Figure 1.

Cardiovascular responses to orthostatic stress. (a) Shows the normal response to standing in healthy controls. (b) Shows the significant fall in systolic blood pressure on standing in all patients with FD. (c) Shows the significant decrease in estimated blood pressure at brain level induced by standing in patients with FD. (d) Shows that despite severe systemic hypotension while standing, patients with FD had only minimal changes in mean MCA velocity that were comparable with normal controls without hypotension. SBP: systolic blood pressure; FD: familial dysautonomia; MCA: middle cerebral artery. Data are mean ± s.e.m.