Abstracts

Rationale: Delirium is a frequent cause of hospitalization in elderly patients. Pathophysiology of delirium is debated. Non-convulsive seizures and delirium share common risk factors. We intended to seek how often non-convulsive status epilepticus (NCSE) co-occurred with delirium and to assess the contribution of NCSE to the symptoms.Methods: We prospectively realised 24 hours continuous EEG-monitoring (C-EEG) in 32 consecutive patients over 65 years old presenting with delirium as assessed by the validated geriatric delirium scale CAM (confusion assessment method) Classical causes of delirium were sought. Clinical, biological and imaging characteristics, length of hospitalisation and outcome were studied and compared between patients with delirium and NCSE and patients with delirium and no epileptic discharges. Results: C-EEG detected continuous epileptiform discharges compatible with NCSE in 28 %, focal inter-ictal discharges (IED) in 12 % and bilateral independent IED in 3 % of older patients with delirium. Continuous epileptiform discharges were associated with a longer hospitalisation stay and higher mortality rate. Continuous epileptiform discharges co-occurred with another likely cause of delirium in all cases: drugs in 80%, ionic imbalances in 70 %, infection in 60% and cognitive impairment in 60%. Cognitive impairment and dehydration were more frequent in patients with continuous epileptiform discharges. Conclusions: NCSE is detected in 28 % of elderly patients with delirium when c-EEG is used. NCSE occurs regardless of the underlying cause and is associated with a worse prognosis.