Benign paroxysmal positional vertigo pathophysiology

It is understood that BPPV is the result of free floating calcium carbonate crystal formation (canalolithiasis) inside the semicircular canals. Movement of these otoconia with head movement will result in inappropriate stimulation of hair cells following movement of the endolymph. In some studies it was demonstrated that people with BPPV in their first degree family are at more risk of development of the disease themselves. One of the theories behind the familial aspect of BPPV is that these families might have less adhesive gelatinous matrix of the utricular macula which predisposed them to BPPV. On microscopic histopathological analysis, crystals with combination of a gelatinous matrix and calcium carbonate are characteristic findings of otoconia in BPPV.

The normal physiology of semicircular canals can be understood as follows:^[1]

• One of the most important inner ear structures are horizontal, superior (anterior) and posterior semicircular canals.
• There is an osseous ampullae at the end of each semicircular canal which consist of ampulla crest, the crista ampullaris, and hair cells.
• Semicircular canals are hollow structures with endolymph inside them.
• The movement of endolymph following changing head position will stimulate hair cells to send an impulse to the brain, determining the head position.
• The horizontal semicircular canal detects the head movement in the transverse plane (head turning to right and left).
• The superior (anterior) semicircular canal detects head rotational movement in the sagittal plane (head nodding).
• The posterior semicircular canal detects head rotational movement in the coronal plane (head touching the shoulders)

• It is understood that BPPV is the result of free floating calcium carbonate crystal formation (canalolithiasis) inside the semicircular canals.^[2]
• These debris are normally attached to the membrane of utriculus, a gravity-sensitive structures in the inner ear.
• Movement of these otoconia with head movement will result in inappropriate stimulation of hair cells following movement of the endolymph.
• The inappropriate impulses to the brain will result in false sensation of spinning.

• The development of idiopathic BPPV may be the result of multiple genetic mutations.^[3][4]
• In some studies it was demonstrated that people with BPPV in their first degree family are at more risk of development of the disease themselves.
• One of the theories behind the familial aspect of BPPV is that these families might have less adhesive gelatinous matrix of the utricular macula which predisposed them to BPPV.

Conditions associated with BPPV include:^[5][6]

• Migraine headache
• Diabetes mellitus
• Meniere disease

• there is no gross pathology findings with BPPV.

• On microscopic histopathological analysis, crystals with combination of a gelatinous matrix and calcium carbonate are characteristic findings of otoconia in BPPV.^[2]

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