A sensation, as of a cold breeze or a bright light, that precedes the onset of certain disorders, such as an epileptic seizure or an attack of migraine.

Related to the sense of hearing.

The theory of BPPV, where free-floating debris can migrate into a semicircular canal and cause short episodes of vertigo when it moves within the canal.

Central vestibular system
Parts of the central nervous system (brain and brainstem) that process information from the peripheral vestibular system about balance and spatial orientation.

Portion of the inner ear concerned with hearing.

Cochlear implant
A prosthetic device that, unlike hearing aids which amplify sound, bypass the outer, middle, and inner ear and directly stimulate auditory nerve fibers.

Conductive hearing loss
Hearing loss produced by abnormalities of the outer ear or middle ear. These abnormalities create a hearing loss by interfering with the transmission of sound from the outer ear to the inner ear.

A variant of BPPV in which the debris is stuck to the cupula of a semicircular canal rather than being loose within the canal.

Unsteadiness, imbalance, or loss of equilibrium; often accompanied by spatial disorientation (a sensation of not knowing where one's body is in relation to the vertical and horizontal planes).

Lightheadedness; does not involve a rotational component (see vertigo).

The fluid within the semicircular canals and vestibule (utricle and saccule).

Eustachian tube
Connects the middle ear space with the throat; maintains equal air pressure on both sides of the tympanic membrane (eardrum).

A health condition characterized by an abnormally acute hearing due to heightened irritability of the sensory neural mechanism. Not unlike tinnitus, hyperacusis is considered a frequent symptom of stress, life crises, and migraines.

Complex system of chambers and passageways of the inner ear; includes both the hearing and balance portions of the inner ear.

An inflammation of the labyrinth.

Middle ear
Air-filled cavity containing the ossicles and tympanic membrane, the function of which is to transfer sound energy from the outer ear to the cochlea of the inner ear.

Mixed hearing loss
Hearing loss produced by abnormalities in both the conductive and sensorineural mechanisms of hearing.

Involuntary, alternating, rapid and slow movements of the eyeballs.

Ossicles (incus, malleus, stapes)
Tiny bones of the middle ear that conduct sound from the tympanic membrane to the oval window of the inner ear.

Calcium carbonate crystals found in the utricle and saccule of the inner ear. Damage to the otoliths may lead to BPPV.

Oval window
Oval-shaped opening from the middle ear into the inner ear. The footplate of the stapes fits into the oval window.

The fluid that fills the space between the semicircular canals and vestibule (utricle and saccule) and the surrounding bone.

Peripheral vestibular system
Parts of the inner ear concerned with balance and body orientation; consists of the semicircular canals, utricle, and saccule. Peripheral in this context means outside the central nervous system (brain and brainstem), to which the peripheral system sends information.

Perilymph fistula
Abnormal opening that permits perilymph from the inner ear to leak into the middle ear.

Round window
Membrane-covered opening between the inner ear and the middle ear.

Sac-like inner ear organ containing otoliths; senses vertical motion of the head.

Sensorineural hearing loss
Hearing loss produced by abnormalities of the cochlea or the auditory nerve or of the nerve pathways that lead beyond the cochlea to the brain.

Temporal bone
Part of the skull in which the inner ear is located.

Noise or ringing in the ears.

Tympanic membrane
Eardrum; separates the external ear canal from the middle-ear air cavity.

Sac-like inner ear organ containing otoliths; senses forward, backward, and side-to-side motion of the head.

Perception of movement (either of the self or surrounding objects) that is not occurring or is occurring differently from how it is perceived.

Vestibulo-cochlear nerve
Nerve that carries information from the inner ear to the brain. Also called the eighth cranial nerve, auditory nerve, or acoustic nerve.