Abstracts

Rationale:
Continuous EEG (cEEG) is the gold standard for detecting seizures and abnormalities in critically ill patients, but in the settings of limited human and financial resources and presence of electrical artifacts, it could be sometimes challenging to achieve it.




The purpose of the current study was to assess the effectiveness, safety and utility of this simplified EEG (sEEG) recording using 8 sub-dermal needle electrodes in critically ill patients compared to standard cEEG.




Methods:
This is an interventional prospective study on a sample of adult patients admitted to the intensive care unit of Hotel Dieu de France Hospital in Beirut where an EEG was clinically indicated. The sEEG was completed using 8 non-disposable subdermal needle electrodes placed according to the International 10-20 system: frontopolar (Fp1/Fp2), central (C3/C4), temporal (T3/T4) and occipital (O1/O2). Each sEEG was immediately followed by a cEEG using 21 cup electrodes.




The protocol was approved by the institution ethics committee. Patients’ medical records were reviewed for clinical and radiological data collection. Clinical outcomes were recorded, including any reported complications of the technique; EEG findings were documented (background characterization including epileptiform discharges (ED), rythmic periodic patterns (RPPs), and seizures).




The overall agreement between sEEG and cEEG was assessed using Cohen’s Kappa coefficient and detection rates between both tests was compared using McNemar's test. A p-value of 0.05 was considered clinically significant. To evaluate the performance diagnostic of sEEG compared to cEEG, we calculated sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). A Fisher’s exact test was used to study the association between two categorical variables. The analyses were performed using R statistical software version 3.5.3.




Results:
Thirty patients, mean age of 69.87 years (SD 15.08), one third being females underwent an average of 15.83 minutes of sEEG recording then 18.45 hours of cEEG.There were no complications related to electrode placement except one patient who had redness at the subdermal site insertion. 16.7 % had post anoxic injury, 56.7 % had acute brain injury and the rest had toxi-metabolic etiologies. Of note that 16.7 % had history of seizures. Cohen’s Kappa test value was 0.76 indicating a good level of agreement between the two tests. There was no significant relationship between the EEG results and outcome. Regarding sEEG findings: 43.3 % had normal background or mild diffuse slowing. Among them one developed ED on cEEG, and 2 others had drug-induced burst suppression pattern (NPV of 0.77). Other sEEG findings were: 33.3% had ED, periodic discharges or seizures, 10 % had BS, and 13.3 % had severe diffuse slowing. Overall, sEEG had a sensitivity of 83.33 % a specificity of 100% to detect abnormalities and a PPV of 1.




Conclusions:
The rapid sEEG was found to be a useful method for detecting RPPs and seizures in critically ill patients and can miss abnormalities only in rare cases compared to cEEG.









Funding: The study was funded by a grant from Saint Joseph University Faculty of Medicine (#FM379)