Ataxia - lack of voluntary coordination of muscle movements that include balance and gait abnormality.
Benign paroxysmal positional vertigo (BPPV) – condition in which certain head movements or positions, such as looking up or turning over in bed, bring on vertigo that lasts 30 seconds or less.
Brain stem auditory evoked response test (BAER) – diagnostic test to measures how the brain processes sound. It can help locate the cause of some types of dizziness.
Caloric test – diagnostic test in which warm and/or cold water is poured into the ear. If the balance system is working properly, it will be stimulated and the patient will feel dizzy.
Canalith repositioning maneuver (CRP) – form of vestibular rehabilitation therapy in which a series of specific head-position changes results in displaced canaliths being moved from the semi-circular canal to the utricle.
Canaliths (also called otoconia) – tiny crystals of calcium carbonate within the inner ear. Their movement tells the brain about the body’s movement up or down, to the left or right, or backwards or forwards.
Cervicogenic Dizziness (CGD) – dizziness, imbalance, unsteadiness, or a sense of imbalance resulting from a neck-related injury or disorder.
Cochlea – snail-shaped structure in the inner ear; it is the main organ of hearing.
Computed Tomography (CT) scan (also called computerized axial tomography (CAT) scan) – diagnostic test that can reveal details, for example the inside of the ear and head, not seen in conventional X-rays.
Computerized dynamic posturography (CDP) – diagnostic test that measures postural control while standing in either static or dynamic conditions.
Developmental optometrist - a highly specialized doctor of optometry who has completed advance studies in vision care. Also know as behavioural optometrists.
Diplopia - a pathological condition of vision in which a single object appears double - aka double vision.
Diuretic – drug that promotes water loss from the body, through the urine. Used to treat high blood pressure (hypertension), diuretics may bring on dizziness due to a sudden drop in blood pressure when rising from a sitting, kneeling or lying position.
Dix-Hallpike test – diagnostic test that reveals which canal is involved in benign paroxysmal positional vertigo (BPPV).
Dizziness – general term for all symptoms of wooziness, imbalance or instability.
Electronystagmography (ENG) – diagnostic test to detect involuntary movement of the eye (nystagmus). Eye movements are recorded using electrodes placed on the external eye muscles. Also see Videonystagmography.
Endolymph – fluid filling part of the labyrinth of the inner ear.
Endolymphatic hydrops – see Ménière's disease
Eye saccades – rapid eye movements that allow the eye to “jump” from one fixed target to another. Eye saccades do not involve the vestibular system; they just involve the use of brainstem nuclei that control eye muscles.
Hyperventilation – rapid or deep breathing that reduces the carbon dioxide content of the blood and brings on dizziness.
Hyperosmia - sensitivity to odours
Illyngophobia – excessive fear of vertigo or a fear of feeling dizzy when looking down from a high place.
Imbalance – inability to keep one’s balance, especially when standing or walking.
Labyrinth (also called inner ear) – part of the ear that contains the organ of hearing (cochlea) and the organs of balance (semicircular canals, saccule and utricle).
Labyrinthitis – condition in which the vestibular nerve becomes inflamed, resulting in dizziness or vertigo as well sudden hearing loss.
Light-headedness – feeling of nearly fainting, similar to the feeling you might get if you hold your breath for a long time.
Mal de Débarquement (MdD) Syndrome – rare disorder in which the patient has a persistent feelings of dizziness or body sway after being exposed to an unstable surface for an extended time.
Ménière's disease (also called endolymphatic hydrops) – condition in which the endolymphatic sac fails to absorb fluid properly. This change in inner-ear fluid pressure results in dizziness and hearing loss.
Middle ear – space immediately behind the eardrum. This part of the ear contains the three bones of hearing: the hammer (malleus); anvil (incus); and stirrup (stapes).
Migraine - a neuromuscular headache, meaning it can be triggered by annoyance or disturbance to the nerves or blood vessels in the brain.
Migraine with brainstem aura - migraine that originates in the brainstem and is often accompanied by dizziness, aka central migraine.
Multiple sensory deficits – condition associated with dizziness in which damage to nerves of the eye and arms or legs reduces information about balance to the brain.
Neurologist – doctor who specializes in diseases and disorders of the brain and central nervous system, including migraine.
Neuro-ophthalmologist – specialist eye doctor that focuses on vision problems related to the nervous system, including the optic nerve and visual pathways.
Neuro-otologist – highly specialized otolaryngologist who diagnoses and treats complex conditions that affect the balance system, ears, skull base, temporal bone, and related structures of the head and neck.
Nystagmus – involuntary, rapid, back-and-forth movements of the eyes.
Ocular motor testing – diagnostic test to determine a patient’s ability to focus on stationary and moving targets.
Optokinetic reflex – a combination of eye saccade and smooth pursuit movements that enables following a moving object with the eyes and, when it moves out of the field of vision, automatically moves the eye back to the position it was in when the object was first seen; relies on the vestibular system.
Orthostatic hypotension – see Postural hypotension
Oscillopsia – a visual disturbance in which objects appear to oscillate, jerk or wiggle.
Otoconia – see Canaliths
Otolaryngologist (also known as ENTs) – doctors who specialize in problems of the ear, throat, nose and neck.
Otolith organs – collective term for two structures in the inner ear (saccule and utricle) that sense gravity and linear acceleration.
Otology – the branch of medicine that studies the ear and its diseases.
Ototoxic – having or producing an adverse effect on the organs or nerves that are involved in hearing or balance. This could be due to drugs, foods, irritation, or other means.
Perilymphatic fistula (PLF) – tear in one or both of the small, thin membranes that separate the air- filled middle ear and the fluid-filled space of the inner ear.
Phonophobia - sensitivity to loud sounds
Photophobia - sensitivity to light
Postural hypotension (also called orthostatic hypotension) – sudden dramatic drop in blood pressure when rising from a sitting, kneeling, or lying position. The prime symptom of postural hypotension is dizziness or faintness.
Post trauma vision syndrome (PTVS) - Vision problems after traumatic brain injury. Common pathological conditions of PTVS include: oculomotor dysfunction (eye tracking); binocular dysfunction (eye teaming); and accommodative dysfunctions (eye focusing).
Post-traumatic vertigo – dizziness that follows a neck or head injury.
Saccades – see Eye saccades
Semicircular canals – three curved hollow tubes in the inner ear that are part of the balance organ (labyrinth). The canals are joined at their wide ends and are filled with endolymph.
Smooth pursuit – smooth movements that allow the eye to track a moving target. Smooth pursuit movements do not involve the vestibular system; they just involve the use of brainstem nuclei that control eye muscles.
Somatosensory - relating to or denoting sensations (such as pressure, pain or warmth) that involve parts of the body not associated with the primary sense organs (such as sight, balance, or taste). Also called somesthetic.
Stroke – sudden death of brain cells due to a lack of oxygen, caused by blockage of blood flow or rupture of an artery to the brain. A stroke is a medical emergency.
Tinnitus – noise or ringing in the ears.
Transient Ischemic Attack (TIA) – temporary interruption of blood flow to a part of the brain, usually lasting only a few minutes. A TIA is a medical emergency and may signal the possibility of a stroke.
Tullio’s phenomenon – vertigo, dizziness, nausea or involuntary eye movement (nystagmus) brought on by sound.
Utricle – one of two otolith organs, the utricle is sensitive to changes in horizontal movement.
Vertigo – the specific sensation that you or your surroundings are spinning or tilting.
Vestibular disorders – disorders of the body’s balance (vestibular) system in the inner ear that cause a range of symptoms and conditions.
Vestibular Evoked Myogenic Potential (VEMP) test – diagnostic test to assess if the saccule, as well the inferior vestibular nerve and central connections, are intact and working normally. During the VEMP test, headphones are worn and small electrodes are attached to the skin over the: cervical (neck) muscles – cVEMP test; ocular (eye) muscles (oVEMP test); or leg muscles – leg VEMP test (not commonly used as a clinical test).
Vestibular migraine - migraine that originates in the inner ear, aka peripheral migraine, migraine-associated vertigo, migraine-associated dizziness, migraine-related vestibulopathy and migrainous vertigo.
Vestibular neuritis (also called vestibular neuronitis) – condition in which the vestibular nerve becomes inflamed, usually due to a virus, causing dizziness or vertigo.
Vestibular schwannoma – see Acoustic neuroma
Vestibulo-spinal reflex (VSR) – stabilizes the body in space. If something is wrong with this reflex, a patient might feel unstable.
Videonystagmography (VNG) – diagnostic test that assesses the coordination of eye movements, the semicircular canals of the inner ear and its connections to the central nervous system. Eye movements are video recorded. VNG is much more accurate than ENG (electronsytagmography).
Visual midline shift syndrome (VMSS) - a condition characterised by dysfunction of the ambient visual process, causing a misperception of self in space, and a shift in perceived visual midline.
Visual-vestibular mismatch (VVM) – disorder where information from the ear and eyes regarding movement fails to synchronize; this creates a confusion that in turn results in imbalance, nausea, light-headedness and vertigo.