The spectrum of epileptic syndromes with fixation off sensitivity persisting in adult life

Purpose: The term "fixation off sensitivity" (FOS) was proposed by Panayiotopoulos to describe epilepsy/electroencephalography (EEG) changes evoked by the suppression of central vision and fixation. The EEG pattern usually consists of spike/polyspike and waves localized in occipital regions. FOS occurs mainly in children with idiopathic occipital partial epilepsies and rarely in adults. In this retrospective study we evaluated the clinical data, EEG, and magnetic resonance imaging (MRI) findings of patients with epilepsy and FOS persisting in adult life to better define the spectrum of syndromes.

Methods: We selected 15 consecutive patients (12 female/3 male; age range 19-59 years). The main inclusion criterion was the diagnosis of epilepsy with FOS persisting in adult life. We retrospectively analyzed clinical EEG and neuroimaging data.

Key findings: We observed a female prevalence (F/M = 12/3). Eight patients presented both simple and complex partial seizures, whereas seven had only complex partial seizures. Partial seizures evolved into generalized seizures/hemiconvulsions in nine cases. The FOS pattern consisted of spike-and-wave and slow-wave abnormalities with posterior localization (bilateral in eight/monolateral in seven). We recorded seizures in 10/15 patients. All showed a posterior onset (bilateral in 2/left in 2/right in 6). FOS was prevalent in symptomatic epilepsy (cortical malformations in 7; celiac disease in 3; calcified vascular malformation in 1). One patient presented cryptogenic epilepsy and only three idiopathic epilepsy (Gastaut syndrome).

Significance: FOS can be observed in adult life in idiopathic epilepsy, representing the "prolongation" of the same phenomenon arisen during childhood. Nevertheless, it often represents the EEG expression of symptomatic epilepsies (cortical malformations/celiac disease).