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Fixation-off sensitivity (FOS) refers to seizures or EEG abnormalities elicited by the elimination of central vision/fixation, even in the presence of light.1 Typically, a paroxysmal discharge occurs within 1–3 seconds of eye closure, persists throughout the eye-closed state, and disappears immediately on eye opening.2

Glucose transporter type 1 (GLUT1) deficiency due to SLC2A1 mutations causes a wide spectrum of neurologic disorders ranging from severe encephalopathy with developmental delay, epilepsy, ataxia, and acquired microcephaly to atypical less severe variants. Early diagnosis is crucial for prompt initiation of a ketogenic diet. Recognizing GLUT1 deficiency syndrome (GLUT1DS) may be challenging and results in delayed diagnosis. Here we describe the clinical and molecular findings of patients with SLC2A1 mutations referred to our adult Epilepsy Center. Patients with a clinical history suggestive of GLUT1DS were screened for SLC2A1 mutations. Blood samples were collected from probands and first-degree relatives. A lumbar puncture was performed in two patients in fasting state, and cerebrospinal fluid and blood glucose measurement were undertaken at the same time. Since 2010, 19 GLUT1DS probands have been screened for SLC2A1 mutations. We identified four different SLC2A1 mutations in three sporadic cases and one family. Three mutations (c.130_135delTACAAC, c.342_343insA, and c.845A > G) were novel, whereas one was previously reported in the literature associated with a different phenotype (c.497_499delTCG). Here we describe a small case series of patients with sporadic and familial GLUT1DS presenting with a broad phenotypic heterogeneity which is likely to be responsible for the considerable delay in diagnosis.

The aim of this study is to describe the possible co-occurrence of narcolepsy type 1 and generalized epilepsy, focusing on diagnostic challenge and safety of dual treatments.Four patients with comorbidity for narcolepsy type 1 and idiopathic generalized epilepsy are reported: in three cases the onset of epilepsy preceded narcolepsy type 1 appearance, whereas in one case epileptic spells onset was subsequent. Patients presented with absences, myoclonic and tonic-clonic seizure type: in the patient with tonic-clonic seizures the dual pathology was easily recognized, in the other cases the first diagnosis caused the comorbid disease to be overlooked, independent of the time-course sequence. All four patients underwent neurological examination, video-electroencephalogram during which ictal and interictal epileptic discharges were recorded, and sleep polysomnographic studies. Repeated sleep onset rapid eye movement periods (SOREMPs) were documented with the multiple sleep latency test (MLST) in all the four cases. All patients had unremarkable brain magnetic resonance imaging studies and cerebrospinal hypocretin-1 was assessed in two patients, revealing undetectable levels. The association of antiepileptic drugs and substances currently used to treat narcolepsy type 1, including sodium oxybate, was effective in improving seizures, sleep disturbance, and cataplexy.Narcolepsy type 1 may occur in association with idiopathic generalized epilepsy, leading to remarkable diagnostic and therapeutic challenges. Electrophysiological studies as well as a comprehensive somnologic interview can help confirm the diagnosis in patients with ambiguous neurological history. Sodium oxybate in combination with antiepileptic drugs is safe and effective in treating cataplexy and excessive daytime sleepiness.