BPPV is a mechanical problem in the inner ear. It occurs when some of the calcium carbonate crystals (otoconia) that are normally embedded in gel in the utricle, become dislodged and migrate into one or more of the 3 fluid filled semicircular canals. When enough of these particles accumulate in one of the canals, they interfere with the normal fluid movement that these canals use to sense head motion, causing the ear to send false signals to the brain.
- Benign – not life threatening.
- Paroxysmal – it comes in sudden, brief spells.
- Positional – It is triggered with certain positions and movements of the head.
- Vertigo – Results in a false sense of rotatory movement.
Fluid in the semi-circular canals does not normally react to gravity. However, the crystals will move with gravity, thereby moving the fluid in the canal, when it would normally stay still. When the fluid moves, nerve endings in the canal are excited, resulting in a message to the brain that the head is moving in a particular direction, even though it isn’t. When the information being sent to the brain from the inner ear does not match with the information being received from the eyes or with what the muscles and joints are doing, this mismatched information is perceived by the brain as spinning, or vertigo. These spells are generally fairly short lived, between spells some people are symptom free, while others may feel a mild sense of imbalance resulting in nausea.
BPPV is fairly common, effecting about 1 in 1000 people per year, with a lifetime prevalence of about 2.5%. The vast majority of cases occur for no apparent reason, with many people reporting onset of symptoms after getting out of bed and feeling the room begin to spin. There have been associations made between BPPV and trauma, migraine, inner ear infection. There may also be correlation with the side people sleep on. These correlations are not well understood.
Diagnosis of BPPV is made by using the Dix-Hallpike or roll tests, moving a patient’s head into provocative positions, to elicit movement of the dislodged crystal in the canal. The resultant error signals in the brain result in quite a distinct pattern of eye movement called nystagmus. The relationship between the eye muscles and the inner ear, allows the eye to stay focused while we are moving. As the dislodged crystals cause the brain to think that the head is moving, it causes the eyes to move, which makes it look as though the room is spinning.
Treatment of BPPV in the vast majority of cases involves using gravity to reposition the crystals in the correct position in the utricle via a series of simple but very specific, mechanical movements of the head and neck called canalith repositioning manoeuvres. In the case of cupulolitheasis, a rapid head movement in the plane of the affected canal is used to dislodge the crystals first. One of the most common techniques used is known as the Epley Manoeuvre, however this is not always successful, depending on the diagnosis of the particular canal involved.
Generally, treatment success with these mechanical procedures is quite good with upwards of 90% of clients resolving after 1-3 treatments. The rarer cupulolithiasis or stuck crystal can be more stubborn, as can BPPV that result from trauma and which may involve more than one canal. In these cases, the canals need to be corrected one at a time.
Unfortunately, BPPV is a condition which can re-occur periodically with long term re-occurrence rates as high as 50% within a 5 year period. It does appear to generally re-occur in the same canal and as such your therapist may be comfortable teaching you home exercises to attempt to self-correct.