Muscling in on multiple sclerosis

Multiple sclerosis (MS), a neurodegenerative disease, causes periodic attacks of neurologic symptoms such as limb weakness and mobility defects. And while MS patients' walking abilities and muscle strength are examined on a regular basis, doctors have yet to determine when the lower limb muscles begin to deteriorate. That's important because with earlier identification of mobility problems, doctors would be able to implement early intervention programs that could make all the difference for those with MS.

Now, Dr. Alon Kalron and his fellow researchers from Tel Aviv University's Sackler Faculty of Medicine and the Multiple Sclerosis Centre in Sheba Medical Center, Tel-Hashomer, have discovered that specific laboratory tests for leg muscle endurance and gait - the pattern of movement while walking or running - are highly effective in identifying mobility deficits at the initial stage of MS. These deficits are difficult to discover during standard neurological testing.

According to Dr. Kalron, who was supervised by Profs. Anat Achiron and Zeevi Dvir, patients in the early stages of MS had 40 percent less muscle endurance compared to their healthy counterparts. Additionally, distinct abnormalities were observed in their walking patterns. The study, which was published in the Journal of Neurologic Physiotherapy, could help researchers understand the mechanisms underlying the evolution of MS, and improve the management of patients afflicted with the disease.

One step at a time

Reduced muscle endurance may be one of the earliest signs of MS and is a common complaint among patients, but it is hard to detect, says Dr. Kalron. In order to quantify muscle fatigue, the researchers conducted a study that included 52 patients in the early stage of MS, and a control group of 28 healthy subjects.

Participants were examined using an isokinetic dynamometer, a special instrument for measuring lower limb muscle strength and endurance. They were asked to attempt to bend or straighten a knee exerting maximum effort, and maintain this position for 30 seconds. Muscle fatigue was calculated by measuring the decline in muscle strength during that period. On average, those in the early stages of MS were not able to maintain their strength - they demonstrated 40 percent less endurance compared to the healthy control group.

Multiple sclerosis (MS) is a disease in which the nerves of the central nervous system (brain and spinal cord) degenerate. Myelin, which provides a covering or insulation for nerves, improves the conduction of impulses along the nerves and also is important for maintaining the health of the nerves. In multiple sclerosis, inflammation causes the myelin to disappear. Consequently, the electrical impulses that travel along the nerves decelerate, that is, become slower. In addition, the nerves themselves are damaged. As more and more nerves are affected, a person experiences a progressive interference with functions that are controlled by the nervous system such as vision, speech, walking, writing, and memory.