An MRI Investigating of the Lower Limb Musculature in Patients with Chronic Inflammatory Demyelinating Polyneuropathy

Abstract

IntroductionChronic inflammatory demyelinating polyneuropathy (CIDP) is an autoimmune disease characterized by peripheral nerve demyelination. Patients present with sensory and motor deficits, including symmetrical diffused muscle weakness especially in distal muscles. Studies have focused mainly on the neuropathic aspects of CIDP and its involvement in paresis, showing lesions in various nerve plexes including the lumbar nerve roots. Weakness in patients with CIDP has been reported predominantly in the distal musculature. However, changes in muscle quality and quantity have not been explored systematically throughout the lower limb. Thus, the purpose of this study was to use magnetic resonance imaging (MRI) to compare anatomical differences in the quadriceps femoris and triceps surae muscle complexes in a group of patients with CIDP and control subjects.MethodsTo date, five patients with CIDP (3 males, 2 females) and six healthy controls (4 males, 2 females) and matched on age (45 to 68 years) have been investigated. On separate days, MRI (T1) of the lower limb musculature was acquired via serial axial plane scans in a 3.0‐Tesla magnet with a 3D FLASH sequence: (0.9mm slice thickness with slice separation of 1mm ranging from 280 to 400 slices). All MRI scans were analyzed using OsiriX imaging processing software. On a single thigh slice (two‐thirds distance proximal to distal) and leg slice (one‐third distance proximal to distal) total muscle area was computed for the quadriceps femoris (rectus femoris, vastus lateralis, vastus intermedius, vastus medialis), and the triceps surae (soleus, lateral and medial gastrocnemii) groups, respectively. Contractile muscle area (fat and connective tissue removed) for each muscle group was determined using a pixel threshold intensity algorithm. Percentage of fat infiltration was computed by subtracting contractile muscle area from total muscle area.ResultsPatients with CIDP had ~24% less total anatomical cross‐sectional area (ACSA) in both quadriceps femoris and the triceps surae compared to controls. Patients with CIDP, however had ~35% less contractile muscle tissue in the quadriceps femoris whereas the triceps surae were ~51% lower in contractile tissue, compared with controls. The ACSA of the triceps surae of CIDP patients consisted of ~40% fat whereas the quadriceps femoris ACSA had ~16% fat infiltration. Furthermore, the control group's ACSA consisted of ~9% and 5% fat, respectively in the triceps surae and quadriceps.ConclusionPatients with CIDP have less total thigh ACSA with increased intramuscular fat infiltration compared with controls indicative of lower muscle quality in CIDP. Fatty infiltration in the CIDP group are greater in the anterior thigh compared to posterior leg. This indicates that in addition to lower muscle quantity and quality in CIDP, distal musculature seems to be affected to a greater degree by the nerve impairments noted in CIDP.Support or Funding InformationSupported by NSERCThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.