Yield of First and Subsequent EEGs in Patients with Newly Diagnosed Focal Epilepsy
Daniel Newman1, Dennis Dlugos2, Manu Hegde3, Jules Beal4, Jonathan Halford5, Jacqueline French6
1Touro College of Osteopathic Medicine, Harlem, NY, USA, 2Departments of Neurology and Pediatrics, Children's Hospital of Philadelphia, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA, 3Department of Neurology, University of California San Francisco, San Francisco, CA, USA, 4Department of Pediatrics, Division of Child Neurology, Weill Cornell Medical, New York, NY, USA, 5Department of Neurology, Medical University of South Carolina, Charleston, SC, USA, 6Department of Neurology, NYU School of Medicine, New York, New York, U.S.A.
Objective:
To assess the diagnostic yield of first and second EEG in confirmed newly diagnosed focal epilepsy.
Background:
The Human Epilepsy Project is a multicenter, international prospective observational study that enrolled newly diagnosed persons with focal epilepsy within 4 months of initial diagnosis.
Design/Methods:
Subjects with normal tests were adjudicated by 3 epileptologists to confirm a diagnosis of focal epilepsy. Per protocol, subjects who did not have a clinical EEG that captured epileptiform abnormality, or seizure underwent a 1-hour EEG after partial sleep deprivation. All subjects had digital EEG uploaded to a cloud database, which was reviewed by an EEG core to determine any abnormality/epileptiform activity. Other EEGs were identified in collected medical records.
Results:
Of 399 subjects 231 (57.9%) had focal abnormalities on first EEG. Of all subjects, 160 EEGs (40.1%) were epileptiform with/without focal slowing and 71 (17.8%) showed only focal slowing. 161 (40.4%) had a second EEG for review. Of 239 with no epileptiform abnormalities (initially normal (IN) or initial focal slow (IFS)), 122 (51.0%) had a second EEG for review. The yield for epileptiform activity for those with IFS was 21/38 (55.3%) vs 28/84 (33.3%) for IN. In addition, 15 (17.9%) of IN demonstrated focal slowing on second EEG. Overall, for IN/IFS subjects who had a second EEG, 62 (50.8%) showed a clinically relevant abnormality (focal slow or epileptiform). 47 (29.2%) patients with 2 EEGs never demonstrated any abnormalities. In total 61 (38.1%) of the 160 initially epileptiform EEGs had a second EEG. None demonstrated a clinically relevant new finding.
Conclusions:
The yield of finding epileptiform abnormalities after the first EEG decreases on the second EEG, which is consistent with current literature. If no epileptiform activity is captured on an initial EEG, there is benefit to subsequent EEG to better define epileptogenic focus and type.
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