Stable muscle atrophy in long-term paraplegics with complete upper motor neuron lesion from 3- to 20-year SCI.

Spinal Cord. 2008 Apr;46(4):293-304. Epub 2007 Oct 23. Stable muscle atrophy in long-term paraplegics with complete upper motor neuron lesion from 3- to 20-year SCI. Kern H, Hofer C, Mödlin M, Mayr W, Vindigni V, Zampieri S, Boncompagni S, Protasi F, Carraro U. Source Department of Physical Medicine, Ludwig Boltzmann Institute of Electrostimulation and Physical Rehabilitation, Wilhelminenspital, Vienna, Austria. Abstract STUDY DESIGN: Unrandomized trial. OBJECTIVES: To investigate the structural and functional relationships and the progression of muscle atrophy up to 20 years of spastic paraplegia. SETTING: Clinical follow-up in Vienna, Austria; muscle biopsies analyzed by light microscopy in Padova and by electron microscopy (EM) in Chieti, Italy. METHODS: Force was measured as knee extension torque; trophism by computer tomography scan; tissue composition and fiber morphology by histopathology and EM. RESULTS: In the long-term group of patients (17.0+/-2.6 years), force and size of thigh muscles were only slightly different from those of mid-term subjects (2.2+/-0.5 years). Histology and ultrastructure confirm that the difference in average size of muscle fibers between long-term and mid-term paralyzed leg muscles is actually very small. In addition, muscle fibers maintain the striated appearance characteristic of normal skeletal fibers even after 14-20 years of paralysis. Ultrastructural alterations of the activating and metabolic machineries, and the presence of fibers with lower motor neuron denervation features, may explain the low-force output and the reduced endurance of paretic muscles. CONCLUSION: The stable muscle atrophy that characterizes long-lasting spastic paraplegia suggests that there are no upper-time limits to begin a training program based on functional electrical stimulation. PMID: 17955034 [PubMed - indexed for MEDLINE]