Frequency and Timing of Nonconvulsive Status Epilepticus in Comatose Post-Cardiac Arrest Subjects Treated with Hypothermia

Abstract

Background Therapeutic hypothermia (TH) improves outcomes in comatose patients resuscitated from cardiac arrest. However, nonconvulsive status epilepticus (NCSE) may cause persistent coma. The frequency and timing of NCSE after cardiac arrest is unknown. Methods Review of consecutive subjects treated with TH and receiving continuous EEG (cEEG) monitoring between 8/1/2009 and 11/16/2010. Demographic data, survival, and functional outcome were prospectively recorded. Each cEEG file was analyzed using standard definitions to define NCSE. Data were analyzed using descriptive and non-parametric statistics. Results Mean age of the 101 subjects was 57 years (SD 15) with most subjects being male (N = 55, 54%) and experiencing out-of-hospital cardiac arrest (N = 78; 77%). Ventricular fibrillation was the initial cardiac rhythm in 39 (38%). All subjects received TH. Thirty subjects (30%) awoke at a median of 41 h (IQR 30, 61) after cardiac arrest. A total of 29/30 (97%) subjects surviving to hospital discharge were awake. Median interval from arrest to placement of cEEG was 9 h (IQR 6, 12), at which time the mean temperature was 33.9°C. NCSE occurred in 12 (12%) subjects. In 3/12 (25%) subjects, NCSE was present when the cEEG recording began. In 4 subjects, NCSE occurred within 8 h of cEEG recording. One (8%) subject with NCSE survived in a vegetative state. Conclusions NCSE is common in comatose post-cardiac arrest subjects receiving TH. Most seizures occur within the first 8 h of cEEG recording and within the first 12 h after resuscitation from cardiac arrest. Outcomes are poor in those who experience NCSE.

Combination of Initial Neurologic Examination, Quantitative Brain Imaging and Electroencephalography to Predict Outcome After Cardiac Arrest

“…3,25 Our hospital implemented 22-channel digital cEEG recordings for the first 48 h after resuscitation from CA as standard monitoring for all comatose post-cardiac arrest patients in August 2009. 13 cEEGs were interpreted during patient care by board certified neurologists, and malignant patterns were defined as follows: non-convulsive status epilepticus (NCSE), convulsive status epilepticus (CSE), myoclonic status epilepticus (MSE) and generalized periodic epileptiform discharges (GPEDs). The definition of each malignant pattern has been described previously.…”

“…The definition of each malignant pattern has been described previously. 13 Myoclonic status epilepticus was characterized as the presence of myoclonic jerks or facial movements associated with GPEDs or with the bursts in a burst suppression pattern. The presence of reactivity and continuous background was not always provided in the clinical interpretation and was not included in the report of the EEG for this study.…”

“…13,23,24 Briefly, TTM at 33°C was induced with rapid infusion of 30 cc/kg of 4°C saline and thermostatically controlled surface cooling devices (Gaymar Industries, Orchard Park, NY; Arctic Sun, Bard Medical Division, Louisville CO) and maintained for 24 hrs. Intravascular cooling is rarely employed after cardiac arrest in our cohort.…”

“…[9][10][11][12][13][14][15][16][17][18][19] The combination of multiple modalities is recommended because no single test short of physical examination meeting brain death criteria can predict neurologic outcome correctly. [20][21][22] We previously reported that combining the initial neurologic examination with continuous EEG (cEEG) was superior to any individual test for predicting outcome after CA.…”

Occurrence of overt seizures in comatose survivor patients treated with targeted temperature

“…Hypothermia has antiepileptic effects, and yet seizures in patients recovering from cardiac arrest can occur despite therapeutic hypothermia, and furthermore, the risk of seizures may increase during rewarming. Any information on seizure incidence in comatose patients treated with targeted hypothermia is scarce (Karkar et al., 2002; Maeda, Hashizume, & Tanaka, 1999; Rittenberger et al., 2012; Rossetti et al., 2007; Synek, 1990). …”