Non-Convulsive Status Epilepticus (NCSE) in ICU: Bedside Usefulness of TCD in Comatose Patient Diagnosis. When the EEG Is Too Far

Nonconvulsive status epilepticus (NCSE) is an important cause for unexplained impairment of consciousness in the intensive care unit (ICU). However, the diagnosis is frequently missed, with negative impact on patient’s outcome. The widespread use of continuous EEG monitoring in the ICU has enabled recognition of some equivocal patterns that do not meet the proposed criteria for NCSE. Whether to use antiepileptic drugs (AEDs) in that scenarios remains controversial. Thus, there is an urge for other investigational modalities, which can help in stratifying the risk of ictality, ictogenicity, epileptogenicity, and secondary neuronal injury. All these potentials would impact the decision for AEDs initiation, escalation, and duration. Hyper-perfusion is the hemodynamic pattern of epilectogenic zone (seizure activity), which can be assessed by measuring the flow velocities of the intracranial vessels. The transition from hyperperfusion to hypoperfusion might denote treatment success, or exhaustion of the neurons, depending on the clinical scenarios. Transcranial Doppler/duplex (TCD/TCCS) represents a noninvasive tool for monitoring cerebral hemodynamics during NCSE.