Magnetic resonance imaging in infantile spasms: effects of hormonal therapy.

Magnetic resonance imaging (MRI) was performed on five patients with infantile spasms who were treated with relatively low doses of adrenocorticotrophic hormone (ACTH) to study the extent of brain shrinkage induced by ACTH therapy. MRI prior to ACTH therapy revealed periventricular hyperintensity (PVH) areas and poor myelination in four patients. In one case, MRI performed 2 days after initiation of ACTH therapy also showed PVH and poor myelination. Brain shrinkage was observed 2 weeks after initiation of ACTH therapy. The most impressive follow-up finding upon MRI was the decrease in PVH found in four patients. The differentiation between myelinated white matter and surrounding cortex became poorer in three cases. Cortical atrophy progressed in all patients but ventricular dilation progressed in only one patient. At the end of ACTH therapy, ventricular dilation progressed in all cases. These findings suggest that loss of water not only from periventricular white matter but also from cortex is the main etiological factor of brain shrinkage induced by ACTH.