Approach to Muscle Disorders

Question 1

Positive vs negative symptoms

Answer 1

+ are things that shouldn’t be there but are (ex: myalgias, myoglobinuria, cramps)
- are things that are not working right (ex: weakness, exercise intolerance, atrophy)

Question 2

3 Ts to determine muscle syndromes

Answer 2

Timing
Topography
Type

Question 3

Myopathic pattern of muscle weakness

Answer 3

Proximal weakness
Ex: standing from seated, reaching overhead
Also in NMJ disorders

Question 4

Dermatomyositis

Answer 4

A humoral mediated inflammatory myopathy
Affects any age range
Antibody and complement mediated (capillary destruction, perifascicular atrophy and necrosis with inflammatory infiltrate)
Classical skin findings
Increased risk of malignancy and interstitial lung disease
Treatment includes steroids, IVIG, and immunomodulators

Question 5

Fasciculation

Answer 5

Spontaneous activity of a motor unit
Considered a sign of denervation
May reflect reinnervation and collatreal sprouting in process (takes weeks to appear after injury)
Benign fasciculations can occur without neuronal injury
Concern for injury when accompanied by weakness/atrophy

Question 6

Myasthenia gravis

Answer 6

An autoimmune NMJ disorder with microdestruction of the motor endplate and decreated available postsynaptic nicotinic AChR
Causes weakness and fatigability
Improves with cold, rest, and acetylcholinesterase inhibitors
Treat with immunomodulators