Muscular disorders Flashcards
(16 cards)
What are fasciculations?
Visible, fast, fine, spontaneous muscle twitches
What are some causes of fasciculations?
“Physiological - Stress, caffeine, fatigue
Denervated muscle due to hyper excitability
Motor neurone disease”
What is myotonia?
“Failure of a muscle to relax after use
(Locking, sticking or cramping of the muscle)”
What are some causes of myotonia?
Chloride and sodium channelopathies
What are some things examined for in muscle examination?
“Inspection
Palpation
Strength testing
Fatiguability”
How is muscle strength graded?
“MRC muscle power grading:
- 0 - No movement at all
- 1 - flicker of movement when attempting to contract muscle
- 2 - Some muscle movement if gravity removed but none against gravity
- 3 - movement against gravity but not against resistance
- 4 - Movement against resistance but not full strength
- 5 - Normal strength”
What are some inflammatory myopathies?
“Polymyositis
Dermatomyositis
Inclusion body myositis”
What is polymyositis?
Idiopathic inflammatory myopathy that causes symmetrical, proximal muscle weakness
What is dermatomyositis?
Clinically similar to polymyositis but also has typical cutaneous manifestations
Describe the aetiology of polymyositis and dermatomyositis
”- Idiopathic, autoimmune
- Higher prevalence in females (2:1)
- Peak incidence age 40-50”
Describe the pathophysiology of dermatomyositis and polymyositis
- T cell mediated process against (unidentified) muscle antigens
- CD8+ T cells and macrophages surround, invade and destroy healthy, non-nectrotic muscle fibres
What are some symptoms of polymyositis?
”- Symmetrical, proximal muscle weakness in the upper and lower extremities
- Insidious onset, worsening over months
- Often specific problems e.g. difficulty brushing hair, climbing stairs
- Myalgia in 25-50% (usually mild)”
What are some signs of polymyositis?
”- Muscle wasting
- Confrontational testing - direct testing of power
- Isotonic testing - 30 second sit to stand”
What are some skin symptoms of dermatomyositis?
“Gottron’s sign
Shawl sign
Heliotrope rash”
What is shown?
Gottron’s sign
