Abstracts

Rationale: Syncope is common, especially in veterans who are older and with multiple comorbidities. Despite careful evaluation, cause of syncope remains unknown in 41% of cases (Kapoor, 1990). This study aims to determine diagnostic yield of epilepsy monitoring unit (EMU) evaluation and estimate the frequency of psychogenic pseudo-syncope for veterans with syncope of unknown origin referred to our center. Methods: We retrospectively reviewed EMU admission from January 2013 to April 2016. Patients were included if they were referred for syncope, falls, or drop attacks, and at least one type of cardiac workup was unrevealing. Data collected included: demographics, duration and frequency of symptoms, medical and psychiatric diagnoses, previous diagnostic studies, anti-epileptic medications. Diagnosis of psychogenic pseudo-syncope required discordant presence of intact posterior dominant rhythm in the setting of clinical unresponsiveness with loss of postural tone without evidence of hypotension or bradycardia. Results: We reviewed 454 cases. Forty-nine patients met inclusion criteria. Age ranged between 30 ?" 79 years. All except two were female. Prior evaluation included electrocardiogram in all patients, echocardiogram in 33, Holter monitoring in 17, tilt table test in 10, and vascular imaging in 26 patients. Sixteen patients (32.6%) were diagnosed with psychogenic pseudo-syncope. Spells captured in three cases (6.1%) were epileptic in origin, with resulting ictal bradycardia or asystole in two patients. Six patients (12.2%) were diagnosed with post-tussive syncope with evidence of cough preceding the event and diffuse slowing with or without attenuation on EEG. Six cases (12.2%) had orthostatic hypotension with spells, one with diffuse slowing on EEG. The diagnosis remained inconclusive in 18 patients (36.7%). Mean age for cases with pseudo-syncope was 52.8 years old (range 41-65). Duration of symptoms was 1 - 40 years (mean 9 years). Event frequency was 10 per day to once per 3 months (mean 45 per month). Average numbers of psychiatric and medical diagnoses were 2.4 and 3.8, respectively. Induction by hyperventilation, photic stimulation, and verbal suggestion successfully reproduced pseudo-syncope in 12 patients. Mean age for cases with physiologic diagnoses was 56.6 years old (range 37-75). Duration of symptoms was 1 month to 15 years (mean 4.9 years). Event frequency was 3 per day to 2 per year (mean 27 per month). Numbers of psychiatric and medical diagnoses were 1.6 and 6, respectively. In terms of age, duration of symptoms, event frequency, and medical/psychiatric diagnoses, there was no statistical difference between groups with physiologic versus psychogenic diagnoses in our study. Conclusions: Video EEG monitoring in EMU is a useful tool for further evaluation of patients with apparent syncope of unclear origin. Diagnosis was reached during EMU admission in 63.2% of cases. In our population, 32.6% of cases were proven to have pseudo-syncope -- the majority of which were diagnosed upon performing provocative induction. Funding: None.