The Vestibular System · why the room spins, and why it's rarely your neck

Story

Connected to · 6

cofactor · 2

Calcium
Otoconia, the inner ear's "ear stones", are calcium carbonate crystals that are denser than the fluid around them. When you tilt your head, gravity pulls on the gel-like membrane they sit on, the membrane drags the hair cells' bundles to one side, and the brain learns how your head is oriented relative to gravity.
Nervous
The semicircular canals sense rotation, not straight-line movement. When you turn your head, the fluid inside lags behind by inertia, bends a gel-like flap called the cupula, and with it the hair cells' bundles, which fire signals down the nerve at once. In an elevator going straight up or down, they stay quiet.

regulates · 3

Ankle Sprain
Standing steady depends on the brain combining position signals from the eyes, the vestibular system of the inner ear, and the joints and muscles, and constantly re-weighting them. The ligaments and tissues around the ankle are themselves position reporters; after a sprain that signal can get worse, and so does the ability of the body to sense the ankle starting to roll and correct it. This is one reason one sprain invites the next, and why recovery should include balance training on purpose.
Osteoporosis
Vertigo makes falls more likely, especially in older people, and one fall can cost far more than the dizziness itself. Repositioning maneuvers make the vertigo of benign paroxysmal positional vertigo (BPPV) clear up sooner; whether that goes on to prevent falls and fractures has not been tested directly.
Vitamin D
A Korean multicenter randomized trial (Jeong 2020) gave vitamin D and calcium only to people with BPPV whose repositioning had worked and whose blood vitamin D was low (25(OH)D below 20 ng/mL, that is, 50 nmol/L), and recurrence over a year fell from 46.7% to 37.8%. The trial did not test whether people who are not short of vitamin D benefit; repositioning is still the treatment itself, and the result does not carry over to falls or fractures.

contrast · 1

Stroke
With sudden vertigo, the first job is to tell a benign inner-ear problem from a stroke in the blood supply to the back of the brain. Early brain imaging misses a sizable share of these strokes, while a bedside eye-movement exam (HINTS) done by an experienced clinician is more sensitive. If vertigo comes with slurred speech, weakness in an arm or leg, or trouble walking, go to the emergency department right away.

Read full story

Stop 1/7

Balance comes from three senses

EVIDENCEGUIDE 1 · REVIEW 2

READ THE ORIGINAL

You stay upright not because of one organ, but because three streams of information vote in your brain: the vestibular system of the inner ear (the sensor set that handles balance), which measures how your head turns and accelerates; your eyes, which use the scene around you as a reference; and proprioception (the body's sense of where its own joints and muscles are), which reports pressure under your feet and the angles of your joints from the bottom up. When the three agree, the world feels stable — so stable you never notice it.

When the three disagree and the brain cannot reconcile them, you feel dizzy. The most widely accepted explanation of motion sickness is exactly this conflict: you look down at your phone in a car, your eyes say nothing is moving (the inside of the car is still), and your inner ear says you are rocking. One piece of counter-evidence makes the point: people who have lost inner-ear vestibular function entirely do not get motion sick — a conflict needs two voices, and with one missing there is nothing to argue about.

You can feel it in daily life too: standing on one leg with your eyes closed is much harder than with them open. Take one stream away, and the others have to work overtime.

One kind of vertigo cannot wait: with double vision, slurred speech, one-sided weakness or an inability to stand — or vertigo that arrives on its own rather than being set off by a change in head position — seek medical care immediately; it may be a stroke.

Educational content, not medical advice — consult a clinician.

Back

The Vestibular System · why the room spins, and why it's rarely your neck

Story

Connected to · 6

cofactor · 2

Calcium
Otoconia, the inner ear's "ear stones", are calcium carbonate crystals that are denser than the fluid around them. When you tilt your head, gravity pulls on the gel-like membrane they sit on, the membrane drags the hair cells' bundles to one side, and the brain learns how your head is oriented relative to gravity.
Nervous
The semicircular canals sense rotation, not straight-line movement. When you turn your head, the fluid inside lags behind by inertia, bends a gel-like flap called the cupula, and with it the hair cells' bundles, which fire signals down the nerve at once. In an elevator going straight up or down, they stay quiet.

regulates · 3

Ankle Sprain
Standing steady depends on the brain combining position signals from the eyes, the vestibular system of the inner ear, and the joints and muscles, and constantly re-weighting them. The ligaments and tissues around the ankle are themselves position reporters; after a sprain that signal can get worse, and so does the ability of the body to sense the ankle starting to roll and correct it. This is one reason one sprain invites the next, and why recovery should include balance training on purpose.
Osteoporosis
Vertigo makes falls more likely, especially in older people, and one fall can cost far more than the dizziness itself. Repositioning maneuvers make the vertigo of benign paroxysmal positional vertigo (BPPV) clear up sooner; whether that goes on to prevent falls and fractures has not been tested directly.
Vitamin D
A Korean multicenter randomized trial (Jeong 2020) gave vitamin D and calcium only to people with BPPV whose repositioning had worked and whose blood vitamin D was low (25(OH)D below 20 ng/mL, that is, 50 nmol/L), and recurrence over a year fell from 46.7% to 37.8%. The trial did not test whether people who are not short of vitamin D benefit; repositioning is still the treatment itself, and the result does not carry over to falls or fractures.

contrast · 1

Stroke
With sudden vertigo, the first job is to tell a benign inner-ear problem from a stroke in the blood supply to the back of the brain. Early brain imaging misses a sizable share of these strokes, while a bedside eye-movement exam (HINTS) done by an experienced clinician is more sensitive. If vertigo comes with slurred speech, weakness in an arm or leg, or trouble walking, go to the emergency department right away.

Read full story

Stop 1/7

Balance comes from three senses

EVIDENCEGUIDE 1 · REVIEW 2

READ THE ORIGINAL

You stay upright not because of one organ, but because three streams of information vote in your brain: the vestibular system of the inner ear (the sensor set that handles balance), which measures how your head turns and accelerates; your eyes, which use the scene around you as a reference; and proprioception (the body's sense of where its own joints and muscles are), which reports pressure under your feet and the angles of your joints from the bottom up. When the three agree, the world feels stable — so stable you never notice it.

When the three disagree and the brain cannot reconcile them, you feel dizzy. The most widely accepted explanation of motion sickness is exactly this conflict: you look down at your phone in a car, your eyes say nothing is moving (the inside of the car is still), and your inner ear says you are rocking. One piece of counter-evidence makes the point: people who have lost inner-ear vestibular function entirely do not get motion sick — a conflict needs two voices, and with one missing there is nothing to argue about.

You can feel it in daily life too: standing on one leg with your eyes closed is much harder than with them open. Take one stream away, and the others have to work overtime.

One kind of vertigo cannot wait: with double vision, slurred speech, one-sided weakness or an inability to stand — or vertigo that arrives on its own rather than being set off by a change in head position — seek medical care immediately; it may be a stroke.

Educational content, not medical advice — consult a clinician.