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Polymyositis Treatments and How do they work:

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Polymyositis Treatments and How do they work:

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Polymyositis Treatment : Johns Hopkins Myositis Center

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Polymyositis Treatment : Johns Hopkins Myositis Center

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Polymyositis is an inflammatory muscle disease that typically begins in adulthood. It causes muscle pain and weakness, similar to dermatomyositis, but without the skin rash that defines dermatomyositis. Because of this, diagnosing polymyositis often involves ruling out other conditions.

Image 1: The exact cause of polymyositis is unclear, but it's believed to involve the immune system. Muscle fibers start showing more MHC class 1 antigens than usual. CD8 T cells from the immune system then move into the muscle tissue. When these CD8 T cells find and bind to the matching MHC-1 antigens on the muscle fibers, they get activated and release substances called perforin and granzyme. These substances cause the muscle fibers to die (Chandra et al, 2023).

When examining the muscle tissue under a microscope, we can see the inflammation is mostly within individual muscle fibers. These muscle fibers, although sometimes appearing normal, are invaded by CD8+ T cells as mentioned above. The affected muscles often show a mix of muscle fiber damage, including degeneration, necrosis, regeneration, and atrophy, but in a scattered, rather than a patterned, distribution (Kumar V. et al, 2020).

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Continuing Education Activity

Polymyositis, a relatively uncommon autoimmune disorder, develops due to abnormal activation of cytotoxic T lymphocytes (CD8 cells) and macrophages against muscular antigens that result in rhabdomyolysis and ultimately presents as a proximal myopathy. This activity outlines the evaluation and treatment of polymyositis and highlights the role of the interprofessional team in the care of patients with this condition.

Objectives:

Review the etiology of polymyositis.

Describes the appropriate evaluation process for polymyositis.

Outline the management options for polymyositis.

Summarize the interprofessional team strategies for improving care coordination and communication to enhance the care of patients with polymyositis.

Access free multiple choice questions on this topic.
Introduction

Idiopathic inflammatory myopathies involve four major subtypes that include polymyositis, dermatomyositis, inclusion body myositis, and necrotizing myopathy. Bohan and Peter categorized myopathies into 7 classes.[1] Polymyositis, an autoimmune and chronic inflammatory myopathy, is characterized by symmetrical proximal muscle weakness due to the involvement of endomysial layers of skeletal muscles versus dermatomyositis, which involves the perimysial layers of muscles along with dermatological presentations.[2]

Polymyositis develops over the months as compared to inclusion body myositis (IBM), which is a slowly progressive chronic myopathy developing in older individuals over a period of months to years with more severe symptoms. IBM develops secondary to either an autoimmune reaction or due to a degenerative process as a result of a persistent retroviral infection such as human T-cell leukemia virus type 1 (HTLV-1).[3] Being an autoimmune disorder, polymyositis, a rheumatological disease, requires long-term treatment with steroids or immunomodulators along with the treatment of the underlying etiological factors. Although this is a rare disorder, polymyositis should be a part of the differential diagnosis of patients experiencing unexplained muscle weakness as the failure to make a diagnosis can have a significant impact on the patient's quality of life due to severe complications.

Etiology

Polymyositis (PM), an autoimmune disorder, develops due to abnormal activation of cytotoxic T lymphocytes (CD8 cells) and macrophages against muscular antigens as well as the strong extrafusal muscular expression of major histocompatibility complex 1 causing damage to the endomysium of skeletal muscles.[4][5]

Different cytokines, including interleukins, tumor necrosis factor (TNF), etc. play an important role in causing rhabdomyolysis. It mostly affects individuals already suffering from some kind of systematic disease due to viral infections, malignancies, or other autoimmune disorders. The commonly responsible viruses for polymyositis are the retroviruses human immunodeficiency virus (HIV) and HTLV1, and hepatitis C virus that possibly cause this inflammatory muscle degeneration by causing endomysial damage leading to edematous swelling and nodular mass formation in the myocytes.[6][7]

Coxsackievirus is another reason for this autoimmune disorder due to the abnormal functioning of major histocompatibility complex (MHC) secondary to the release of the cytokines after damaging the intima and endothelium of blood vessels.[8] Another important etiological factor for polymyositis-induced rhabdomyolysis is an underlying malignancy, e.g., lung carcinoma, genitourinary malignancy or lymphomas, etc. The presence of polymyositis also increases the possibility of having carcinoma in 2-5 years after the diagnosis, especially non-Hodgkin lymphoma. It has the highest risk of development followed by lung carcinoma and bladder carcinomas.[9]

Other causes include the presence of certain HLA variants (A1, B8, DR3), the presence of another autoimmune disease such as celiac disease,[10] and the use of few medications such as hydralazine, procainamide, antiepileptics, and angiotensin-converting enzyme (ACE) inhibitors due to their ability to act as a hapten. A study reported that 24% of patients on statin therapy developed polymyositis.[11]

Epidemiology

Autoimmune disorders are the leading cause of increased mortality among the middle-aged population in the United States with varying incidence rates.[12] Polymyositis rarely presents in childhood and usually affects people above the age of 20 years. Dermatomyositis, however, has a bimodal age distribution affecting the population between 5 to 15 years and 45 to 60 years.[13]

The chances of disease development are almost double in women than in men, which is exactly the opposite of IBM. In the USA population, the rate of development of this autoimmune disorder is about 0.5 to 8.4 cases per 100,000 individuals. Having ethnic variation, it has been more commonly reported in Blacks than in Whites.

Pathophysiology

The following pathophysiological mechanisms have been proposed to define the main reason for rhabdomyolysis occurring in polymyositis.

Direct damage due to the cellular immune response that develops as a result of abnormal activation of cytotoxic T cells (CD8) and macrophages with some involvement of type B lymphocytes and dendritic cells.

Indirectly, damage can happen due to the release of inflammatory mediators in circulation by the cells such as cytokines and interleukins. A study reported a significant increase in pro-inflammatory cytokine IL-21, both in the muscle and serum of affected patients, along with the increased expression of IL-21 receptors (IL-21R) in damaged muscle fibers in these patients.[14] T helper type 1 (Th-1) response due to the release of cytokines (TNF, interferon-gamma, IL-12) and T helper type 17 (Th17) response due to its pro-inflammatory mediators (IL-17, IL-22, and IL-6) are other potential pathogenic mechanisms for causing polymyositis.[15][16]

In addition to causing direct damage, certain cytokines such as IL-1alpha and IL-17 also upregulate the nuclear factor kappa B (NF-kappaB) signaling pathway to increase MHC-1 class expression. NF-kappaB also damages myofibrils by affecting the myocytes' differentiating ability negatively.[17]

Other possible pathological causes for polymyositis include damage to vascular endothelium leading to extravasation of inflammatory mediators from circulation as well as the involvement of humoral immune response depending on the presence of certain antibodies.

Histopathology

Polymyositis is a chronic inflammatory disease, so multiple small foci of inflammatory and necrotic changes and regenerative nodules can be seen on biopsy. Histopathological findings of polymyositis show endomysial mononuclear infiltrate consisting of mostly CD8 T cells and macrophages along with necrotic myofibrils in the early-stage. Late-stage changes include occluded capillaries secondary to inflammatory changes caused by endothelial damage and increased deposition of connective tissue and extracellular matrix. Polymyositis can be differentiated from inclusion body myositis due to the presence of intracytoplasmic inclusion bodies in IBM, and from dermatomyositis due to perimysial infiltrates of CD4 cells as well as B lymphocytes.

History and Physical

The first step to diagnose polymyositis in the early stage is to get a detailed history, including family history, medication history, and any antecedent infections. Polymyositis is a relatively challenging diagnosis due to the absence of dermatological findings when compared to dermatomyositis. The following points should be asked in detail to make an accurate diagnosis.

1. Gradual onset of myopathy with or without associated myalgia

2. Presence of joint pains to rule out other autoimmune disorders

3. The pelvic girdle is involved more commonly as compared to the shoulder muscles, so inquire about the difficulty in standing up from the sitting posture. Patients with upper body involvement can have difficulty in hair combing, inability to raise arms above head, and holding the neck in an upright posture.

4. Patients having the systematic spread can complain of dysphagia due to pharyngeal or esophageal muscle involvement, breathing difficulty, or chest tightness due to infiltrative cardiomyopathy or pericarditis, etc.

Presenting features

The hallmark of polymyositis is a progressive disease with symmetric involvement of proximal girdle muscles (shoulder and pelvis muscles) and neck flexors that can be painful at times.[2] Hip extensors can be involved in some patients making it difficult for them to climb stairs or to have posture change. Patients may complain of the inability of overhead abduction or to get up from the seated position. Disease progression to distal muscles can result in abnormal fine movements such as writing and playing musical instruments. Constitutional symptoms include low-grade fever, anorexia, arthralgia, and weight loss. Polymyositis can cause interstitial lung disease (ILD), especially in anti-Jo-1 positive patients, presenting as shortness of breath and dry cough.[18] Other presenting complaints are chest tightness and exertional dyspnea due to restrictive cardiomyopathy, constipation, or bloating due to gastrointestinal involvement and tightening and discoloration of fingers due to Raynaud phenomenon.

The physical examination must include a complete motor and sensory examination of affected muscles. Though the sensory examination is usually normal in these patients, motor examination reveals a decrease in power in the affected portion depending on disease severity with lost tendon reflexes in severe muscular atrophy. Patients with restrictive polymyositis can present with limited mobility of truncal muscles, especially abnormal flexion that is called camptocormia.[19] The involvement of nasopharyngeal muscles can cause nasal speech, while, in the presence of ILD, crackles can be heard at the lung bases. If polymyositis is associated with any malignancy, then features of that particular neoplasia can be seen e.g., lymphadenopathy in non-Hodgkin lymphoma. Skin rashes can be found in the presence of other autoimmune disorders such as mixed connective tissue disorder.

Evaluation

The multi-modal approach consisting of hematologic and serologic testing, imaging, electromyography, nerve conduction studies, and biopsy findings is used to evaluate a patient with suspected polymyositis. A complete blood count (CBC) can show an elevated lymphocyte count in the majority of the patients and frequently thrombocytosis as well. Erythrocyte sedimentation rate (ESR) can be elevated due to chronic inflammation. Serum creatine kinase (CK) levels can be as high as up to 50 times the normal range (22 to 198 units/liter), indicating myocyte damage due to chronic inflammation. It can be of great clinical use to monitor disease progression by having serial examinations and CK monitoring.

Multiple antibodies can be elevated in polymyositis, such as a non-specific antinuclear antibody (ANA), which can be positive in around 33 percent of the patients with polymyositis. If ANA turns out to be positive, then specific antibody testing is done to confirm PM, which is the anti-signal recognition particle (SRP) in the serum. The presence of anti-aminoacyl tRNA synthetases (ARS) antibodies can show the association of PM with an autoimmune syndrome know as the anti-synthetase syndrome. This is characterized by a group of varying physical presenting features such as inflammation-induced myopathy, joint pain, Raynaud's phenomenon, and fibrotic lung disease.[20] In the case of statin-induced PM, a unique 3-hydroxy-3-methylglutaryl coenzyme A reductase IgG immunoglobulin (anti- HMGCR) can be elevated.[21]

Almost all the patients with PM will have abnormal electromyography (EMG) findings such as varying amplitude and velocity of the membranous action potential, and fibrillation in potentials due to membrane irritability, etc. A vital investigation to make a definitive diagnosis of myopathy is a magnetic resonance imaging (MRI) or EMG guided biopsy that shows perivascular and endomysial mononuclear infiltrates (cytotoxic T lymphocytes and macrophages) and areas of necrosis staining pink due to high eosin stain binding.[22]

Imaging studies such as MRI, computed tomography (CT) scan, or ultrasonography can be useful to locate an area of muscle damage and also to diagnose underlying malignancy. Whole-body magnetic resonance imaging is of utmost significance to exactly diagnose the damaged muscular area.[23]

If the patient presents with dysphagia, a barium swallow can be performed. In the case of lung disease, pulmonary function tests (PFTs) can be done. If PM has caused damage to cardiomyocytes, then an electrocardiogram (EKG) and echocardiography can be performed.

Treatment / Management

Polymyositis is treated with a combination of different pharmacological and non-pharmacological modalities. Pharmacological treatment mainly includes corticosteroids. Prednisone and methylprednisolone are the most common corticosteroids used for polymyositis with a starting dose of 1mg/kg of prednisone a day. The steroids are tapered off gradually and not withdrawn suddenly. The second-line treatment option includes the use of immune-modulators (methotrexate, azathioprine, cyclosporine) in those patients who either do not respond to steroids or develop severe adverse effects due to steroids usage. Cyclophosphamide, an immune-modulator, works efficiently, especially in patients with the involvement of the pulmonary interstitium.[24] In the case of chronic refractory polymyositis, intravenous immunoglobulins (IVIG) can be used. A study showed improvement in around 70% of the patients after the use of IVIG.[25]

IVIG also shows significant improvement in patients having dysphagia due to esophageal involvement.[26] Ceratin biologics such as infliximab and etanercept, have been used in treating refractory cases of PM.[27] Other therapies option include tacrolimus, a calcineurin inhibitor, that has proven to be beneficial in patients having a refractory disease with simultaneous use of prednisolone.[28] Mycophenolate mofetil and the anti-CD20 monoclonal antibody rituximab have also been found to be useful in treating refractory cases of polymyositis.

Patients with different systems involved must be evaluated by the concerned specialty e.g. cardiologist for cardiomyopathy, pulmonologist for ILD, a speech therapist for voice change, etc. Non-pharmacological treatment includes physical therapy of the affected muscles to prevent disuse atrophy. These patients must be advised to have supervised resistive strength training activities.[29] These individuals should be advised to have a diet rich in proteins that help in muscle building.

Differential Diagnosis

If a patient presents with myopathy, the following conditions must be excluded to make an absolute diagnosis.

1. Electrolyte imbalance-induced myopathy that can commonly occur due to the loss of potassium, phosphate, or magnesium from the body. Hypokalemia/Hypophosphatemia can cause muscle cramps and aches leading to a myopathic situation similar to PM.

2. Another important category that must be kept in the differential is endocrinological disorders, e.g., hypothyroidism or hyperthyroidism, diabetes mellitus, and metabolic syndrome, etc. These hormonal disorders can make proximal musculature weak, making the clinical presentation similar to PM.

3. Other autoimmune disorders should be ruled out to diagnose polymyositis. The most common differential is dermatomyositis that is easily differentiated by the dermatologic presentation and endomysial presentation on biopsy. Other disorders to keep in mind for making the diagnosis of PM are myasthenia gravis, mixed connective tissue disorder, systemic lupus erythematosus (SLE), scleroderma, iatrogenic myopathies, and myositis-induced myopathies (focal/giant cell myositis).

4. A history of chronic steroid use should be taken to exclude steroid-induced myopathy or Cushing syndrome.

5. Patients with a previous diagnosis of fibromyalgia or polymyalgia rheumatica (PMR) can complain about muscle pain and weakness. These patients must be carefully evaluated to exclude these causes. Amyotrophic lateral sclerosis (ALS) can cause myopathy, so it should be excluded as well.

6. Drugs can be an important cause of myopathies, so all the drugs having a tendency for myopathy should be kept in mind, such as statins, alcohol derivates, e.g., ethanol, antimetabolites (vincristine), azathioprine, chloroquine/primaquine, and anti-fungal agents.

Prognosis

Polymyositis, being a chronic disease, is associated with a grave prognosis in the long run. In addition to causing disability and affecting the quality of life of the patient, this disease has also been found to be associated with a 10% mortality rate, especially in those who also develop cardiac dysfunction or malignant conditions.[30] The majority of patients usually respond to steroid therapy. This disease has the worst prognosis in the patients having refractory disease, older females, Blacks, and patients having systematic involvement.

Complications

Although polymyositis is a rare disease, it has been found to be associated with increased morbidity and mortality due to its associated comorbid conditions, e.g., the involvement of major vessels or gastrointestinal tract, etc. Patients with polymyositis have about 2.2% risk of having myocardial infarction as compared to the general population.[31] Patients with polymyositis are most likely to be diagnosed with cancer within the first year following the diagnosis of polymyositis, so age and gender-specific evaluation for malignancy should be done in all the patients with PM.[32] According to a study, the presence of a high neutrophil/lymphocyte ratio in patients above the age of 60 years greatly increases the risk of having carcinoma of lung/bladder or non-Hodgkin lymphoma.[33]

Polymyositis affects the distal musculature of the esophagus in the late stage of disease in up to 70% of the patients leading to the inability to swallow, as well as regurgitation problems that can cause aspiration pneumonia.[34] The involvement of the lungs can increase the mortality rate due to having an adverse impact on the quality of life. The presence of PM in the females of the child-bearing age group can result in a fetal loss in the case of active disease.

PM can induce a hypercoagulable state in the plasma leading to the increased incidence of thromboembolism.[35] An increase in the risk of development of amyotrophic lateral sclerosis was also observed in a study in patients with PM.[36] Osteoporosis risk has been found to be elevated in patients with PM.[37]

Deterrence and Patient Education

Since polymyositis can cause multiple comorbid conditions, it is mandatory to properly guide the patients to lessen their suffering. The following points should be explained to patients to prevent future consequences.

1. Guide patients to prevent extreme cold weather conditions due to potential chances of cold-induced necrosis of extremities due to Raynaud phenomenon-induced vascular obliteration/spasm.

2. Patients with esophageal motility disorder should be educated to avoid lying down immediately after a meal.

3. Prophylactic supplements containing calcium and vitamin D should be started early to prevent disease or steroids induced osteoporosis.

4. Detailed information should be provided to the patient if there is a possibility of having any underlying malignancy in high-risk candidates such as older male patients having broad systematic involvement.[38]

5. The importance of physical training should be emphasized.

Enhancing Healthcare Team Outcomes

A strong clinician-patient relationship is mandatory to improve healthcare outcomes along with good communication among an interprofessional team, which includes a rheumatologist, neurologist, gastroenterologist, pulmonologist, a primary clinician, a physiotherapist, a dietician, and nurses. Without proper management, the morbidity and mortality from polymyositis are high. However, successful diagnosis and treatment at the initial stage can help patients live longer.

References

Disclosure: Ayesha Sarwar declares no relevant financial relationships with ineligible companies.

Disclosure: Alexander Dydyk declares no relevant financial relationships with ineligible companies.

Disclosure: Shraddha Jatwani declares no relevant financial relationships with ineligible companies.

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Idiopathic inflammatory myopathies involve four major subtypes that include polymyositis, dermatomyositis, inclusion body myositis, and necrotizing myopathy.

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This is the official document with the case study presentation of a patient with polymyositis. Below is a summary of the case with the main points and our group's thought process along the development of the case. 

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The patient, a 61 year old male, arrived to the ER with a 3 week history of generalized weakness and dysphagia of solids . Upon physical examination he showed proximal limb weakness .

Laboratory testing showed elevated leukocytes, but there wasn’t an apparent source of infection. This can lead us to start thinking about an inflammatory disease. Tumor markers were found to be elevated, but after a CT scan, there wasn’t evidence of any malignancy.

Elevated aspartate transaminase (AST), alanine transaminase (ALT), and creatine phosphokinase (CK) were found and this finding can already lead us to start thinking about a muscle wasting syndrome, mainly due to the elevated AST and CK.

Viral panels were performed and were negative. But this was important to perform because viral infections have been related to the development of these idiopathic inflammatory myopathies.

After 3 days in the hospital, symptoms worsened due to mismanagementl; so a neuromuscular disease was suspected. Lumbar punture showed CSF values within normal parameters. Nerve conduction velocities showed reduced amplitude in compound muscle action potential and nerve conduction faiure consistent with axonal polyneuropathy. This could have been associated with the diabetes and not necessarily due to the myopathy.

Electromyography results were not consistent with a demyelinating polyneuropathy; but regardless, the patient was treated with IV immunoglobulin and no clinical improvements were made. The thought process behind this treatment might have been that if autoantobodies were causing the inflammatory response, IVIG contains antibodies that can neutralize pathogenic autoantobodies.

After that the patient developed cardiac insuficientcy. The cardiac symptoms developed by the patients could have been due to respiratory insuficiency causing an ischemic attack in the heart. This can happen because of oropharyngeal muscle weakness; which is also what leads to dysphagia.

An autoimmune disease was suspected and antobodies were requested. Complement C3 was decreased and anti-signal recognition particles were positive. A decreased C3 suggest that C3 protein is being consumed perhaps by an inflammatory process. Anto-SRP are related to inflammatory myopathies. So an inflammatory myopathy was suspected and patient was treated with rituximab, a monoclonal antobody that targets CD20, depleting B cells and halting the effect of the adaptive immune response

A muscle biopsy was taken and infiltraiton of mononuclear and polymorphonuclear cells in the endomysium was observed; indicative of polymyositis.

Unfortunately, the patient developed an infection which eventually lead to a septic shock and he died.

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Medical Treatments

1. Corticosteroids

Prednisone: The first-line treatment typically involves high doses of oral prednisone to reduce inflammation. Dosage is often started high and then gradually tapered based on patient response and side effects.

2. Immunosuppressive Agents

Azathioprine (Imuran): Often used in combination with corticosteroids to help reduce steroid dosage and manage symptoms.

Methotrexate: Another common immunosuppressant used to control inflammation and reduce corticosteroid dependency.

Mycophenolate mofetil (CellCept): An alternative for patients who do not respond well to azathioprine or methotrexate.

3. Biologic Agents

Rituximab (Rituxan): Used in refractory cases where patients do not respond to standard therapies. It targets B cells, a type of immune cell involved in the inflammatory process.

4. Intravenous Immunoglobulin (IVIG)

IVIG is used for severe or resistant cases. It can help modulate the immune system and reduce muscle inflammation.

Non-Medical Treatments

1. Physical Therapy

Customized exercise programs designed by a physical therapist to improve muscle strength, flexibility, and endurance without overexerting the muscles.

2. Occupational Therapy

Assistance with daily activities and adaptive strategies to maintain independence and quality of life.

3. Speech Therapy

For patients experiencing difficulty swallowing or speaking due to muscle weakness, a speech therapist can provide exercises and strategies to improve these functions.

4. Diet and Nutrition

A balanced diet rich in protein to support muscle repair and overall health. Nutritional counseling may be needed to address swallowing difficulties or other dietary restrictions.

5. Regular Monitoring and Follow-Up

Regular follow-up with a rheumatologist or a specialist in neuromuscular diseases to monitor disease progression and treatment response. This includes routine blood tests to check muscle enzyme levels (e.g., creatine kinase), as well as periodic muscle strength evaluations and lung function tests if respiratory muscles are affected.

Lifestyle Modifications

1. Rest and Activity Balance

Balancing rest with physical activity to avoid overexertion while staying active enough to maintain muscle strength.

2. Avoiding Triggers

Identifying and avoiding potential triggers that may exacerbate symptoms, such as certain medications, infections, or stress.

Experimental Treatments

Stem Cell Therapy and Other Emerging Therapies

Ongoing research is exploring the use of stem cell therapy and other innovative treatments. Participation in clinical trials may be an option for some patients.

Supportive Care

1. Support Groups

Joining support groups for individuals with polymyositis can provide emotional support, practical advice, and a sense of community.

2. Mental Health Support

Addressing mental health is crucial, as chronic illnesses can be associated with anxiety and depression. Counseling or therapy may be beneficial.

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Polymyositis Diagnosis : Johns Hopkins Myositis Center

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Diagnostic Tests and Expected Results in Polymyositis: 

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Diagnostic Tests and Expected Results in Polymyositis: 

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Polymyositis Disease Education Series Archives - Johns Hopkins Myositis Center

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Polymyositis is an autoimmune disease that causes inflammation in the muscles. It's also commonly paired with other rheumatic diseases such as scleroderma, rheumatoid arthritis, or lupus.

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How to identify a patient with polymyositis 

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How to identify a patient with polymyositis 

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Diagnosis of Polymyositis: A Multimodal Approach

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Diagnosis of Polymyositis: A Multimodal Approach

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Diagnosing polymyositis involves a multi-modal approach including hematologic and serologic testing, imaging, electromyography (EMG), nerve conduction studies, and biopsy findings:

1. Blood Tests:

Complete Blood Count (CBC): May show elevated lymphocyte count and thrombocytosis.

Erythrocyte Sedimentation Rate (ESR): Often elevated due to chronic inflammation.

Serum Creatine Kinase (CK): Significantly elevated (up to 50 times normal), indicating muscle damage.

2. Antibody Testing:

Antinuclear Antibody (ANA): Positive in about 33% of cases.

Specific Antibodies: Anti-signal recognition particle (SRP) and anti-aminoacyl tRNA synthetases (ARS) for polymyositis and anti-synthetase syndrome; anti-HMGCR for statin-induced polymyositis.

3. Electromyography (EMG):

Abnormal findings such as varying amplitude and velocity of action potentials and fibrillation potentials due to membrane irritability.

4. Imaging:

MRI: Used to locate muscle damage and guide biopsy. Whole-body MRI is significant for diagnosing the exact damaged area.

CT Scan and Ultrasonography: Help locate muscle damage and diagnose underlying malignancy.

5. Biopsy:

MRI or EMG Guided Biopsy: Shows perivascular and endomysial mononuclear infiltrates and areas of necrosis.

6. Additional Tests:

Barium Swallow: For patients with dysphagia.

Pulmonary Function Tests (PFTs): If lung disease is suspected.

EKG and Echocardiography: To assess potential cardiomyocyte damage.

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This video delves into Polymyositis and Dermatomyositis, highlighting their symptoms, diagnostic processes, and treatment options. More importantly, teaches us how to differentiate Polymyositis and Dermatomyositis, which are both are autoimmune myopathies characterized by inflammation and weakness of proximal muscles with extra muscular manifestations, but the involvement of skin and the antibodies are what primarily differentiates one from the other; these being: Anti-SR for polymyositis and Anti-Mi2- for dermatomyositis. It's important to differentiate between the two most similar, in order to provide better management and care.

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Which antibodies were found to be positive in this patient, suggesting an inflammatory myopathy?

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What was the outcome after the patient received IV Immunoglobulin therapy?

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Which test confirmed the diagnosis of polymyositis in this patient?

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Myositis Support and Understanding. (2019, July 15). Polymyositis - Myositis support and understanding. https://understandingmyositis.org/myositis/polymyositis/

Kumar, V., Abbas, A. K., & Aster, J. C. (2020). Robbins and Cotran pathologic basis of disease (10th ed.). Elsevier.

Chandra, Tanya & Aggarwal, Rohit. (2023). A Narrative Review of Acthar Gel for the Treatment of Myositis. Rheumatology and therapy. 10. 10.1007/s40744-023-00545-1.

Osmosis & Geeky Medics. (2022, May 12). Pathophysiology of polymyositis [Video]. YouTube. https://www.youtube.com/watch?v=yw87XQWXTPo&ab_channel=osmosisandgeekymedicscore

Sarwar A, Dydyk AM, Jatwani S. Polymyositis. In: StatPearls. StatPearls Publishing, Treasure Island (FL); 2023. PMID: 33085276.

Seetharaman, M., MD. (n.d.). Polymyositis Treatment & management: approach considerations, extramuscular manifestations of polymyositis, inpatient and outpatient care. https://emedicine.medscape.com/article/335925-treatment?form=fpf

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This article describes Acthar Gel as a treatment for Myositis, mentioning it's effectiveness and safety.

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The story of a patient living with Polymyositis

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The story of a patient living with Polymyositis

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This podcast describes the journey of a patient living with Polymyositis. Michole Jones shares personal narratives of the challenges she had to overcome, some medical insights, and the supportive resources that helped her. The patient also explains the difficulty of this disease, not only for her but for the caregivers too. Another important point stated is the perception that society has toward patients living with this chronic illness. The conversation offers hope and advice to others going through the same process.

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Michole J lives with rare muscle disease polymyositis (PM), which falls under the umbrella of muscular dystrophy. PM is an uncommon inflammatory disease that affects the entire body — and while Michole began to exhibit symptoms in her late 20s, she was diagnosed at age 30 with the rarest form. Living with the condition create mobility challenges, from climbing stairs, lifting objects, raising her arms, and even becoming rapidly exhausted from any kind of movement, to breathing issues due to the spread of inflammation to her lungs. Michole’s mission is to bring more awareness to invisible illness, reminding us that we may not all have the same illness (or any illness at all), but that our struggles are still the same. Tune in as Michole shares: how she first started experiencing symptoms that it took almost three years and several hospitalizations for her to get a diagnosis that her symptoms overlap with numerous other chronic illnesses that polymyositis is a progressive disease, and largely affects her limbs that she was never offered mental health support along her diagnosis and treatment journey that she’s now got the additional diagnosis of ILD — interstitial lung disease the struggle of being believed when living with invisible illness how her mother has stepped up as an advocate for her since her diagnosis, and how they have become even closer as a result how caregivers experience chronic illness and disability alongside their loved ones the importance of remote work opportunities for her why the cost of healthcare and treatments can be debilitating for patients discrimination she’s faced from the public how race has impacted her experiences in the medical system (and beyond) her frustration with lack of representation in rare disease how a lack of curiosity in the healthcare system is causing problems for patients how she’s learned to say “no” why it’s useful to develop a meaningful relationship with your practitioners This is a public episode. If you’d like to discuss this with other subscribers or get access to bonus episodes, visit uninvisiblepod.substack.com/subscribe

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In the image, the muscles highlighted in red indicate where the proximal weakness is mostly presented. 

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Weakness: mild to moderate

bilateral

affects large and proximal muscles (example: shoulders, hips)

spares distal muscles (example: hands)

progresses over weeks to months

Patient can present difficulty in several daily activities... (Myositis Support and Understanding, 2019b)

climbing stairs

rising from chair

lifting arms

Mild myalgia

Dysphagia, if pharynx or esophagus is affected

dyspnea

dysphonia

Fatigue