Benign Paroxysmal Positional Vertigo - Cause

Cause

Within the labyrinth of the inner ear lie collections of calcium crystals known as otoconia or otoliths. In patients with BPPV, the otoconia are dislodged from their usual position within the utricle and migrate over time into one of the semicircular canals (the posterior canal is most commonly affected due to its anatomical position). When the head is reoriented relative to gravity, the gravity-dependent movement of the heavier otoconial debris (colloquially "ear rocks") within the affected semicircular canal causes abnormal (pathological) fluid endolymph displacement and a resultant sensation of vertigo. This more common condition is known as canalithiasis.

In rare cases, the crystals themselves can adhere to a semicircular canal cupula rendering it heavier than the surrounding endolymph. Upon reorientation of the head relative to gravity, the cupula is weighted down by the dense particles thereby inducing an immediate and maintained excitation of semicircular canal afferent nerves. This condition is termed cupulolithiasis.

There is evidence in the dental literature that malleting of an osteotome during closed sinus floor elevation, otherwise known as osteotome sinus elevation or lift, transmits enough percussive and vibratory forces capable of detaching otoliths from their normal location and leading to the symptoms of BPPV.

It can be triggered by any action which stimulates the posterior semi-circular canal which may be:

• Tilting the head
• Rolling over in bed
• Looking up or under
• Sudden head motion
• Post head injury

BPPV may be made worse by any number of modifiers which may vary between individuals:

• Changes in barometric pressure - patients often feel symptoms approximately two days before rain or snow
• Lack of sleep (required amount of sleep may vary widely)
• Stress

BPPV is one of the most common vestibular disorders in patients presenting with dizziness and migraine is implicated in idiopathic cases. Proposed mechanisms linking the two are genetic factors and vascular damage to the labyrinth.

Although BPPV can occur at any age, it is most often seen in people over the age of 60. Besides aging, there are no major risk factors known for developing BPPV, although previous episodes of trauma to the head or inner ear infections known as labyrinthitis, may predispose individuals to future development of BPPV.