Clinical studies on psychological and environmental factors of dizziness reported after the Kumamoto earthquake

Abstract

. The subjects were divided into three groups. Seventy-four subjects who reported dizziness that exacerbated after the earthquake and visited the hospital for a repeat checkup before the scheduled date were designated as the dizziness exacerbated group ( ) after the earthquake group. Thirty-four subjects who had no previous history of dizziness and first experienced it after the earthquake were designated as dizziness developed after the earthquake group. Further, one-hundred and six subjects who did not show any exacerbation of dizziness after the earthquake and visited the hospital for dizziness checkup as scheduled, were designated as the dizziness exacerbated ( ) after the earthquake group. The relationship between dizziness after the earthquake and kinetosis (motion sickness experienced in childhood or after becoming an adult) was studied. The results revealed that in the dizziness exacerbated ( ) after the earthquake group a significant difference (P 0.001) was observed with respect to being less prone to motion sickness on reaching adulthood. The relationship between the susceptibility to motion sickness after becoming an adult, and dizziness exhibited after the earthquake was also studied. In a comparison between the dizziness exacerbated ( ) after the earthquake group and dizziness exacerbated ( ) after the earthquake group, the latter showed a significant difference (0.02 P 0.05) with respect to being susceptible to motion sickness after becoming an adult. Similarly, a comparison between the dizziness exacerbated ( ) after the earthquake group and dizziness developed after the earthquake group, in the latter a significant difference (P 0.01) was observed with respect to being susceptible to motion sickness on reaching adulthood. The results suggested that the number of subjects who were susceptible to motion sickness in childhood and continued to be susceptible after becoming an adult was higher in the dizziness exacerbated ( ) after the earthquake group and the dizziness developed after the earthquake group. The results also suggested that, more often than not, subjects who could not adapt well to vestibular stimu-

Vestibular Function After the 2016 Kumamoto Earthquakes: A Retrospective Chart Review

“…Otoliths are structures composed of a gelatinous matrix combined with calcium carbonate, which is found in the endolymphatic viscous fluid of the saccule and utricle of the inner ear. The inertia experienced by otolith organs stimulates hair cells and their afferent nerves during head movements (7,32,34). The low frequency (0.1-3.5 Hz) (35) horizontal and vertical linear accelerations induced during earthquakes are detected by the vestibular organs, especially the otolith.…”

“…Furthermore, frequent physical shaking may directly impair the vestibular system. Hence, I believe that major earthquakes may concuss the inner ear leading to saccular otolith dysfunction and otoconial detachment from the otolith macula, resulting in canalithiasis and/or cupulolithiasis (7,32,34). Large earthquakes and the physiological and psychological stress they elicit can worsen cardiovascular function (38,39), which can result in inner ear dysfunction and tissue damage (i.e., hair cell loss and damage to their afferent nerves) through circulatory disturbances in the inner ear, leading to MD, SDV, BPPV, or VBI (40).…”