title: Generalized tonic-clonic seizures detected by implantable loop recorder devices: diagnosing more than cardiac arrhythmias.
abstract: BACKGROUND
  Both syncope and seizures are important causes of recurrent, unexplained episodes of loss of consciousness. Implantable loop recorders have identified serious arrhythmias in patients with repeated syncope; however, implantable loop recorder detection of seizures is less well established.
  
  
  OBJECTIVE
  The purpose of this study was to provide in-depth analysis of a characteristic myopotential pattern recorded by implantable loop recorders during generalized tonic-clonic seizures.
  
  
  METHODS
  Fourteen patients with refractory, video-EEG-documented epilepsy (complex partial, atonic, tonic, or generalized tonic-clonic seizures) underwent implantable loop recorder placement as part of a study protocol evaluating cardiac rhythm abnormalities in patients at high risk for sudden unexpected death in epilepsy.
  
  
  RESULTS
  Twelve generalized tonic-clonic seizure episodes were detected by the implantable loop recorder in six patients. Implantable loop recorder and EEG recordings of generalized tonic-clonic seizures were identical and revealed a tonic phase (sustained, rapid, high-frequency myopotentials) transitioning to a clonic phase (periodic bursts of high-frequency myopotentials with a decelerating burst frequency from 3-6 Hz to 1-2 Hz) prior to seizure termination. With the nonprogrammable bandpass filter of 0.85 to 32 Hz in the implantable loop recorder, all generalized tonic-clonic seizure episodes had escaped automatic detection and required activation by family members. None of the 76 nongeneralized tonic-clonic seizure episodes recorded on the implantable loop recorder in the 14 patients exhibited the stereotypical tonic-clonic pattern that defines generalized seizures.
  
  
  CONCLUSIONS
  Recognizing this specific myopotential pattern on an implantable loop recorder might help diagnose generalized tonic-clonic seizures as a cause of recurrent, unexplained episodes of loss of consciousness. Having a programmable bandpass filter in the implantable loop recorder might increase its diagnostic yield for such patients.
authors.affiliation: Department of Medicine, Thomas Jefferson University Hospital, Philadelphia, Pennsylvania 19107, USA. reginald.ho@jefferson.edu
authors.forename: Reginald T
authors.initials: RT
authors.lastname: Ho
authors.forename: Tammi
authors.initials: T
authors.lastname: Wicks
authors.forename: Dale
authors.initials: D
authors.lastname: Wyeth
authors.forename: Maromi
authors.initials: M
authors.lastname: Nei
mesh_terms: D000328:Adult; D001145:Arrhythmias, Cardiac / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology*; D003937:Diagnosis, Differential; D004562:Electrocardiography / Q000295:instrumentation*; D004867:Equipment Design; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019736:Prostheses and Implants; D012640:Seizures / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology