Functional electrical stimulation as a safe and effective treatment for equine epaxial muscle spasms: Clinical evaluations and histochemical morphometry of mitochondria in muscle biopsies

Functional Electrical Stimulation (FES) has been used extensively over several decades to reverse muscle atrophy during rehabilitation for spinal cord injury patients. The benefits of the technology are being expanded into other areas, and FES has been recently utilized for injury rehabilitation and performance enhancement in horses. Six retired horses (age from 10 to 17 yrs) that had been previously used mainly for dressage riding were selected for this study. Clinical evaluation found epaxial muscle spasms in all horses with minimal to no pelvic extension when manually palpated. FES treatments were performed on the sacral/lumbar region 3 times per week for a period of 8 weeks, obtaining a total of 22 treatments per horse. The Modified Ashworth Scale for grading muscle spasms found a one grade improvement after approximately four FES treatments, indicating improved functional movement of the sacral/lumbar region, supporting the evidence by clinical palpations that a reduction in epaxial muscle spasms occurred. Skeletal muscle biopsies Pre and Post FES treatments were obtained from the <em>longissimus lumborum</em> muscle. Cryosections were stained with a Hemotoxylin-Eosin (H-E), and nicotinamide adenine dinucleotide tetrazolium reductase reaction (NADH-TR). The eventual size change of the muscle fibers were evaluated by morphometry in the H-E and NADH-TR stained cryosections, while in the NADH-TR slides the histochemical density and distribution of mitochondria were also determined. The main results of the morphometric analyses were: 1) As expected for the type of FES treatment used in this study, only a couple of horses showed significant increases in mean muscle fiber size when Pre- vs Post-FES biopsies were compared; 2) In the older horses, there were sparse (or many in one horse) very atrophic and angulated muscle fibers in both Pre- and Post-FES samples, whose attributes and distribution suggests that they were denervated due to a distal neuropathy; 3) The hypothesis of generalized FES-induced muscle fiber damage during epaxial muscle training is not supported by our data since: 3.1) Denervated muscle fibers were also present in the Pre-FES biopsies and 3.2) Only one horse presented with several long-term denervated muscles fibers Post-FES; 4) Preliminary data indicate an increased density and distribution of mitochondria in Post-FES biopsies, suggesting that the clinical improvements in the FES treated horses may be related to daily increased muscle contraction and perfusion induced by FES training. In conclusion, FES in horses is a safe treatment that provides clinical improvements in equine epaxial muscle spasms

Biology of muscle atrophy and of its recovery by FES in aging and mobility impairments: roots and by-products

There is something in our genome that dictates life expectancy and there is nothing that can be done to avoid this; indeed, there is not yet any record of a person who has cheated death. Our physical prowess can vacillate substantially in our lifetime according to our activity levels and nutritional status and we may fight aging, but we will inevitably lose. We have presented strong evidence that the atrophy which accompanies aging is to some extent caused by loss of innervation. We compared muscle biopsies of sedentary seniors to those of life long active seniors, and show that these groups indeed have a different distribution of muscle fiber diameter and fiber type. The senior sportsmen have many more slow fiber-type groupings than the sedentary people which provides strong evidence of denervation-reinnervation events in muscle fibers. It appears that activity maintains the motoneurons and the muscle fibers. Premature or accelerated aging of muscle may occur as the result of many chronic diseases. One extreme case is provided by irreversible damage of the <em>Conus</em> and <em>Cauda Equina</em>, a spinal cord injury (SCI) sequela in which the human leg muscles may be completely and permanently disconnected from the nervous system with the almost complete disappearance of muscle fibers within 3-5 years from SCI. In cases of this extreme example of muscle degeneration, we have used 2D Muscle Color CT to gather data supporting the idea that electrical stimulation of denervated muscles can retain and even regain muscle. We show here that, if people are compliant, atrophy can be reversed. A further example of activity-related muscle adaptation is provided by the fact that mitochondrial distribution and density are significantly changed by functional electrical stimulation in horse muscle biopsies relative to those not receiving treatment. All together, the data indicate that FES is a good way to modify behaviors of muscle fibers by increasing the contraction load per day. Indeed, it should be possible to defer the muscle decline that occurs in aging people and in those who have become unable to participate in physical activities. Thus, FES should be considered for use in rehabilitation centers, nursing facilities and in critical care units when patients are completely inactive even for short periods of time

Recovery from muscle weakness by exercise and FES: lessons from Masters, active or sedentary seniors and SCI patients.

To access publisher's full text version of this article click on the hyperlink belowMany factors contribute to the decline of skeletal muscle that occurs as we age. This is a reality that we may combat, but not prevent because it is written into our genome. The series of records from World Master Athletes reveals that skeletal muscle power begins to decline at the age of 30 years and continues, almost linearly, to zero at the age of 110 years. Here we discuss evidence that denervation contributes to the atrophy and slowness of aged muscle. We compared muscle from lifelong active seniors to that of sedentary elderly people and found that the sportsmen have more muscle bulk and slow fiber type groupings, providing evidence that physical activity maintains slow motoneurons which reinnervate muscle fibers. Further, accelerated muscle atrophy/degeneration occurs with irreversible Conus and Cauda Equina syndrome, a spinal cord injury in which the human leg muscles may be permanently disconnected from the nervous system with complete loss of muscle fibers within 5-8 years. We used histological morphometry and Muscle Color Computed Tomography to evaluate muscle from these peculiar persons and reveal that contraction produced by home-based Functional Electrical Stimulation (h-bFES) recovers muscle size and function which is reversed if h-bFES is discontinued. FES also reverses muscle atrophy in sedentary seniors and modulates mitochondria in horse muscles. All together these observations indicate that FES modifies muscle fibers by increasing contractions per day. Thus, FES should be considered in critical care units, rehabilitation centers and nursing facilities when patients are unable or reluctant to exercise.European Regional Development Fund-Cross Border Cooperation Programme Slovakia-Austria (Interreg-IVa), project Mobilitat im Alter, MOBIL Ludwig Boltzmann Institute of Electrical Stimulation and Physical Rehabilitation, Austria Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Austria Faculty of Physical Education and Sports, Comenius University in Bratislava, Slovakia Austrian national cofinancing of the Austrian Federal Ministry of Science and Research Ludwig Boltzmann Society (Vienna, Austria) EU Commission Shared Cost Project RISE - Austrian Ministry of Science United States Department of Health & Human Services National Institutes of Health (NIH) - USA NIH National Institute of Arthritis & Musculoskeletal & Skin Diseases (NIAMS