Viêm mê nhĩ

Labyrinthitis

Viêm mê nhĩ

Author: Barry Strasnick, MD, FACS, Chairman, Professor, Department of Otolaryngology – Head and Neck Surgery, Eastern Virginia Medical School
Coauthor(s): Amalia Renee Steinberg, MD, Resident Physician, Department of Otolaryngology, Eastern Virginia Medical School; Mark E Boston, MD, Chairman, Department of Otolaryngology-Head and Neck Surgery, Wilford Hall Medical Center, Lackland Air Force Base
source: http://www.emedicine.com

Updated: Mar 27, 2008

Introduction ( Giới thiệu)

Background

Labyrinthitis 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 infection or systemic infection.

Viêm mê nhĩ là một tình trạng nhiễm trùng của tai trong hoặc mê nhĩ. Về mặt lâm sàng,tình trạng này gây ra những rối loạn về thăng bằng và sức nghe thay đổi theo các mức độ và có thể ảnh hưởng đến một hoặc cả hai tai.VI khuẩn hoặc vi rút có thể gây nên viêm cấp ở mê nhĩ cùng với các nhiễm trùng khu trú khác hoặc nhiễm trùng hệ thống.

Pathophysiology ( Sinh lý bệnh)

The 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 toward 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 person. 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. Histopathologic 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 in insolation 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 (see Pediatrics, MeaslesPediatrics, MumpsCytomegalovirus Infection; Pediatrics, 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. Infections of the middle ear or mastoid most commonly spread to the labyrinth through a dehiscent horizontal semicircular canal. Usually, the dehiscence is the result of erosion by a cholesteatoma.

Suppurative labyrinthitis resulting from otitis is uncommon in the postantibiotic era. When suppurative labyrinthitis occurs, it almost always is associated with cholesteatoma. Profound hearing loss, severe vertigo, ataxia, and nausea and vomiting are common symptoms of bacterial labyrinthitis.

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. In these cases, 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. Audiography 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.

Frequency

United States

Viral labyrinthitis is the most common form of labyrinthitis observed in clinical practice. One study reported that 37 of 240 patients who presented 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.1 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.2

Mortality/Morbidity

Deaths 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%.2,3 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.2 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 altered Na+/K+ transport.1

Age

Viral 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.4 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.

Clinical

History

A 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.

  • Symptoms
    • Vertigo (timing and duration, association with movement, head position, and other characteristics)
    • Hearing loss (unilateral or bilateral, mild or profound, duration, and other characteristics)
    • Aural fullness
    • Tinnitus
    • Otorrhea
    • Otalgia
    • Nausea or vomiting
    • Fever
    • Facial weakness or asymmetry
    • Neck pain/stiffness
    • Upper respiratory tract infection symptoms (preceding or concurrent)
    • Visual changes
  • Past medical conditions
    • Episodes of dizziness or hearing loss
    • Infections
    • Sick contacts
    • Ear surgery
    • Hypertension/hypotension
    • Diabetes
    • Stroke
    • Migraine
    • Trauma (head or cervical spine)
    • Family history of hearing loss or ear disease
  • Medications
    • Aminoglycosides and other ototoxic medications
    • Beta-blockers and other antihypertensives
    • Tranquilizers, including benzodiazepines
    • Antiepileptics
    • Illicit drugs

Physical

In the physical examination include a complete head and neck examination with emphasis on the otologic, ocular, and cranial nerve portions of the examination. A brief neurologic examination is also necessary. Seek the presence of meningeal signs if meningitis is a consideration.

  • Otologic examination
    • Perform an external inspection for signs of mastoiditis, cellulitis, or prior ear surgery.
    • Inspect the ear canal for otitis externa, otorrhea, or vesicles.
    • Inspect the tympanic membrane and middle ear for the presence of perforation, cholesteatoma, middle ear effusion, or acute otitis media.
  • Ocular examination
    • Inspect the ocular range of motion and pupillary response.
    • Perform a funduscopic examination to assess for papilledema.
    • Observe for nystagmus (spontaneous, gaze-evoked, and positional). Perform a Dix-Hallpike test if the patient can tolerate it.
    • If visual changes are suggested, consult an ophthalmologist.
  • Neurologic examination
    • Perform a complete cranial nerve examination.
    • Assess for balance using the Romberg test and tandem gait.
    • Assess cerebellar function by performing finger-to-nose and heel-to-shin tests.

Causes

Little direct evi

ence suggests a viral cause for labyrinthitis; however, a wealth of epidemiologic 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 histologic finding of axonal degeneration in the vestibular nerve suggests a viral etiology for vestibular neuritis.1 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.

  • Potential viral causes
    • Cytomegalovirus
    • Mumps virus
    • Varicella-zoster virus
    • Rubeola virus
    • Influenza virus
    • Parainfluenza virus
    • Rubella virus
    • Herpes simplex virus 1
    • Adenovirus
    • Coxsackievirus
    • Respiratory syncytial virus
  • Potential bacterial causes
    • S pneumoniae
    • Haemophilus influenzae
    • Moraxella catarrhalis
    • N meningitidis
    • Streptococcus species
    • Staphylococcus species
    • Proteus species
    • Bacteroides species
    • Escherichia coli
    • Mycobacterium tuberculosis

Differential Diagnoses

Benign Paroxysmal Positional Vertigo Multiple Sclerosis
CNS Causes of Vertigo Otitis Media
Inner Ear, Autoimmune Disease Skull Base, Tumors, Other CPA Tumors
Inner Ear, Ototoxicity Stroke, Ischemic
Inner Ear, Perilymphatic Fistula Transient Ischemic Attack
Inner Ear, Sudden Hearing Loss Vestibular Neuronitis
Meniere Disease
Migraine-Associated Vertigo

Other Problems to Be Considered

Vertebrobasilar insufficiency
Presyncope dizziness
Cerebellar infarct
Dysequilibrium of aging
Drug-induced vertigo, hearing loss, or both

Laboratory Studies

  • No specific laboratory studies are available for labyrinthitis.
  • Routine serology testing often fails to reveal an infectious organism, and, when results are positive, methods to determine if the same organism caused the damage to the membranous labyrinth are not available. Obtain appropriate tests to help exclude other possible etiologies in the differential diagnosis.
  • Examine cerebrospinal fluid if meningitis is suggested.
  • If a systemic infection is considered, a CBC count and blood cultures are indicated.
  • Perform culture and sensitivity testing of middle ear effusions if present, and select appropriate antibiotic therapy accordingly.

Imaging Studies

  • CT scan
    • Consider a CT scan prior to lumbar puncture in cases of possible meningitis.
    • A CT scan is also useful to help rule out mastoiditis as a potential cause.
    • A temporal bone CT scan may aid in the management of patients with cholesteatoma and labyrinthitis.
    • A noncontrast CT scan is best for visualizing fibrosis and calcification of the membranous labyrinth in persons with chronic labyrinthitis or labyrinthitis ossificans.
  • MRI
    • MRI can be used to help rule out acoustic neuroma, stroke, brain abscess, or epidural hematoma as potential causes of vertigo and hearing loss.
    • The cochlea, vestibule, and semicircular canals enhance on T1-weighted postcontrast images in persons with acute and subacute labyrinthitis.5 This finding is highly specific and correlates with objective and subjective patient assessment. Recent improvements in MRI techniques may make this the study of choice for suspected labyrinthitis.

Other Tests

  • Audiography
    • Obtain an audiogram in all patients who may have labyrinthitis. Evaluate critically ill and severely vertiginous patients when stable and able to tolerate the test. The audiogram may show different findings depending on the etiology of the labyrinthine inflammation.
    • Persons with viral labyrinthitis have mild-to-moderate high-frequency SNHL in the affected ear, although any frequency spectrum may be affected.
    • Suppurative (bacterial) labyrinthitis typically results in severe-to-profound unilateral hearing loss. In cases of meningitis, the loss is often bilateral.
    • Persons with serous (bacterial) labyrinthitis have unilateral high-frequency hearing loss in the affected ear. A conductive loss in the same ear may occur secondary to effusion.
  • Vestibular testing
    • Caloric testing and an electronystagmogram may help in diagnosing difficult cases and in establishing a prognosis for recovery.
    • Persons with viral labyrinthitis have nystagmus with unilateral caloric vestibular paresis/hypofunction.
    • Persons with suppurative (bacterial) labyrinthitis have nystagmus and an absent caloric response on the affected side.
    • Persons with serous (bacterial) labyrinthitis usually have normal electronystagmogram results, but they may have a decreased caloric response in the affected ear. However, the presence of a middle ear effusion can attenuate the caloric response and cause a false-positive finding.

Treatment

Emergency Department Care

  • The initial treatment of viral labyrinthitis consists of bed rest and hydration. Most patients can be treated on an outpatient basis. However, they should be cautioned to seek further medical care for worsening symptoms, especially neurologic symptoms (eg, diplopia, slurred speech, gait disturbances, localized weakness or numbness).
  • Patients with severe nausea and vomiting may benefit from intravenous fluid and antiemetic medications. Diazepam or other benzodiazepines are occasionally helpful as a vestibular suppressant. A short course of oral corticosteroids may be helpful. Currently, the role of antiviral therapy is not established.
  • Steroids (methylprednisolone) were found to be more effective than antiviral agents (valacyclovir) for recovery of peripheral vestibular function in patients with vestibular neuritis in a randomized controlled trial by Strupp et al.6 This may also apply to the treatment of viral labyrinthitis.
  • The antiviral drugs acyclovir, famciclovir, and valacyclovir shorten the duration of viral shedding in persons with herpes zoster oticus and may prevent some auditory and vestibular damage if started early in the clinical course. Administer corticosteroids to reduce inflammation and edema in the facial canal and labyrinth.
  • For bacterial labyrinthitis, antibiotic treatment is selected based on culture and sensitivity results. Antibiotic treatment should consist of a broad-spectrum antibiotic or combination therapy with CNS penetration until culture results are available. Treat the vertigo symptomatically as indicated. The use of steroids in meningogenic hearing loss is controversial.
  • Recent studies have shown that antioxidant therapy7 and cochlear microperfusion8 may be useful adjuvant treatments in the future.

Consultations

  • Consult a neurosurgeon in the event of suppurative intracranial complications.
  • Consultation with an infectious disease specialist may be warranted in the presence of systemic infection or unusual or atypical infections.

Medication

Medication used in the treatment of labyrinthitis is primarily for relief of symptoms. Several medications have antivertiginous properties (eg, meclizine, scopolamine, ephedrine, dimenhydrinate, diazepam) and others are useful as antiemetics (eg, promethazine, prochlorperazine). Most acute episodes of labyrinthitis are short-lived and self-limited.

Antihistamines

These agents prevent the histamine response in sensory nerve endings and blood vessels. They are effective in treating vertigo.

Meclizine (Antivert)

Decreases excitability of middle ear labyrinth and blocks conduction in middle ear vestibular-cerebellar pathways. Effects are associated with therapeutic effects in relief of nausea and vomiting.

Adult

25 mg PO q4-6h

Pediatric

<12 years: Not established
>12 years: Administer as in adults

May increase toxicity of CNS depressants, neuroleptics, and anticholinergics

Documented hypersensitivity

Pregnancy

B – Fetal risk not confirmed in studies in humans but has been shown in some studies in animals

Precautions

Caution in angle-closure glaucoma, prostatic hypertrophy, pyloric or duodenal obstruction, and bladder neck obstruction

Dimenhydrinate (Dramamine)

1:1 salt of 8-chlorotheophylline and diphenhydramine thought to be useful, particularly, in treatment of vertigo. Through central anticholinergic activity, diminishes vestibular stimulation and depresses labyrinthine function.

Adult

50 mg PO/IM q4-6h or 100 mg supp q8h

Pediatric

<2 years: Not established
2-6 years: Up to 12.5-25 mg PO q6-8h; not to exceed 75 mg/d
6-12 years: 25-50 mg PO q6-8h; not to exceed 150 mg/d
>12 years: Administer as in adults

Alcohol or other CNS depressants may have additive effect; caution when administering concurrently with potentially ototoxic antibiotics—may mask ototoxic symptoms, resulting in irreversible damage

Documented hypersensitivity; do not administer to neonates; IV products may contain benzyl alcohol, which has been associated with fatal “gasping syndrome” in premature infants and low-birth-weight infants

Pregnancy

B – Fetal risk not confirmed in studies in humans but has been shown in some studies in animals

Precautions

Do not treat severe emesis with antiemetic drugs alone; may contain either sulfites or tartrazine, which may cause allergic-type reactions in susceptible persons; may impede diagnosis of conditions such as brain tumors, intestinal obstruction, and appendicitis; may obscure signs of toxicity from overdosage of other drugs

Anticholinergic

These agents are thought to work centrally by suppressing conduction in the vestibular cerebellar pathways.

Scopolamine (Isopto)

Blocks action of acetylcholine at parasympathetic sites in smooth muscle, secretory glands, and CNS. Antagonizes histamine and serotonin action. Transdermal scopolamine may be most effective agent for motion sickness. Use in treatment of vestibular neuronitis limited by slow onset of action.

Adult

0.6 mg PO q4-6h or 0.5 mg transdermally q3d

Pediatric

6 mcg/kg/dose IV/IM/SC or 0.2 mg/m2 q6-8h; not to exceed 0.3 mg/dose

May decrease antipsychotic effectiveness of phenothiazines and/or phenothiazines may increase anticholinergic adverse effects (adjust phenothiazine dosages as necessary); tricyclic antidepressants may increase anticholinergic adverse effects (eg, dry mouth, constipation, urinary retention) because of additive effect (tricyclic antidepressants with less anticholinergic activity may be beneficial)

Documented hypersensitivity; primary glaucoma (including initial stages); pyloric obstruction; toxic megacolon; hepatic disease; paralytic ileus; severe ulcerative colitis; renal disease; obstructive uropathy; myasthenia gravis

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

Caution in elderly persons because of increased incidence of glaucoma; large doses may suppress intestinal motility and precipitate or aggravate toxic megacolon; may aggravate hiatal hernia associated with reflux esophagitis; may cause dysuria and necessitate catheterization in patients with prostatism; use cautiously in patients with asthma or allergies—reduction in bronchial secretions can lead to inspissation and formation of bronchial plugs

Benzodiazepines

By binding to specific receptor sites, these agents appear to potentiate effects of GABA and facilitate inhibitory GABA neurotransmission and other inhibitory transmitters. These effects may prevent vertigo and emesis.

Diazepam (Valium)

Effective in treating vertigo. Depresses all levels of CNS, including limbic and reticular formation, possibly by increasing activity of GABA, which is major inhibitory neurotransmitter. Individualize dosage and increase it cautiously to avoid adverse effects.

Adult

5-10 mg PO/IV/IM q4-6h

Pediatric

<6 months: Not recommended
>6 months: 0.05-0.3 mg/kg/dose IV/IM over 2-3 min, repeat in 2-4 h if necessary; or 0.12-0.8 mg/kg/d PO divided q6-8h; not to exceed 10 mg/dose

Phenothiazines, barbiturates, alcohols, and MAOIs increase CNS toxicity

Documented hypersensitivity

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)

Phenothiazines

These agents are effective in treating emesis, possibly because of their effects in the dopaminergic mesolimbic system.

Promethazine (Phenergan)

Antidopaminergic agent effective in treatment of emesis. Blocks postsynaptic mesolimbic dopaminergic receptors in brain and reduces stimuli to brainstem reticular system.

Adult

25 or 50 mg PO/IM/PR q4-6h

Pediatric

<2 years: Contraindicated
>2 years: 0.25-1 mg/kg PO/IV/IM/PR 4-6 times/d prn

May have additive effects when used concurrently with other CNS depressants or anticonvulsants; with epinephrine may cause hypotension

Documented hypersensitivity; children <2 y (incidences of death due to respiratory depression)

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

Can be associated with CNS depression, dry mouth, extrapyramidal symptoms, hypertension, and skin rash; caution in cardiovascular disease, impaired liver function, seizures, sleep apnea, and asthma

Prochlorperazine (Compazine)

Antidopaminergic drug that blocks postsynaptic mesolimbic dopamine receptors, has anticholinergic effect, and can depress reticular activating system (possibly responsible for relieving nausea and vomiting).

Adult

5-10 mg PO/IM q6h
25-mg PR supp q12h

Pediatric

2.5 mg PO/PR q8h or 5 mg PO/PR q12h prn; not to exceed 15 mg/d
0.1-0.15 mg/kg/dose IM and change to PO as soon as possible
IV administration not recommended

Other CNS depressants or anticonvulsants may cause additive effects; with epinephrine, may cause hypotension

Documented hypersensitivity; bone marrow suppression; narrow-angle glaucoma; severe liver or cardiac disease

Pregnancy

D – Fetal risk shown in humans; use only if benefits outweigh risk to fetus

Precautions

Drug-induced Parkinson syndrome or pseudoparkinsonism occurs frequently; akathisia is most common extrapyramidal reaction in elderly persons; lowers seizure threshold; caution with history of seizures

Monoaminergics

These agents may relieve vertigo, possibly through modulating the sympathetic system.

Ephedrine (Pretz-D)

Stimulates release of epinephrine stores, producing alpha- and beta-adrenergic receptors.

Adult

25 mg PO q4-6h

Pediatric

<2 years: Not recommended
2-5 years: 3 mg PO q6-8h
>5 years: 6.25 mg q6-8h

Further Inpatient Care

  • Most patients with labyrinthitis can be evaluated and treated in the ED and then discharged.
  • Some patients with intractable vertigo and vomiting may require admission.
  • For those with a possible condition such as vertebrobasilar ischemia or a brainstem tumor, admission to the hospital may be appropriate under the direction of a neurologist, a neurosurgeon, or both.

Further Outpatient Care

  • In cases of labyrinthitis resulting from otitis media, perform a myringotomy and evacuate the effusion. A ventilation tube also may be indicated.
  • Mastoiditis and cholesteatoma are handled best with surgical drainage and debridement by way of a mastoidectomy.
  • Patients with persistent vestibular symptoms may be candidates for vestibular rehabilitation. For many patients with chronic vertigo due to a peripheral vestibular etiology, a simple home program of vestibular habituation head movement exercises reduced symptoms of imbalance during stance and gait, according to Cohen and Kimball.9
  • 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.

Prognosis

  • The acute symptoms of vertigo and nausea and vomiting resolve after several days to weeks in all forms of labyrinthitis; however, hearing loss is more variable.
  • Suppurative labyrinthitis nearly always results in permanent and profound hearing loss, whereas hearing loss associated with viral labyrinthitis may recover somewhat. Dysequilibrium and/or positional vertigo also may be present long-term following resolution of the acute infection.
  • Permanent hearing loss occurs in 10-20% of children with meningitis.
  • Permanent SNHL occurs in approximately 6% of patients with herpes zoster oticus.10

Patient Education

Miscellaneous

Medicolegal Pitfalls

  • Failure to diagnose a potentially life-threatening condition, such as meningitis, cerebrovascular ischemia, or brainstem tumor
  • Failure to counsel patients regarding the potential for injury to themselves or others if they operate heavy machinery or drive a vehicle while vertiginous or while taking certain medications to control symptoms

Special Concerns

  • Noninfectious labyrinthitis is very rare in children; therefore, seek an alternative diagnosis in patients this age. Labyrinthitis resulting from otitis media or meningitis is not uncommon in children.
  • Avoid scopolamine (or use with extreme caution) in elderly patients.

Acknowledgments

The authors and editors of eMedicine gratefully acknowledge the contributions of previous author, Nicholas Y Lorenzo, MD, to the development and writing of this article.

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