Abstracts

Rationale: Glucose transporter type I deficiency syndrome (GLUT1-DS) is the fourth most frequent single-gene epilepsy refractory to standard antiepileptic drugs (1). The human brain is supplied by D-Glucose and require the glucose type I transporter (Glut 1), which resides at the endothelial cell and is encoded by the GLUT1 gene at chromosome 1p34.2 (SLC2A1 gene) (2). The most frequent seizures types reported are generalized tonic–clonic (53%), absence (49%), complex partial (37%) and myoclonic (27 %); and variable electrographic abnormalities: with exclusively normal findings or slowing, spike wave activity, polyspike wave activity, as well as spikes, which could be generalized, generalized and focal, generalized and multifocal, focal or multifocal (3). With the correct diagnosis and early implementation of the ketogenic diet, the expectation regarding the epileptiform activity is the complete resolution in some studies (4, 5).

Methods: We conducted a retrospective analysis of the patients with drug resistant epilepsy who were treated with the ketogenic diet between December 2012 and May 2021, with the objective to describe the electrographic abnormalities of the patients with GLUT1-DS prior to the initiation of the ketogenic diet and 3 months after the ketogenic diet. Parents had genetic confirmation and adhered to the diet.

Results: 34 patients on the ketogenic diet were reviewed. 10 patients had a clinical diagnosis of GLUT1-DS, but only 5 had the genetic confirmation (SLC2A1 gene mutation). The mean age of the patients at seizure onset was 15.6 months (range: 3-60, SD±2.12); at the diagnosis was 42.8 months (range: 19-79, SD±14.85) and at the onset of ketogenic diet was 44.8 months (range: 20-83, SD±15.56). 3 patients were female.

Myoclonic seizures (4), generalized motor seizures (3), absences (2) and focal motor (1) were described. 4 patients had abnormal movements and 3 had ataxia. The brain MRI was normal in all. 3 patients had an abnormal EEG and were on classical ketogenic diet. The main ratio of Ketogenic diet was 2:1 (1.75:1 – 2.25:1). Clinically, all 5 patients were seizure free after ketogenic diet was started.

EEG features included 1 patient with an abnormal background characterized by generalized slowing. 3 patients had epileptiform discharges before and after ketogenic diet onset. Notched delta, focal spike and wave, generalized spike/polyspike and wave, and centrotemporal spikes bilaterally were found. The amplitude of the spikes were high in all (see table 2). Post ketogenic diet, the patient number 1 showed reduction of the spike frequency (measured in spike/minute) by 92 %, while the patients numbers 4 and 5 showed augmentation of the spike frequency in 905 % and 357 % respectively.

Conclusions: Ketogenic diet is the choice treatment for patients with GLUT1-DS. Electrographic features could show worsening after ketogenic diet in spite of seizure control. Use of the EEG as a means of tracking progress of this disorder is limited and will need longer outcome trials. Centrotemporal spikes have not been previously reported in patients with GLUT-1 DS.

Funding: Please list any funding that was received in support of this abstract.: None.