section Measles, Mumps, Cytomegalovirus Infection, and Rubella. Meningitis and otitis media may be complicated by bacterial labyrinthitis, which can occur by either direct bacterial invasion (suppurative labyrinthitis) or through the passage of bacterial toxins and other inflammatory mediators into the inner ear (serous labyrinthitis). Meningitis typically affects both ears, whereas otogenic infections typically cause unilateral symptoms. Bacteria spread from the cerebrospinal fluid to the membranous labyrinth by way of the internal auditory canal or cochlear aqueduct. Treatment of suppurative labyrinthitis is aimed at eradicating the underlying infection, providing supportive care to the patient, draining middle ear effusions or mastoid infections, and preventing the spread of infection. Labyrinthitis ossificans often follows suppurative labyrinthitis; therefore, decisions regarding cochlear implantation must be made early. Meningitis also may result in progressive hearing loss secondary to necrosis and fibrosis of the membranous cochlea and labyrinth. Serous labyrinthitis occurs when bacterial toxins and host inflammatory mediators, such as cytokines, enzymes, and complement, cross the round window membrane, causing inflammation of the labyrinth in the absence of direct bacterial contamination. This condition is associated with acute or chronic middle ear disease and is believed to be one of the most common complications of otitis media. Toxins, enzymes, and other inflammatory products infiltrate the scala tympani, forming a fine precipitate just medial to the round window membrane. Penetration of the inflammatory agents into the endolymph at the basilar turn of the cochlea results in a mild high-frequency SNHL. Audiogram testing reveals mixed hearing loss when a middle ear effusion is present. Vestibular symptoms may occur but are less common. Treatment is aimed at eliminating the underlying infection and clearing the middle ear space of effusion. The hearing loss is usually transient but may persist if the otitis is left untreated. FrequencyUnited StatesViral labyrinthitis is the most common form of labyrinthitis observed in clinical practice. One study reported that 37 of 240 patients presenting with positional vertigo had viral labyrinthitis. The prevalence of sudden SNHL is estimated at 1 case in 10,000 persons, with up to 40% of these patients complaining of vertigo or dysequilibrium. Auditory and vestibular symptoms develop in approximately 25% of patients with herpes oticus, in addition to the facial paralysis and vesicular rash that characterize the disease. Bacterial labyrinthitis is rare in the postantibiotic era, although bacterial meningitis remains a significant cause of hearing loss. Auditory symptoms, vestibular symptoms, or both may be present in as many as 20% of children with meningitis. Mortality/MorbidityDeaths associated with labyrinthitis are not reported except in cases of meningitis or overwhelming sepsis. The morbidity of labyrinthitis, especially bacterial labyrinthitis, is significant. In the pediatric population, the risk of hearing loss secondary to meningitis is estimated to be 10-20%.1 Streptococcus pneumoniae appears to be the causative agent most likely associated with hearing loss, although some studies place Neisseria meningitidis as the most significant agent. Bacterial labyrinthitis, regardless of etiology, accounts for one third of all cases of acquired hearing loss. One study reported dizziness in 23% of patients following pneumococcal meningitis. Ménière disease may follow an episode of suppurative or serous labyrinthitis and is most likely due to fibrosis of the endolymphatic sac and alteredNa+/K+ transport. AgeViral labyrinthitis is usually observed in adults aged 30-60 years and is rarely observed in children. Meningogenic suppurative labyrinthitis is usually observed in children younger than 2 years, which is the population most at risk for meningitis. Otogenic suppurative labyrinthitis can be observed in persons of any age in the presence of cholesteatoma and in untreated acute otitis media. Serous labyrinthitis is more common in the pediatric age group, in which the vast majority of both acute and chronic otitis media cases are observed. CLINICALSection 3 of 10
HistoryA thorough medical history, including symptoms, past medical history, and medications, is essential to diagnosing labyrinthitis as the cause of the patient's vertigo or hearing loss.
PhysicalInclude in the physical examination a complete head and neck examination with emphasis on the otologic, ocular, and cranial nerve portions of the examination. A brief neurological examination is also necessary. Seek the presence of meningeal signs if meningitis is a consideration.
CausesLittle direct evidence suggests a viral cause for labyrinthitis; however, a wealth of epidemiological evidence implicates a number of viruses as potentially causing inflammation of the labyrinth. Viral labyrinthitis is often preceded by an upper respiratory tract infection and occurs in epidemics. The histological finding of axonal degeneration in the vestibular nerve suggests a viral etiology for vestibular neuritis. The bacteria that cause labyrinthitis are the same bacteria responsible for meningitis and otitis. Gram-negative organisms are found more commonly when cholesteatoma is the inciting factor.
DIFFERENTIALSSection 4 of 10
Benign Paroxysmal Positional Vertigo CNS Causes of Vertigo Complications of Otitis Media Inner Ear, Autoimmune Disease Inner Ear, Meniere Disease, Medical Treatment Inner Ear, Meniere Disease, Surgical Treatment Inner Ear, Ototoxicity Inner Ear, Perilymphatic Fistula Inner Ear, Sudden Hearing Loss Migraine-Associated Vertigo Skull Base, Tumors, Other CPA Tumors
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| Drug Name | Diazepam (Valium) |
|---|---|
| Description | Depresses all levels of CNS (eg, limbic and reticular formation), possibly by increasing activity of GABA. Individualize dosage and increase cautiously to avoid adverse effects. |
| Adult Dose | 2-10 mg PO tid or 5-10 mg IV/IM in an acute setting |
| Pediatric Dose | 1-2.5 mg PO tid |
| Contraindications | Documented hypersensitivity; narrow-angle glaucoma; history of addiction, alcohol intoxication, myasthenia gravis |
| Interactions | Increases toxicity of benzodiazepines in CNS with coadministration of phenothiazines, barbiturates, alcohols, and MAOIs |
| Pregnancy | D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus |
| Precautions | Caution with other CNS depressants, low albumin levels, or hepatic disease (may increase toxicity) |
| Drug Name | Lorazepam (Ativan) |
|---|---|
| Description | By increasing action of GABA, which is a major inhibitory neurotransmitter in the brain, may depress all levels of CNS, including limbic and reticular formation. |
| Adult Dose | 1-2 mg PO/IV/IM tid |
| Pediatric Dose | Not established |
| Contraindications | Documented hypersensitivity; preexisting CNS depression, hypotension, and narrow-angle glaucoma |
| Interactions | CNS toxicity of benzodiazepines increases when used concurrently with alcohol, phenothiazines, barbiturates, and MAOIs |
| Pregnancy | D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus |
| Precautions | Caution in renal or hepatic impairment, myasthenia gravis, organic brain syndrome, or Parkinson disease |
These agents are used for relief of nausea and vomiting.
| Drug Name | Prochlorperazine (Compazine) |
|---|---|
| Description | May relieve nausea and vomiting by blocking postsynaptic mesolimbic dopamine receptors through anticholinergic effects and depressing reticular activating system. In addition to antiemetic effects, it has the advantage of augmenting hypoxic ventilatory response, acting as a respiratory stimulant at high altitude. |
| Adult Dose | PO: 10 mg q6h IV: 2.5-10 mg slow push q6h PR: 25 mg q12h |
| Pediatric Dose | <2 years: Not established 2-12 years: 2.5 mg PO bid/tid >12 years: Administer as in adults |
| Contraindications | Documented hypersensitivity; bone marrow suppression, narrow-angle glaucoma, and severe liver or cardiac disease |
| Interactions | Coadministration with other CNS depressants or anticonvulsants may cause additive effects; with epinephrine, may cause hypotension |
| Pregnancy | C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus |
| Precautions | Drug-induced Parkinson syndrome or pseudoparkinsonism occurs quite frequently; akathisia is most common extrapyramidal reaction in elderly persons; lowers seizure threshold; caution with history of seizures |
Nucleoside analogs are initially phosphorylated by viral thymidine kinase to eventually form a nucleoside triphosphate. These molecules inhibit HSV polymerase with 30-50 times the potency of human alpha-DNA polymerase.
| Drug Name | Famciclovir (Famvir) |
|---|---|
| Description | Prodrug that, when biotransformed into active metabolite (penciclovir), may inhibit viral DNA synthesis/replication. |
| Adult Dose | 500 mg PO tid for 7 d |
| Pediatric Dose | Not established |
| Contraindications | Documented hypersensitivity; impaired renal function |
| Interactions | Coadministration with probenecid or cimetidine may increase toxicity; coadministration increases bioavailability of digoxin |
| Pregnancy | B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals |
| Precautions | Caution in renal failure or coadministration of nephrotoxic drugs |
| Drug Name | Valacyclovir (Valtrex) |
|---|---|
| Description | Prodrug rapidly converted to the active drug acyclovir. More expensive but has a more convenient dosing regimen than acyclovir. |
| Adult Dose | 1000 mg PO tid for 7 d |
| Pediatric Dose | Not established |
| Contraindications | Documented hypersensitivity; renal transplantation or renal failure |
| Interactions | Probenecid, zidovudine, or cimetidine coadministration prolongs half-life and increases CNS toxicity |
| Pregnancy | B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals |
| Precautions | Caution in renal failure and coadministration of nephrotoxic drugs; associated with onset of hemolytic uremic syndrome |
| Drug Name | Acyclovir (Zovirax) |
|---|---|
| Description | Has affinity for viral thymidine kinase and, once phosphorylated, causes DNA chain termination when acted upon by DNA polymerase. Compliance problem; requires 5 daily doses. |
| Adult Dose | 800 mg PO 5 times/d for 7 d or 15 mg/kg IV divided tid for 5-10 d |
| Pediatric Dose | Not established |
| Contraindications | Documented hypersensitivity; renal failure or impairment |
| Interactions | Concomitant use of probenecid or zidovudine prolongs half-life and increases CNS toxicity |
| Pregnancy | B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals |
| Precautions | Caution in renal failure or when using nephrotoxic drugs |
Have anti-inflammatory properties and cause profound and varied metabolic effects. Modify the body's immune response to diverse stimuli.
| Drug Name | Prednisone (Deltasone, Orasone, Meticorten) |
|---|---|
| Description | Standard agents administered in cases of sudden hearing loss and may play a role in the treatment of viral labyrinthitis. Their role in treatment of bacterial labyrinthitis and meningogenic hearing loss is controversial. |
| Adult Dose | 40-60 mg PO qd for 5 d, then taper over 5 d |
| Pediatric Dose | Not established |
| Contraindications | Documented hypersensitivity; viral infection, peptic ulcer disease, hepatic dysfunction, connective tissue infections, and fungal or tubercular skin infections; GI disease |
| Interactions | Coadministration with estrogens may decrease clearance; concurrent use with digoxin may cause digitalis toxicity secondary to hypokalemia; phenobarbital, phenytoin, and rifampin may increase metabolism (consider increasing maintenance dose); monitor for hypokalemia with coadministration of diuretics |
| Pregnancy | B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals |
| Precautions | Abrupt discontinuation may cause adrenal crisis; hyperglycemia, edema, osteonecrosis, myopathy, peptic ulcer disease, hypokalemia, osteoporosis, euphoria, psychosis, myasthenia gravis, growth suppression, and infections may occur |
Patients with persistent vestibular symptoms may be candidates for vestibular rehabilitation. A follow-up audiogram should be performed in all patients with hearing loss and in patients who were not tested at presentation. An auditory brainstem response test is indicated for younger children.
Inner Ear, Labyrinthitis excerpt
Article Last Updated: Mar 6, 2008
