Diseases of Muscles and nerves

Question 1

What are common symptoms of muscle disease

Answer 1

Weakness of skeletal muscle (resp & swallowing muscles important)
Cardiac symptoms (cardiomyopathy, arrythmia)
Cramps/muscle pain, stiffness
Myoglobinuria

Babies: floppy, poor suck/feeding/failure to thrive

Question 2

What is myoglobinuria?

Answer 2

Muscle breakdown product present in urine
Very dark colour (coca-cola)

Question 3

what are the signs of muscle diseases

Answer 3

WEAKNESS
(may have atrophy/hypertrophy)
Tendon reflexes often normal.
Do not cause sensory signs.

Question 4

what are the investigations for muscle diseases?

Answer 4

History + examination
Bloods: Creatine Kinase (elevated when theres muscle damage)
Electromyography (EMG)
Muscle Biopsy: sturcture, biochemistry (enzyme testing), inflammation
Genetic testing

Question 5

What are congenital/genetic causes of Muscle Disease

Answer 5

Contractile: congenital myopathies
Structural: muscular dystrophies (more severe and progressive muscle weakness, Duchennes muscular dystrophy)
Coupling: channelopathies (can give paroxysmal disorders, muscle stiffness: myotonia)
Energy: metabolic myopathies (cause pain on exercise)

Question 6

What are acquired muscle disease causes

Answer 6

Electrolyte disturbances (esp >/< K levels)
endocrine (thyroid, adrenal, Vitamin D)
Autoimmune inflammatory muscle disease
Latrogenic: medications (steroids/statins)

Question 7

What type of disease is inflammatory muscle disease

Answer 7

autoimmune

Question 8

what are the 2 types of inflammatory Muscle Disease

Answer 8

Polymyositis (just involves muscle)
Dermatomyositis (involves muscle + skin)

Question 9

What are the characteristics of Inflammatory muscle disease

Answer 9

Any Age onset
Acute or subactute: cause painful weak muscles
DM: has a characteristic rash (face and hands)

Question 10

How does Inflammatory Muscle disease test results look

Answer 10

High Creatinine Kinase
autoantibodies.

Question 11

What further testing should be done for Inflammatory bowel disease after bloods

Answer 11

Tumour screen (esp. DM, paraneoplastic process)
EMG & biopsy (would see classic inflammatory changes)

Question 12

What is the treatment for Inflammatory Muscle disease

Answer 12

Immunosuppression (steroids early phase)
may be replaced by steroid sparing agents: azathioprine, cyclophosphamide

Question 13

What is Myasthenia Gravis

Answer 13

Autoimmune condition where the acetylcholine receptor is blocked by an acetylcholine receptor antibody.

Question 14

What is the Key clinical manifestation of Myasthenia Gravis.

Answer 14

Fatiguable weakness
weakness which gets worse with repetitive movement.

Question 15

What are the two forms of Myasthenia Gravis

Answer 15

Ocular and Generalised

Question 16

What is affected in Ocular Myasthenia Gravis

Answer 16

Eyelids (ptosis)
muscles of eye movement (diplopia)

Question 17

What is affected in generalised myasthenia Garvis

Answer 17

Limbs
Bulbar (chew, swallow, talk)
Breathing (significant complications)

Question 18

what investigations would you carry out for Myasthenia Gravis

Answer 18

test for: Acetylcholine receptor antibodies or anti-MuSK antibodies
50% in ocular and 80% in general have acetylcholine receptor antibodies that you can test in blood.
Neurophysiology:
CT chest (Thymoma: benign/malignant)

Question 19

What is the Myasthenia Gravis treatment

Answer 19

Symptomatic: cholinesterase inhibitors (pyridostigmine)

Disease modifying: Immunoglobulin/plasma exchange
steroids
steroid sparing immunosuppression (azathioprine)
Thymectomy