Brief description on Sudden SNHL

1. SUDDEN SENSORINEURAL
HEARING LOSS
DR. HARJITPAL SINGH
ASSISTANT PROFESSOR,
DEPARTMENT OF ENT & HNS,
DR RKGMC HAMIRPUR

2. DEFINITION
Subjective sensation of
hearing impairment in one or both ears
developing within 72 hours and a decrease in
hearing of more than or equal to 30 decibels
(dB), on 3 consecutive frequency in
comparison to normal ear on audiometry.

3. DEFINITION(cont)
The audiometric criteria of a 30
dB sensorineural loss in at least three
consecutive frequencies can be difficult to
show clinically as premorbid audiometry is
rarely available. Therefore the hearing loss is
defined in relation to the contralateral side.

4. FOUR LEVELS OF CERTAINTY
There are four levels of ‘certainty’ about
the ‘newness’ of the hearing loss in the affected ear:
1. Very certain: Patient had previous audiometric evaluation.
2. Certain: Patient had no prior otologic history and feels
his or her premorbid hearing was normal bilaterally.
3. Fairly certain: Patient had a long-standing hearing problem
and reports that the current episode of SSNHL is
subjectively poorer.
4. Uncertain: The clinician feels there was some preexisting
hearing loss, but the hearing loss was never
documented.

5. STATISTICS
• First described by De Klevn in 1944.
• Around 15000 cases reported per year worldwide
• Limited Indian data available.
• The true incidence of SSNHL may be higher than these
estimates because affected individuals who recover quickly
do not present for medical care.
• It should be considered as a medical emergency as there
are chances for retrieval of the hearing.
• Although individuals of all ages can be affected, the
peak incidence is between the fifth and sixth decade of life.
• SSNHL occurs with equal incidence in men and women

6. STATISTICS(cont)
• Nearly all cases are unilateral; 2-5% of patients
have bilateral involvement.
• Identifiable causes are found for 7% to 45% of
patients with SSNHL.
• Tinnitus occurs in about 80% of patients
• Vertigo, indicating an associated peripheral
vestibular dysfunction, in about 30%.
• Up to 80% of patients report a feeling of ear
fullness.

7. STATISTICS(cont)
• Onset occurs in < 72 hours
• Recovery rate without treatment 32% to 79%
• Usually within two weeks of onset
• Only 36% patients have complete recovery.
• Chances of recovery are less after one month.
• Cases with a potentially discoverable etiology
fall into one of several broad categories
including infectious, autoimmune, traumatic,
vascular, neoplastic, metabolic, and neurologic

8. IDENTIFIABLE CAUSES OF SUDDEN
SENSORINEURAL HEARING LOSS

9. ETIOLOGY
• Viral and infectious
• Autoimmune
• Vascular
• Neurologic
• Neoplastic
• Hypoxia
• Metabolic causes
• Ototoxicity
• Traumatic
• Meniere’s disease
• Psychogenic
• Idiopathic

10. ETIOLOGY: VIRAL & INFECTIOUS
Viral infection causes Sudden SNHL
by causing cochleitis
• Meningococcal meningitis
• Herpesvirus (simplex, zoster, varicella, cytomegalovirus)
• Measles, Mumps, Rubella
• Human immunodeficiency virus
• Mycoplasma
• Cryptococcal meningitis
• Toxoplasmosis
• Syphilis
• Rubella

11. VIRAL LABYRINTHITIS
• Viruses reach the inner ear by blood stream affecting stria
vascularis
endolymph
Organ of corti
Eg :- Measels ,Mumps ,CMV
• The direct proof of invasion of viruses like Herpes zoster ,
Herpes simplex ,Rubella ,Influenza ,HIV, EBV in the labyrinth
is not known but they are clinically known to cause hearing
loss.

12. ETIOLOGY: BACTERIAL CAUSES
• Due to bacterial labyrinthitis as a complication of
CSOM or iatrogenic or spread through
hematological route.
• The membranous labyrinth is totally destroyed
causing the SNHL
• Causative bacteria involved in labyrinthitis
 Haemophilus influenza
 Neisseria meningitidis
 Streptococcus species
 Staphylococcus species
 Proteus species

13. ETIOLOGY: VASCULAR
 Vertebrobasilar insufficiency
 Sickle cell disease
 Leukemia
 Polycythemia
 Macroglobulinemia
 Cardiopulmonary bypass

14. ETIOLOGY: VASCULAR(comt)
THEORIES:
• Embolic phenomenon, thrombosis, vasospasm,
and hypercoagulable or high viscosity states
• Sudden anoxic injury to the cochlea.
• The cochlea is extraordinarily intolerant of
blood supply disruptions.

15. ETIOLOGY: AUTOIMMUNE
 Autoimmune inner ear disease
 Ulcerative colitis
 Relapsing polychondritis
 Systemic Lupus erythematosus ( SLE )
 Polyarteritis nodosa
 Cogan’s syndrome
 Wegener’s granulomatosis

16. ETIOLOGY: AUTOIMMUNE(cont)
• Unclear, but are presumed to include:
Vasculitis of vessels supplying the inner ear
Autoantibodies directed against inner ear
Cross-reacting antibodies.

17. ETIOLOGY: TRAUMATIC CAUSES
• Breaks in the membranous labyrinth
– Intracochlear
– Oval and/or round window
• History – inciting event
– Blow to the head :Temporal bone fracture
– Otologic surgery
– Sneezing
– Bending over
– Lifting a heavy object
– Exposure to sudden changes in barometric pressure eg. Flying,
SCUBA diving

18. ETIOLOGY: NOISE INDUCED
• It is seen in acoustic trauma.
• Due to sudden loud noise of over 140 dB.
• Rupture of Reissner’s membrane.
• Damage to organ of corti, hair cells.
• Mixing of perilymph & endolymph occurs due
to the loud noise leading to hearing loss.
• May be accompanied by vertigo.

19. ETIOLOGY: HYPOXIA INDUCED
• Hypoxia to the brain causes direct cell death of
the cochlear or nerve cells leading to SNHL.
• Hypercapnia also causes SNHL by deactivation of
enzyme carbonic anhydrase which may
participate in the generation of the
endocochlear potential.

20. ETIOLOGY: METABOLIC CAUSES
• Acute and chronic renal failure.
• Alport syndrome: renal disease with hearing loss.
• Hyperlipidemia
• Hypothyroidism
• Iron-deficiency anemia increases the risk
• Diabetes mellitus: It has been postulated that
diabetes is associated with microangiopathic
injury, hence a vascular event and a possible
etiological factor for SSNHL.

21. ETIOLOGY: OTOTOXICITY
• Drugs which damage the inner ear are called ototoxic.
• They cause sensorineural hearing loss, tinnitus, vertigo.
1.AMINOGLYCOSIDES
 Streptomycin,Gentamycin,Tobramycin are primarily
VESTIBULOTOXIC.
• Destroy type1 hair cells of crista ampullaris.
• In large doses can damage cochlea.
Neomycin, Kanamycin, Amikacin, Sisomycin and
Dihydrostreptomycin COCHLEOTOXIC.
• Destroy outer hair cells, starting at basal coil and
progressing up to apex of cochlea.

22. ETIOLOGY: OTOTOXICITY (cont)
2.Diuretics
Ethacrynic acid, furosemide and bumetanide cause
edema and cystic changes in stria vascularis
3.Salicylates
4.Antimalarials(Quinine)
It cause vasoconstriction in the small vessels of the
cochlea and stria vascularis.
5.Cytotoxic drugs
 Cisplatin, Carboplatin, Vinca alkaloids, Mainly
affect outer hair cells of cochlea.

23. ETIOLOGY: OTOTOXICITY (cont)
6.Miscellaneuos
• Desferoxamine:- High freq hearing loss due to outer
hair cell damage
• Mercury and its compounds
• Gold
• Lead
• Arsenic
• Aniline dyes
• Alcohol
• Tobacco
• Marijuana

24. ETIOLOGY: NEURAL CAUSES
• Meningitis
• Multiple sclerosis
• Sarcoidosis
• Friedreich's ataxia
• Amyotrophic lateral sclerosis
• Vogt-Koyanagi-Harada syndrome
• Xeroderma pigmentosum

25. ETIOLOGY: NEOPLASTIC
• Acoustic neuroma
• Leukemia
• Multiple Myeloma
• Metastasis to internal auditory canal
• Meningeal carcinomatosis

26. IDIOPATHIC SSNHL
• Idiopathic SSNHL is a diagnosis of exclusion.
• SSNHL is termed as idiopathic after ruling out
all the known causes of SSNHL.

27. WORK UP
• History
• Clinical examination
• Otological examination
• Audiometric evaluation
• Blood work up
• Radiological examination

28. EXAMINATION
• General examination: to rule out systemic
pathologies
• Neurological examination to rule out cranial
nerve involvement as in acoustic neuroma
• Cardiovascular evaluation to rule out
thromboembolism
• Ear Examination

29. LABORATORY STUDIES
Laboratory studies should be directed by the
history and physical examination findings.
• Fluorescent treponemal antibody-absorption (FTA-Abs) or
VDRL test for syphilis
• Antinuclear antibodies (ANA), rheumatoid factor, and ESR for
autoimmune diseases
• Coagulation profile for coagulopathy
• CBC count and differential for infection
• Thyroid-stimulating hormone (TSH) for thyroid disease
• Fasting blood glucose for diabetes mellitus
• Cholesterol and triglycerides for hyperlipidemia
• HIV test

30. IMAGING STUDIES
• CT scans are not recommended in the initial
evaluation of patients with presumptive SSNHL.
• CT Imaging of temporal region – to rule out
labyrinthitis or other complications of CSOM.
• In young patients, for whom only a small
possibility of detecting a vestibular schwannoma
exists, a noncontrast temporal bone CT scan
could be obtained.
• Magnetic resonance imaging (MRI) with (DPTA)
enhancement is the criterion standard test for
diagnosing CPA masses.

31. AUDIOGRAM OF A PATIENT WITH SSNHL

32. TREATMENT
• Multimodal treatment.
• Investigations to find any specific cause.
• Treatment should be started early
• Patient should be admitted for treatment.

33. Combined
therapy
Vasodilators
Diuretics
Plasma
Expanders
Corticosteroids
Vitamins

34. BED REST
• Patient should be admitted and advised bed
rest.
• Especially in case membrane rupture is
suspected as the cause for SSNHL.

35. OXYGEN THERAPY
 Intermittent oxygen inhalation at 4-6 liters per minute for 15
minutes every 6 hourly.
 Provide more oxygen to the nerve tissue by increasing the
perilymph oxygenation.
 Carbogen (5% CO2 + 95% O2) inhalation – Increases the partial
pressure of O2 in perilymph . CO2 is a known potent vasodilator of the
vestibulocochlear vasculature, resulting in increased blood flow.
 Improvement in hypoxia induced SSNHL.
 Oxygen therapy in the form of hyperbaric oxygen has also shown
good results.

36. STEROID TREATMENT
• Treatment of choice when the loss is retro-
cochlear, and are the only effective treatment.
• Prednisolone in tapered doses over a period of 3
weeks.
• Proton pump inhibitors given along with steroids.
• Intratympanic injection of steroids is being tried
alternative to oral steroids as it has shown to
penetrate the inner ear effectively in animal
studies.

37. VASODILATORS
• Like xanthinol nicotinate, glycerol.
• Betahistine : 16mg three times a day
• Glyceryl Trinitrate / Nitroglycerine patch
• Helps to relieve vasospasm.
• Improves blood supply to the nerve tissue.
• Glycerol increases the cochlear and cerebral
blood flow significantly after intravenous
administration

38. ANTIVIRAL COURSE
• A course of antiviral drug – Valcivir, Acyclovir,
Famciclovir.
• Valcivir : 1 gm three times a day for a week.
• Acyclovir : 800 mg four times a day for a week.
• Famciclovir : 500 mg three times a day for a
week
• To treat viral infection if any.

39. OTHERS
• Stellate ganglion block : blocks sympathetic activity
and results in vasodilatation of the vertebral artery.
Effective within 2 weeks of onset of SSNHL.

40. SURGERY
• Exploration of the middle ear with repair of an
inner ear fistula is recommended in patients with
a clear history of sudden hearing loss associated
with diving, straining, altitude change, or recent
otologic surgery.
• The role of surgery in patients who do not
improve with non-surgical therapy remains
controversial.

41. TREATMENT OF SPECIFIC CAUSES
• Anticoagulants like heparin in case thrombo-
embolism is suspected.
• Low molecular weight dextran: to treat
hypercoaguable states. Increases capillary
blood flow by hypervolaemic haemodilution
and by decreasing factor VIII; this results in
increased cardiac output and tissue blood
flow. Contraindicated in patients with cardiac
failure and bleeding disorders.

42. TREATMENT OF SPECIFIC CAUSES
• Thyroxine supplementation: in case of SSNHL due to
hypothyroid state.
• Treatment or control of DM, HTN and hyperlipidemia.
• Treatment of BACTERIAL LABYRINTHITIS
Broad-spectrum antibiotic.

43. DEFINITION OF RECOVERY
• Complete: if the follow-up PTA (dB HL) or SRT (dB
HL) Improved to within 10 dB of pre-sudden
hearing loss hearing levels.
• Partial: if the follow-up PTA (dB HL) or SRT (dB HL)
improved to within 50% of pre-sudden
hearing loss hearing levels.
• No recovery: if the follow-up PTA (dB HL) or
SRT(dB HL) was less than 50% of of recovery
of pre-sudden hearing loss hearing levels.

44. PROGNOSTIC FACTORS IN SUDDEN SNHL

45. SUMMARY
• Most patients with SSNHL cannot be given a cause
for their diagnosis.
• Highest incidence in 50-60 yrs old.
• Recovery usually begins within two weeks of onset
• SSNHL is considered to be a true otologic
emergency, given the observation that there is less
recovery of hearing when treatment is delayed.
• Recovery rate without treatment 32% to 79%
• Recovery usually begins within two weeks of onset

46. SUMMARY(cont)
• In order for the hearing gain to be appreciated by
the patient, the hearing in the affected ear must
be brought to 30 dB or better or to within 15 dB
of the contralateral ear.
• Intratympanic injections of corticosteroids may be
an alternative, particularly for patients who have
or are at high risk of complications from oral
therapy
• In view of these results 6 months has been given
as a reasonable follow-up period.