Inclusion Criteria:  Age ≥ 18 years old All patients complaining of instability when standing up and referred for an ENMG Patient informed and having expressed his non-opposition to participating in the research  Exclusion Criteria:  Patient's refusal to participate in the study Impossibility to stand No affiliation to health insurance Patients under a legal protection measure or unable to express their will Patient under the State Medical Assistance (AME) Patient under 18 years old Pregnant women, parturients and breast-feeding mothers