Conductive Hearing Loss: Problem with sound travelling from the environment to the inner ear; the sensory system may be working correctly, but sound does not reach it.
Example: Earplugs cause conductive hearing loss.
Sensorineural Hearing Loss: Caused by issues with the sensory system or vestibulocochlear nerve in the inner ear.
Basic Ear Anatomy
Outer Ear
Middle Ear
Inner Ear
Structures
Pinna: External portion of the ear
External Auditory Canal: Tube into the ear
Tympanic Membrane: Eardrum
Eustachian Tube: Connects the middle ear with the throat to equalize pressure
Malleus, Incus, Stapes: Small bones in the middle ear connecting the tympanic membrane to the inner ear structures
Semicircular Canals: Sense head movement (vestibular system)
Cochlea: Converts sound vibrations into nerve signals
Vestibulocochlear Nerve: Transmits signals from semicircular canals and cochlea to the brain
Presentation of Hearing Loss
May be gradual and unnoticed by the patient, noticed by others instead.
Sudden onset (less than 72 hours) requires thorough assessment.
Associated Symptoms
Tinnitus: Ringing in the ears
Vertigo: Sensation that the room is spinning
Pain: May indicate infection
Discharge: May indicate outer or middle ear infection
Neurological Symptoms
Risks
Hearing loss can increase the risk of dementia; treating it (e.g., with hearing aids) may reduce this risk.
Webers and Rinnes Tests
Used to differentiate between sensorineural and conductive hearing loss using a tuning fork.
Webers Test
Place vibrating tuning fork on the center of the forehead.
Normal: Sound is heard equally in both ears.
Sensorineural Loss: Sound louder in the normal ear.
Conductive Loss: Sound louder in the affected ear.
Rinnes Test
Place vibrating tuning fork on mastoid process to test bone conduction.
Move fork near the ear canal to test air conduction.
Normal (Rinnes positive): Air conduction better than bone conduction.
Abnormal (Rinnes negative): Bone conduction better than air conduction, indicating conductive hearing loss.