“Benign” temporal lobe epilepsy with hippocampal sclerosis: A forgotten entity?

Mesial temporal lobe epilepsy, a well-characterized epilepsy syndrome, is most commonly accompanied by the pathological feature of hippocampal sclerosis. Patients with mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS) typically present in childhood to early adolescence. We describe a cohort of patients who presented with their first epileptic seizure in late adulthood with atypical features. We characterized five patients with late-onset MTLE-HS by describing their demographics, electroclinical features, imaging, autoantibody status, and response to antiseizure medication (ASM) therapy. All five patients had their first seizure after the age of 50 with no history of initial precipitating incidents. None of our patients had positive serum or CSF autoantibodies and they have all remained seizure-free for a minimum of two years on ASMs alone. Two patients had motor vehicle crashes associated with seizures whilst three patients experienced seizures in sleep. A milder form of MTLE, previously described as benign TLE, does exist in routine clinical practice. These patients respond well to ASM therapy, but potentially harmful consequences such as motor vehicle crashes can occur in the untreated.