Effect of betel nut chewing on the otolithic reflex system.

Objective: This study investigated the effect of betel nut chewing on the otolithic reflex system.

Methods: Seventeen healthy volunteers without any experience of chewing betel nut (fresh chewers) and 17 habitual chewers underwent vital sign measurements, ocular vestibular-evoked myogenic potential (oVEMP), and cervical VEMP (cVEMP) tests prior to the study. Each subject then chewed two pieces of betel nut for 2min (dosing). The same paradigm was repeated immediately, 10min, and 20min after chewing. On a different day, 10 fresh chewers masticated chewing gum as control.

Results: Fresh chewers exhibited significantly decreased response rates of oVEMP (53%) and cVEMP (71%) after dosing compared with those from the predosing period. These abnormal VEMPs returned to normal 20min after dosing. In contrast, 100% response rates of oVEMP and cVEMP were observed before and after masticating chewing gum. In habitual chewers, the response rates of oVEMP and cVEMP were 32% and 29%, respectively, 20min after dosing.

Conclusion: Chewing betel nuts induced a transient loss of the otolithic reflexes in fresh chewers but may cause permanent loss in habitual chewers.

Significance: Chewing betel nuts can cause a loss of otholitic reflex function. This creates a risk for disturbed balance and malfunction, for instance, during driving.