Comparison of semiologies between tilt-induced psychogenic nonsyncopal collapse and psychogenic nonepileptic seizures

We sought to characterize the clinical features of tilt-induced psychogenic nonsyncopal collapse (PNSC) from a cohort of young patients and to compare the semiologies between PNSC and EEG-confirmed psychogenic nonepileptic seizures (PNES). A PNSC diagnosis was made if a clinical event occurred during tilt-table testing that the patient regarded as fainting, but neither hypotension nor EEG changes were present. A diagnosis of PNSC was made in 17.6% of all patients referred during the 15-month study period. Cohorts with psychogenic nonsyncopal collapse (n=40) and PNES (n=40) did not differ in age (15.5±2.2 versus 14.6±2.7, p=.11) or female gender (80% versus 72.5%, p=.43). Psychogenic nonsyncopal collapse events were briefer than PNES events (median: 45 versus 201.5s, p<.001). Negative motor signs (head drop, body limpness) predominated in PNSC (85% versus 20%, p<.001), while the positive motor signs of convulsion occurred more often with PNES (90% versus 30%, p<.001). Behavioral arrest (25% versus 32.5%, p=.46) and eye closure (85% versus 72.5%, p=.21) did not differ between PNSC and PNES. Patients with PNSC were more likely to be tearful before (30% versus 7.5%, p=.02) and after (62.5% versus 7.5%, p<.001) an event. In conclusion, although overlap exists, the features of PNSC generally appear similar to neurally mediated syncope, while the features of PNES generally appear similar to epileptic seizures. Psychogenic nonsyncopal collapse and PNES likely represent similar disorders that differ primarily by clinical semiologies and referral patterns.