title: Syncope or seizure? The diagnostic value of the EEG and hyperventilation test in transient loss of consciousness.
abstract: In a prospective study of consecutive patients (age 15 or over) with transient loss of consciousness 45 patients had a history of seizure and 74 patients had a history of syncope. All patients had an EEG, ECG, laboratory tests and a hyperventilation test and were followed for an average of 14.5 months. Epileptiform activity in the interictal EEG had a sensitivity of 0.40 and a specificity of 0.95 for the diagnosis of a seizure. Epileptiform activity nearly doubled the probability of a seizure in doubtful cases. If no epileptiform activity was found, this probability remained substantially the same. The hyperventilation test had a sensitivity of 0.57 and a specificity of 0.84 for the diagnosis of syncope. A positive test increased the probability of syncope half as much in doubtful cases. A negative test did not exclude syncope. Laboratory tests were not helpful except for an ECG which was helpful in elderly patients.
authors.affiliation: Academic Hospital, Leiden, The Netherlands.
authors.forename: W A
authors.initials: WA
authors.lastname: Hoefnagels
authors.forename: G W
authors.initials: GW
authors.lastname: Padberg
authors.forename: J
authors.initials: J
authors.lastname: Overweg
authors.forename: R A
authors.initials: RA
authors.lastname: Roos
authors.forename: J G
authors.initials: JG
authors.lastname: van Dijk
authors.forename: H A
authors.initials: HA
authors.lastname: Kamphuisen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003937:Diagnosis, Differential; D004562:Electrocardiography; D004569:Electroencephalography; D005260:Female; D006801:Humans; D006985:Hyperventilation / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012640:Seizures / Q000175:diagnosis* / Q000503:physiopathology; D013575:Syncope / Q000175:diagnosis* / Q000503:physiopathology; D014474:Unconsciousness / Q000503:physiopathology