Assessment of otolith function using cervical and ocular vestibular evoked myogenic potentials in individuals with motion sickness

Abstract

The involvement of otolith organs in motion sickness has long been debated; however, equivocal findings exist in literature. The present study thus aimed at evaluating the otolith functioning in individuals with motion sickness. Cervical and ocular vestibular evoked myogenic potentials were recorded from 30 individuals with motion sickness, 30 professional drivers and 30 healthy individuals. The results revealed no significant difference in latencies and amplitudes between the groups (p>0.05). Nonetheless, thresholds were significantly elevated and inter-aural asymmetry ratio significantly higher in motion sickness susceptible group (p < 0.001) for both the potentials. All the individuals in the motion sickness group had high asymmetry ratio at least on one of the two potentials. Thus, reduced response and/or asymmetric otolithic function seem the likely reasons behind motion sickness susceptibility.

Higher Asymmetry Ratio and Refixation Saccades in Individuals with Motion Sickness

“…T he present study revealed no significant difference for cVEMP latencies (P1 and N1) in individuals with motion sickness from that of individuals without motion sickness. The results of the present study are in coherence with earlier studies (Tal et al, 2006;Fowler et al, 2014;Singh et al, 2014). The results suggest that the neural portion of the sacculocollic pathway is not affected in individuals with motion sickness.…”

“…Similarly, the present study also revealed no significant difference in P1N1 complex amplitudes between the two groups. These findings are consistent with earlier studies (Tal et al, 2007;Buyuklu et al, 2009;Singh et al, 2014). However, a few of the earlier studies (Tal et al, 2006;Fowler et al, 2014) are in incongruity with these findings, where it was reported to have affected amplitude in individuals with motion sickness more than that of individuals without motion sickness.…”

“…Thus, it can be interpreted that individuals with motion sickness may have pathology of the sacculocollic pathway. This finding is in coherence with the studies reported previously (Helling et al, 2003;Singh et al, 2014). However, a few studies (Tal et al, 2007;Buyuklu et al, 2009;Fowler et al, 2014) show inconsistency with it.…”

“…A cutoff score of 3.0 was used as the indication criterion for presence of motion sickness. Similar criteria have been adapted in other studies (Simmons et al, 2010;Singh et al, 2014). All the participants were informed initially about the study in detail, and a written consent form was obtained from all the participants.…”

“…However, other studies have come across with no significant statistical difference between the two groups (Tal et al, 2006;Buyuklu et al, 2009). Also the presence of a higher interaural asymmetry ratio in the motion-sickness population was reported in a few studies (Singh et al, 2014), but other studies assert the converse (Buyuklu et al, 2009;Fowler et al, 2014). Furthermore, a recent study on ocular VEMP revealed the presence of higher interaural asymmetry ratio and no difference across latency and amplitude in the motionsickness population (Xie et al, 2012).…”