What causes sudden vertigo, and why a simple head manoeuvre often fixes it

Most brief, spinning dizziness that strikes when you roll over in bed or tip your head back is not a sign of anything sinister. It is benign paroxysmal positional vertigo, or BPPV — short-lived episodes of vertigo set off by rapid changes in head position, and one of the commonest causes of dizziness seen in primary care and ear, nose and throat clinics [s1]. Its cause is mechanical, and so is the most effective treatment: in randomised trials, a repositioning technique called the Epley manoeuvre cleared the vertigo in 56% of people, against 21% given a dummy procedure [s1].

A mechanical problem with a mechanical fix

BPPV happens when tiny calcium-carbonate crystals, normally embedded in one part of the inner ear, come loose and drift into a semicircular canal, where they make the balance organ misfire with movement. The Epley manoeuvre is a sequence of slow head and body positions that rolls those crystals back out of the canal. A Cochrane review gathered 11 trials with 745 patients to test whether it works [s1].

It does. Complete resolution of vertigo occurred far more often after the Epley manoeuvre than after a sham manoeuvre or no treatment (odds ratio 4.42, 95% confidence interval 2.62 to 7.44; five studies, 273 participants), with the proportion of people resolving rising from 21% to 56% [s1]. The Dix-Hallpike test — the positional test used to diagnose BPPV — turned from positive to negative far more often in the treated group too (OR 9.62, 95% CI 6.0 to 15.42; eight studies, 507 participants) [s1]. In one trial a single Epley treatment outperformed a week of thrice-daily Brandt-Daroff exercises done at home (OR 12.38, 95% CI 4.32 to 35.47) [s1]. Adverse effects were infrequent [s1]. Where the Epley was tested against other particle-repositioning manoeuvres, such as the Semont or Gans techniques, the review found no clear difference between them [s1] — several approaches work, and the reassuring message is that the mechanical treatment as a category is what matters. BPPV is not evenly spread: the patients in these trials ranged from 18 to 90 years old, with a male-to-female ratio of about 1 to 1.5 [s1].

What the guideline says

The American Academy of Otolaryngology's 2017 BPPV guideline update, drawing on 2 clinical practice guidelines, 20 systematic reviews and 27 randomised controlled trials, points in the same direction [s2]. Its explicit aims include increasing the use of the repositioning manoeuvres that actually treat the problem, while reducing two things clinicians reach for out of habit: vestibular-suppressant medications, such as sedating antihistamines, which dull symptoms without fixing the cause, and unnecessary radiographic imaging like CT or MRI scans [s2]. The starting point is diagnosis: the guideline recommends confirming posterior-canal BPPV with the Dix-Hallpike positional test rather than assuming it [s2]. The manoeuvre is quick, drug-free and low-risk, which is why the evidence favours it over medication for typical BPPV.

Vertigo that is not BPPV

The reviews here concern one specific, benign cause of vertigo, and not every spinning sensation fits it [s1]. Vertigo that is constant rather than triggered by a change in position, or that comes with a new severe headache, double vision, slurred speech, facial or limb weakness, numbness, trouble walking, or a sudden change in hearing, is not the picture of ordinary BPPV and can signal a stroke or another neurological problem. That combination is a reason to seek urgent medical attention rather than to try a home manoeuvre. Vertigo accompanied by hearing loss, ringing or a sense of fullness in one ear points to a different inner-ear disorder and also warrants assessment.

What this means in practice

For the common, positional kind, the useful message is that a mechanical problem has a mechanical answer, and that sedative "anti-dizziness" pills are not the treatment the best evidence supports [s2]. The Epley manoeuvre is often performed by a clinician or physiotherapist who can first confirm which ear and which canal is involved, and some are taught to repeat a version of it at home. Whether a particular bout of dizziness is BPPV, and whether it is safe to treat that way, is a clinical judgement this article does not make — but the diagnosis is common, the fix is simple, and it rarely requires a drug.