Contribution of the EEG in the Diagnostic Workup of Patients with Transient Neurological Deficit and Acute Confusional State at the Emergency Department the EMINENCE Study

Objectives: To investigate the usefulness of emergency electroencephalogram(emEEG) in the differential diagnosis of transient neurological deficits(TND) and acute confusional state(ACS). Methods: An analysis was performed on a subset of patients included in EMINENCE, a retrospective study of subjects admitted to the Emergency Department(ED) of our tertiary hospital during a 1-year period. The analysis was limited to patients with neurological symptoms/signs compatible with cerebral hemispheric origin or with ACS of < 24h duration. We evaluated the usefulness of emEEG in the diagnostic workup of TND and ACS. Results: Speech disorder(75.3%), hyposthenia(68.1%) and ACS(62.9%) were the signs/symptoms with the highest percentage of abnormal emEEG, especially concerning epileptic discharges. Seizures(85.7%) and encephalopathy(74.3%) were the final diagnoses with the highest percentage of abnormal emEEG, particularly, epileptic discharges and focal slow waves in patients discharged as seizures and bilateral slow waves and triphasic waves in patients discharged as encephalopathy. The presence/absence of epileptic discharges associated with focal slow waves discriminated between seizures and vascular disease, especially in hyposthenia (100% seizures when epileptic discharges were present vs 50% when absent). Migraine with aura(66%) and unknown diagnosis(56%) were the final diagnoses with the most normal emEEG. The rapid timing of the emEEG recording compared to the patient's admission allowed us to perform the test in 29.5% of patients who were still symptomatic, of whom 79% had an abnormal emEEG. Discussion: EmEEG contributed to the diagnosis mainly when speech disorder, hyposthenia and ACS were the admission signs/symptoms and especially for the final diagnosis of seizures and encephalopathy.