Sudden sensorineural hearing loss for same ms ent exam for 10 marker

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Sudden Sensorineural Hearing Loss (SSHL) - 10 Marker (MS ENT)

Definition

SSHL is defined as a decrease in hearing of ≥30 dB at 3 contiguous frequencies occurring within a 72-hour period (NIDCD / AAO-HNS 2012 Clinical Practice Guideline).

It is a syndrome, not a diagnosis
Also called "sudden deafness"
Must be treated as an otologic emergency

Incidence & Epidemiology

Incidence: 5-20 per 100,000 persons/year
Accounts for 2-3% of unselected otologic outpatient visits
Peak incidence: 6th decade of life
Male = Female (equal distribution)
Usually unilateral; simultaneous bilateral is very rare
Most common presentation: waking up with hearing loss in one ear

Etiology

Despite >100 proposed etiologies, most cases are idiopathic. The major categories are:

Category	Examples
Infectious	Viral (mumps, herpes zoster, HSV, CMV, EBV, measles, rubella, Lassa fever, HIV, Zika, West Nile), Bacterial (syphilis, Lyme disease, meningitis)
Neoplastic	Acoustic neuroma/vestibular schwannoma (1% of acoustic neuromas present as SSHL), meningioma, epidermoid, CPA tumors, lymphoma/leukemia
Traumatic	Temporal bone fracture, perilymphatic fistula, acoustic trauma, barotrauma, inner ear concussion
Ototoxic	Aminoglycosides, chemotherapeutics (cisplatin), aspirin overdose
Vascular	Vertebrobasilar insufficiency, labyrinthine artery occlusion, hypercoagulable states, sickling disorders
Autoimmune	Autoimmune inner ear disease, Wegener's granulomatosis, Cogan syndrome, Sjögren's syndrome, polyarteritis nodosa
Metabolic	Diabetes, hypothyroidism
Idiopathic (ISSNHL)	Majority of cases - no identifiable cause after workup

Four Principal Pathogenetic Theories for ISSNHL:

Viral labyrinthitis - most favoured; herpes family viruses, mumps (virus isolated from perilymph); 28% report preceding URTI
Vascular occlusion - labyrinthine artery end-artery occlusion/spasm; cochlea is extremely sensitive to ischemia
Intracochlear membrane rupture - Reissner's membrane or basilar membrane breaks causing perilymph-endolymph mixing
Autoimmune - inner ear-specific antibodies; responds to steroids

Clinical Features

Unilateral hearing loss - sudden onset, often noticed on awakening
Aural fullness - very common, sometimes the only complaint
Tinnitus - variable degree; may precede hearing loss
Vertigo/disequilibrium - present in ~40% of patients
Rarely: bilateral, sequential, or fluctuating

Investigations

Audiometry (Essential)

Pure tone audiogram (PTA) - confirms SNHL, quantifies severity, determines audiogram shape
Audiogram patterns: flat, upsloping, downsloping ("ski-slope"), mid-frequency notch
Speech discrimination scores
Tympanometry - normal (type A) in SNHL

Blood Tests (Low yield unless directed by history)

CBC, ESR, CRP
FBS/HbA1c (diabetes)
Thyroid function tests
Lipid profile
VDRL/FTA-ABS (syphilis serology)
Coagulation profile, ANA, ANCA (if autoimmune suspected)
HIV serology

Imaging

MRI with gadolinium (MRI brain + IAM) - mandatory to exclude retrocochlear pathology, especially acoustic neuroma (1% present as SSHL), CPA tumors, demyelination
CT temporal bone - if trauma/cholesteatoma suspected

Other

Electronystagmography (ENG) if vertigo present
Auditory Brainstem Response (ABR)

Prognosis

Without any treatment, 30-65% of patients have spontaneous complete or partial recovery.

Four Prognostic Factors:

Factor	Better Prognosis	Worse Prognosis
Severity of loss	Mild-moderate	Severe/profound
Audiogram shape	Upsloping, mid-frequency	Downsloping, flat
Vertigo	Absent	Present
Age	Younger	Older

Profound loss with downsloping audiogram + vertigo = worst prognosis

Treatment

1. Systemic Corticosteroids (First-line)

Prednisone 1 mg/kg/day (max 60 mg/day), 10-14 day course with slow taper
Mechanism: anti-inflammatory, reduces cochlear edema, improves strial blood flow
If partial recovery at end of 10 days - extend full dose for another 10 days
Must counsel about side effects (hyperglycemia, BP, peptic ulcer)

2. Intratympanic (IT) Steroids

Dexamethasone or methylprednisolone injected into middle ear (transtympanic)
Advantages: high inner ear drug concentration without systemic side effects
Preferred in: diabetes, glaucoma, cataracts, hypertension, peptic ulcer disease
As primary treatment: equivalent to systemic steroids (not superior)
As salvage therapy: recommended when incomplete response to systemic steroids (meta-analyses show significant benefit)
AAO-HNS guideline: "Clinicians should offer IT steroids when incomplete recovery follows systemic therapy"

3. Hyperbaric Oxygen Therapy (HBO)

Increases oxygen partial pressure to ischemic cochlea
Cochrane 2012: increases chance of 25% improvement (RR 1.39), absolute improvement ~16 dB
Used as adjunct, especially in late presenters

4. Other Treatments (Limited/No proven benefit in RCTs)

Vasodilators: IV histamine, papaverine, nicotinic acid - not proven
Carbogen (95% O2 + 5% CO2) - increases perilymph O2 tension; used empirically
Anticoagulants/Haemorheological agents: Low-molecular-weight dextran, pentoxifylline, heparin
Antivirals (acyclovir) - no added benefit in RCTs over steroids alone
"Shotgun regimen" - combination of multiple agents empirically; no proven benefit

5. Supportive

Treat underlying cause if identified (anti-TB, antibiotics for Lyme/syphilis, tumour surgery, etc.)
Hearing rehabilitation: hearing aid if permanent loss; cochlear implant for profound bilateral loss
Reassurance and counselling

Summary Table for Quick Revision

Feature	Key Point
Definition	≥30 dB SNHL at 3 contiguous frequencies within 72 hours
Most common cause	Idiopathic (ISSNHL)
Commonest theory	Viral labyrinthitis
Emergency	Yes - treat urgently
Spontaneous recovery	30-65% without treatment
Investigation of choice	MRI IAM + gadolinium (to exclude acoustic neuroma)
First-line treatment	Oral corticosteroids (prednisone 1 mg/kg/day)
Salvage treatment	Intratympanic steroids
Worst prognostic sign	Profound loss + vertigo + downsloping audiogram
1% of acoustic neuromas	Present as SSHL

Sources: Cummings Otolaryngology Head and Neck Surgery, Ch. 152; Bailey and Love's Short Practice of Surgery 28th Ed.; Scott-Brown's Otorhinolaryngology Head & Neck Surgery Vol. 2, Ch. 60

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