Multiple Sclerosis (MS) is a chronic, often unpredictable disease of the central nervous system (CNS), which includes the brain and spinal cord. The condition involves the immune system mistakenly attacking the protective layer around nerve fibers, called myelin. While this damage primarily causes neurological symptoms, pain is a very common complaint, affecting up to two-thirds of people with MS. This pain can manifest in many ways, leading to questions about whether MS specifically targets the joints themselves.
The Direct Answer: MS Does Not Cause Primary Joint Inflammation
Multiple Sclerosis is fundamentally a neurological disease and does not cause primary, inflammatory arthritis like rheumatoid arthritis (RA). The autoimmune attack in MS is directed at the myelin sheath within the CNS, disrupting nerve signal transmission, resulting in neurological symptoms such as weakness, numbness, and spasms. In contrast, autoimmune diseases that cause true joint pain, like RA, involve the immune system attacking the synovium, the tissue lining the joints. While MS causes painful symptoms, it does not directly trigger the joint inflammation characterized by swelling, warmth, and stiffness that defines arthritis. The pain experienced near joints in MS is typically categorized as neuropathic pain, arising from nerve damage, or musculoskeletal pain.
Secondary Musculoskeletal Pain Resulting from MS Symptoms
The majority of joint-related discomfort in MS is musculoskeletal pain, an indirect result of how the condition affects muscle control and movement. This pain is a mechanical consequence of neurological dysfunction, placing abnormal stress on the joints, ligaments, and tendons. It is often described as a dull ache, throbbing, or stiffness around the joints, particularly in the lower back, hips, knees, and ankles.
Chronic muscle tightness and spasms, known as spasticity, are a common source of this joint strain. Spastic muscles exert constant, abnormal pulling forces on the joints they cross, leading to pain in the hips, knees, and lower back. This tension can also contribute to contractures, which are painful shortenings of the muscles and tendons around a joint.
MS-related weakness and loss of coordination can significantly alter a person’s walking pattern, or gait. Compensatory movements, such as hiking a hip or swinging a leg, introduce uneven and excessive wear on the ankle and knee joints. This abnormal biomechanics leads to secondary pain, especially in weight-bearing joints. Reduced mobility and prolonged periods of sitting or lying down, often due to fatigue, also lead to muscle deconditioning and stiffness, contributing to overall joint discomfort.
Common Comorbid Conditions That Mimic Joint Pain
When someone with MS experiences true joint pain, it is often due to a co-occurring health condition, known as a comorbidity. These conditions are common in the general population but must be identified separately from the MS pathology itself. The most common cause of true joint pain is Osteoarthritis, a wear-and-tear condition that causes cartilage breakdown.
Certain inflammatory autoimmune conditions, such as Rheumatoid Arthritis (RA) and psoriatic arthritis, can also occur alongside MS. RA attacks the joint lining and causes symmetrical joint swelling and stiffness, which is distinct from the pain caused by MS spasticity. Studies suggest that people with MS may have a higher risk of developing RA than the general population.
Some MS treatments may also indirectly contribute to musculoskeletal issues. For instance, the use of glucocorticoids (steroids) to manage acute relapses can increase the risk of bone density loss and osteoporosis. This can lead to vertebral compression fractures, causing severe back pain that may be mistakenly attributed to MS itself.
Targeted Management Strategies for MS-Related Pain
The most effective management for MS-related joint pain involves addressing the underlying neurological symptoms causing the mechanical stress. Physical therapy (PT) and occupational therapy (OT) are essential, offering tailored exercises to improve balance, strength, and coordination. Therapists teach stretching and strengthening routines to reduce spasticity and correct compensatory movement patterns that strain the joints.
Medications are often used to manage musculoskeletal pain. Muscle relaxants, such as baclofen, are commonly prescribed to reduce muscle spasticity, which directly lessens the pulling force on joints like the hips and knees. For pain that is inflammatory or due to a separate comorbidity like osteoarthritis, nonsteroidal anti-inflammatory drugs (NSAIDs) may be used.
Lifestyle adjustments also play a role in reducing overall joint load and discomfort. Maintaining a healthy body weight helps reduce stress on weight-bearing joints, particularly the knees and ankles. Incorporating regular, gentle movement and stretching helps prevent the stiffness and deconditioning that result from prolonged immobility.