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. INTERPRETATION: 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.

Autosomal dominant inheritance of centrotemporal sharp waves in rolandic epilepsy families.

PURPOSE: Centrotemporal sharp (CTS) waves, the electroencephalogram (EEG) hallmark of rolandic epilepsy, are found in approximately 4% of the childhood population. The inheritance of CTS is presumed autosomal dominant but this is controversial. Previous studies have varied considerably in methodology, especially in the control of bias and confounding. We aimed to test the hypothesis of autosomal dominant inheritance of CTS in a well-designed family segregation analysis study. METHODS: Probands with rolandic epilepsy were collected through unambiguous single ascertainment. Siblings in the age range 4-16 years underwent sleep-deprived EEG; observations from those who remained awake were omitted. CTS were rated as present or absent by two independent observers blinded to the study hypothesis and subject identities. We computed the segregation ratio of CTS, corrected for ascertainment. We tested the segregation ratio estimate for consistency with dominant and recessive modes of inheritance, and compared the observed sex ratio of those affected with CTS for consistency with sex linkage. RESULTS: Thirty siblings from 23 families underwent EEG examination. Twenty-three showed evidence of sleep in their EEG recordings. Eleven of 23 recordings demonstrated CTS, yielding a corrected segregation ratio of 0.48 (95% CI: 0.27-0.69). The male to female ratio of CTS affectedness was approximately equal. CONCLUSIONS: The segregation ratio of CTS in rolandic epilepsy families is consistent with a highly penetrant autosomal dominant inheritance, with equal sex ratio. Autosomal recessive and X-linked inheritance are rejected. The CTS locus might act in combination with one or more loci to produce the phenotype of rolandic epilepsy.

Continuous EEG monitoring in the intensive care unit: technical and staffing considerations.

Continuous EEG monitoring in the intensive care unit (ICU) is superficially similar to that which occurs in the epilepsy monitoring unit, but it also presents unique technical challenges. ICU monitoring imposes an expectation of reliability on EEG recording equipment exceeding that which may be demanded by other settings; performance requirements may also differ. Reliable network connectivity between ICUs and other hospital locations is necessary, as is provision for off-site EEG review and display. Staffing should be adequate to support continuous recording, including performing hookups at off-hours. Selection of electrode number, type, and application method requires weighting of monitoring needs, nursing concerns, and imaging requirements.

Continuous EEG monitoring in the intensive care unit.

It is now feasible and desirable to continuously monitor brain function with EEG in critically ill patients. Nonconvulsive seizures are more common than previously recognized and may contribute to impaired mental status and brain injury. Alerting stimuli commonly elicit periodic or ictal-appearing EEG patterns. Cerebral ischemia can be detected at a reversible stage with continuous EEG monitoring (cEEG). With the current availability of treatments for acute ischemia, this early detection has great potential for the prevention of stroke, but is only now beginning to be utilized for this purpose. The intensive care unit poses many technical difficulties for EEG acquisition, and artifact recognition is more important than ever. Recording synchronized video with EEG is essential for maximizing the efficiency and accuracy of cEEG interpretation, and quantitative EEG analysis can be quite helpful. The role of the EEG technologist is particularly important in these patients to aid in recognizing and minimizing artifact, to enhance communication between electroencephalographers and clinicians, to assess the effect of alerting stimuli, and to note possible subtle clinical correlates of electrographic seizures.