Daily Variation in an Intracranial EEG Feature in Humans Detected by a Responsive Neurostimulator System

• Published in: Epilepsia (Copenhagen) Vol. 48; no. 8; pp. 1614 - 1620
• Main Authors: Duckrow, Robert B., Tcheng, Thomas K.
• Format: Journal Article
• Language: English
• Published: Malden, USA Blackwell Publishing Inc 01.08.2007; Blackwell
• Subjects: Adolescent; Adult; Anticonvulsants. Antiepileptics. Antiparkinson agents; Biological and medical sciences; Brain Mapping; Cerebral Cortex - physiopathology; Circadian Rhythm - physiology; Complexity; Electric Stimulation Therapy - adverse effects; Electric Stimulation Therapy - instrumentation; Electric Stimulation Therapy - methods; Electrodes, Implanted; Electrodiagnosis. Electric activity recording; Electroencephalography - statistics & numerical data; Epilepsy; Epilepsy - diagnosis; Epilepsy - physiopathology; Epilepsy - prevention & control; Equipment Safety; Evaluation Studies as Topic; Feedback - physiology; Female; Headache. Facial pains. Syncopes. Epilepsia. Intracranial hypertension. Brain oedema. Cerebral palsy; Humans; Investigative techniques, diagnostic techniques (general aspects); Line length; Male; Medical sciences; Middle Aged; Nervous system; Nervous system (semeiology, syndromes); Neurology; Neuropharmacology; Nonlinear energy; Pharmacology. Drug treatments; Temporal Lobe - physiopathology; Human; Nervous system diseases; Epilepsy-Line length-Nonlinear energy-Complexity; Epilepsy; Central nervous system disease; Nonlinearity; Daily variation; Stereoelectroencephalography; Cerebral disorder; Complexity
• ISSN: 0013-9580; 1528-1167
• DOI: 10.1111/j.1528-1167.2007.01091.x

Purpose: Based on the observation that epileptic seizures can occur at specific times of the day, we looked for daily variation in an intracranial electrographic feature used by a responsive neurostimulator system to detect seizures. Methods: A computationally efficient measure of intracranial EEG energy or complexity, the line length baseline, was calculated and reported by an external responsive neurostimulator during a clinical trial of device safety. Data were obtained from 24 consecutive patients with medically intractable epilepsy undergoing intracranial monitoring over 2 to 54 days to localize the seizure onset zone. Measurements from individual subjects made at different times of day over many days were displayed on a single 24‐h cycle and fit with a cosine function to characterize the time of the maximum value. The timing of epileptic seizures was also noted. Results: The time of the maximum line length baseline value had a bimodal distribution with relative peaks at 05:30 and 15:00 hours. The time of the maximum value did not associate with specific brain regions, except that a nocturnal peak was not measured from temporal neocortex. The temporal distribution of maximum values was similar to the timing of epileptic seizures. Conclusion: The line length baseline feature of the intracranial EEG shows daily variation with location specific characteristics within individual subjects.