Low signal intensity of motor cortex in SWI sequence: a radiological marker for motor neuron disease?

We describe 03 patients with motor neuron disease: one with primary lateral sclerosis (PLS) (Figure 1) and two with amyotrophic lateral sclerosis (ALS) (Figures 2 and 3) whose brain MRI disclosed hypointense signal in precentral gyri gray matter in susceptibility weighted imaging (SWI) in High-Field MRI (3T). MRI techniques have been used with variable success in identifying upper motor neuron (UMN) involvement in ALS1. Our report also describes similar findings in one patient with PLS. Hypointensity in precentral gyrus gray matter in SWI is presumably related to iron accumulation, proportionally to severity of UMN impairment2,3. Recent data have proposed hypointense signal in precentral gyri gray matter as a neuroimaging biomarker for ALS4.