Periodic focal epileptiform discharges

William O. Tatum, Anteneh M. Feyissa, Karim ReFaey, Sanjeet S. Grewal, Mohammed A. Alvi, Ramiro Castro-Apolo, Grayson Roth, Ivan Segura-Duran, Deependra Mahato, Henry Ruiz-Garcia, Eva Pamias-Portalatin, Kirsten Yelvington, Kaisorn Chaichana, Perry Bechtle, Alfredo Quinones-Hinojosa

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Objective: To report intraoperative periodic focal epileptiform discharges (PFEDs) during awake craniotomy using high-density electrocorticography (HD-ECoG). Methods: We retrospectively analyzed 81 patients undergoing awake craniotomy between 9/29/2016 and 7/5/2018. Intraoperative HD-ECoG was performed with direct electrocortical stimulation (DECS) for functional brain mapping. Real-time interpretation was performed and compared to scalp EEG when performed. Perioperative seizures, surgical complications, and characteristics of PFEDs were assessed. Results: 69/81 patients (mean age 48.5 years) underwent awake surgery; 55 operated for brain tumor, 11 for epilepsy and 3 for cavernomas. A focal abnormality on brain MRI was present in 63/69 (91.3%) patients. 43/69 (62.3%) patients had seizures preoperatively, 4/69 (5.7%) had seizures during DECS. PFEDs were identified in 11 patients (15.9%); 2 on depth recording and 9 during intraoperative HD-ECoG. 32 patients (46.3%) had preoperative EEG. HD-ECoG detected more epileptiform discharges (EDs) than standard EEG (32/43; 74.4% vs 9/32; 28.1%) (p = <0.001). Of 9/43 patients with PFEDs on HD-ECoG, 7 patients also had scalp EEG but only one case had EDs (p = 0.02), and 0/32 had periodic EDs. Conclusions: Intraoperative PFEDs are novel, highly focal EDs approximating a single gyrus. In patients with brain tumors, PFEDs did not demonstrate a relationship to pre-operative seizures though has similarities to other common waveforms in patients with epilepsy. Significance: PFEDs expand our understanding of the interictal-ictal continuum and highlight improved temporo-spatial information obtained from increasing sensor density during intracranial EEG recording.

Original languageEnglish (US)
Pages (from-to)1320-1328
Number of pages9
JournalClinical Neurophysiology
Issue number8
StatePublished - Aug 2019


  • Brain tumor
  • Craniotomy
  • Electrocorticography (ECoG)
  • High-density (HD)
  • Periodic focal epileptiform discharges (PFEDs)
  • Periodic lateralized epileptiform discharges (PLEDs)

ASJC Scopus subject areas

  • Sensory Systems
  • Neurology
  • Clinical Neurology
  • Physiology (medical)


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