Beware of nonconvulsive seizures in prolonged disorders of consciousness: Long-term EEG monitoring is the key.

OBJECTIVE:Evaluate the prevalence of epileptic seizures (ES) and epileptiform discharges (EDs) in patients with prolonged disorders of consciousness (DOC), and potential influence of amantadine on epilepsy. METHODS:We conducted a retrospective study in 34 patients hospitalized in a DOC care unit for prolonged DOC between 2012 and 2018, who received a long-term EEG monitoring (LTM). We reviewed the prevalence of ES, EDs and nonconvulsive seizures (NCSz), the type of DOC recovery treatment administered, and neurological outcome. RESULTS:LTM was more effective than standard EEGs in detecting EDs (32% vs 21% respectively). Moreover, 12% of the LTM showed NCSz. Among patients with EDs in LTM, 73% showed no EDs in standard EEG recordings, even when performed more than once. The presence of EDs and/or NCSz in LTM was significantly associated with the occurrence of remote clinical epileptic seizures (p = 0.017) but did not influence neurological outcome (p = 1). Amantadine was not associated with higher occurrence of EDs/NCSz or clinical seizures. CONCLUSION:In our prolonged DOC population, LTM showed more pathological results (EDs and NCSz) than standard EEGs, which was significantly associated with remote clinical seizures. SIGNIFICANCE:The use of LTM might be advised to rule out NCSz in patients with prolonged DOC.