What happens to BPPV crystals after maneuvers remove them? 

After successful maneuvers, one of our readers wondered about the fate of the removed crystals.  Do they go back to their original position in the gravity sensor, get washed away from the inner ear, or dissolve?  If so, can they regenerate?

Read more: What happens to BPPV crystals after maneuvers remove them? 

The otoconia are the crystals of calcium carbonate in the inner ear that are used to sense gravity.  They are already forming in the fetus as early as two months of gestation.  Calcium builds up on a collagen matrix to form each otoconium.  They are embedded in a similar sticky protein matrix that holds them to the gravity sensors loosely enough that they and the membrane can shift as the head moves.  This movement as you tilt your head allows you to sense gravity.  They are designed to be permanent and to last throughout life.

Unfortunately, they do not always remain healthy.  Calcium can erode from the crystals in some disorders, leaving a moth-eaten appearance.   Older people often show cracks and furrows on the surface of the crystals, and pieces of broken crystals can be seen.  Head trauma, lack of bloodflow, calcium disorders such as osteoporosis, and genetic defects in otoconia formation can all contribute to degeneration.  Some antibiotics (aminoglycosides) can dissolve calcium from the crystals in addition to other serious effects on the inner ear. 

When successful maneuvers are done for BPPV, the crystals are removed from the semicircular canals where they don’t belong, and return to the sac containing the utricle, a gravity sensor.  However, they don’t necessarily re-attach.  They may just settle down in the sac, waiting for an opportunity to go back into the canal and cause BPPV again.  They always remain within the inner ear.  If they do undergo slow degeneration, the calcium leaves but the collagen matrix may remain. 

Unless you have been exposed to aminoglycoside antibiotics or have serious defects of the inner ear, there are dense piles of otoconia on the utricle that are still attached even when you have had BPPV.  This means that the utricle continues to function, but with aging it will become a bit less effective.  The damaged or wandering crystals do not get replaced once they are detached from the utricle, and no new ones form. 

In experimental animals, otoconia can be removed from the utricle by centrifuging (spinning the animals at high acceleration).  This is very similar to the movements in some spinning “G-force” amusement park rides.   These rides are not a good idea if you want to keep your otoconia in place as long as possible.