1/2. vertigo in virtual reality with haptics: case report.A researcher was working with a desktop virtual environment system. The system was displaying vector fields of a cyclonic weather system, and the system incorporated a haptic display of the forces in the cyclonic field. As the subject viewed the rotating cyclone field, they would move a handle "through" the representation of the moving winds and "feel" the forces buffeting the handle as it moved. Stopping after using the system for about 10 min, the user experienced an immediate sensation of postural instability for several minutes. Several hours later, there was the onset of vertigo with head turns. This vertigo lasted several hours and was accompanied with nausea and motion illusions that exacerbated by head movements. Symptoms persisted mildly the next day and were still present the third and fourth day, but by then were only provoked by head movements. There were no accompanying symptoms or history to suggest an inner ear disorder. physical examination of inner ear and associated neurologic function was normal. No other users of this system have reported similar symptoms. This case suggests that some individuals may be susceptible to the interaction of displays with motion and movement forces and as a result experience motion illusions. Operators of such systems should be aware of this potential and minimize exposure if vertigo occurs.- - - - - - - - - - ranking = 1keywords = environment (Clic here for more details about this article) |
2/2. Illusion of tilting of the visual environment. Report of five cases.The symptom of sudden tilting of the visual surroundings is described in detail based on experience with five patients. patients perceive the visual fields as suddenly turning through a variable arc, most frequently 90-180 degrees, usually associated with dizziness. In three patients with vertebral-basilar artery disease, visual tilting was more closely related to local pontomedullary ischemia than to posterior cortical ischemia. It is suggested that most instances of this illusion are due to disorders of the vestibular-otolithic apparatus or its central connections, most frequently from vertebral-basilar ischemia.- - - - - - - - - - ranking = 4keywords = environment (Clic here for more details about this article) |