title: Muscle MRI STIR signal intensity and atrophy are correlated to focal lower limb neuropathy severity.
abstract: OBJECTIVE
  The objective is to determine if muscle MRI is useful for assessing neuropathy severity.
  
  
  METHODS
  Clinical, MRI and electromyography (EMG) examinations were performed in 17 patients with focal lower limb neuropathies. MRI Short Tau Inversion Recovery (STIR) signal intensity, amyotrophy, and muscle fatty infiltration measured after T1-weighted image acquisition, EMG spontaneous activity (SA), and maximal voluntary contraction (MVC) were graded using semiquantitative scores and quantitative scores for STIR signal intensity and were correlated to the Medical Research Council (MRC) score for testing muscle strength. Within this population, subgroups were selected according to severity (mild versus severe), duration (subacute versus chronic), and topography (distal versus proximal) of the neuropathy.
  
  
  RESULTS
  EMG SA and MVC MRI amyotrophy and quantitative scoring of muscle STIR intensity were correlated with the MRC score. Moreover, MRI amyotrophy was significantly increased in severe, chronic, and proximal neuropathies along with fatty infiltration in chronic lesions.
  
  
  CONCLUSIONS
  Muscle MRI atrophy and quantitative evaluation of signal intensity were correlated to MRC score in our study. Semiquantitative evaluation of muscle STIR signal was sensitive enough for detection of topography of the nerve lesion but was not suitable to assess severity. Muscle MRI could support EMG in chronic and proximal neuropathy, which showed poor sensitivity in these patients.
authors.affiliation: Service de Physiologie Clinique-Explorations Fonctionnelles, AP-HP, Hôpital Lariboisière, 2 rue Ambroise Paré, 75010, Paris, France.
authors.forename: N
authors.initials: N
authors.lastname: Deroide
authors.forename: V
authors.initials: V
authors.lastname: Bousson
authors.forename: L
authors.initials: L
authors.lastname: Mambre
authors.forename: E
authors.initials: E
authors.lastname: Vicaut
authors.forename: J D
authors.initials: JD
authors.lastname: Laredo
authors.forename: Nathalie
authors.initials: N
authors.lastname: Kubis
mesh_terms: D000328:Adult; D000368:Aged; D003937:Diagnosis, Differential; D004576:Electromyography / Q000379:methods; D005240:Feasibility Studies; D006801:Humans; D035002:Lower Extremity / Q000294:innervation; D008279:Magnetic Resonance Imaging / Q000379:methods; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000294:innervation*; D009133:Muscular Atrophy / Q000175:diagnosis*; D010523:Peripheral Nervous System Diseases / Q000175:diagnosis*; D011843:Radiculopathy / Q000175:diagnosis