Dermatomyositis or Inflammation of Muscles
Dermatomyositis is a chronic inflammatory disease of skin and muscles along with patches of raised reddish or scaly rash. The rash can be on the bridge of the nose, around the eyes, or on sun-exposed areas of the neck and chest. Generally it is over the knuckles. When the inflammation of the muscle occurs without skin disease, the condition is known as Polymyositis. Dermatomyositis is one of a group of acquired muscle diseases called inflammatory myopathies. Dermatomyositis may occur at any age, but it mostly affects adults in their late 40s to early 60s or children between 5 and 15 years of age. Women have Dermatomyositis more often than men do. Dermatomyositis usually develops over weeks or months. The most common symptom is muscle weakness, usually affecting those muscles that are closest to the trunk of the body. Patients may have difficulty rising from a sitting position, climbing stairs, lifting objects, or reaching overhead. In some cases, distal muscles those not close to the trunk of the body may be affected later in the course of the disease. Difficulty in swallowing also known as dysphasia may occur. Occasionally, the muscles ache and are tender to touch. Patients may also feel fatigue and discomfort and have weight loss or a low-grade fever.
Criterion for the diagnosis of disease
There is a set of four criterions which may aid in the diagnosis of the disease.
- Progressive proximal symmetrical weakness
- Elevated levels of muscle enzymes,
- Abnormal finding on electromyography
- Abnormal finding on muscle biopsy
- There is a fifth criterion which is that of cutaneous involvement of disease
Signs and Symptoms
- Muscle pain
- Patchy skin rash
- Bluish purple discolored skin rash
- Red skin rash
- Swelling
- Interstitial pneumonitis
- Breathing difficulty
- Coughing
- Red inflamed skin over joints
- Vitiligo over joints
- Brownish pigmentation over joints
- Skin atrophy over joints
- Ulcers
- Growth of excess hair
- Abnormal electrocardiogram
- Excess muscle protein in urine
- Rhabdomyolysis
- Malaise
- Fever
- Weakness
- Swelling of eyelids
- Swelling around eyes
- Patchy facial redness
- Upper back redness
- Red forearms
Causes Leading to Dermatomyositis
- Genetic susceptibility
- Immunological abnormalities like presence of antibodies in blood
- Autoantibodies to nuclear antigens (ANA) and cytoplasmic antibodies i.e., antitransfer RNA synthetases antigens may be present.
- Infectious agents, including viruses like coxsackie; parvo virus etc may be related to the development of disease
- Drugs like Penicillamine, statin drugs, quinidine, and phenylbutazone may be related to the development of disease
- Dermatomyositis may be initiated or exacerbated by silicone breast implants or collagen injections.
Diagnostic Investigations
- Electromyography – Electrical activity in the muscles vary if they are diseased
- Blood analysis – May demonstrate elevated levels of muscle enzymes like creatine kinase and aldolase and also Autoantibodies may be present in the blood
- Muscle Biopsy – May reveal signs of inflammation and if there is some infection
- Skin Biopsy
- Magnetic Resonance Imaging (MRI) – May demonstrate some inflammation in the muscles.
Treatment and Drugs
- Corticosteroids like Prednisolone are generally prescribed to the patients
- Immunosuppressant’s like Azathiorpine and Methotrexate may be used either alone or in conjunction with steroids
- Physical therapy to regain and maintain the tone of muscles
- Surgery may be done in some cases to relieve some complications
- Analgesics are generally prescribed to have an effective control over pain
- Plasmapheresis is the latest modality
- Other modalities include Radiotherapy, Monoclonal Antibodies and fewer new drugs
