Sudden sensori-neural hearing loss

Dr. Vishal Sharma

Defining triad (Wilson, 1980)

1. Sensori-neural deafness of > 30 dB HL

2. over > 3 contiguous frequencies

3. occurring in < 3 days

– Within 12 hrs: Cummings

Synonyms & alternatives

• Sudden sensorineural hearing loss is also

called acute cochlear dysfunction

• Sudden sensorineural hearing loss

accompanied by acute vertigo is also called

acute cochleo-vestibular dysfunction

• Deafness occuring over days or weeks is

called rapidly progressive hearing loss

Epidemiology• Annual incidence (USA) is 5 - 20 cases / 1 lakh

• 47-70 % resolve spontaneously (do not report)

• True incidence rate is higher

• Gender not a risk factor

• Unilateral cases: 96-99%

• Bilateral cases: 1-4%

• Left ears are affected more (55%)

Age (years) Distribution in 1220 cases (Shaia & Sheehy, 1976)

< 30 13 %

30 – 39 13 %

40 – 49 21 %

50 – 59 22 %

60 – 69 18 %

> 70 13 %

Etiology

1. Idiopathic (single largest group: 90 - 95%)

2. Cochlear causes

3. Retro-cochlear causes

4. Miscellaneous

• Psychogenic

• Malingering

Criteria for idiopathic SSNHL

• SSNHL present

• No other cranial nerve involvement except

eighth cranial nerve

• No other etiology is known

Idiopathic SSNHLVarious hypotheses are:

1. Labyrinthine viral infection (viral cochleitis)

2. Labyrinthine vascular compromise

3. Membrane rupture

4. Immune-mediated inner ear damage

5. Activation of cochlear nuclear factor kappa B

1. Labyrinthine viral Infection (20 – 40 %)

• Herpes, mumps, measles, maternal rubella,

cytomegalovirus, varicella zoster

2. Labyrinthine vascular compromise

• caused by thrombosis, embolus, reduced blood

flow, vasospasm

• Western diet (rich in saturated fat), alcohol intake

& tobacco smoking are predisposing factors

3. Membrane rupture (Simmons)

• Pts hear pop sound before sudden deafness

• Oval & round window perilymph fistulae leak

perilymph into middle ear low perilymph

pressure & relative endolymphatic hydrops

• Rupture of intra-cochlear membranes mixing

of perilymph & endolymph altering endo-

cochlear potential

4. Immune-mediated inner ear damage

• Antigen-antibody complex mediated

destruction of cochlea

• Cross-reacting circulating antibodies seen in

65 % pt of SSNHL. Associated conditions are:

Cogan syndrome Relapsing polychondritis

Systemic lupus erythematosus

Polyarteritis nodosa Temporal arteritis

5. Activation of cochlear nuclear factor kappa B

Merchant et al (2005) proposed this new theory

Nuclear factor kappa B (NFҚ B) functions by:

regulating inflammatory response + apoptosis

regulating intracellular Ca & neuronal

excito-toxicity

NFҚ B activation is associated with destruction

of spiral ganglion neurons & cochlear hair

cells causing ISSNHL

1. Infection: bacterial, viral, spirochaetal,

mycoplasma

2. Trauma: temporal bone #, acoustic trauma,

barotraumas, perilymph fistula, radiotherapy

3. Vascular: hyper-coagulable states, thrombo-

embolism, hypertension, migraine

4. Hematological: polycythemia, leukemia, anemia

Cochlear causes

Cochlear causes

5. Oto-toxicity: aminoglycoside, aspirin, frusemide,

antimalarials, cisplatin

6. Endolymphatic hydrops

7. Metabolic: diabetes mellitus, hypothyroidism,

hyperlipidemia, renal failure

8. Auto-immune: Cogan syndrome, systemic lupus

erythematosus, relapsing

polychondritis

Retro-Cochlear causes

• Meningitis

• Encephalitis

• Tumor: Vestibular schwannoma, other tumors

of cerebello-pontine angle

• Multiple sclerosis

• Metastasis

Clinical Features

• Medical Emergency

• Sensori-neural hearing loss

• Tinnitus: seen in 60 - 70% pt

• Vertigo: seen in 20 - 40% pt

• Aural fullness: seen in 15 - 30% pt

• Viral URTI: seen in 20 - 40% pt

Patient Evaluation

• Early diagnosis & Tx improves prognosis

• Deafness: onset, duration, severity, previous HL

• Associated vertigo / tinnitus / aural fullness

• Exclude trauma (noise / baro / temporal bone #)

• Exclude ototoxicity / DM / hypothyroidism /

blood dyscrasia / hyperlipidemia / renal failure

• Tuning fork tests & fistula test

• Perform careful neurological examination

Basic Laboratory Investigations

1. Complete Blood Count + ESR: for infection

2. BT, CT, PT, aPTT & INR: for bleeding disorder

3. VDRL, FTA-Abs, TPHA, TPI: for syphilis

4. ANA, Rh factor, other auto-antibody titre

5. T3, T4, TSH: for hypothyroidism

6. FBS & PPBS: for diabetes mellitus

7. Fasting lipid profile: for hyperlipidemia

8. Urea & Creatinine: for renal failure

Imaging Studies

1. MRI with gadolinium contrast (gold standard):

1-2% pt with ISSNHL have IAC or CPA tumors

3-12% pt with acoustic neuroma have SSNHL

2. CT scan temporal bone + contrast

• Detect anatomic defects (Mondini dysplasia or

enlarged vestibular aqueduct syndrome)

Contrast M.R.I.: acoustic neuroma

Mondini dysplasia sac-like cochlea

(black arrow)

amorphous vestibule

without any defined

semicircular canals

(white arrow)

enlarged vestibular

aqueduct (red arrow)

Enlarged vestibular aqueduct

Audiometry

• Pure-tone Audiometry

• Speech Audiometry

• Tympanometry & acoustic reflex tests

• SISI & Tone Decay Test

• Oto-acoustic emission

• BERA

• High-frequency hearing loss: PTA at 4 & 8 kHz

exceeds PTA at 250 & 500 Hz by > 30

dB

• Low-frequency hearing loss: PTA at 250 & 500

Hz exceeds PTA at 4 & 8 kHz by > 30

dB

• Flat-type hearing loss: equal hearing losses

at each frequency

• Profound hearing loss: no response at

maximum intensity for > 2

frequencies

• Reference : Nakashima T, et al. Laryngoscope

1993;103:1145-49.

• Presence of OAE indicates preservation of

some outer hair cell function

• ABR reflects function of neural pathways

• ABR & OAE results also assist in diagnosing

psychogenic hearing loss & malingering

• Vestibular tests are obtained when indicated

by history & physical examination

Treatment

Treatment options(a) Vasodilators

(b) Rheologic agents

(c) Anti-inflammatory agents (Steroids)

(d) Anti-viral agents

(e) Diuretics

(f) Hyperbaric oxygen

(g) Surgery

General Treatment

1. Bed rest & avoid strenuous exercise

2. Avoid following aggravators:

Alcohol Smoking

Stress Sleep deprivation

CNS stimulants Fatty diet

Straining Loud noise

Vasodilators: reverse hypoxia

• Betahistine: 16 mg TID, PO for 3 wk

• Xanthinol nicotinate: 300 mg slow IV Q12H

500 mg BD, PO for 3

wk

• Carbogen (5% CO2 + 95% O2) inhalation: for

30 min, 8 times / day at 1 hour intervals in

O.T.

• Nimodipine: 30 mg BD-TID, PO for 3 wk

Rheologic Agents

blood viscosity to blood flow & O2 delivery

• Low-molecular-weight dextran: 10 ml / kg / d X 7d

• Pentoxifylline: 400 mg TID, PO for 3-4 wk

• Diatrizoate meglumine infusion: 40 ml/d X 7d

• Hydroxy-ethyl starch: 500-1000 ml/d X 7d

• Anticoagulants (heparin & warfarin): obsolete

Cortico-Steroids

• Anti-inflammatory agents

• Prednisolone: 1mg / kg / d in single or divided

doses for 10 d taper over 3 weeks

• Intratympanic dexamethasone solution (8

mg/mL): 0.3–0.4 mL with hyaluronidase on

alternate days after grommet insertion in PIQ

Grommet in P.I.Q.

Post-steroid recovery

Side-effects of Steroids• Hyperglycemia

• Hypertension

• Gastric ulceration

• Osteoporosis

• Flaring of infection & delayed wound healing

• Psychiatric disturbance (insomnia, euphoria)

• Weight gain & trunk obesity

Anti-virals & Diuretics• Anti-virals

• Acyclovir: 800 mg PO, 5 times / day for 7 days

• Famciclovir: 250 mg PO, TID for 7 days

• Diuretics

• Used in SSNHL due to endolymphatic hydrops

• Hydrochlorothiazide: 25 mg PO, BD for 3-4 wk

Hyperbaric oxygen

• Consists of exposure to 100% oxygen at

pressure of 250 kPa for 60 minutes in a multi-

place hyperbaric chamber along with high

doses of gluco-corticoids

• Best results achieved if treatment started

early

Surgery

• Repair of oval & round window perilymph

fistulae has been used in cases of ISSNHL

associated with positive fistula test or history

of recent trauma or barotrauma

• No standard methods are detailed

Result evaluation (Wilson)

• Complete recovery:

• PTA or SRT: < 10 dB of pre-SSNHL value

• Partial recovery:

• PTA / SRT: > 50% recovery of pre-SSNHL value

• No recovery:

• PTA / SRT: < 50% recovery of pre-SSNHL value

Result evaluation

• Patient with pre-SSNHL value of:

• Pure Tone Average = 30 dB

• Speech Reception Threshold = 30 dB

• Complete recovery: PTA or SRT 30 - 40 dB

• Partial recovery: PTA or SRT 41 - 45 dB

• No recovery: PTA or SRT > 45 dB

Spontaneous Recovery

• Spontaneous recovery rates for SSNHL range

from 47 - 70%, combining categories of

complete & partial recovery

• Most spontaneous recoveries occur within 2

weeks

Results

• No high-quality, randomized, controlled trial

shows efficacy of any medical therapy

• Most studies don't show significant beneficial

effect of vasodilators, acyclovir, rheological

agents, hyperbaric oxygen over placebo

• Corticosteroid therapy is only accepted

therapy for ISSNHL. Recovery rates = 40 - 60%

Favorable prognosis

1. Tx starting <10 days after onset of SSHL

2. Mild to moderate SNHL

3. Low or mid frequency SNHL

4. Presence of tinnitus (doubtful significance)

Unfavorable prognosis1. High frequency deafness (especially 8 kHz)

2. Hearing loss > 90 dB HL

3. Vertigo / vestibular changes evident on ENG

4. Bilateral sensori-neural deafness

5. Tx starting >15 days after onset of deafness

6. Age < 15 years or > 65 years

7. Elevated ESR (>25)

8. Poor speech discrimination score

Further Study

• Leong, A.C. et al. (2007). Sudden hearing loss - A 12

minute consultation. Clinical Otolaryngology. 32: 391–394

• Xenellis J. et al. (2006). Idiopathic sudden sensorineural

hearing loss: prognostic factors. J.L.O. 120, 718–724

• Xenellis J. et al. (2006) Intra-tympanic steroid treatment in

ISSNHL. Otolaryngol. Head Neck Surg. 134, 940–945

• Aoki D. et al. (2006) Evaluation of superhigh-dose steroid

for SSNHL. Otolaryngol. Head Neck Surg. 134, 783–787

• Bennett M. et al. (2005) Hyperbaric oxygen therapy for

ISSNHL & tinnitus: J. Laryngol. Otol. 119: 791-798,

• Wilson W. et al. (1980) The efficacy of steroids in the

treatment of ISSNHL. Arch. Otolaryngol. 106, 772–776

Thank You