Correlation between quantitative EMC and muscle MRI in patients with axonal neuropathy

The aim of the study was to investigate whether there are correlations betw een electromyography (EMG) data and findings in muscle magnetic resonance i maging (MRI). Quantitative EMG data and the amount of pathologic spontaneou s activity (PSA) were compared with MRI signal intensities of the tibialis anterior muscles of 20 patients with axonal polyneuropathy and 14 healthy s ubjects. Using hierarchical regression analysis, the mean motor unit action potential (MUAP) size index (SI) and the amount of PSA were accurate predi ctors of T1-weighted signal intensity in MRI, an expression of fatty degene ration. The MUAP SI was superior to MUAP amplitude in explaining the varian ce of T1 signal intensity. Age was not a relevant factor. A high correlatio n was found between the amount of PSA and the Te-weighted signal intensity in short tau inversion recovery sequence. Magnetic resonance imaging demons trates the structural changes and thus visualizes the outcome of the functi onal changes of denervation and reinnervation detected by EMG. (C) 2000 Joh n Wiley & Sons, Inc.