Lekcja 6: Kliniczne aspekty urazów i chorób mięśni 2 | Clinical Aspects of Muscle Injuries and Diseases 2

Learning Objectives 🚀

By the end of this lesson, you’ll be able to understand and perform the following skills in English, using relevant medical terminology:

  • 📝 Identify Common Chronic Muscle Disorders: Understand the different types of chronic muscle disorders, including muscular dystrophies, myositis, fibromyalgia, myasthenia gravis, and chronic tendinopathies.
  • 🔍 Recognize Etiology and Risk Factors: Identify the key risk factors and causes for each chronic muscle disorder to aid in prevention and early diagnosis.
  • 🩺 Evaluate Clinical Manifestations: Use observation and other methods to accurately describe the clinical signs and symptoms associated with each disorder.
  • 🧠 Understand Diagnostic Tools: Learn the value of various diagnostic techniques, including genetic testing, blood tests, electromyography, and imaging, in diagnosing chronic muscle disorders.
  • 💊 Implement Treatment Strategies: Develop an understanding of treatment options for chronic muscle disorders, including medications, physical therapy, and surgical interventions.
  • ⚠️ Anticipate Potential Complications: Recognize the possible complications that may arise if chronic muscle disorders are not treated properly and emphasize the importance of timely intervention.

Chronic Muscle Disorders

Chronic muscle disorders encompass a variety of conditions that result in prolonged muscle dysfunction, weakness, and pain. These disorders can be caused by genetic factors, autoimmune responses, or long-term overuse. This lesson covers some of the most common chronic muscle disorders, including muscular dystrophies, myositis, fibromyalgia, myasthenia gravis, and chronic tendinopathies.

Muscular Dystrophies (MDs)

Muscular dystrophies (MDs) are a group of inherited, progressive muscle disorders that result in muscle degeneration and weakness. The most well-known types include Duchenne Muscular Dystrophy (DMD) and Becker Muscular Dystrophy (BMD). DMD is the most severe form, typically affecting young boys, while BMD is a milder form. Both types primarily affect skeletal muscles, but heart and respiratory muscles may also be involved as the disease progresses.

Etiology and Risk Factors

  • Genetic Mutations: MDs are caused by mutations in the dystrophin gene, which is responsible for producing dystrophin, a protein crucial for maintaining the stability of muscle fibers.
  • Inheritance: Both DMD and BMD are X-linked recessive disorders, meaning the defective gene is located on the X chromosome, primarily affecting males.
  • Family History: A family history of muscular dystrophy significantly increases the risk of inheriting the disorder.

Pathophysiology

As muscle fibers degenerate, they are replaced by fat and fibrotic tissue, which leads to progressive weakness and loss of function.

  • Duchenne Muscular Dystrophy: The absence of dystrophin leads to the breakdown and death of muscle fibers, causing rapid and severe muscle deterioration.
  • Becker Muscular Dystrophy: Some dystrophin is produced, which leads to a milder and slower progression of symptoms.

Duchenne vs. Becker Muscular Dystrophy

FeatureDuchenne Muscular Dystrophy (DMD)Becker Muscular Dystrophy (BMD)
Onset AgeEarly childhood (usually before 5 years)Later childhood to early adulthood
Dystrophin ProductionAbsentReduced or abnormal
SeveritySevereMilder, slower progression
Ambulation LossBy early teensMay retain ability to walk into adulthood
Cardiac InvolvementCommonCommon but less severe
Respiratory InvolvementSeverePossible, but typically less severe

Clinical Manifestations

  • Progressive Muscle Weakness: Typically starts in the lower extremities and pelvic muscles and later spreads to the upper limbs, neck, and respiratory muscles.
  • Pseudohypertrophy: Calf muscles may appear enlarged due to the accumulation of fat and fibrotic tissue.
  • Gait Abnormalities: Waddling gait or toe-walking, frequent falls.
  • Cardiorespiratory Complications: Respiratory muscle weakness, respiratory failure, and cardiomyopathy.
  • Loss of Ambulation: DMD patients often lose the ability to walk by adolescence, while BMD patients may retain some mobility into adulthood.

Diagnostic Approach

  • Genetic Testing: Identifies mutations in the dystrophin gene, confirming the diagnosis.
  • Elevated Creatine Kinase (CK) Levels: CK levels are significantly elevated due to ongoing muscle damage.
  • Muscle Biopsy: Shows the absence or reduction of dystrophin in muscle tissue.

Treatment

  • Corticosteroids: Medications like prednisone can slow the progression of muscle degeneration.
  • Physical Therapy: Helps maintain mobility, strengthen muscles, and reduce contractures.
  • Gene Therapy: Emerging treatments aim to correct the underlying genetic mutations.
  • Assistive Devices: Wheelchairs, ventilatory support, and other assistive devices as the disease progresses.

Complications

  • Respiratory Failure: Weakening of respiratory muscles can lead to respiratory complications.
  • Cardiomyopathy: Progressive heart muscle weakening can lead to heart failure.
  • Loss of Mobility: Most patients with DMD lose the ability to walk by adolescence.

Case Study

Patient J.D., a 7-year-old male, was brought to the pediatric clinic with a history of frequent falls, difficulty climbing stairs, and progressive muscle weakness over the past year. The patient's parents reported that he often walks on his toes and has a waddling gait. There is no significant history of trauma or injury. Family history is notable for an uncle on the maternal side who exhibited similar symptoms during childhood.
J.D. was admitted for further evaluation due to progressive weakness impacting daily activities. No recent illness or significant trauma was noted prior to symptom onset.
On examination, J.D. displayed marked pseudohypertrophy of the calf muscles, proximal muscle weakness predominantly in the lower limbs, and difficulty rising from the floor (positive Gower's sign). His gait was characterized by toe-walking and a waddling movement.
Laboratory testing revealed significantly elevated serum creatine kinase (CK) levels. Genetic analysis identified a mutation in the dystrophin gene. A muscle biopsy confirmed the absence of dystrophin protein in muscle tissue.

Plan:

Medication: Initiate corticosteroid therapy with prednisone to help slow the progression of muscle weakness.

Physical Therapy: Recommend ongoing physiotherapy aimed at maintaining muscle strength, improving mobility, and minimizing contractures.

Monitoring: Regular follow-up is scheduled to evaluate respiratory function and cardiac status.

Supportive Care: Discuss the use of assistive devices as required, including orthotic supports and potential planning for wheelchair use in the future.

Follow-Up: Routine monitoring for cardiac and respiratory complications will be necessary. The family has been provided with educational resources regarding genetic counseling and support groups due to the hereditary nature of the condition.

Interactive Task : Based on J.D.'s clinical presentation, family history, and diagnostic findings, determine the most likely form of muscular dystrophy.

Myositis (Polymyositis and Dermatomyositis)

Myositis refers to a group of chronic, autoimmune disorders that cause inflammation and weakness of the muscles. The two main types are Polymyositis (PM), which primarily affects the muscles, and Dermatomyositis (DM), which affects both muscles and the skin.

Etiology and Risk Factors

  • Autoimmune Response: Caused by the immune system mistakenly attacking muscle fibers, leading to chronic inflammation.
  • Environmental Triggers: Infections, medications, or environmental factors may trigger myositis in genetically susceptible individuals.
  • Gender: More common in women, especially dermatomyositis.

Pathophysiology

  • Polymyositis (PM): Involves inflammation primarily of the proximal muscles, such as the shoulders, hips, and neck.
  • Dermatomyositis (DM): Similar to PM but includes characteristic skin manifestations, such as a heliotrope rash around the eyes and Gottron’s papules on the knuckles.
  • Inflammation results from immune cell infiltration of muscle fibers and, in DM, immune complex deposition in blood vessels.

Polymyositis vs. Dermatomyositis

FeaturePolymyositis (PM)Dermatomyositis (DM)
Primary Muscle InvolvementProximal muscles (shoulders, hips, neck)Proximal muscles + skin involvement
Skin InvolvementNoneHeliotrope rash, Gottron’s papules
Gender PrevalenceMore common in femalesMore common in females
Immune MechanismT-cell mediated muscle inflammationB-cell and immune complex-mediated inflammation
TreatmentCorticosteroids, immunosuppressive drugsCorticosteroids, immunosuppressive drugs, sun protection

Clinical Manifestations

  • Symmetrical Muscle Weakness: Involves shoulders, hips, and neck, affecting both sides of the body.
  • Skin Rashes in Dermatomyositis: Reddish-purple rash around the eyes (heliotrope rash) and scaly eruptions on the knuckles (Gottron’s papules).
  • Fatigue: Due to chronic muscle inflammation.
  • Dysphagia: Difficulty swallowing due to involvement of esophageal muscles.

Diagnostic Approach

  • Elevated Muscle Enzymes: CK and aldolase levels are typically elevated.
  • Electromyography (EMG): Detects abnormal electrical activity in inflamed muscles.
  • Muscle Biopsy: Confirms inflammation and immune cell infiltration in muscle tissue.

Treatment

  • Corticosteroids: High doses of steroids like prednisone are the first-line treatment.
  • Immunosuppressive Drugs: Methotrexate or azathioprine for long-term management.
  • Physical Therapy: Helps maintain muscle strength and prevent contractures.
  • Sun Protection: Avoiding sun exposure is crucial for DM patients.

Complications

  • Chronic Muscle Weakness: Persistent weakness due to ongoing inflammation.
  • Skin Complications: In DM, persistent skin rashes can lead to scarring or pigmentation changes.
  • Dysphagia and Aspiration: Swallowing difficulties can lead to aspiration pneumonia.
Case Study

Patient A.L., a 45-year-old female, presented to the rheumatology clinic with complaints of progressive muscle weakness over the past 6 months. The patient reports difficulty climbing stairs, getting up from a seated position, and lifting objects above shoulder level. Additionally, A.L. describes experiencing significant fatigue and skin changes, including a reddish-purple discoloration around her eyes and scaly patches on her knuckles. There is no significant history of trauma, and the patient denies any recent infections. Family history is non-contributory.
A.L. was admitted for evaluation of her worsening muscle weakness and skin changes. There was no history of recent infections or use of medications known to trigger muscle inflammation.
On examination, A.L. exhibited symmetrical proximal muscle weakness involving the shoulders and hips. There was also a heliotrope rash noted around both eyes, and Gottron's papules were present over the knuckles. There was no evidence of joint swelling or tenderness. The patient demonstrated difficulty rising from a seated position without using her hands for support.
Laboratory studies showed elevated creatine kinase (CK) and aldolase levels, indicating muscle inflammation. Electromyography (EMG) revealed abnormal electrical activity consistent with myopathy. A muscle biopsy demonstrated inflammatory cell infiltration in muscle fibers, and characteristic skin changes were noted, suggesting a possible diagnosis.

Plan:

Medication: Initiate high-dose corticosteroid therapy (prednisone) to reduce inflammation. Consider adding methotrexate as a steroid-sparing agent for long-term management.

Physical Therapy: Recommend physical therapy to maintain muscle strength and prevent contractures, focusing on range-of-motion exercises.

Sun Protection: Advise the patient to avoid sun exposure and use broad-spectrum sunscreen due to the risk of exacerbating skin symptoms.

Monitoring: Schedule regular follow-up appointments to assess muscle strength, monitor for side effects of corticosteroids, and evaluate the need for additional immunosuppressive therapy.

Follow-Up: Routine monitoring of muscle enzyme levels (CK and aldolase) will be required to assess treatment response. The patient was provided with educational materials regarding lifestyle modifications, including energy conservation techniques and skin protection measures.

Interactive Task: Based on A.L.'s clinical presentation, physical findings, and diagnostic results, determine the most likely diagnosis, whether polymyositis or dermatomyositis, based on the findings presented.

Fibromyalgia

Fibromyalgia is a chronic pain syndrome characterized by widespread musculoskeletal pain, fatigue, sleep disturbances, and cognitive issues. It is classified as a central sensitization syndrome, where the central nervous system processes pain signals abnormally, amplifying the sensation of pain.

Etiology and Risk Factors

  • Central Sensitization: Resulting from abnormal pain processing in the brain and spinal cord.
  • Genetic Predisposition: A family history of fibromyalgia or other chronic pain syndromes.
  • Stress and Trauma: Physical (e.g., car accidents) or emotional trauma (e.g., PTSD).
  • Gender: More common in women.

Pathophysiology

Fibromyalgia involves dysfunctional pain processing within the central nervous system, resulting in increased sensitivity to pain (allodynia). Altered levels of neurotransmitters like serotonin, norepinephrine, and substance P contribute to heightened pain response.

Clinical Manifestations

  • Widespread Pain: Chronic, diffuse pain affecting muscles, ligaments, and tendons.
  • Tender Points: Specific areas unusually sensitive to pressure.
  • Fatigue: Persistent tiredness not relieved by rest.
  • Sleep Disturbances: Difficulty falling asleep, staying asleep, or waking up unrefreshed.
  • Cognitive Dysfunction: “Fibro fog” involving difficulties with memory, concentration, and thinking.
  • Mood Disorders: Depression and anxiety are common.

Diagnostic Approach

  • Clinical Diagnosis: Based on widespread pain lasting more than three months and tender points.
  • Exclusion of Other Conditions: Blood tests and imaging to rule out other causes.

Treatment

  • Medications: Antidepressants like duloxetine or amitriptyline and anticonvulsants like pregabalin.
  • Cognitive Behavioral Therapy (CBT): Helps manage chronic pain through coping mechanisms.
  • Exercise: Low-impact aerobic activities like swimming or walking.
  • Multidisciplinary Approach: Physical therapy, mental health support, and pain management.

Complications

  • Chronic Fatigue: Persistent fatigue can significantly affect quality of life.
  • Sleep Disorders: Ongoing sleep disturbances can lead to other health issues.
  • Mental Health Issues: Increased risk of depression and anxiety due to chronic pain.
Case Study

Patient M.T., a 38-year-old female, presented to the general medicine clinic with a chief complaint of chronic, widespread musculoskeletal pain that has persisted for over a year. The patient reports a generalized aching sensation affecting her back, shoulders, and hips. Additionally, she describes persistent fatigue that is not relieved by sleep, difficulty falling asleep, and waking up feeling unrefreshed. The patient also reports "fibro fog," which includes episodes of poor concentration and memory lapses. No significant history of trauma or injury was noted, though the patient mentions increased stress due to work and family responsibilities. Family history is notable for a mother with similar symptoms but without a confirmed diagnosis.
On examination, M.T. demonstrated multiple tender points, particularly over the trapezius, lateral epicondyles, and hips, which elicited a heightened pain response. There was no evidence of joint swelling or erythema. Neurological examination was normal, and muscle strength testing showed no significant weakness.
Laboratory tests, including complete blood count (CBC) and thyroid function tests, were within normal limits. Rheumatoid factor and antinuclear antibody (ANA) tests were negative, helping to exclude other rheumatologic conditions. A diagnosis was made based on clinical criteria, including widespread pain lasting more than three months and the presence of multiple tender points.

Plan:

Medication: Prescribe duloxetine to help manage chronic pain and improve mood. Consider adding pregabalin if pain persists.

Cognitive Behavioral Therapy (CBT): Recommend CBT to help the patient develop coping strategies for chronic pain and manage stress.

Exercise: Encourage low-impact aerobic activities such as walking or swimming to improve overall function and reduce pain.

Sleep Hygiene: Provide guidance on improving sleep quality, including establishing a regular sleep schedule and avoiding caffeine in the evening.

Follow-Up: Schedule a follow-up appointment in three months to assess the patient’s response to treatment. Adjust medications as needed based on pain control and side effects. The patient was provided with educational materials regarding lifestyle modifications and support groups for individuals with fibromyalgia.

Interactive Task: Test your understanding by answering the following questions:

Which of the following treatment strategies would be most appropriate to begin for M.T.?
a) High-impact aerobic exercises
b) Cognitive Behavioral Therapy (CBT)
c) Long-term use of opioid medication
d) No treatment is necessary

True or False: M.T.'s symptoms are likely exacerbated by a lack of sleep and high levels of stress.

Interactive Task: Based on M.T.'s clinical presentation, suggest a realistic daily routine that includes exercise, stress management, and sleep hygiene measures to improve her quality of life.

Myasthenia Gravis (MG)

Myasthenia gravis (MG) is a chronic autoimmune disorder that causes weakness and rapid fatigue of voluntary muscles. It is caused by the production of autoantibodies that block or destroy acetylcholine receptors at the neuromuscular junction.

Etiology and Risk Factors

  • Autoimmune Disease: Antibodies attack acetylcholine receptors at the neuromuscular junction.
  • Thymus Abnormalities: Thymomas or other abnormalities are common in MG patients.
  • Gender and Age: More common in women under 40 and men over 60.

Pathophysiology

Autoantibodies bind to acetylcholine receptors, reducing the number of functional receptors and impairing nerve signal transmission to muscles. This results in muscle weakness that worsens with use and improves with rest.

Clinical Manifestations

  • Muscle Weakness: Worsens with activity and improves with rest; affects muscles responsible for eye movement, facial expression, chewing, swallowing, and limb movement.
  • Ptosis and Diplopia: Drooping of the eyelids (ptosis) and double vision (diplopia).
  • Bulbar Symptoms: Difficulty speaking, chewing, and swallowing.
  • Respiratory Muscle Weakness: In severe cases, can lead to myasthenic crisis.

Diagnostic Approach

  • Blood Tests: Detection of acetylcholine receptor antibodies or anti-MuSK antibodies.
  • Electromyography (EMG): Detects impaired neuromuscular transmission.
  • Edrophonium Test: Improvement of muscle strength with edrophonium administration.
  • CT or MRI of the Chest: To check for thymomas.

Treatment

  • Acetylcholinesterase Inhibitors: Pyridostigmine increases acetylcholine at the neuromuscular junction.
  • Immunosuppressive Therapy: Corticosteroids and other immunosuppressive drugs.
  • Thymectomy: Surgical removal of the thymus gland.
  • Plasmapheresis and IVIg: Used in severe cases to remove or neutralize autoantibodies.

Complications

  • Myasthenic Crisis: Severe respiratory muscle weakness requiring emergency intervention.
  • Respiratory Infections: Weakened respiratory muscles can lead to increased risk of infections.
  • Ocular Complications: Persistent ptosis and double vision affecting daily activities.
Case Study  

Patient R.K., a 65-year-old male, was referred to the neurology clinic with a primary complaint of progressive muscle weakness, particularly towards the end of the day. The patient reports experiencing drooping of his eyelids and episodes of double vision over the past several months. He also describes difficulty chewing and swallowing, particularly in the evenings, and occasional slurred speech. There is no history of trauma or neurological conditions. The patient’s medical history is notable for hypertension, well-controlled with medication.
On examination, R.K. exhibited bilateral ptosis, more pronounced after prolonged upward gaze. Muscle strength testing revealed fatigable weakness in the upper limbs, especially during repetitive movements. Cranial nerve examination showed difficulty maintaining eye position, consistent with diplopia. Bulbar muscle weakness was noted, with the patient demonstrating mild dysarthria and difficulty swallowing.
Laboratory testing revealed the presence of acetylcholine receptor antibodies. Electromyography (EMG) demonstrated a decremental response in muscle action potentials with repetitive nerve stimulation, consistent with impaired neuromuscular transmission. A chest CT scan was performed, revealing an enlarged thymus, suggestive of thymoma.

Plan:

Medication: Start pyridostigmine to increase acetylcholine availability at the neuromuscular junction, thereby improving muscle strength.

Immunosuppressive Therapy: Initiate corticosteroid therapy to reduce autoimmune activity. Consider azathioprine if long-term immunosuppression is needed.

Thymectomy: Refer to a thoracic surgeon for evaluation and potential thymectomy, given the presence of thymoma.

Monitoring: Schedule regular follow-up appointments to monitor muscle strength, respiratory function, and potential side effects of treatment.

Follow-Up: The patient will require ongoing monitoring for potential complications, including respiratory difficulties and increased risk of infections due to immunosuppressive therapy. Educational materials were provided regarding the importance of medication adherence and recognizing symptoms of a myasthenic crisis.

Interactive Task: Based on R.K.'s clinical presentation, physical findings, and diagnostic results, determine which treatment option would be most effective in managing his symptoms and discuss the potential benefits of thymectomy in this patient.

Chronic Tendinopathies

Chronic tendinopathies refer to long-term degeneration of tendons due to overuse, mechanical stress, or repetitive trauma. Unlike acute tendinitis, which is characterized by inflammation, chronic tendinopathies involve tendinosis, where there is degeneration of the tendon’s collagen fibers without significant inflammation.

Etiology and Risk Factors

  • Overuse: Repetitive motion or excessive strain on a tendon without adequate recovery time leads to tendon degeneration.
  • Age: Tendon elasticity decreases with age, making older individuals more prone to tendinopathies.
  • Poor Biomechanics: Improper technique in sports or work-related activities can overload tendons.
  • Previous Injury: A history of tendinitis or tendon injury increases the likelihood of developing tendinopathy.

Pathophysiology

In chronic tendinopathies, repetitive microtrauma to the tendon leads to the breakdown of collagen fibers, resulting in degenerative changes rather than inflammation. Tendons lose their normal structure and strength, making them prone to further injury.

Chronic Tendinopathies vs. Tendinitis

FeatureChronic TendinopathiesTendinitis
Nature of DisorderDegenerative (tendinosis)Inflammatory
SymptomsChronic pain, thickening of tendonAcute pain, localized tenderness
InflammationMinimal to noneSignificant
TreatmentRest, rehabilitation, shockwave therapy, surgeryNSAIDs, rest, physical therapy
DurationLong-termShort-term (acute)

Clinical Manifestations

  • Chronic Pain: Persistent pain localized to the affected tendon, which often worsens with movement or activity.
  • Decreased Range of Motion: Tendon stiffness can limit joint mobility, making daily activities difficult.
  • Thickening of the Tendon: Degenerative changes can cause the tendon to become thickened and less flexible.

Diagnostic Approach

  • Ultrasound/MRI: These imaging techniques are used to visualize degenerative changes in tendons and assess the extent of damage.
  • Physical Examination: Evaluates pain, swelling, and reduced mobility of the affected joint or tendon.

Treatment

  • Rest and Rehabilitation: Avoiding activities that aggravate the condition and focusing on rest and rehabilitation.
  • Physical Therapy: Strengthening the surrounding muscles to reduce stress on the tendons and improve joint function.
  • Anti-inflammatory Medications: Nonsteroidal anti-inflammatory drugs (NSAIDs) can provide temporary relief but are less effective in treating the degenerative nature of tendinosis.
  • Shockwave Therapy: A non-invasive treatment that uses acoustic waves to stimulate healing in chronic tendinopathies.
  • Surgery: In severe cases, surgical intervention may be required to remove damaged tissue and stimulate tendon healing.

Complications

  • Chronic Pain: Persistent pain that can significantly affect daily activities.
  • Reduced Mobility: Tendon stiffness can lead to reduced joint function and limited range of motion.
  • Tendon Rupture: Severe degeneration may lead to a complete rupture, requiring surgical repair.
Case Study

Patient S.L., a 45-year-old male, presented to the outpatient orthopedic clinic with a complaint of persistent pain in the right elbow that has been ongoing for the past two weeks. The patient describes the pain as sharp and localized, particularly over the lateral aspect of the elbow. The pain worsens with activities involving wrist extension or gripping objects, such as lifting a suitcase or shaking hands. The patient denies any history of trauma or previous elbow injuries but reports that the symptoms began after an intense weekend of home renovations involving repetitive hammering and painting.

Physical Examination: On examination, S.L. demonstrated tenderness over the lateral epicondyle of the right elbow. Pain was reproduced with resisted wrist extension and passive wrist flexion. There was mild swelling over the lateral aspect of the elbow, but no significant thickening of the tendon was noted. Muscle strength was otherwise normal, and no signs of systemic involvement were present.

Diagnostics: Laboratory tests, including inflammatory markers, were normal. Ultrasound imaging showed mild thickening and hypoechogenicity of the common extensor tendon, with evidence of increased vascularity consistent with an acute inflammatory response.

Plan:

Medication: Prescribe a short course of NSAIDs to help reduce pain and inflammation.

Physical Therapy: Initiate physical therapy focusing on eccentric strengthening exercises of the wrist extensors to aid in recovery.

Activity Modification: Advise the patient to avoid repetitive activities that exacerbate symptoms and to use an elbow strap during activities involving wrist extension.

Follow-Up: Schedule a follow-up appointment in four weeks to evaluate symptom progression and adjust treatment as necessary.

Interactive Task: Based on S.L.'s clinical presentation, physical findings, and diagnostic results, determine whether this case is more consistent with chronic tendinopathy or acute tendinitis. Provide reasoning for your assessment, considering features such as pain duration, inflammation, and imaging findings.