Inclusion Criteria:  Patient whose age is ≥ 18 years French-speaking patient.  Patient presenting on admission to the emergency department with an isolated AVS defined by a course of more than one hour and less than one week and the presence of at least one symptom among:  vertigo: an illusion of displacement of the subject in relation to surrounding objects or surrounding objects in relation to the subject, a sensation of rotation, displacement of the body in the vertical plane, instability described as pitching or as a "spinning head", sometimes associated with vegetative signs (nausea, vomiting, pallor, sweating, slowing of the heart rate) and/or spontaneous or positional nystagmus, and/or a gait disorder: such as imbalance with lurching, or a shaky gait, or simple instability. A patient may be included several times during the study period provided that they are distinct acute episodes of isolated AVS.  Exclusion Criteria:  Patient under guardianship or curatorship Patient deprived of liberty Patient under court protection Patient objecting to the use of his/her data for this research Patient with focal neurological signs concomitant with AVS: a language or writing disorder, a speech disorder such as dysarthria, a disorder in the execution of voluntary movements, a sensory, motor or visual deficit, involuntary abnormal movements Patient with a history of oculomotor paralysis.