Abstracts

Rationale: The incidence of both epilepsy and dementia rises with age. Memory decline, confusion and amnesia are symptoms commonly described in both conditions. In addition, epilepsy and Alzheimer’s disease (AD) may co-exist and the latter accounts for approximately 12% of seizures in elderly. Epilepsy itself can lead to cognitive impairment in particular if appropriate diagnosis and treatment are delayed. Therefore, correct diagnosis of these conditions is vital and often difficult. The aim of our study was to evaluate the diagnostic value of continuous inpatient video EEG in the investigation of patients with memory decline and paroxysmal events. Methods: We identified all patients who were referred to the inpatient epilepsy monitoring unit (EMU) by our dementia specialist in the last three years with presenting symptoms of memory decline and paroxysmal events. Our electronic database was searched to collect data on demographics, presenting symptoms, suspected diagnosis, MRI findings, routine and prolonged video-EEG interictal and ictal abnormalities, and EMU diagnosis.Results: Twenty one patients (12 females) with a mean age of 61.9±11.5 years (age range 42-90 years) who met the inclusion criteria were studied. Patients with confirmed diagnosis of epilepsy were excluded. The most common referring symptom was memory decline. The great majority of patients had paroxysmal events that consisted of confusion, starring, and /or behavioral changes. The suspected underlying diagnosis was mild cognitive impairment in 10 patients, fronto-temporal dementia in 4, neurodegenerative disease in 2, encephalitis in 2, AD in 1, attention deficit disorder in 1 and stroke in 1. The most common MRI finding was chronic ischemic white matter disease in 7 of 14 patients (2 of which also had atrophy). Routine EEGs were performed in 10 patients and revealed non specific findings (7 showed either bitemporal or unilateral temporal slowing). EMU stay ranged from 3 to 14 days (4.9 ±2.7 days). Multiple paroxysmal events were recorded in 11 patients (52.3%). The most common interictal EEG finding was focal slowing in 8 patients (6 of which had temporal and 2 frontal slowing). Interictal epileptiform abnormalities were reported in 1 patient. EMU evaluation clarified the diagnosis in 3 patients (14%). One patient was diagnosed with epilepsy (4.8%), one with psychogenic non epileptic seizures and another one with atrial fibrillation. In the remainder, lack of interictal epileptiform abnormalities and ictal electrographic changes did not support the diagnosis of epilepsy.Conclusions: Our study showed that continuous inpatient video EEG successfully captures paroxysmal events in more than 50% of patients with cognitive decline. In our patient population EMU evaluation was useful in establishing the correct diagnosis in approximately 14% of patients. In our patient group epilepsy co-existed with mild cognitive impairment in approximately 5% of patients. In the remainder, lack of interictal abnormalities and ictal patterns safely argues against the epileptic nature of the paroxysmal episodes.