Muscle and Nerve Diseases Flashcards
What are the symptoms of muscle disease?
- Poor suck / feeding / failure to thrive / floppy
- Weakness of skeletal muscle
- Short of breath (respiratory muscles)
- Poor swallow (aspiration)
- Cardiomyopathy
- Cramp, pain, myoglobinuria
Myoglobin is muscle breakdown – you excrete in your urine and it makes the urine black
What are the signs of muscle disease?
- Wasting/ hypertrophy
- Normal or reduced tone and reflexes
- Motor weakness…NOT sensory
Why might hypertrophy result from a muscle disease?
Muscle cannot relax
What is the investigation for a muscle disease?
- History and examination
- CK - Creatinine phosphokinase – sometimes elevated in the blood in muscle degenerative diseases
- EMG - EMG – electrical myography – electrode is placed within the muscle to test electrical funciton
- Muscle biopsy
–Structure
–Biochemistry
–Inflammation
•Genetic testing
What are the classifications of muscle disease?
- Muscular dystrophies - usually genetic - to do with structure of the muscle
- Channelopathies - usually episodic
- Metabolic muscle disease - an issue with the way the muscle uses energy, usually due to enzymes
- Inflammatory muscle disease
- Congenital myopathies
- Iatrogenic - medication - statins cause inflammation or degeneration of the muscles
Which part of the muscle contracts and shortens?
Myosin fibrils
Give examples of muscular dystrophies
- Duchenne’s MD - related to dystrophin protein
- Becker’s MD - also dystrophin gene, milder form of duchenne’s
- Facioscapulohumeral MD
- Myotonic dystrophy
- Limb-Girdle MD
Give examples of muscle channelopathies
- Familial hypokalemic periodic paralysis
- Hyperkalemic periodic paralysis
- Paramyotonia congenita (chlorine deficiency)
- Myotonia congenita (chlorine deficiency)
Myotonia – can’t relax their muscles – muscles have continually low level contraction – if you shake their hand they can’t release their grip
What are metabolic muscle disorders?
- Disorders of carbohydrate metabolism
- Disorders of lipid metabolism
- Mitochondrial myopathies/ cytopathies
- Endocrinopathy (thyroid, Cushing)
- Biochemical abnormalities
Glycogen – used for immediate rapid muscle activity, eventually run out – fatty acids are the next supply. Disorders of carbohydrate and lipid metabolism is often more prevalent after excersize
Give examples of inflammatory muscle diseases
Polymyositis
Dermatomyositis - Dermatomyositis – inflammation of the skin too (characteristic rash) – often as a result of malignancy – paraneoplastic phenomenon
What are the symptoms of inflammatory muscle disease?
Pain as a result of inflammation
Patient generally feels unwell
What is the investigation for inflammatory muscle disease?
- Increase in Creatinint Phosphokinase
- EMG, inflammation and myopathic
- Biopsy
–PM: CD8 cells
–DM: humeral-mediated, B cells and CD4 cells
What is treatment for polymyositis and dermatomyositis?
Immunosuppression
What is the presentation of disorders of the neuromuscular junction?
Fatiguable weakness:
–Limbs
–Eyelids (ptosis)
–Muscles of mastication (chewing), swallow
–Talking
–SOB - Affects all NMJ’s so can cause respiratory failure
–diplopia
Clear feature of NMJ problems is fatigue – muscles start strong and then get weaker. As day goes on – progressive problem with muscle weakness – diplopia because of muscle weakness in the eye.
Why does fatigue in the muscle happen?
Because acetylcholine becomes gradually reduced throughout the day in the synapse