Magnetic resonance signal abnormalities along the pyramidal tracts in amyotrophic lateral sclerosis.

Magnetic resonance imaging (MRI) studies of the brain were reviewed in 16 patients with amyotrophic lateral sclerosis (ALS), representative of a large and homogeneously studied series, 11 of whom showed signal abnormalities along the pyramidal tracts. These were more frequent in patients with more severe upper motor neuron signs but did not correlate with disease severity. Our study suggests that MRI signal abnormalities along the pyramidal tracts are common in ALS and may reflect the severity of pyramidal tract degeneration.