Paroxysmal eye-head movements in Glut1 deficiency syndrome

Abstract

Objective: To describe a characteristic paroxysmal eye-head movement disorder that occurs in infants with Glut1 deficiency syndrome (Glut1 DS).

Methods: We retrospectively reviewed the medical charts of 101 patients with Glut1 DS to obtain clinical data about episodic abnormal eye movements and analyzed video recordings of 18 eye movement episodes from 10 patients.

Results: A documented history of paroxysmal abnormal eye movements was found in 32/101 patients (32%), and a detailed description was available in 18 patients, presented here. Episodes started before age 6 months in 15/18 patients (83%), and preceded the onset of seizures in 10/16 patients (63%) who experienced both types of episodes. Eye movement episodes resolved, with or without treatment, by 6 years of age in 7/8 patients with documented long-term course. Episodes were brief (usually <5 minutes). Video analysis revealed that the eye movements were rapid, multidirectional, and often accompanied by a head movement in the same direction. Eye movements were separated by clear intervals of fixation, usually ranging from 200 to 800 ms. The movements were consistent with eye-head gaze saccades. These movements can be distinguished from opsoclonus by the presence of a clear intermovement fixation interval and the association of a same-direction head movement.

Conclusions: Paroxysmal eye-head movements, for which we suggest the term aberrant gaze saccades, are an early symptom of Glut1 DS in infancy. Recognition of the episodes will facilitate prompt diagnosis of this treatable neurodevelopmental disorder.

Figure 1. Eye–head gaze saccades

In each of these 3 gaze shifts, movement of the eyes is followed by a head movement in the same direction. There is a period of fixation between eye movements (total time: 1.8 seconds, interval between frames: 150 ms).

Figure 2. Timing of eye movements

(A) Time of onset of eye saccades in a single patient over a 15-second period (excerpt from video 3). Saccades occur at variable intervals. (B) Distribution of intervals between onset of saccades in 4 individual patients. Bins are 50 ms. Top graph is the same patient as in A (number of eye movements per patient, top to bottom: 40, 94, 78, 90; total = 302).