Investigations

• EEG ^c
• hyperventilation test: (at least 2 symptoms associated with episode reproduced) ^c

Why?

Epileptiform features on an EEG makes a seizure more likely, and a positive hyperventilation test makes one less likely

Patient	Target Disorder and Reference Standard	Diagnostic Test	LR+ (95% CI)	Post-test Probability	LR- (95% CI)	Post-test Probability
unexplained transient loss of consciousness c (pre-test probability: 38%)	seizure (clinical features)	epileptiform EEG	7.4 (2.7 to 21)	82%	0.63 (0.50 to 0.81)	28%
		hyperventilation test	0.29 (0.13 to 0.62)	15%	1.9 (1.4 to 2.8)	54%