Disorders of Hearing

1. Disorders of Hearing Pathology of the Ear

3. Structures of the Auditory Pathway Outer EarMiddle Ear Pinna Tympanic Membrane External Canal Ossicles (Malleus, Incus, Stapes) Eustachian Tube Inner EarCentral Auditory Pathway Cochlea 8th Nerve Cochlear Nuclei Superior Olivary Complex Lateral Lemnisci Inferior Colliculi Medial Geniculate Body Auditory Cortices

4. Conductive Hearing Loss • Abnormality or disease of the outer and/or middle ear. • AC scores poorer than BC -- ABG > 10 dB • Often abnormal tympanograms • Often absent or elevated acoustic reflexes • Once speech is loud enough to be heard, word recognition is typically good. • Generallycan be treated medication and/or surgery.

5. Unilateral Otitis Media • Low frequency conductive hearing loss • Tympanograms may be flat or shallow with a negative pressure peak • Otoscopy abnormal • May or may not be pain

6. Sensory or Sensorineural Hearing Loss • Hearing loss resulting from abnormality and/or pathology affecting the cochlea or auditory nerve. • AC scores equal to BC -- ABG < 10 dB • Often normal tympanograms • Often even though speech is loud enough to be detected, word recognition can be impaired. • Often not responsive to medical intervention. • Hearing aids can help alleviate communication difficulties.

7. Hearing WNL 250-1000 Hz steeply sloping to a profound sensorineural hearing loss above 4000 Hz bilaterally.

8. Otitis Media • Negative pressure in middle ear space • often secondary to Eustachian tube dysfunction • can cause retraction of TM • Fluid can accumulate behind TM • May or may not be infected • can become very thick and adhesive • Untreated • can resolve • can perforate TM and recur • can have serious complications (e.g. meningitis, permanent hearing loss)

9. Unilateral Otitis Media • Low frequency conductive hearing loss • Tympanograms may be flat or shallow with a negative pressure peak • Otoscopy abnormal • May or may not be pain

10. Otosclerosis • Progressive conductive hearing loss typically unilateral. • Carhart’s notch • Tympanogram is normal or shallow. • Absent or abnormally elevated acoustic reflexes

11. SENSORINEURAL HEARING LOSS = LESS SENSITIVE TO SOUND SPEECH IS UNCLEAR

12. Disorders of the Inner Ear Meniere’s Disease Endolymphatic Hydrops Tinnitus Vertigo Fluctuating Hearing Loss Ototoxicity Induced by aminoglycosides Induced by loop diuretics Induced by cancer treatment

13. Meniere’s Disease • Fluctuating (but often progressive), unilateral sensorineural hearing loss. • Tinnitus • Episodic vertigo

14. Disorders of the Inner Ear Noise Exposure Recreational Noise Occupational Noise Environmental Noise Temporal Bone Fractures Meningitis Presbycusis

15. Noise Induced Hearing Loss • Bilateral, sensorineural loss. • Noise notch at 4000 Hz • Tympanogram and acoustic reflexes WNL

16. Presbycusis • Age related hearing loss • Bilateral sensorineural hearing loss often worse in the high frequencies and tends to progress. • Tympanograms normal • Word recognition scores often depressed.

17. Left: Hearing WNL. • Right: Moderate sloping to severe mixed loss.

18. Left: • PTA: 45 dB HL • SRT: 40 dB HL • Word Recognition: 98% at 80 dB HL • Right: • PTA: 58 dB HL • SRT: 50 dB HL • Word Recognition: 68% at 90 dB HL

19. Hearing WNL 250-1000 Hz steeply sloping to a profound sensorineural hearing loss above 4000 Hz bilaterally.