DTI changes of brachial plexus nerve roots in amyotrophic lateral sclerosis and their correlation with electrophysiology.

BACKGROUND: Amyotrophic lateral sclerosis (ALS) is a progressive motor neuron disease with peripheral nerve involvement, but current diagnostics are limited. Diffusion tensor imaging (DTI) may improve microstructural assessment and correlate with clinical markers. We investigated the diffusion properties of the brachial plexus in ALS and examined their relationships with electrophysiological parameters of upper limb nerves. MATERIALS AND METHODS: We enrolled 25 ALS patients and 22 age- and sex-matched healthy controls. DTI of the brachial plexus was conducted to measure fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD). Differences in DTI parameters between the two groups were analyzed. Correlations between DTI parameters and ALS Functional Rating Scale-Revised (ALSFRS-R) scores, along with electrophysiological measurements, were assessed. RESULTS: In ALS patients compared to controls, FA and AD values were significantly lower (p ≤ 0.002), while the RD value was significantly higher (p = 0.002). There were no statistically significant differences in MD (p = 0.540). Both FA and AD showed a positive correlation with ALSFRS-R score, ALSFRS-upper limb score, and compound muscle action potential amplitude of median, ulnar, and radial nerves (r ≥ 0.480; p ≤ 0.015). The RD values showed a negative correlation with ALSFRS-upper limb score and motor nerve conduction velocity of median, ulnar, and radial nerves (r ≤ -0.415; p ≤ 0.039). CONCLUSION: FA, AD, and RD values of DTI showed the potential to identify microstructural changes in the brachial plexus nerve roots of ALS patients and may serve as potential indicators of nerve conduction function in the upper extremities. RELEVANCE STATEMENT: DTI may reveal microstructural changes in ALS brachial plexus, correlating with nerve dysfunction, offering novel biomarkers for evaluation of upper limb neurodegeneration. KEY POINTS: Lower Fractional anisotropy (FA) and axial diffusivity (AD), and higher radial diffusivity (RD) were shown in amyotrophic lateral sclerosis (ALS) brachial plexus. Diffusion tensor imaging (DTI) parameters correlated with clinical and electrophysiological parameters. FA, AD, and RD detected ALS nerve microstructural changes, indicating abnormal conduction function.