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Polymyositis
338
SECTION 3 PAINFUL CONDITIONS
relatively benign. Mixed connective tissue disease (MCTD), which combines elements of polymyositis, systemic lupus erythematosus, and scleroderma, can also present a diagnostic dilemma. If MCTD is being considered in the differential diagnosis of scleroderma, testing for the presence of anti–nuclear ribonucleoprotein antibody will prompt the clinician to suspect that MCTD is the culprit rather than classic scleroderma.
Treatment The treatment of scleroderma has its basis in the treatment of specific organ system dysfunction related to the disease rather than any treatment that is specifically aimed at treatment of the underlying disease itself. Early treatment of organ system dysfunction is critical if the clinician hopes to improve the quality of life and prognosis for the patient suffering from scleroderma. Nowhere is this statement more valid than when dealing with renal dysfunction. The early use of angiotensin-converting enzyme inhibitors and vasodilators such as minoxidil is indicated to control hypertension and improve renal blood flow.
CHAPTER
The use of nonsteroidal anti-inflammatory drugs and corticosteroids in low doses to treat synovitis, arthritis, and myositis should be considered early in the course of the disease. The calcium channel blockers may help ameliorate the symptomatology associated with Raynaud’s phenomenon, and there is anecdotal evidence that topical nitroglycerin ointment may also help provide symptomatic relief. Methotrexate and penicillamine may help slow the progression of fibrosis, especially of the skin and digits. Treatment of reflux with histamine-blocking agents, use of bed blocks, and multiple small feedings may also provide symptomatic relief and help prevent lower esophageal erosions and stricture. Oral antibiotics may also be used if malabsorption secondary to bacterial overgrowth in dilated small intestine and bowel is a problem. As with the other connective tissue diseases, the rational use of occupational and physical therapy can help decrease pain and preserve and improve function.
SUGGESTED READING Waldman SD: Connective tissue diseases. In: Pain Management. Philadelphia, Saunders, 2007.
201
Polymyositis Less common than rheumatoid arthritis, systemic lupus erythematosus, or scleroderma, polymyositis is a connective tissue disease of unknown etiology. The disease is characterized by muscle inflammation that progresses to degenerative muscle disease and atrophy. There are many variants of polymyositis, including dermatomyositis, which is, from a clinical viewpoint, simply polymyositis with significant cutaneous manifestations. Affecting women twice as frequently as men, polymyositis can overlap with basically all of the connective tissue diseases, making diagnosis on purely clinical grounds somewhat more challenging. Generally not occurring in adults before the age of 40 or after the age of 60, there is a childhood variant that carries a poor prognosis. The clinician should be aware that there is a strong correlation with the presence of malignancy in patients who present with polymyositis, and a search for underlying malignancy must be an integral part of any diagnostic workup and treatment plan of patients suspected of having
polymyositis. Whether the malignancy serves as a trigger to the autoimmune response to muscle in this disease or is simply a trigger to an unknown cascade of events has yet to be elucidated. It is interesting to note that there is a greater incidence of malignancy in those patients suffering from dermatomyositis relative to polymyositis. The type and location of tumor are not consistent, making the search for associated occult malignancy all the more difficult.
Signs and Symptoms The onset of polymyositis is often preceded by an acute infection, often viral in nature. The onset of symptoms may be acute or may come on gradually, with the patient thinking that he or she simply has not shaken the initial febrile illness. Rash and muscle weakness are generally the presenting symptoms, with the proximal muscle groups
CHAPTER 201 POLYMYOSITIS
generally affected initially more commonly than the distal muscle groups. Myalgias and polyarthralgias may be present, as may constitutional symptoms resembling polymyalgia rheumatica (see later). In some patients, the onset of profound muscle weakness may be rapid, with the patient presenting with the inability to rise from a sitting position or the complaint of the inability to raise the arms above the head to comb or curl his or her hair. In rare patients, weakness of the muscles controlling the vocal cords may cause dysphasia that may be mistaken for myasthenia gravis or a stroke. In severe cases, acute respiratory insufficiency may occur, and the association of recent febrile illness may yield the mistaken diagnosis of Guillain-Barre´ disease. Involvement of the gastrointestinal tract may lead to symptoms as described for scleroderma. Cardiac arrhythmias and conduction defects are seen in many patients suffering from polymyositis, as is renal failure due to acute myoglobinuria from rhabdomyolysis in acute exacerbations of the disease. In general, the small muscles of the hands and feet are spared, as are the muscles of facial expression. When patients with polymyositis exhibit significant cutaneous manifestations, for clinical purposes, the disease is called dermatomyositis. A heliotrope periorbital blush is pathognomonic for the disease. There may be a peeling or splitting of skin over the radial sides of the digits that is highly suggestive of dermatomyositis. A generalized maculopapular rash may also appear. Subcutaneous calcific nodules may be present in many patients with undiagnosed and untreated disease.
Laboratory Testing There is no specific diagnostic test for polymyositis or dermatomyositis. The erythrocyte sedimentation rate is usually elevated, as is the serum muscle enzyme determinations, especially in acute disease. The monitoring of creatine kinase (CK) levels may serve as a useful guide as to the efficacy of treatment. Approximately 60% of patients with polymyositis have antibodies to thymic nuclear antigen.
339
Differential Diagnosis As with the other connective tissue diseases, the overlap of symptoms can make the diagnosis of a specific disease difficult on purely clinical grounds. The findings of proximal muscle weakness, characteristic skin rash (in the case of dermatomyositis), positive electromyography, and elevated serum muscle enzymes strongly support the diagnosis of polymyositis or dermatomyositis. If the diagnosis is still in doubt, muscle biopsy may help clarify the situation as in most cases it will be diagnostic.
Treatment Corticosteroids are the first drug of choice for acute polymyositis. A starting dose of 60 mg is usually adequate to control the acute inflammatory response and improve the clinical symptoms. The corticosteroids can be tapered based on both the clinical response to the drug and the decrease in elevated serum CK to normal. The minimum dose of corticosteroid necessary to control symptoms and depress CK should be used to avoid steroid-induced myopathy, which may confuse the clinical management and exacerbate the patient’s disability. A trial of immunosuppressive drugs including methotrexate, cyclosporine, azathioprine, and cyclophosphamide may be considered if corticosteroids fail to control the disease or the side effects associated with the drug preclude its use. It should be remembered that weakness unresponsive to the therapies mentioned may be secondary to associated malignancies (e.g., paraneoplastic syndrome), and that treatment of the tumor may be required to improve the patient’s weakness. The use of physical and occupational therapy to optimize function and to help the patient learn to use assistive devices is indicated early in the course of the disease.
SUGGESTED READING Waldman SD: Connective tissue diseases. In: Pain Management. Philadelphia, Saunders, 2007.
SECTION 3 PAINFUL CONDITIONS
relatively benign. Mixed connective tissue disease (MCTD), which combines elements of polymyositis, systemic lupus erythematosus, and scleroderma, can also present a diagnostic dilemma. If MCTD is being considered in the differential diagnosis of scleroderma, testing for the presence of anti–nuclear ribonucleoprotein antibody will prompt the clinician to suspect that MCTD is the culprit rather than classic scleroderma.
Treatment The treatment of scleroderma has its basis in the treatment of specific organ system dysfunction related to the disease rather than any treatment that is specifically aimed at treatment of the underlying disease itself. Early treatment of organ system dysfunction is critical if the clinician hopes to improve the quality of life and prognosis for the patient suffering from scleroderma. Nowhere is this statement more valid than when dealing with renal dysfunction. The early use of angiotensin-converting enzyme inhibitors and vasodilators such as minoxidil is indicated to control hypertension and improve renal blood flow.
CHAPTER
The use of nonsteroidal anti-inflammatory drugs and corticosteroids in low doses to treat synovitis, arthritis, and myositis should be considered early in the course of the disease. The calcium channel blockers may help ameliorate the symptomatology associated with Raynaud’s phenomenon, and there is anecdotal evidence that topical nitroglycerin ointment may also help provide symptomatic relief. Methotrexate and penicillamine may help slow the progression of fibrosis, especially of the skin and digits. Treatment of reflux with histamine-blocking agents, use of bed blocks, and multiple small feedings may also provide symptomatic relief and help prevent lower esophageal erosions and stricture. Oral antibiotics may also be used if malabsorption secondary to bacterial overgrowth in dilated small intestine and bowel is a problem. As with the other connective tissue diseases, the rational use of occupational and physical therapy can help decrease pain and preserve and improve function.
SUGGESTED READING Waldman SD: Connective tissue diseases. In: Pain Management. Philadelphia, Saunders, 2007.
201
Polymyositis Less common than rheumatoid arthritis, systemic lupus erythematosus, or scleroderma, polymyositis is a connective tissue disease of unknown etiology. The disease is characterized by muscle inflammation that progresses to degenerative muscle disease and atrophy. There are many variants of polymyositis, including dermatomyositis, which is, from a clinical viewpoint, simply polymyositis with significant cutaneous manifestations. Affecting women twice as frequently as men, polymyositis can overlap with basically all of the connective tissue diseases, making diagnosis on purely clinical grounds somewhat more challenging. Generally not occurring in adults before the age of 40 or after the age of 60, there is a childhood variant that carries a poor prognosis. The clinician should be aware that there is a strong correlation with the presence of malignancy in patients who present with polymyositis, and a search for underlying malignancy must be an integral part of any diagnostic workup and treatment plan of patients suspected of having
polymyositis. Whether the malignancy serves as a trigger to the autoimmune response to muscle in this disease or is simply a trigger to an unknown cascade of events has yet to be elucidated. It is interesting to note that there is a greater incidence of malignancy in those patients suffering from dermatomyositis relative to polymyositis. The type and location of tumor are not consistent, making the search for associated occult malignancy all the more difficult.
Signs and Symptoms The onset of polymyositis is often preceded by an acute infection, often viral in nature. The onset of symptoms may be acute or may come on gradually, with the patient thinking that he or she simply has not shaken the initial febrile illness. Rash and muscle weakness are generally the presenting symptoms, with the proximal muscle groups
CHAPTER 201 POLYMYOSITIS
generally affected initially more commonly than the distal muscle groups. Myalgias and polyarthralgias may be present, as may constitutional symptoms resembling polymyalgia rheumatica (see later). In some patients, the onset of profound muscle weakness may be rapid, with the patient presenting with the inability to rise from a sitting position or the complaint of the inability to raise the arms above the head to comb or curl his or her hair. In rare patients, weakness of the muscles controlling the vocal cords may cause dysphasia that may be mistaken for myasthenia gravis or a stroke. In severe cases, acute respiratory insufficiency may occur, and the association of recent febrile illness may yield the mistaken diagnosis of Guillain-Barre´ disease. Involvement of the gastrointestinal tract may lead to symptoms as described for scleroderma. Cardiac arrhythmias and conduction defects are seen in many patients suffering from polymyositis, as is renal failure due to acute myoglobinuria from rhabdomyolysis in acute exacerbations of the disease. In general, the small muscles of the hands and feet are spared, as are the muscles of facial expression. When patients with polymyositis exhibit significant cutaneous manifestations, for clinical purposes, the disease is called dermatomyositis. A heliotrope periorbital blush is pathognomonic for the disease. There may be a peeling or splitting of skin over the radial sides of the digits that is highly suggestive of dermatomyositis. A generalized maculopapular rash may also appear. Subcutaneous calcific nodules may be present in many patients with undiagnosed and untreated disease.
Laboratory Testing There is no specific diagnostic test for polymyositis or dermatomyositis. The erythrocyte sedimentation rate is usually elevated, as is the serum muscle enzyme determinations, especially in acute disease. The monitoring of creatine kinase (CK) levels may serve as a useful guide as to the efficacy of treatment. Approximately 60% of patients with polymyositis have antibodies to thymic nuclear antigen.
339
Differential Diagnosis As with the other connective tissue diseases, the overlap of symptoms can make the diagnosis of a specific disease difficult on purely clinical grounds. The findings of proximal muscle weakness, characteristic skin rash (in the case of dermatomyositis), positive electromyography, and elevated serum muscle enzymes strongly support the diagnosis of polymyositis or dermatomyositis. If the diagnosis is still in doubt, muscle biopsy may help clarify the situation as in most cases it will be diagnostic.
Treatment Corticosteroids are the first drug of choice for acute polymyositis. A starting dose of 60 mg is usually adequate to control the acute inflammatory response and improve the clinical symptoms. The corticosteroids can be tapered based on both the clinical response to the drug and the decrease in elevated serum CK to normal. The minimum dose of corticosteroid necessary to control symptoms and depress CK should be used to avoid steroid-induced myopathy, which may confuse the clinical management and exacerbate the patient’s disability. A trial of immunosuppressive drugs including methotrexate, cyclosporine, azathioprine, and cyclophosphamide may be considered if corticosteroids fail to control the disease or the side effects associated with the drug preclude its use. It should be remembered that weakness unresponsive to the therapies mentioned may be secondary to associated malignancies (e.g., paraneoplastic syndrome), and that treatment of the tumor may be required to improve the patient’s weakness. The use of physical and occupational therapy to optimize function and to help the patient learn to use assistive devices is indicated early in the course of the disease.
SUGGESTED READING Waldman SD: Connective tissue diseases. In: Pain Management. Philadelphia, Saunders, 2007.