Hearing Loss - Differential Diagnosis Framework



Hearing Loss Types:

• Conductive

• Sensorineural

• Mixed

Presbycusis is the most common type in adults (bilateral age related hearing loss)



History:

• Duration of hearing loss?

• Bilateral?

• Fluctuating?

• Progressive?



The evaluation should also include a:

• Neurologic review

• History of:

	• Diabetes mellitus

	• Stroke

	• Vasculitis

	• Head or ear trauma

	• Use of ototoxic medications

	• Family history of ear conditions and hearing loss



Exam:

• Hearing tests such as the whispered voice test or audiometry

• Patients should then undergo examination for:

	• Cerumen impaction

	• Exostoses

	• Other abnormalities of the external canal and tympanic membrane

	• Neurologic examination:

		○ Cranial nerves - tumors of the auditory nerve (acoustic neuroma) and stroke may affect cranial nerves V and VII.

	• Head and neck masses and lymphadenitis? Infection or cancer



Tuning Fork Tests (512 Hz)

Weber Test:

• Lateralization to good ear indicates sensorineural hearing loss

• Lateralization to bad ear indicates conductive hearing loss

Rinne Test:

• Normal: Air > bone

• Conductive hearing loss: Bone > Air conduction



Conductive Hearing Loss

Conductive problems involve the tympanic membrane and middle ear, and interfere with transmitting sound and converting it to mechanical vibrations.

• Outer Ear:

	○ Obstruction of external canal by cerumen

	○ Obstruction of external canal by exostoses (surfer’s ear)

	○ Obstruction of external canal by foreign body

	○ Otitis externa

• Middle Ear:

	○ Cholesteatoma

	○ Ossicular chain disruption

	○ Otitis media

	○ Otosclerosis

Tympanic Membrane:

• Perforation, tympanosclerosis



Sensorineural Hearing Loss

Sensorineural problems affect the conversion of mechanical sound to neuroelectric signals in the inner ear or auditory nerve (CN 8).

• Unilateral:

	○ Internal auditory artery infarct (Labyrinthine artery) – Sudden Onset

	○ Meniere disease

	○ Vestibular Schwannoma/Acoustic neuroma

	○ Viral

	○ Idiopathic SNH (80% to 90% of cases cause unknown)

• Bilateral:

	○ Presbycusis - is the most common type in adults

	○ Ototoxic medications (Aminoglycosides, ASA, etc.)

	○ Meningitis complications

	○ Neurofibromatosis type II

	○ Susac’s syndrome

	○ Superficial Siderosis

	○ Mitochondrial disorders

	○ Noise trauma

	○ MS, CVA

• Infectious Conditions:

	○ Labyrinthitis

	○ Epstein-Barr virus

	○ Group A Streptococcus

	○ Herpes simplex virus

	○ Herpes zoster virus

	○ HIV

	○ Lyme disease

	○ Meningitis

	○ Syphilis

Cerebellopontine angle tumor/neoplasm

• Trauma:

	○ Barotrauma, ear trauma, or head trauma

	○ Noise exposure



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