Fig. 3

Recumbent and Standing Dizziness and Lightheaded Symptoms in Stratified Groups. Controls and CFS were stratified based on ROC thresholds of 2. Four controls had Dizziness and Lightheadedness symptoms only when standing. The other 21 controls were asymptomatic. Eleven CFS subjects reported scores < 2 while recumbent and standing; 8 had no Dizziness and 6 had no Lightheadedness. For Persistent OI, 16 reported recumbent and standing symptoms ≥ 2, and, in Postural OI, 12 reported only standing complaints ≥ 2. CFS subjects with recumbent and standing complaints ≥ 2 had significantly higher symptoms compared CFS subjects with no symptoms and those only with standing symptoms. Lines indicate trend of score from recumbent to standing. *p < 0.05 Mann–Whitney U test Postural OI controls vs. No OI controls. Black bars indicate p < 0.05, Mann–Whitney U test vs. CFS No OI and CFS Persistent OI CFS group for recumbent and standing symptoms