Muscle Diseases Flashcards
what is polymyalgia rheumatica and who does it affect
a chronic inflammatory condition of unknown aetiology that affects elderly individuals (>50)
what are symptoms of polymyalgia rheumatica
proximal myalgia of hip and shoulder girdles accompanying morning stiffness that lasts more than 1 hour and improves as day goes on
how is polymyalgia rheumatica diagnosed
examination for muscle weakness there is no diagnostic test but it is almost always association with raise CRP and PV/ESR
how is polymyalgia rheumatica treated
low dose steroids (prednisolone 15mg daily) used as diagnostic tool dose gradually reduced over 18 months
what are complications of polymyalgia rheumatica
15% of patient with PMR develop giant cell arteritis (GCA) and 40-50% of patients with GCA have associated PMR this relationship aint fully established
what is giant cell arteritis
the most common form of systemic vasculitis in adults unknown aetiology and occurs in older patients
when should giant cell arteritis be considered
new onset headache in patients >50 with elevated ESR, CPR or plasma viscosity
what does giant cell arteritis look like histologically
transmural inflammation of intima, media and adventitia of affected arteries as well as patchy infiltration of lymphocytes, macrophages and multinucleate giant cells vessel wall thickening can result in arterial luminal narrowing resulting in distal ischaemia
what are symptoms of giant cell arteritis
visual disturbances (swollen optic disc) headaches (temporal or occipital areas) jaw claudication (ischaemia or maxillary artery - discomfort on chewing or speaking) scalp tenderness esp on direct palpation (combing hair?) temporal artery thickening fatigue, malaise, fever
how is giant cell arteritis diagnosed
raised inflammatory markers temporal artery biopsy
what is biopsy findings of giant cell arteritis
mononuclear infiltration or granulomatous inflammation, usually with multinucleate giant cells
how is giant cell arteritis treated
prednisolone 40mg if no visual impairment prednisolone 60mg if visual symptoms steroid decrease vascular inflammation
when should treatment be given in giant cell arteritis and how long for
as soon as diagnosis suspected - dont delay for biopsy dose gradually tapered over around 2 years
what is polymyositis
idiopathic inflammatory myopathy that causes symmetrical, proximal muscle weakness
what is dermatomyositis
clinically similar but also has typical cutaneous manifestations
what is prevalence of polymyositis & dermatomyositis
more common in women (2:1) and usually affects adults >20 especially those 45-60
what is the pathogenesis of polymyositis & dermatomyositis
CD8+ T cells along with macrophages surround muscle fibres and eventually invade and destroy them an autoimmune response to nuclear and cytoplasmic auto antigen is detected in 60-80% of patients
what antibodies does polymyositis & dermatomyositis share with other autoimmune diseases
ANA, anti-RNP
what antibodies is unique to polymyositis & dermatomyositis
anti-Jo-1 and anti-SRP
what is symptoms of polymyositis
insidious onset muscle weakness often with particular activity eg climbing stair myalgia dysphagia (poor prognostic sign) ILD occurs in 5-30% (esp for anti-Jo patients)
what is symptoms of dermatomyositis
similar to polymyositis with V shaped rash over chest, gottrons papules and heliotrope rash
how is polymyositis & dermatomyositis diagnosed
raised inflammatory markers and CK antibodies MRI may be useful EMG findings abnormal in 90% muscle biopsy crucial as shows fibres in varying stages of inflammation, necrosis and regeneration
what are the abnormal EMG findings in polymyositis & dermatomyositis
short duration low voltage polyphasic motor unit action potentials with spontaneous fibrillation activity
what is the treatment in polymyositis & dermatomyositis
prednisolone 40mg combined with immunosuppressive drugs such as methotrexate or azathioprine
