“De novo” absence status epilepticus: case report with 8-year follow-up

Case presentation: A 53-year-old woman went to the emergency room (ER) confused for four days. Lab tests and a CT scan were normal, so, she was referred to a routine psychiatric evaluation. However, her family went to a neurologist, who found a disoriented patient unable to count to 10, perform calculations, remember date or own address. She didn’t show focal signs. History of rare seizures in adolescence. The electroencephalogram (EEG) showed continuous, generalized, 3-5 Hz spike-and-wave discharges (SWD). The diagnosis was late-onset absence status epilepticus. Two hours after 5 drops of clonazepam 2.5 mg/ml, she woke up with normal cognition but no recollection of the past week. EEG recorded the next day showed posterior dominant rhythm (PDR) at 7.5 Hz, with brief bursts of fragmented 3 Hz SWD. Upon questioning, she reported having “startles” since adolescence, suggesting idiopathic generalized epilepsy (IGE). Subsequent EEGs on 10/05/2017, 11/21/2018, 02/12/2020, 12/21/2022, and 12/21/2023 had normal background activity with PDR at 10 Hz. All of them showing brief bursts of fragmented, generalized 3-5 Hz SWD. She occasionally has myoclonic seizures but has not had any new absence seizures or convulsions. Discussion: Late-onset absence status epilepticus (LO-ASE) is rare and can occur in adults and the elderly as a late relapse of IGE or in de novo patients without a seizure history. De novo LO-ASE is frequently described in women, often triggered by benzodiazepine withdrawal, alcohol or psychotropic drug intoxication, none of which in this history. LO-ASE is characterized by a prolonged and fluctuating confusional state, with or without minor abnormal motor components. The EEG shows various ictal patterns, from typical or atypical generalized spike-and-wave discharges to complex asymmetric irregular sharp and slow waves with anterior predominance. The evolution of our case revealed the persistence of mild and rare morning myoclonic seizures. This LO-ASE likely emerged on a substrate of juvenile myoclonic epilepsy. The eight-year follow-up evidenced the chronic nature of this IGE with a good response to anti-seizure medication. This report provides a detailed view of the clinical and EEG evolution of a rare case of LO-ASE in a middle-aged woman over 8 years period. It emphasizes the need to consider this condition in the differential diagnosis of confusional states in ERs, especially in patients with history of seizures to prevent complications and improve clinical outcomes in such cases. Final comments: This case of absence status epilepticus in a middle-aged patient, highlighs the importance of clinical suspicion of ASE and IGE in ER, and the use of EEG in such diagnosis