title: High frequency oscillations for lateralizing suspected bitemporal epilepsy.
abstract: In some cases of single focus epilepsy, conventional video electroencephalography (EEG) cannot reveal the epileptogenic focus even when intracranial electrodes are used. Here, we tested whether analyzing high frequency oscillations (HFOs) can be used to determine the ictal onset zone in suspected bitemporal epilepsy and improve seizure outcome.
  
  
  
  We prospectively studied 13 patients with refractory temporal seizures who were treated over a 4-year period and underwent bilateral placement of intracranial electrodes. Subdural strips were used in all cases, and depth electrodes were implanted into mesial temporal lobes in 10 patients. The mean patient age was 30.92 years, and 30.7% of patients were male. Patients were monitored by conventional and wide-band frequency amplifiers.
  
  
  
  Conventional invasive EEG monitoring of interictal periods showed bilateral epileptiform abnormalities in 12 patients (92.3%) and unilateral epileptiform abnormalities in one (7.7%), and monitoring of ictal periods revealed unilateral seizure origins in nine patients (69.2%) and bilateral origins in four (30.8%). In contrast, high frequency invasive EEG monitoring of interictal periods showed bilateral HFOs in seven patients (53.8%) and unilateral HFOs in six (46.2%), and monitoring of ictal periods revealed unilateral HFOs in all 10 patients who were tested. Three patients were not monitored during ictal periods because of time limitations. All 13 patients subsequently underwent a standard unilateral temporal lobectomy and have been followed-up for a minimum of 12 months. Eleven (84%) had a Class I outcome, one (8%) a Class II outcome, and one a Class III outcome.
  
  
  
  Bilateral placement of subdural strip and depth electrodes for seizure monitoring in patients with suspected bitemporal epilepsy is both safe and effective. Monitoring high frequency oscillations can help determine the laterality of the onset zone when localization using conventional EEG or brain MRI fails.
authors.affiliation: Department of Neurology, Xuan Wu Hospital, Capital Medical University, Beijing 100053, China; Beijing Key Laboratory of Neuromodulation, Beijing 100053, China.
authors.forename: Chunyan
authors.initials: C
authors.lastname: Liu
authors.affiliation: Department of Neurology, Xuan Wu Hospital, Capital Medical University, Beijing 100053, China; Department of Functional Neurology, Lu He Hospital, Capital Medical University, Beijing 101149, China.
authors.forename: Ruihua
authors.initials: R
authors.lastname: Zhang
authors.affiliation: Beijing Institute of Functional Neurosurgery, Xuan Wu Hospital, Capital Medical University, Beijing 100053, China.
authors.forename: Guojun
authors.initials: G
authors.lastname: Zhang
authors.affiliation: Beijing Institute of Functional Neurosurgery, Xuan Wu Hospital, Capital Medical University, Beijing 100053, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Yu
authors.affiliation: Department of Functional Neurosurgery, Lu He Hospital, Capital Medical University, Beijing 101149, China.
authors.forename: Junli
authors.initials: J
authors.lastname: Tai
authors.affiliation: Beijing Institute of Functional Neurosurgery, Xuan Wu Hospital, Capital Medical University, Beijing 100053, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Du
authors.affiliation: Department of Neurology, Xuan Wu Hospital, Capital Medical University, Beijing 100053, China.
authors.forename: Liping
authors.initials: L
authors.lastname: Li
authors.affiliation: Department of Neurology, Xuan Wu Hospital, Capital Medical University, Beijing 100053, China; Beijing Key Laboratory of Neuromodulation, Beijing 100053, China. Electronic address: wangyuping01@sina.cn.
authors.forename: Yuping
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000293:Adolescent; D000328:Adult; D058256:Brain Waves; D000069279:Drug Resistant Epilepsy / Q000175:diagnosis* / Q000503:physiopathology* / Q000601:surgery; D000069280:Electrocorticography; D004567:Electrodes, Implanted; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012640:Seizures / Q000175:diagnosis* / Q000503:physiopathology* / Q000601:surgery; D013702:Temporal Lobe / Q000503:physiopathology* / Q000601:surgery; D016896:Treatment Outcome; D055815:Young Adult
keywords: Bilateral intracranial electrodes; Bitemporal; Epilepsy; Fast ripple; High frequency oscillations; Ripple