Canalith
Canalith
Three names come up constantly in conversations about positional vertigo, usually as if they were interchangeable options on a menu. They are not. They embody three different ideas about what to do with debris that has ended up in the wrong part of the inner ear, and the differences matter — which is exactly why the choice belongs to the clinician who examined you.
Read this as an explainer, not as instructions. There are no steps here to follow at home, deliberately. A repositioning procedure is chosen on the basis of a diagnosis: which ear, which canal, and which behaviour the debris is showing. Performed on the wrong side or the wrong diagnosis it can be ineffective, can move debris somewhere less convenient, or can provoke a severe reaction — and vertigo that turns out not to be positional at all is a reason to be examined, not repositioned. These procedures should be learned from and directed by a clinician.
All three assume the same underlying story, which we covered in why the room spins when you roll over in bed. Tiny calcium carbonate crystals that normally sit in a gravity-sensing patch have come loose and drifted into one of the semicircular canals — the loops that sense rotation. Gravity then drags them through the canal whenever your head changes orientation, producing a rotation signal your brain has no reason to disbelieve. Hence the brief, violent, position-dependent spin.
Given that story, there are only two things you can do. You can use gravity deliberately, moving the head through a sequence of positions so the debris travels out of the canal to somewhere harmless. Or you can accept its presence and repeatedly provoke the response until the brain stops reacting so strongly. The first is repositioning, the second habituation. Epley and Semont are repositioning; Brandt-Daroff is habituation. That is the deepest division among the three.
The Epley manoeuvre, described by John Epley in 1992 and also known as the canalith repositioning procedure, is a sequence of head and body positions held in turn, designed to walk the debris around the canal and out of its far end, back into the chamber where loose crystals do no harm.
Its defining characteristics are that it is slow and sequential. Each position is held long enough for the debris to finish settling before the next change, and each change takes the head a further step around the arc of the canal. The mental image is a marble tipped gently around the inside of a curved tube until it falls out of the open end.
This also explains why the version matters. The sequence is mirrored for the left and the right ear, and it is built around the geometry of a particular canal — most commonly the posterior canal, where loose debris most often ends up. The same movements applied to the opposite side are not a neutral act, which is the usual reason a clinician will not simply hand out a diagram.
The Semont liberatory manoeuvre, described by Semont, Freyss and Vitte in 1988, targets the same problem with the opposite tactic. Where Epley coaxes, Semont uses momentum: a rapid movement from one side-lying position to the other, through sitting, so that the debris is dislodged and thrown clear rather than eased around.
The reason for the difference is partly the possibility that debris is not floating freely at all but has become attached to the sensing structure at the base of the canal. Gently tipping something that is stuck achieves nothing; a brisk movement is intended to shake it loose. Semont also involves a different set of positions from Epley, which can suit a particular neck, back or hip better.
The speed that makes it work is also what makes it a poor candidate for self-experimentation: a rapid whole-body movement, performed unsupervised by someone whose head is about to start spinning, is a fall risk. It has its own side and canal specificity too.
The Brandt-Daroff exercises, described by Brandt and Daroff in 1980, are a different kind of thing altogether, and this is where most of the confusion comes from. They are not a single procedure performed once by a clinician but a set of repetitions performed by the patient, in sets across the day and over days or weeks, as prescribed.
Their goal is habituation rather than relocation: by repeatedly and deliberately provoking a diminishing response, the aim is that the nervous system learns to weight the false signal less heavily, with the incidental possibility that repeated movement helps disperse the debris. The consequence is that they are expected to be uncomfortable in a way a successful repositioning procedure is not. Someone told to do Brandt-Daroff has been asked to sign up for a course of work.
Because they are less precisely targeted at one canal and one side, Brandt-Daroff exercises are sometimes prescribed as follow-up work at home, or when a repositioning procedure is not appropriate or has not been effective. That is a clinical judgement, not a preference.
You may hear others named — the half somersault, described by Foster and colleagues in 2012, is another repositioning approach, and separate procedures exist for canals other than the posterior one. The same rule applies to all of them.
Every one of these procedures encodes an answer to three questions: is the problem debris in a canal at all; if so, which ear; and which canal. A clinician answers those by taking a history and performing a positional test, watching the direction, latency and duration of your eye movements as your head is moved into specific positions. Those eye movements are the readout, they are not something you can observe in yourself, and no diary entry or article substitutes for them.
What you can usefully bring to that examination is a record: when episodes happen, how long they last, which movement provokes them, which side, what comes with them — the material covered in how to keep a vertigo diary your doctor can actually use.
Canalith does not choose a manoeuvre for you and does not tell you which ear is involved; it cannot know either. The guided sessions stay hidden until you confirm that a clinician has prescribed a specific exercise and told you which side it is for. From then on its job is faithful execution and record-keeping: it holds the timings from the published protocols, moves a figure through the positions alongside you, marks each change with a haptic and a spoken cue so you can keep your eyes closed, and logs that you did it. The app is not on the App Store yet; there is a waitlist on the home page, and support answers questions about how it works.
This article is an explainer, not medical advice, and nothing in it is a set of instructions. Do not attempt a repositioning manoeuvre that has not been prescribed for you, and do not begin one after only reading about it. See a clinician about new or recurring vertigo. Treat it as urgent — emergency care, the same day — if vertigo comes on suddenly together with any of: double vision, weakness or numbness on one side, trouble speaking or swallowing, a severe or unusual headache, difficulty walking or standing, or new hearing loss in one ear.