Affected-Ear-Up 90°Maneuver Proves That Nystagmus Does Not Occur by the Stimulation to the Macula of the Utricle

Background: The utricular macula is located on the floor of the utricle, approximately in the plane of the lateral semicircular canal, and is oriented to respond best to lateral tilts and side-to-side or fore-and-aft translations of the head. However, the details of the otolith ocular reflex are unknown. Pathophysiology of transient direction-changing geotropic positional nystagmus is a canalolithiasis in the lateral semicircular canal. The principle of affected-ear-up 90° maneuver is moving debris from a long arm to the utricle, therefore debris stimulates the utricular macula in the sitting position after the treatment. Objective: To clarify whether nystagmus occurs by the stimulation to the macula of the utricle. Methods: The subjects were 10 patients with lateral semicircular canal canalolithiasis. After the diagnosis, we performed affected-ear-up 90° maneuver immediately. We observed eye movements in the sitting position (chin-down 30°) just after the treatment. Results: No one showed nystagmus in the sitting position after the treatment. In all patients, positional nystagmus disappeared within 7 days after the treatment. Conclusion: Nystagmus does not occur by the stimulation to the macula of the utricle. Hence, we cannot assess the function of the utricle by the analysis of eye movements, and ocular counter-rolling is considered to be a semicircular canal ocular reflex.

Light Cupula:To Be Or Not to Be?

Benign paroxysmal positional vertigo(BPPV)represents the most common form of positional vertigo.It is caused by dislodged otoconia that freely float in the semicircular canals(canalolithiasis)or attach to the cupula(cupulolithiasis).A cupulolithiasis-type(or a heavy cupula-type)of BPPV implicating the lateral semicircular canal(LSCC)exhibits persistent ageotropic direction-changing positional nystagmus(DCPN)in a head-roll test.However,in some cases,unlike any type of BPPV,persistent geotropic DCPN cannot be explained by any mechanisms of BPPV,and don’t fit the current classifications.Recently,the notion of light cupula has been introduced to refer to the persistent geotropic DCPN.In this study,we looked at the clinical features of light cuplula and discussed the possible mechanisms and therapeutic strategies of the condition.The notion of light cupula is a helpful addition to the theory of peripheral positional vertigo and nystagmus.