Balance for the clinic: the vestibulo-ocular reflex and nystagmus
- Applied anatomy
The inner ear keeps the eyes steady when the head moves; when one side fails, the eyes drift and beat back: that is nystagmus.
What it is
Balance combines the inner ear, vision and body sense, integrated in the brainstem and cerebellum. The vestibulo-ocular reflex (VOR) moves the eyes opposite to the head so the image stays still. When one labyrinth or vestibular nerve fails, the two sides no longer balance: the patient feels spinning and the eyes show nystagmus. Reading the timing of the vertigo and the type of nystagmus tells you whether the problem is peripheral (ear) or central (brain), which is the key decision at the bedside.
Applied anatomy
- Three semicircular canals per side (horizontal, anterior, posterior) at right angles; each ampulla holds a cupula with hair cells.
- Otolith organs: utricle and saccule with maculae weighted by otoconia (calcium carbonate crystals).
- Vestibular nerve to the vestibular nuclei in the brainstem and to the cerebellum.
- Horizontal VOR pathway: vestibular nuclei, opposite abducens nucleus (lateral rectus) and, through the medial longitudinal fasciculus, the medial rectus of the other eye.
Clinical physiology
- Each canal pairs with one on the other side; at rest both fire equally. Head rotation increases firing on one side and reduces it on the other.
- A sudden one-sided loss mimics constant rotation: the eyes drift slowly and a fast corrective beat follows, producing nystagmus and vertigo.
- The brain compensates over days to weeks, which is why vestibular rehabilitation works.
Timing of vertigo points to the cause
| Pattern | Typical cause | Hearing |
|---|---|---|
| Seconds, triggered by head position | BPPV | Normal |
| Minutes to hours, recurrent attacks | Ménière disease | Fluctuating loss, tinnitus, fullness |
| Days, constant, after a viral illness | Vestibular neuritis | Normal |
| Days, constant, with hearing loss | Labyrinthitis | Reduced |
| Acute with neurological signs or inability to walk | Posterior fossa stroke (central) | Usually normal |
Clinical correlation
- Do not treat every dizzy patient as 'labyrinth': ask about timing, triggers, hearing and neurological symptoms.
- Vertigo with weakness, slurred speech, double vision or vision problems is a stroke warning until proven otherwise.
- Vestibular suppressant drugs help acute nausea but delay compensation if used for long.
- BPPV is the most common type of vertigo and is cured at the bedside, not with drugs.
Next step / Initial management
- Bedside exam: spontaneous and gaze nystagmus, HINTS, Dix-Hallpike, gait and a full cranial nerve and cerebellar exam.
- BPPV: repositioning manoeuvre (Epley) and home exercises; no imaging when the exam is typical.
- Vestibular neuritis: short course of vestibular suppressants and antiemetics for the first days, then early vestibular rehabilitation.
- Refer as an emergency (same day, stroke pathway) if vertigo comes with neurological signs, new severe headache, inability to walk, or a central pattern on HINTS.
- Refer routinely to ENT for recurrent vertigo with hearing loss (possible Ménière), atypical or refractory BPPV, or persistent imbalance.
Test yourself
Think of the answer, then tap the question to see it.
A woman has seconds of spinning each time she rolls over in bed; hearing is normal. What test confirms the diagnosis?
The Dix-Hallpike manoeuvre, which reproduces vertigo with nystagmus in BPPV; treatment is a repositioning manoeuvre such as Epley.
Which reflex keeps a reading text still while you shake your head, and which bedside test checks it?
The vestibulo-ocular reflex, which turns the eyes opposite to the head. The head impulse test checks it; caloric testing is another way.
A patient has acute constant vertigo and cannot stand unaided; there is pure vertical nystagmus. Peripheral or central?
Central: pure vertical or torsional nystagmus and inability to stand point to the brainstem or cerebellum. Emergency referral on the stroke pathway.
Elsewhere in DurgiPedia
Connections
Educational content; it does not replace a medical assessment and is not a clinical instruction. For a real case, follow current guidelines and specialist advice.
Sources: Physiology, Vestibular System (StatPearls (NCBI Bookshelf), 2023); Balance Disorders (National Institute on Deafness and Other Communication Disorders (NIDCD), NIH, 2018); Ménière's Disease (National Institute on Deafness and Other Communication Disorders (NIDCD), NIH, 2024); Benign positional vertigo (MedlinePlus, US National Library of Medicine, 2025).
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Representative model, for educational purposes only.