Musculoskeletal disfunction in MS patients

MS may affect the musculoskeletal system indirectly, producing complications that are as varied as the direct symptoms of MS. Hammer toes, foot inversion and increased plantar flexion may occur secondary to spasticity, resulting in significant gait abnormalities. Decreased control accompanied by decreased sensation in the legs may result in overuse syndromes. These include a variety of musculoskeletal problems associated with the knee. Chronic hyperextension from imbalance of muscle strength or incoordination may damage the posterior ligaments of the knee. The resulting knee pain and weakness may further affect an already unstable gait pattern. A knee brace will help prevent damage to the posterior ligaments of the knee due to chronic hyperextension.

The normal functioning of the hip and sacral area also depend on a balance of the surrounding muscles. An imbalance due to MS may result in sacral torsion or rotation; pain in the hip area then results in an inefficient walking pattern.

The most common musculoskeletal complaint in MS is chronic low back pain. Often the patient's posture is poor, producing a loss of lumbar lordosis. Fatigue exacerbates this problem. Poor balance can create a forward flexion at the hips and add to the development of chronic back pain. Paraspinal spasticity can also cause chronic low back pain. If the problem is one of poor walking posture, the pattern needs to be corrected, and if spasticity is contributing to the problem, it must be lessened.

In the normal nervous system, muscle groups work together with alternate agonistic and antagonistic function. This coordination of movements makes them smooth and strong. In MS this system of balance can be disturbed so that opposing muscles contract and relax at the same time, producing spasticity. Spasticity tends to occur most frequently in a specific group of muscles that are responsible for maintaining upright posture referred to as anti-gravity or postural muscles. These include gastrocnemius, quadriceps, gluteus maximus, erector spinae and adductors.

When spasticity is present, the increased stiffness in the muscles means that a great deal of energy is required to perform everyday activities. The reduction of the spasticity induces greater freedom of movement and strength, frequently accompanied by less fatigue and increased coordination. The major ways by which spasticity is reduced include stretching exercises, physical therapy and the use of drugs. Local back care with heat, massage and ultrasound waves are frequently helpful, and exercises designed to relieve back muscle spasm may be recommended. In the MS patients spinal manipulation (rapid twisting or pushing of the spinal cord) is not recommended as it may irritate the spinal cord and increase neurologic dysfunction. Some times surgery may be needed to relieve the spinal irritation.

Many times it is difficult to distinguish radicular appearing pain from demyelination adjacent to the dorsal root ganglia, giving the appearance of a herniated disc. A burning quality of the radiating pain may indicate MS whereas a decreased reflex may indicate mechanical, discogenic disease. The necessary diagnostic tests include electromyography, magnetic resonance imaging and computerized tomography.

The therapist must be alert to the fact that there may be additional treatable rehabilitative problems in the MS patient that may or may not be related to MS. These must be identified and managed to allow for productive rehabilitation. Encephalos 2009, 46(3):129-131.

Key words: Multiple sclerosis, musculoskeletal dysfunction, pain, spasticity.