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Sensorineural hearing loss
Introduction
• History• Physical examination• Auditory testing• Vestibular testing• Laboratory testing• Radiographic testing
Sensorineural hearing loss
Etiology
• Development & Hereditary disorder• Infectious disorder• Pharmacologic disorder• Trauma• Neurologic disorder• Vascular & Hematologic disorder
• Immune disorder• Bone disorder• Neoplasms• Endocrine &
Metabolic disorder• Disorder of
unknown etiology
**Sudden Sensorineural hearing loss**
History
• Unilateral / Bilateral• Chronicity• Tinnitus / Vertigo• Otalgia / Otorrhea• Headache• Eye symptoms
• Underlying disease
• Ototoxic drugs• Hx of trauma• Noise exposure• Family Hx
Physical Examination
• Weber / Rinne test• Otoscopy• Cranial nerve• Stigmata of associated disease• Generally no abnormality**
Auditory Testing
• Conventional audiometry
• Tympanometry• Acoustic reflex
threshold• Auditory brainstem
response• Electrocochleography• Otoacoustic emission
Clinical evaluation
Laboratory testing• Fluorescent treponemal
antibody absorption test : FTA-ABS
• Microhemagglutination test for Treponema pallidum : MHA-TP
• Venereal disease research laboratory : VDRL
• Routine hematologic studies
• Routine metabolic studies
Vestibular testing• Adjunct in selected patients
Radiographic testing• MRI with Gadolinium
Retrocochlear hearing loss?• Computed tomography
Labyrinthine abnormality?
Etiology
• Development & Hereditary disorder• Infectious disorder• Pharmacologic disorder• Trauma• Neurologic disorder• Vascular & Hematologic disorder• Immune disorder• Bone disorder• Neoplasms• Disorder of unknown etiology
Development & Hereditary disorder
• Waardenburg syndrome• Large vestibular aqueduct syndrome• Usher syndrome• Alport syndrome
Etiology
• Development & Hereditary disorder• Infectious disorder• Pharmacologic disorder• Trauma• Neurologic disorder• Vascular & Hematologic disorder• Immune disorder• Bone disorder• Neoplasms• Disorder of unknown etiology
Infectious disorder
LabyrinthitisSerous labyrinthitis
• Abnormal process within the labyrinth
• Endolymphatic hydrops• Hearing loss and vestibular
dysfunction • Permanent or transient• Sudden onset of
sensorineural hearing loss and acute vertigo
• Viral labyrinthitis is common
Suppurative labyrinthitis • Bacterial invasion of the
inner ear• Profound hearing loss and
acute vertigo • Caused by a fistula between
the middle ear and the labyrinth
• Alternatively, the route of invasion can be meningogenic
• Most common etiology of deafness associated with meningitis
Infectious disorder
Herpes zoster oticus
• Varicella-zoster infection• Most commonly associated
with facial paralysis • HL and vertigo can occur
Infectious disorder
Measles• Not uncommon cause
of deafness in children
• Bilateral HL• Moderate-to-profound
HL• Vestibular function
can be similarly affected
Mumps• Paramyxovirus
infection • Unilateral SNHL • Unilateral deafness in
otherwise healthy children
• Sudden deafness in adult Subclinical mumps infection in those without previous immunity
Infectious disorder
Cytomegalovirus
• Common cause of congenital and progressive HL in children
• Sudden SNHL in adults • Hearing loss
associated with AIDS may represent reactivation of latent CMV infections
Infectious disorder
Syphilis
• Congenital or acquired syphilis • 80% Symptomatic neurosyphilis• HL in syphilis Meningolabyrinthitis • Syphilitic HL Indistinguishable
from Ménière’s disease• Hennebert’s sign (a positive fistula
test without middle ear disease) • Tullio’s phenomenon (vertigo or
nystagmus on exposure to high-intensity sound)
Etiology
• Development & Hereditary disorder• Infectious disorder• Pharmacologic disorder• Trauma• Neurologic disorder• Vascular & Hematologic disorder• Immune disorder• Bone disorder• Neoplasms• Disorder of unknown etiology
Pharmacologic disorder
Aminoglycosides Streptomycin, Kanamycin,
Neomycin, Amikacin, Gentamicin, Tobramycin, and Netilmycin
Death of the hair cell Different patterns of ototoxicity
with different aminoglycosides Unilateral or asymmetric Reversibility of the HL Risk factors
(1) presence of renal disease (2) longer duration of therapy (3) increased serum levels
(4) advanced age (5) concomitant administration
of other ototoxic drugs
Ototopical preparations
Neomycin, Gentamicin, and Tobramycin-containing
Cochlear or vestibular ototoxicity
Avoid the use of aminoglycoside-containing topical preparations in uninflamed ears with tympanic membrane perforations
Ingredients of ototopical preparations also have ototoxic potential
Polymyxin B, Propylene glycol, Acetic acid, Antifungal agents
Pharmacologic disorder
Loop diuretics Effect by blocking sodium
and water reabsorption in the proximal loop of Henle
Reversible SNHL Bilateral and symmetric Sudden in onset Alteration of
endolymphatic ion concentration and endocochlear potential
Risk factors (1) Renal failure (2) Rapid infusion (3) Aminoglycoside
administration
Antimalarials
Quinine Tinnitus, SNHL, & Visual disturbances
Chincinonism Tinnitus, headache, nausea, and disturbed vision
Quinine appears to be primarily on hearing and usually is transient
Permanent hearing loss may occur with large doses or in sensitive patients
Pharmacologic disorder
Salicylates Aspirin Tinnitus and
reversible SNHL HL Dose-dependent Moderate-to-severe
range SNHL, loss of otoacoustic
emissions, reduced cochlear action potentials
Alteration of the “tips” of auditory nerve fiber tuning curves
Alteration in turgidity and motility of outer hair cells
Nonsteroidal antiinflammatory
drugs Naproxen, Ketoralac &
Piroxicam Ototoxicity resulting from
use of NSAIDs is rare Only reversible physiologic
changes, without major morphologic changes
Pharmacologic disorder
Vancomycin Almost received
Vancomycin & loop diuretics or aminoglycosides
Ototoxicity Intravenously Permanent or transient
SNHL Excreted by the kidney Renal failure
Vancomycin half-life Increase ototoxicity
Itself ototoxic Unclear
Erythromycin Uncommon Partially Intravenously Reversible on
discontinuation No reports
- Newer macrolide - Clarithromycin
- Azithromycin
Pharmacologic disorder
Nitrogen mustards Antineoplastic agents Mechlorethamine has
Serious ototoxicity Limited use Severe
toxic Shrinkage of the organ of
Corti Loss of inner and outer
hair cells
Cisplatinum Cell-cycle nonspecific
cancer chemotherapeutic agent
Dose-limiting SNHL Adults (25% to 86%) Children (84% to 100%) Bilateral / Irreversible Tinnitus or vertigo HL Dose-related Progressive outer hair
cell loss Inner hair cells, neural
structures and the stria vascularis are affected
Pharmacologic disorder
Vincristine and vinblastine
The vinca alkaloids Potent neurotoxicity Peripheral neuropathy Cranial neuropathies,
ataxia, and hearing loss
Loss of hair cells and primary auditory neurons
Eflornithine Drug treatment of
trypanosomiasis Some
Pneumocystis carinii pneumonia, Cryptosporidiosis, Leishmaniasis, and Malaria
Cause major and dose-related SNHL
Pharmacologic disorder
Deferoxamine Iron-chelating agent Auditory and visual
neurotoxicity Particularly with
larger doses in younger patients
The SNHL is reversible in some patients when the dosage is reduced
Lipid-lowering drugs
Wallerian-like degeneration
High doses of HMG-CoA reductase inhibitors
Optic& vestibulocochlear nerve degeneration
No clinically significant effect on vision or hearing
Etiology
• Development & Hereditary disorder• Infectious disorder• Pharmacologic disorder• Trauma• Neurologic disorder• Vascular & Hematologic disorder• Immune disorder• Bone disorder• Neoplasms• Disorder of unknown etiology
Trauma
Head injury Blunt head injury alone
Concussive injury of the labyrinth
Labyrinthine injury SNHL
Temporal bone fracture Labyrinthine concussion
Longitudinal fractures Similar to acoustic trauma
Limited to the high F Worse at 4 kilohertz
Transverse fractures Complete loss of auditory & vestibular function
Penetrating injuries Subluxation ofthe
stapes into the vestibule Profound SNHL
Trauma
Noise-induced HL & Acoustic trauma
First published in the 1930s
Common occupationally-induced disabilities
Common in industry Caused by excessive
noise exposure Temporary SNHL that
recovers over the next 24 to 48 hours
High intensity & repeated Permanent
Outer hair cell Most effect
More damage in - High-frequency sound - Continuous sound - Pure tones
Symmetric & Bilateral HL Limited to 3 kHz, 4 kHz,
and 6 kHz Greatest loss 4 kHz Progress rapidly in first
10 to 15 years of exposure
Trauma
Noise-induced HL & Acoustic trauma
Common patterns Flat & downsloping losses
Acoustic trauma Unilateral or asymmetric
OSHA does not allow unprotected exposures greater than 90 dBA based on an 8 hour/day time weighted average (TWA)
Variability Age, gender, race, and coexisting vascular disease
No known way to predict susceptibility to NIHL
Protection Earplugs or earmuffs
Many hazardous noise exposures are not occupational in origin
Trauma
Barotrauma Unequalized pressure
differentials between the middle and external ears
Occurs during flying or underwater diving
Pain, hyperemia and possible perforation of the tympanic membrane
Edema and ecchymosis of the middle ear mucosa
Conductive HL may result
Perilymphatic fistula Pathologic communication
between the perilymphatic space of the inner ear and the middle ear
Congenital or acquired Occur at either the round
or oval windows
Perilymphatic fistula
Congenital Occur in the stapes
footplate with labyrinthine anomalies
Such as Mondini dysplasia
Communicate with the subarachnoid space and result in cerebrospinal fluid leak and possible meningitis
Profound hearing loss
Acquired Result of
- Barotrauma - Direct trauma of temporal - Indirect trauma of temporal - Complication of stapedectomy
Sudden SNHL and vertigo after a head injury, barotrauma, or heavy lifting or straining
May be spontaneously Diagnosis
Middle ear exploration
Trauma
Irradiation
Conventional fractionated irradiation of the temporal bone
Fractionated irradiation Limited extent to treat vestibular schwannoma
Difficult to determine because of the limited data available
Stereotactic irradiation (“radiosurgery”) for vestibular schwannoma
This modality Risk of SNHL High as with microsurgical removal
Etiology
• Development & Hereditary disorder• Infectious disorder• Pharmacologic disorder• Trauma• Neurologic disorder• Vascular & Hematologic disorder• Immune disorder• Bone disorder• Neoplasms• Disorder of unknown etiology
Neurologic disorders
Multiple sclerosis Multiple areas of CNS
demyelination, inflammation, and glial scarring
Age 20 to 30 years More common in women Cause Unknown 4% to 10% of MS SNHL Progressive or sudden Bilateral, unilateral,
symmetric, or asymmetric Speech discrimination
Normal or reduced
Abnormalities of the ABR MRI Periventricular
white-matter plaques on T2-weighted images
Neurologic disorders
Benign intracranial hypertension
Pseudotumor cerebri Increased intracranial
pressure Without evidence of mass
lesion, obstructive hydrocephalus, intracranial infection, or hypertensive encephalopathy
Headache and visual blurring Pulsatile tinnitus SNHL and vertigo More in young, obese women
SNHL Fluctuating, low-F Unilateral or bilateral Vertigo and aural fullness Diagnosis
Papilledema CSF pressure > 200 mmH2O ABR abnormalities
Management - Weight loss- Acetazolamide- Furosemide- Lumbar-peritoneal shunting
Etiology
• Development & Hereditary disorder• Infectious disorder• Pharmacologic disorder• Trauma• Neurologic disorder• Vascular & Hematologic disorder• Immune disorder• Bone disorder• Neoplasms• Disorder of unknown etiology
Vascular and hematologic disorders
Migraine• Headache and visual aura• Basilar migraine
Vertigo, SNHL Tinnitus, aural fullness Distortion & recruitment
• 46% Bilateral, low-F-SNHL
• Fluctuated HL • Similarity, between basilar
migraine and Ménière’s Dz.• Drugs in basilar migraine
No systematic study
Vertebrobasilar arterial occlusion
• Brainstem syndromes• Anterior inferior cerebellar
artery (AICA) • Occlusion of AICA SNHL• Thrombosis or embolism • Area infarcted Inferior pons• Acute AICA infarction• Acute vertigo with N/V• Facial paralysis, SNHL• Tinnitus, gaze paralysis• Loss of pain and temperature
sensation on the face• Ipsilateral Horner’s syndrome
Vascular and hematologic disorders
Waldenström’s macroglobulinemia
• Abnormally large amounts of IgM in the plasma
• Increased blood viscosity • Subsequent ischemic lesions• Progressive & sudden SNHL• SNHL responded to
alkylating agents or plasmapheresis
Vascular and hematologic disorders
Sickle cell anemia• Incidence of SNHL• ~ 22% of sickle cell
disease• Progressive or sudden• Associated with sickle
cell crises
Vascular and hematologic disorders
Leukemias & Lymphomas
• SNHL Leukemic infiltrates Inner ear hemorrhage Vascular occlusion Labyrinthine ischemia
Etiology
• Development & Hereditary disorder• Infectious disorder• Pharmacologic disorder• Trauma• Neurologic disorder• Vascular & Hematologic disorder• Immune disorder• Bone disorder• Neoplasms• Disorder of unknown etiology
Immune disorders
Cogan’s syndromeo Attacks of acute non-
syphilitic interstitial keratitis
o Auditory and vestibular dysfunction
o Unilateral or bilateral SNHL
o Severe vertigo, nausea, vomiting, and tinnitus
o Progresses to a profound loss over months
o Ophthalmologic findings o If treated SNHL is
responsiveo Aggressive treatment with
steroids
Immune disorders
Polyarteritis nodosa
o Necrotizing vasculitis of small- and medium-sized arteries
o Myriad of findings, including weight loss, fatigue, fever, anorexia, arthritis, neuropathy, hypertension, renal failure, abdominal pain, and SNHL
o Biopsy Necrotizing vasculitiso Unilateral or bilateral o Facial paralysis also may be seeno Management
- Aggressive doses of steroids - Immunosuppressive drugs
Immune disorders
Relapsing polychondritis
o An inflammatory reaction in multiple cartilages
o The auricles 1st affectedo Arthritis and eye findings o HL Conductive
Sensorineural Mixed HL
o SNHL Sudden or progressive
o May be associated with vestibular disturbances
o Rx Steroids Immunosuppresive Dapsone
Immune disorders
Wegener’s granulomatosis
o Necrotizing granulomatous vasculitis involving principally the lungs, airway, and kidneys
o Usually Conductive HLo CHL Involvement of the
eustachian tube or middle ear
o SNHL If extends into the inner ear
Immune disorders
Primary autoimmune
inner ear disease
o McCabe Bilateral SNHL responsive to immunosuppressive drugs
o Sudden or progressive HLo Involves both earso Associated with vestibular
symptoms o Strongly mimic Ménière’s
disease
o Humoral autoimmunity Abnormal
o Responsiveness of the HL to steroids or cytotoxic drugs The hallmark
o Used Methotrexate Reduce the need for continued high-dose steroids
Etiology
• Development & Hereditary disorder• Infectious disorder• Pharmacologic disorder• Trauma• Neurologic disorder• Vascular & Hematologic disorder• Immune disorder• Bone disorder• Neoplasms• Disorder of unknown etiology
Bone disorders
Otosclerosis Primarily causes
CHL Uncommonly
Progressive SNHL Especially in late
disease CT images
Radiolucent area surrounding the cochlea
Advanced otosclerosis Bilateral profound mixed hearing loss
Bone disorders
Paget’s disease Osteitis deformans Most common in older ~ 50% of Paget’s disease
Conductive, SNHL or mixed
Rarely fixed stapes footplate RX
Calcitonin Eidronate disodium
Etiology
• Development & Hereditary disorder• Infectious disorder• Pharmacologic disorder• Trauma• Neurologic disorder• Vascular & Hematologic disorder• Immune disorder• Bone disorder• Neoplasms• Disorder of unknown etiology
Neoplasms
Vestibular schwannoma
Most common neoplasm SNHL
Originate from 8th CN Within the CPA or the IAC Approximately 80% of all
CPA neoplasms Progressive unilateral SNHL Principally the high
frequencies
Neoplasms
Vestibular schwannoma Speech discrimination is
reduced out of proportion to the pure tone thresholds
Sudden SNHL 10% of patient
Unilateral or asymmetric tinnitus
With or without hearing loss Mild or severe vestibular
symptoms or may have none
Disorders of unknown etiology
Presbycusis Aging process Without other apparent
etiology Age-related change
Stiffness of the basilar membrane
30% of aged > 65 years Worse for high
frequencies More severe in men
Schuknecht 4 types
Presbycusis
Neural presbycusis - Loss of auditory nerve fibers
- Reduced speech discrimination out of proportion to their pure tone thresholds
Cochlear presbycusis - Mechanical CHL
Sensory presbycusis - Progressively hair cells loss - Steeply sloping HF-SNHL
Strial presbycusis - Atrophy of the stria vascularis - Flat audiograms
Disorders of unknown etiology
Ménière’s disease
Fluctuant SNHL Tinnitus, episodic vertigo,
and aural fullness Progresses, gradually or
quickly HL Tinnitus “Buzzing” or
“Roaring” Aural fullness Typically
fluctuates
Vertigo Several hours After attacks Fatigued
for 24 hours or more Profound loss is rare Low F Commonly Bilateral in 30% to 50% Endolymphatic spaces
dilatation of the inner ear
Disorders of unknown etiology
Ménière’s disease Vestibular destructive
therapy No effective No therapy Effective in
HL Medical therapy
- Sodium-restricted diet - Diuretic administration
Lack of an objective diagnostic test
Idiopathic endolymphatic hydrops
Other pathologic endolymphatic hydrops processes - Syphilis - Temporal bone trauma - Serous labyrinthitis - Stapedectomy - Autoimmune disease