engleski

Continuous video-EEG, polygraphy and telemetry - the role in the diagnosis of comatose patients

Prolonged continuous digital video and electroencephalographic monitoring (continuous EEG or cEEG) for critically ill and comatose patients has become standard practice in many intensive care units. It was established 30 years ago intraoperatively during carotid endarterectomy. Th is procedure monitors morphology, frequency and amplitude of EEG and provides dynamic information regarding brain functions. cEEG monitoring consists of the longitudinal bipolar montage with minimal 8 electrodes or international 10-20 system, frequent analysis of 2 minutes inserts – relative alpha (RA), elimination of artifacts – continuous RA histogram and measuring of RA variability. Indications for cEEG monitoring are: 1) detection of nonconvulsive seizures (NCS) or nonconvulsive status epilepticus (NCES) in patients with fl uctuating level of consciousness, with prior history of epilepsy or acute traumatic brain injury and subtle stereotypical activities ; 2) monitoring of therapeutic effi cacy of antiepileptic drug (AED) or other drugs administered in patients in induced coma due to increased intracranial pressure or refractory epileptic status or monitoring of the level of sedation ; 3) detection of vasospasm in acute subarachnoid hemorrhage (SAH) and early detection of cerebral ischemia in acute stroke or delayed cerebral ischemia in patients at a high risk of stroke ; 4) detection of systemic disorders: hypoxia, hypotension and acidosis ; and 5) prognosis in patients with ischemic stroke following cardiac arrest or acute traumatic brain injury. EEG can detect seizures or epileptic status in 35%-40% of patients ; in critically ill patients, seizures can be detected by cEEG monitoring in 88% of patients in the fi rst 24 hours. In patients with aneurysmal SAH, there is an increased incidence of epileptic seizures (4%-9%) and NCS or NCES in 10%-19%, especially in the fi rst 18 days, with poor outcome. Reduced RA variability is a biomarker of vasospasm as it allows for early detection of vasospasm by cEEG monitoring in patients with SAH even 2.9 days before it can be detected by digital subtraction angiography or transcranial Doppler sonography. Th e 24-hour monitoring is recommended for non-comatose patients, but in comatose patients longer monitoring is required, as almost 20% of patients experience fi rst epileptic seizures aft er fi rst 24 hours. For patients with SAH, monitoring for up to 48 hours gives clear information on vasospasm.

continuous video-EEG; coma

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