Generalized tonic-clonic seizures detected by implantable loop recorder devices: diagnosing more than cardiac arrhythmias.
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.
Ho
Reginald T
RT
Department of Medicine, Thomas Jefferson University Hospital, Philadelphia, Pennsylvania 19107, USA. reginald.ho@jefferson.edu
Wicks
Tammi
T
Wyeth
Dale
D
Nei
Maromi
M
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