Abnormal axial diffusivity in the deep gray nuclei and dorsal brain stem in infantile spasm treated with vigabatrin

Abstract

We evaluated the DTI changes in the deep gray nuclei and dorsal brain stem, which demonstrated abnormal T2 and/or diffusion signal intensity, in 6 patients with infantile spasm treated with vigabatrin compared with 6 age-matched controls. Regions of interest were placed in the globi pallidi, thalami, and dorsal brain stem; FA, trace, D(‖), and D(⊥) were measured. Patients on vigabatrin had significantly lower FA in both globi pallidi (P = .01) and the dorsal brain stem (P < .01), significantly lower trace in both globi pallidi (P = .01) and the thalami (P = .02 and .01 for right and left, respectively), and significantly lower D(‖) in both globi pallidi (P ≤ .01), the thalami (P < .01), and the dorsal brain stem (P = .03). There were no significant differences in D(⊥) of the globi pallidi, thalami, or dorsal brain stem in patients compared with controls. The findings suggest that axonal changes play a greater role in the observed abnormal signal intensity, with lesser contribution from myelin changes.

Figures

Fig 1.

A 9-month-old with infantile spasm treated with vigabatrin. A−F, Axial T2 (A−C) and diffusion-weighted (D−F) images show increased T2 signal intensity in the globi pallidi; subtle increased T2 signal intensity in the thalami and dorsal brain stem; and increased diffusion signal intensity in the dorsal brain stem (arrows), globi pallidi, and thalami. G−I, Regions of interest are carefully drawn over the FA maps in the globi pallidi (G), thalami (H), and dorsal brain stem (I).