Increased incidence and impact of nonconvulsive and convulsive seizures after traumatic brain injury as detected by continuous electroencephalographic monitoring

Abstract

Object-The early pathophysiological features of traumatic brain injury observed in the intensive care unit (ICU) have been described in terms of altered cerebral blood flow, altered brain metabolism, and neurochemical excitotoxicity. Seizures occur in animal models of brain injury and in human brain injury. Previous studies of posttraumatic seizures in humans have been based principally on clinical observations without a systematic approach to electroencephalographic (EEG) recording of seizures. The purpose of this study was to determine prospectively the incidence of convulsive and nonconvulsive seizures by using continuous EEG monitoring in patients in the ICU during the initial 14 days post-injury.Methods-Ninety-four patients with moderate-to-severe brain injuries underwent continuous EEG monitoring beginning at admission to the ICU (mean delay 9.6 ± 5.4 hours) and extending up to 14 days postinjury. Convulsive and non-convulsive seizures occurred in 21 (22%) of the 94 patients, with six of them displaying status epilepticus. In more than half of the patients (52%) the seizures were nonconvulsive and were diagnosed on the basis of EEG studies alone. All six patients with status epilepticus died, compared with a mortality rate of 24% (18 of 73) in the nonseizure group (p < 0.001). The patients with status epilepticus had a shorter mean length of stay (9.14 ± 5.9 days compared with 14 ± 9 days [t-test, p < 0.03]). Seizures occurred despite initiation of prophylactic phenytoin on admission to the emergency room, with maintenance at mean levels of 16.6 ± 2.8 mg/dl. No differences in key prognostic factors (such as the Glasgow Coma Scale score, early hypoxemia, early hypotension, or 1-month Glasgow Outcome Scale score) were found between the patients with seizures and those without.Conclusions-Seizures occur in more than one in five patients during the 1st week after moderate-to-severe brain injury and may play a role in the pathobiological conditions associated with brain injury. MOST patients with severe traumatic brain injury (TBI) have a prolonged stay in the intensive care unit (ICU), the outcome being a long-term disability or death, with a minority of patients (20-30%) achieving a functionally independent outcome. 1,42,43 Recognized prognostic factors that influence outcome, which are present early after injury, are early hypoxemia, early hypotension, severity of primary insult (assessed on computerized tomography [CT] scans), and admission Glasgow Coma Scale 50 (GCS) score. Adverse secondary events including sustained intracranial hypertension, 1,14,29,43,52 reduced or hyperemic cerebral blood flow (CBF), 25,46 and frank ischemia 45 influence outcome. These prognostic factors indicate that the brain exists in a vulnerable state during the first few days after trauma when secondary insults may worsen the injury and the resultant outcome. HHS Public AccessParamount to this state of vulnerability are altered glucose and oxidative metabolism, 5 altered CBF, 13,31 and ongoing neurochemical changes in e...

Early and persistent impaired percent alpha variability on continuous electroencephalography monitoring as predictive of poor outcome after traumatic brain injury

“…The bandwidth for the PA used in this study was 6 to 14 Hz, which has been standardized in previous reports. 53 …”

“…53 Briefly, a 10-electrode, 14-channel montage was used to assess electrical activity. This montage incorporates eight channels of CZ-referenced activity and eight channels of bipolar derivations.…”

Characterization of the Relationship Between Intracranial Pressure and Electroencephalographic Monitoring in Burst-Suppressed Patients

“…Because of the life-threatening nature of this complication, ICP has become a routinely measured signal in critical patients (Steiner & Andrews, 2006). Other sources of secondary injury such as seizures (Hart, Byer, Slaughter, Hewett, & Easton, 1981; Vespa et al, 1999; Westbrook, Devinsky, & Geocadin, 1998) and spreading depression (Hartings et al, 2009) can be detected through the use of electroencephalography (EEG). As this modality is inexpensive and non-invasive, EEG monitoring can be readily utilized in many patients admitted to a neurointensive care unit.…”

Neurointensive care biophysiological monitoring: Table 1

“…After cardiac arrest, 42% of patients in a coma were found to be in NCSE. People with NCSE have a higher mortality risk 98. This may be due to the underlying cause itself rather than the NCSE 99.…”