(otoconium) n. one of the small particles of calcium carbonate associated with a macula in the *saccule or *utricle of the inner ear.
(BPPV) a common cause of vertigo in which the patient complains of brief episodes of rotatory vertigo precipitated by sudden head movements. It is thought to be due to microscopic debris derived from the *otoliths of the utricle and displaced into one of the semicircular canals, most commonly the posterior semicircular canal. The debris is most commonly thought to be free in the canal (canalithiasis; see canalith) but can be attached to the *cupula (cupulolithiasis; see cupulolith). Diagnosis is by performing a *Dix–Hallpike test. Treatment is with a predetermined set of head movements to move the debris from the semicircular canal (see Epley particle repositioning manoeuvre; Semont liberatory manoeuvre; Brandt-Daroff exercises). Surgery is occasionally used to occlude the relevant semicircular canal, cut the *singular nerve or vestibular nerves, or perform a *labyrinthectomy. Drugs are generally ineffective in the treatment of this condition.... benign paroxysmal positional vertigo
n. (pl. maculae) a small anatomical area that is distinguishable from the surrounding tissue. The macula lutea is the yellow spot on the retina at the back of the eye, which surrounds the greatest concentration of cones (see fovea). Maculae occur in the saccule and utricle of the inner ear (see illustration). Tilting of the head causes the otoliths to bend the hair cells, which send impulses to the brain via the vestibular nerve. See also labyrinth.... macula
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