Causes of Hearing Loss

Ambulatory Topic #2: Causes of Hearing Loss

At my present clinic, my attending does the annual physical exam for the state-employed divers. Many of them have exostoses, which are bony outgrowth of the external auditory canal related to repetitive exposures to cold water. They are common in divers and swimmers. This led us into a conversation about hearing loss and thus my topic of the day.

There are 2 types of hearing loss: Conductive vs Sensorineural

Conductive = caused by lesion in external or middle ear

Sensorineural = lesions in cochlea or CN VIII

Conductive

1.     External canal

a.     WAX! (Cerumen impaction)

b.     Otitis externa (TIP: Don’t forget to palpate external ear before introducing otoscope!)

c.      Exostoses

2.     TM performation

a.     Trauma

b.     Secondary to middle ear infection

3.     Middle ear

a.     Middle ear effusion (Otitis media, allergic rhinitis)

b.     Otosclerosis (bony fusion between stapes and ova = immobilization)

c.      Neoplasm

d.     Congenital malformation

Sensorineural

1.     Old Age (Presbycusis)

a.     Degeneration of sensory cells

b.     MOST COMMON

2.     Too many concerts (Noise-induced hearing loss)

a.     >85 dB for prolonged time

b.     Damaged hair cells

3.     Infection

a.     Viral or bacterial

4.     Drug-induced hearing loss

a.     Aminoglycosides

b.     Cisplatin

c.      Furosemide

d.     Aspirin can cause tinnitus (usually reversible)

5.     Inner ear injury

a.     Skull fx

6.     Meniere’s Dz

a.     Fluctuating, unilateral hearing loss

b.     Ear feels “full”

c.      Vertigo

7.     CNS cause

a.     Acoustic neuroma

b.     Meningitis

c.      Neuritis of auditory nerve

8.     Congenital

a.     TORCH infections

Tips on Hearing Tests:

RINNE vs WEBER

CONDUCTION LOSS	Finding:
Rinne Test (Abnl)	Bone conduction (BC) > Air conduction (AC)
Weber Test	Sound lateralizes to AFFECTED side*
SENSORINEURAL LOSS
Rinne Test (Nl)	AC > BC
Weber Test	Sound lateralizes to UNAFFECTED side

*This means that the tuning fork is heard louder in the ear with the conductive hearing loss.

I remember it as the Rinne test is Abnormal and sound lateralizes to the Affected side. Both start with “A”.



Source: Step Up to Medicine 2nd Ed.