What are tubers, and where do they occur?

Tubers are potato-like nodules of glial proliferation and are the characteristic CNS lesion of tuberous sclerosis. They may occur anywhere in the cerebral cortex, basal ganglia, and ventricular walls (subependymal nodules), and their number and size correlate with clinical features of seizures and mental retardation. Cortical tubers are often isodense with normal brain tissue and are best detected with magnetic resonance imaging (MRI). Subependymal nodules may calcify and are readily detectable with computed tomography (CT) scanning. Fifty percent of plain skull x-rays taken in later childhood also reveal bilateral areas of calcification in the brain.