Chapter 20: Disorders of Hearing and Vestibular Function

The provided chapter meticulously outlines the pathophysiology concerning disruptions in auditory and vestibular function, starting with the anatomy of the ear’s three divisions: external, middle, and inner. External ear issues include obstructions like impacted cerumen and infections such as otitis externa (swimmer's ear). Disorders of the middle ear are frequently linked to eustachian tube dysfunction, which impairs pressure equalization, leading to issues like barotrauma or Otitis Media (OM). OM is commonly seen in children as either Acute Otitis Media (AOM), usually infectious, or Otitis Media with Effusion (OME), involving fluid accumulation without acute infection. A progressive middle ear disorder is otosclerosis, where abnormal spongy bone formation immobilizes the stapes, resulting in conductive hearing loss. Inner ear dysfunction involves the intricate fluid-filled labyrinth containing the cochlea for hearing and the semicircular ducts for balance. Damage here can lead to sensorineural hearing loss, often irreversible, or tinnitus (the perception of abnormal noise). Hearing loss is comprehensively classified by severity and cause (conductive, sensorineural, or mixed) and is diagnosed via tests like audiometry and the Weber/Rinne tests. The vestibular system is primarily responsible for equilibrium and postural reflexes. Vestibular disorders are characterized by vertigo, an illusory sensation of motion. Key peripheral disorders include Benign Paroxysmal Positional Vertigo (BPPV), where displaced otoliths cause positional dizziness, and Ménière disease, marked by excessive endolymph and a classic triad of vertigo, tinnitus, and fluctuating hearing loss. Diagnostic tools for vestibular issues include the Romberg test and videonystagmography, with treatments ranging from physical rehabilitation to pharmacologic agents to suppress vestibular activity.