Transient epileptic amnesia: temporal progression of partially treated disease-a case report

Transient memory loss with preserved consciousness needs precise diagnosis, as it could be owing to different causes requiring different management approaches. Differentiation between causes is difficult on first presentation, but it is important, as different causes have different management approaches and can have serious implications on a patient's life, especially in regards to driving. Transient epileptic amnesia is a treatable condition if diagnosed correctly but can have major consequences when not treated. Transient epileptic amnesia is reported in literature, but reports on the temporal progression of partially treated transient epileptic amnesia are sparse; however, this knowledge could help someone diagnose the disease at least by the second encounter.

We report on a previously healthy, independent, right-handed 72-year-old Sinhalese Sri Lankan man, who had experienced five to seven brief periods of episodic memory loss since 2018, which were attributed to age, anxiety, and stress. He was involved in a car accident in 2000 and remained conscious but had retrograde amnesia. An extensive investigation conducted during his evaluation did not reveal a secondary cause for the accident. He later presented in 2022 with repeated generalized tonic-clonic seizures without secondary cause and an electroencephalogram showed epileptiform activity involving the left temporal lobe during the postictal period. He was diagnosed with transient epileptic amnesia and was started on carbamazepine. His seizures and amnestic episodes settled with the initiation of treatment, and now he is seizure-free after 6 years from the initial presentation of amnestic episodes. However, he has a mild degree of persistent interictal memory impairment.

Transient epileptic amnesia is difficult to diagnose on the first presentation, as it mimics several conditions where there is nonspecific memory loss, and there are often no involuntary movements. However, recurrent and brief amnestic episodes should lead to suspect transient epileptic amnesia over other causes. Transient epileptic amnesia requires a positive diagnosis, as it is treatable if diagnosed. A contraindication to driving and consequences of untreated disease could cause serious consequences, posing a risk to life. This case shows the temporal progression of the disease in a patient with partially treated transient epileptic amnesia.