SM 246: Inflammatory Myopathies Flashcards
What is the most common cause of acquired myopathies?
Inflammatory/autoimmune myopathy - these are treatable
What is an inflammatory myopathy?
An inflammatory response against normal muscle, supporting stroma, or muscle as one of many target tissues
Is all inflammation in muscle an “autoimmune myopathy”?
No - just because you see inflammation on biopsy, doesn’t mean you have inflammation
Do you need inflammation for an “autoimmune myopathy”?
Also no, might not catch it on muscle biopsy
What are the 4 broad types of inflammatory myopathy?
Polymyositis, Deramtomyositis, Inclusion Body Myositis, and Necrotizing Autoimmune Myopathy
What are the two types of Dermatomyositis?
Adult with or without skin involvment, as well as Juvenile
How do all myopathies present in general?
Proximal muscle weakness, no sensory complaints, myalgias and other sites of inflammation throughout the body
How do myopathies effect patients?
Effect day to day activities like sitting, standing, and applying makeup
What is a myalgia?
A muscle pain like running a marathon, sore
Is shortness of breath associated with myopathy?
Yes
What should you ask about in ROS for a myopathy?
Urine color changes (Rhabdo/tea colored urine), swallowing issues (choking issue), medications (statins)
What is the urine color change you should be worried about in a myopathy?
Tea colored urine = rhabdomyolysis
Which medications can cause myopathy?
Statins
What medical conditions can cause myositis and myopathy?
Connective tissue diseases, sarcoidosis, and renal/liver
What should you look for on physical exam in a myopathy?
Muscle bulk/atrophy/fasciculations, check proximal and distal muscles (especially head and neck extensors), Deep Tendon Reflexes (DTRs) and sensory exam
What are fasciculations, and what could they suggest?
Twitches, ALS
Why should you assess head and neck extensors in a muscle weakness patient?
They may go into respiratory failure if they can’t extend their head and neck
What are DTRs?
Deep Tendon Reflexes
What labs should you order in a suspected myopathy?
CK, aldolase + lactic acid, urine Myoglobin, ESR and CRP Myositis antibodies EMG/MRI Muscle biopsy
What are ESR and CRP related to?
Acute phase inflammation, possibly found in myopathy
How is an MRI useful in a myositis?
White areas on an MRI correspond to inflamed muscle and guide biopsy
How does polymyositis present?
Symmetric proximal muscle weakness, occasional facial weakness + dysphagia, myalgias/achiness, slow onset (except for SRP)
What type of polymyositis is rapid onset?
SRP Polymyositis is fast/few weeks, due to antibodies, other things are slow
How does myositis affect the lung?
Myositis often cooccurs with fibrotic lung disease, and should be testing for potential lung disease with Anti-Jo1 antibody
What is the Anti-Jo1 antibody used for?
Tests for potential lung involvement/ILD and urgent pulmonology referral in a myositis patient