Neuromuscular Disorders

Question 1

What is the neurotransmitter in the NMJ?

Answer 1

Acetylcholine

Question 2

What causes botulism?

Answer 2

Clostridium Botulinum

Question 3

How does a bacterial infection produce the neuromuscular disorder?

Answer 3

The toxins cleave presynaptic protein preventing vesicles fusing with the membrane.
Acetylcholine isn’t released in NMJ.

Question 4

How doe botulism present?

Answer 4

Rapid onset weakness with no sensory loss.

Question 5

Lamberton Eaton Syndrome

Answer 5

Anutoantibodies to the Ca2+ so reduced vesicles released as Ca2+ doesn’t enter presynaptic bulb.

Question 6

What is the common cause of Lamberton Eaton Syndrome?

Answer 6

Small Cell Carcinoma

Question 7

What is the most common Neuromuscular disorder?

Answer 7

Myasthenia Gravis

Question 8

When does myasthenia present in the population

Answer 8

Women 3rd decade

Men 6-7th decade

Question 9

What causes myasthenia gravis?

Answer 9

Autoimmune antibodies to the acetylcholine receptors on post synaptic plate.
Reduced receptors mean stamina and increased fatigue.

Question 10

At what percentage loss of receptors do symptoms present?

Answer 10

30%

Question 11

What is Myasthenia Gravis associated with?

Answer 11

Thymic Hyperplasia

Question 12

If left untreated how do the muscles in myasthenia gravis react?

Answer 12

Begin to atrophy

Question 13

In what percentage of patients with myasthenia gravis do ACh antibodies occur?

Answer 13

80-90%

Question 14

What are the clinical signs of Myasthenia Gravis?

Answer 14

Fluctuating weakness
Extraoccular weakness - drooping eyes double vision
Struggle to speak and chew
Proximal limb weakness

Question 15

What is the acute treatment for Myasthenia Gravis?

Answer 15

Acetylcholinesterase inhibitors - Pyridostigmine
IV Immunoglobulin
Plasma Exchange
Thymectomy

Question 16

What is the acute treatment for chronic Myasthenia Gravis?

Answer 16

Steroid

Steroid sparing agents

Question 17

What is the course of steroid used in chronic Myasthenia Gravis?

Answer 17

High does 40-60mg prednisolone for a month

Question 18

What steroid sparing agents are used in chronic Myasthenia Gravis?

Answer 18

Azathioprine

Mycophenolate

Question 19

What drugs should be avoided in a Myasthenia Gravis?

Answer 19

Gentamicin

Question 20

What is the mortality in Myasthenia Gravis?

Answer 20

3/4%

Question 21

What are the commonest causes of death in Myasthenia Gravis?

Answer 21

Respiratory failure
Aspiration pneumonia
Side effects of immunosuppression

Question 22

What are the signs of muscular disease?

Answer 22

Myalgia
Muscle weakness
Wasting
Hypoflexia

Question 23

What are fasciculations?

Answer 23

Visible fast fine spontaneous twitches

Question 24

What are some non pathological causes of fasciculations?

Answer 24

Stress fatigue caffeine

Question 25

What is a pathological cause of fasciculations?

Answer 25

Denervated muscles that are hyper excitable

Question 26

What grading system is used to determine the power in someone's limbs?

Answer 26

MRC - Muscle Power Grading 0 - 5 0 = no movement 5 = normal strength ( subjective to the patient)

Question 27

What investigations are undertaken in a suspected NMJ disease?

Answer 27

Blood test - Creatine Kinase Muscle Biopsy MRI - Muscle tissue

Question 28

Describe the appearance of polymyositis?

Answer 28

Symmetrical rapidly progressing proximal muscle weakness

Question 29

What investigations are undertaken in polymyositis?

Answer 29

Raised Creatine Kinase | Very reactive to steroid <24 hours

Question 30

What's dermatomyositis?

Answer 30

Clinically similar to polymyositis but + Heliotrope rash

Question 31

If a diagnosis of dermatomyositis is affirmed what should be investigated?

Answer 31

Look for malignancy - 50% have a malignancy

Question 32

Describe inclusion body myositis.

Answer 32

6th decade Sow onset weakness Spares the thumbs Non treatable

Question 33

What is the presentation of someone with Myotonic Dystrophy?

Answer 33

``` Myotonia Cataracts Ptosis Frontal balding Cardiac abnormalities ```

Question 34

Myotonia

Answer 34

Inability to relax muscle

Question 35

Statins can induce this.

Answer 35

Drug myopathy

Question 36

What are some causes of Rhabdomyolysis?

Answer 36

Crush injuries Toxins Post convulsions Extreme exercise

Question 37

What is the pathophysiology behind rhabdomyolysis?

Answer 37

Damaged muscles releases Ca2+ Triggers the release of K+ PH4+ and myoglobininto the blood. Acute renal failure and DIC as result.

Question 38

What is DIC (rhabdomyolysis)

Answer 38

Disseminated Intravascular coagulation

Question 39

How does rhabdomyolysis present?

Answer 39

Myalgia Weakness Myoglobulinuria