Skeletal muscles are responsible for voluntary movements, posture, and stability. Any disorder affecting these muscles can significantly impact mobility, strength, and quality of life. Skeletal muscle disorders can result from genetic mutations, inflammation, autoimmune responses, infections, metabolic disorders, or trauma. Below is an overview of common skeletal muscle disorders:
- Muscular Dystrophy (MD)
Muscular dystrophy refers to a group of genetic diseases characterized by progressive weakness and degeneration of skeletal muscles.
Types of Muscular Dystrophy:
- Duchenne Muscular Dystrophy (DMD):
- Cause: X-linked recessive mutation in the dystrophin gene.
- Symptoms: Progressive muscle weakness, starting in the lower limbs and spreading to other muscles. It typically affects boys and leads to difficulty walking, heart problems, and breathing difficulties.
- Progression: DMD generally results in the loss of independent walking by the age of 12 and often leads to respiratory failure in early adulthood.
- Becker Muscular Dystrophy (BMD):
- Cause: Similar to DMD but involves a less severe mutation in the dystrophin gene.
- Symptoms: Similar to DMD but less severe. It progresses more slowly and often affects the thigh muscles and pelvis.
- Myotonic Dystrophy:
- Cause: Genetic mutation leading to defective dystrophia myotonica protein kinase (DMPK) gene.
- Symptoms: Muscle weakness, myotonia (delayed muscle relaxation), cataracts, cardiac arrhythmias, and intellectual impairment. It affects adults and can present with various levels of severity.
Treatment:
- Physical therapy to maintain muscle function, corticosteroids to slow progression, and gene therapy for certain types.
- Polymyositis
Polymyositis is an inflammatory myopathy that involves progressive muscle weakness due to inflammation in the muscle fibers.
Symptoms:
- Proximal muscle weakness (e.g., muscles of the shoulders, hips, and thighs).
- Difficulty swallowing or breathing.
- Fatigue and muscle pain.
- Joint pain in some cases.
Cause:
- Autoimmune disorder where the body’s immune system attacks the muscle tissue.
Treatment:
- Corticosteroids (e.g., prednisone) to reduce inflammation.
- Immunosuppressive drugs (e.g., methotrexate or azathioprine) to manage immune system activity.
- Physical therapy to help maintain muscle strength.
- Dermatomyositis
Dermatomyositis is another inflammatory disease that affects the skin and muscles.
Symptoms:
- Skin rashes: A characteristic red or purple rash appears on the face, chest, and knuckles.
- Proximal muscle weakness similar to polymyositis.
- Difficulty swallowing, speaking, and breathing.
Cause:
- Autoimmune disorder; the immune system attacks both skin and muscle tissues.
Treatment:
- Similar to polymyositis: corticosteroids, immunosuppressive agents, and physical therapy.
- Myasthenia Gravis (MG)
Myasthenia gravis is an autoimmune neuromuscular disorder characterized by muscle weakness and fatigue.
Symptoms:
- Muscle weakness that worsens with activity and improves with rest.
- Drooping eyelids (ptosis) and double vision.
- Difficulty swallowing and speaking.
- Weakness in the arms, legs, and respiratory muscles.
Cause:
- Autoantibodies attack acetylcholine receptors at the neuromuscular junction, preventing normal communication between the nerve and muscle.
Treatment:
- Acetylcholinesterase inhibitors (e.g., pyridostigmine) to increase acetylcholine levels.
- Immunosuppressive drugs (e.g., corticosteroids, azathioprine).
- Plasmapheresis or IV immunoglobulin for acute exacerbations.
- Thymectomy (removal of the thymus) in some cases.
- Amyotrophic Lateral Sclerosis (ALS)
Also known as Lou Gehrig’s disease, ALS is a progressive neurodegenerative disorder that affects both upper and lower motor neurons.
Symptoms:
- Progressive muscle weakness, starting in the hands, feet, and mouth.
- Difficulty speaking, swallowing, and breathing.
- Muscle twitching (fasciculations) and spasticity.
Cause:
- The exact cause is unknown, but it involves the death of motor neurons, which are responsible for voluntary muscle movements.
Treatment:
- There is no cure, but drugs like riluzole can slow the progression.
- Physical therapy, speech therapy, and respiratory support to improve quality of life.
- Fibromyalgia
Fibromyalgia is a chronic condition characterized by widespread muscle pain, fatigue, and tenderness in specific areas of the body (known as trigger points).
Symptoms:
- Widespread musculoskeletal pain.
- Fatigue, sleep disturbances, and memory issues (often referred to as “fibro fog”).
- Muscle stiffness and tenderness.
Cause:
- The exact cause is unknown, but it is believed to involve abnormal processing of pain signals by the brain and spinal cord, leading to heightened pain perception.
Treatment:
- Pain relievers, antidepressants, and anticonvulsants.
- Physical therapy, exercise, and cognitive behavioral therapy (CBT).
- Rhabdomyolysis
Rhabdomyolysis is a condition where skeletal muscle fibers break down and release their contents (such as myoglobin) into the bloodstream, which can lead to kidney damage.
Symptoms:
- Muscle pain, weakness, and swelling.
- Dark-colored urine (due to myoglobin).
- Fatigue, nausea, and confusion.
Cause:
- Severe muscle injury (e.g., from trauma, intense exercise, drug use, or infections) leading to muscle breakdown.
Treatment:
- IV fluids to prevent kidney damage by flushing out toxins.
- Dialysis if kidney failure occurs.
- Medications to address the underlying cause, such as pain relievers or antibiotics.
- Cramps and Spasms
Muscle cramps and spasms are sudden, involuntary contractions of muscles that are often painful.
Symptoms:
- Sudden, sharp pain in the affected muscle (often in the legs, feet, or back).
- Tightness or stiffness in the muscle.
Cause:
- Overuse or dehydration due to intense physical activity.
- Electrolyte imbalances (e.g., low potassium, calcium, or magnesium).
- Poor circulation or muscle fatigue.
Treatment:
- Stretching and massaging the muscle.
- Drinking fluids to rehydrate and restore electrolytes.
- Taking muscle relaxants or pain relievers for severe cramps.
- Muscle Strain and Sprain
A muscle strain (or pull) is an injury to a muscle or its tendon, while a sprain affects a ligament.
Symptoms:
- Muscle strain: Pain, swelling, and limited movement in the affected area.
- Sprain: Pain, swelling, bruising, and difficulty moving the joint.
Cause:
- Overstretching or tearing of muscle fibers or tendons.
- Sudden or excessive movement or force.
Treatment:
- Rest, ice, compression, and elevation (R.I.C.E. method) for the first 48 hours.
- Physical therapy and gradual strengthening exercises.
- Myopathy Due to Endocrine Disorders
Muscle weakness can also result from endocrine disorders such as hypothyroidism or hyperthyroidism.
Symptoms:
- Weakness in muscles (especially in the upper legs and arms).
- Muscle cramps or aches.
Cause:
- Hypothyroidism: Low thyroid hormone levels lead to muscle weakness.
- Hyperthyroidism: Excess thyroid hormone can cause muscle wasting.
Treatment:
- Thyroid hormone replacement therapy for hypothyroidism.
- Anti-thyroid medications or surgery for hyperthyroidism.
Conclusion
Skeletal muscle disorders are varied and can be caused by genetic mutations, autoimmune responses, metabolic imbalances, infections, or trauma. While many of these disorders are progressive and chronic, advances in medicine, physical therapy, and supportive treatments can help manage symptoms, improve quality of life, and sometimes slow the progression of the disease. Early diagnosis and treatment are crucial in managing these disorders effectively.
