Magnetic Resonance Imaging Brachial Plexus Alterations In ALS Patients (P4.101)

OBJECTIVE: To investigate MRI brachial plexus changes in patients with amyotrophic lateral sclerosis (ALS). BACKGROUND: Peripheral axonal loss has a key role in the pathogenesis of ALS. MRI has not been exploited yet to study the peripheral nervous system in ALS. DESIGN/METHODS: Brachial plexus MRI scans were obtained from 18 patients with defined ALS and 9 age-matched healthy controls. Nerve roots and limb girdle muscles were evaluated for the presence of signal alterations (T2, T1 and STIR) and volume changes. Regions of interest (ROIs) of C5, C6 and C7 roots were delineated on axial, T2-weighted volumetric images. ROIs mean volume and T2 signal intensity were measured. Linear measures of adipose tissue thickness between trapezius and supraspinatus muscles were obtained from coronal T1-weighted images. Differences between groups were assessed using Mann-Whitney U test. RESULTS: At visual inspection, increased T2 signal and volume of C5, C6 and C7 nerve roots bilaterally were evident in all patients. Suprascapulis, supra- and infraspinatus muscles T2 and STIR signal alterations were found as well as fat infiltration associated with muscle atrophy, bilaterally. ROI analysis showed that mean T2-signal intensity was higher in left C6 (p=0.05) and C7 (p=0.02) in patients compared with controls. Right C5 and bilateral C6 and C7 root volumes were significantly higher in patients (right C5: p=0.04; right C6: p=0.006; left C6: p=0.01; right C7: p=0.003; left C7: p=0.001). Thickness of adipose tissue between trapezius and supraspinatus muscles was significantly higher in patients on the right side (p=0.024). A similar trend was observed on the left side (p=0.08). CONCLUSIONS: T2-hyperintensity and increased volume of brachial plexus roots support a contribution of neuroinflammation to lower motor neuron and axonal degeneration in ALS. Denervation may explain muscle signal alterations. Increased adipose tissue between trapezius and supraspinatus muscles may represent an indirect marker of muscle atrophy. Study Supported by: