Researchers at Monash University Medical Center, Melbourne, Australia evaluated the yield and clinical utility of outpatient, short-term video-EEG monitoring (OVEM) as a diagnostic tool in routine clinical practice. Of a total of 175 patients with records examined retrospectively, 111 were female and 64 male, with an age-range of 16-87 years (mean 36 years). Mean length of recording was 3.8 hrs (range 1-6.8 hrs). Pre-test frequencies of clinical events were <1 per week (30.1%), 2-6 per week (48.7%), and >7 per week (21.2%). Focal slowing occurred in 24 recordings (13.7%) and background and generalized slowing in 18 (10.3%). Interictal epileptiform discharges (IED) were focal in 15 (8.6%) and generalized in the same frequency. Epileptic seizures were captured in 12 patients (6.9%). Psychogenic nonepileptic seizures (PNES) occurred in 65 (37.1%) patients. The diagnostic yield for PNES was 37.1%, for IED 17.2%, and for epileptic seizures 6.9%. Before OVEM, a provisional diagnosis of epilepsy was made in 136 (77.7%) patients; after OVEM, the diagnosis of epilepsy was changed to PNES in 28.6%, and from PNES to epilepsy in 2.3%. OVEM has a higher yield for PNES than epileptic seizures and IED. The yield of PNES was >5 times that of epileptic seizures, and diagnosis was changed from epilepsy to PNES in > one-fourth of patients. 
COMMENT. Outpatient short-term VEM changes the pre-test diagnosis in 30.9% of patients. It is a useful diagnostic test for PNES and has a higher yield for PNES than epilepsy. OVEM is relatively cheaper than inpatient long-term VEM, but the shorter recording duration may miss some patients with epileptic seizures. OVEM is considered in the diagnostic work-up of suspected PNES prior to an inpatient long-term VEM.