Neurotology & Ear Disorders
After studying this chapter, the student should be able to:
Recognize the common signs and symptoms of external and middle ear disease, particularly those that may lead to prolonged morbidity if misdiagnosed.
Understand the patterns in symptoms associated with cochlear and vestibular dysfunction.
Appreciate risk factors for avoidable causes of ear injury, such as barotrauma, head injury, noise exposure, and ototoxic medications.
Disorders of the ear and their central connections are common contributors to morbidity throughout the human life span, beginning with congenital deafness and progressing with age to childhood ear infections, viral reactivation syndromes, and noise- and age-related hearing loss. Childhood middle ear infections (otitis media) alone affect 5 out of every 6 children before the age of 6 years. Noise-related hearing loss affects >15% of adult men and almost 10% of adult women, and severe hearing loss affects >35% of the elderly. Dizziness of all causes affects about 30% of adults in any age group, and inner ear–specific causes such as benign paroxysmal vertigo affect >25% of individuals over the age of 75 years. These disorders will inflict a higher and higher burden on public health because of the aging of the population. Rapid recognition of symptoms that implicate structural ear injury as well as preventable contributors of neurotologic disease are key to preventing long-term morbidity.
Disorders of the external and middle ear are characterized by physical manifestations and typically unilateral symptoms that make localization unambiguous. Auditory symptoms, when unilateral, are fairly easily localized to the affected side. The strong bilateral representation of central cochlear projections makes unilateral auditory symptoms unusual for central lesions.
Vertigo, dizziness, and spatial misperception can be due to either peripheral (inner ear) or central causes, and making this distinction can be challenging. The vestibular system maintains a fair degree of lateralization all the way to the cerebral cortex but the projections within the cerebral cortex are diffuse. This relates to the variety of central lesions that can create motion perception disorders. When paired with unilateral auditory symptoms in the absence of any central findings, the localization of vertigo is typically the inner ear. In the absence of auditory symptoms, a careful evaluation of other central features needs to be performed in order to distinguish peripheral versus central causes of motion misperception.
Infectious & Inflammatory Disorders of the Ear
Chondritis, specifically auricular chondritis, as it pertains to this section, refers to inflammation of the cartilage of the external ear (Figure 36–1A). It is usually the sequela of perichondritis. The perichondrium is the layer of tissue over the cartilage that provides it nutrients. Causes of chondritis largely ...