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:
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) 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.
As muscle fibers degenerate, they are replaced by fat and fibrotic tissue, which leads to progressive weakness and loss of function.
Feature | Duchenne Muscular Dystrophy (DMD) | Becker Muscular Dystrophy (BMD) |
---|---|---|
Onset Age | Early childhood (usually before 5 years) | Later childhood to early adulthood |
Dystrophin Production | Absent | Reduced or abnormal |
Severity | Severe | Milder, slower progression |
Ambulation Loss | By early teens | May retain ability to walk into adulthood |
Cardiac Involvement | Common | Common but less severe |
Respiratory Involvement | Severe | Possible, but typically less severe |
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 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.
Feature | Polymyositis (PM) | Dermatomyositis (DM) |
Primary Muscle Involvement | Proximal muscles (shoulders, hips, neck) | Proximal muscles + skin involvement |
Skin Involvement | None | Heliotrope rash, Gottron’s papules |
Gender Prevalence | More common in females | More common in females |
Immune Mechanism | T-cell mediated muscle inflammation | B-cell and immune complex-mediated inflammation |
Treatment | Corticosteroids, immunosuppressive drugs | Corticosteroids, immunosuppressive drugs, sun protection |
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 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.
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.
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) 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.
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.
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 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.
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.
Feature | Chronic Tendinopathies | Tendinitis |
Nature of Disorder | Degenerative (tendinosis) | Inflammatory |
Symptoms | Chronic pain, thickening of tendon | Acute pain, localized tenderness |
Inflammation | Minimal to none | Significant |
Treatment | Rest, rehabilitation, shockwave therapy, surgery | NSAIDs, rest, physical therapy |
Duration | Long-term | Short-term (acute) |
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.