Equilibrium Research
Online ISSN : 1882-577X
Print ISSN : 0385-5716
ISSN-L : 0385-5716
原著
Tilt illusion後に回転性めまいが生じたmegadolichovertebrobasilar anomaly3症例
横田 淳一霜田 里絵
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ジャーナル フリー

2013 年 72 巻 2 号 p. 83-90

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The illusion of environmental tilt (tilt illusion) is a rare disorder of visuospatial perception, which suddenly turns through a variable arc, most frequently 90-180°, in either three dimensional planes such as yaw, pitch, and roll planes. This rare phenomenon has been reported to occur with pathologic lesions involving the lateral medullary syndrome (Wallenberg's syndrome) or the transient vertebrobasilar ischemia, less commonly cerebral or cerebellar lesions. To our knowledge, as for the case of such visual illusion with a megadolichovertebrobasilar anomaly (MDVBA), there has been only one case report by Slavin & LoPinto (1987) before. However, the pathophysiology of this rare visual illusion is still unclear.
We report herein on three cases of tilt illusion with a MDVBA, who experienced transiently (within a few minutes) visual inversion of 90°in the pitch plane (patient 1), 30° counter-clockwise rotation in the roll plane (patient 2), and 90°clockwise inversion in the roll plane (patient 3), accompanied with vertigo and nausea. In our outpatient clinic, no abnormal findings could be found out in neurological and neuro-otological studies in the present three cases. MRI findings in each case disclosed compression of the lateral medulla by dolichoectatic vessels. Consequently, it was assumed that compression of the lateral medulla by dolichoectatic vessels the transient ischemia resulting in the inactivation of vestibulo-otolith pathways running from the medulla to the supratentorial structures. In our present cases, it was hypothesized that the tilt illusion might result from the sudden and transient spatial misperception in the cortex such as the posterior parietal cortex between the inappropriate vestibulo-otolith input caused by a transient otolithic dysfunction and other intact visual and somatosensory inputs. In conclusion, the tilt illusion appears to be related to mismatch among vestibular, visual and somatosensory inputs. In order to investigate the pathophysiological mechanism of the tilt illusion, further studies are necessary to systematically examine the vestibular, visual and proprioceptive functions in patients who have experienced the tilt illusion.

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© 2013 一般社団法人 日本めまい平衡医学会
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