Intracortical electroencephalography in acute brain injury.
OBJECTIVE
Continuous electroencephalography (EEG) is used in patients with neurological injury to detect electrographic seizures and clinically important changes in brain function. Scalp EEG has poor spatial resolution, is often contaminated by artifact, and frequently demonstrates activity that is suspicious for but not diagnostic of ictal activity. We hypothesized that bedside placement of an intracortical multicontact electrode would allow for improved monitoring of cortical potentials in critically ill neurological patients.


METHODS
Sixteen individuals with brain injury, requiring invasive neuromonitoring, underwent implantation of an eight-contact minidepth electrode.


RESULTS
Intracortical EEG (ICE) was successfully performed and compared with scalp EEG in 14 of these 16 individuals. ICE provided considerable improvement in signal-to-noise ratio compared with surface EEG, demonstrating clinically important findings in 12 of 14 patients (86%) including electrographic seizures (n = 10) and acute changes related to secondary neurological injury (n = 2, 1 ischemia, 1 hemorrhage). In patients with electrographic seizures detected by ICE, scalp EEG demonstrated no concurrent ictal activity in six, nonictal-appearing rhythmic delta in two, and intermittently correlated ictal activity in two. In two patients with secondary neurological complications, ICE demonstrated prominent attenuation 2 to 6 hours before changes in other neuromonitoring modalities and more than 8 hours before the onset of clinical deterioration.


CONCLUSIONS
ICE can provide high-fidelity intracranial EEG in an intensive care unit setting, can detect ictal discharges not readily apparent on scalp EEG, and can identify early changes in brain activity caused by secondary neurological complications. We predict that ICE will facilitate the development of EEG-based alarm systems and lead to prevention of secondary neuronal injury.
Department of Neurological Surgery, Columbia University College of Physicians and Surgeons, New York, NY, USA. allen.waziri@uchsc.edu
Allen
A
Waziri
Jan
J
Claassen
R Morgan
RM
Stuart
Hiba
H
Arif
J Michael
JM
Schmidt
Stephan A
SA
Mayer
Neeraj
N
Badjatia
Lewis L
LL
Kull
E Sander
ES
Connolly
Ronald G
RG
Emerson
Lawrence J
LJ
Hirsch
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001930:Brain Injuries / Q000175:diagnosis* / Q000503:physiopathology; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000503:physiopathology*; D003700:Delta Rhythm / Q000706:statistics & numerical data; D004567:Electrodes, Implanted; D004569:Electroencephalography / Q000379:methods* / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D007362:Intensive Care Units / Q000458:organization & administration; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012640:Seizures / Q000175:diagnosis / Q000503:physiopathology; D012815:Signal Processing, Computer-Assisted