Prolonged Episodes of Paroxysmal Exertion-Induced Dystonia in Glut1 Deficiency Syndrome.

Glucose transporter type I (Glut1) deficiency syndrome (Glut1DS) is associated with paroxysmal exertion-induced dystonia (PED). Episodes are published as brief, lasting 20 to 30 minutes. Increasingly, Glut1DS patients report prolonged PED of more than 1 hour duration. In a cohort of 60 Glut1DS patients seen in our institution within a 4-year period, a total of 26/60 patients (43%) on ketogenic dietary therapy (KDT) experienced PED. In 18/26 patients (30%), episodes lasted less than 1 hour as previously described. In 8/26 patients (13%), prolonged episodes lasted more than 1 hour up to 1 day despite adequate dietary treatment. We conclude that PED is common in Glut1DS starting in late childhood despite adequate treatment with KDT. Prolonged PED in Glut1DS occurs in a subset of patients, also unresponsive to KDT, and represents a substantial burden to patients and families.