Neuromuscular Disorders

Question 1

What is GBS (Guillain-Barré Syndrome)?

Answer 1

An acute paralytic polyneuropathy that affects the peripheral nervous system. It causes acute, symmetrical, ascending weakness and can also cause sensory symptoms. It is usually triggered by an infection

Question 2

What organisms cause GBS?

Answer 2

Campylobacter jejuni
Cytomegalovirus (CMV)
Epstein-Barr virus (EBV)

Question 3

Sx of GBS?

Answer 3

Sx usually start within 4 wks of triggering infx:
* Symmetrical ascending weakness (starting w/lower limbs)
* Reduced reflexes
* Lower back pain
* Paraesthesia
* Cranial nerve involvement and facial weakness (diplopia and facial droop)

Recovery can take months to years.

Question 4

Ix for GBS

Answer 4

Clinically: Brighton criteria

Other Ix:
* Nerve conduction studies - reduced nerve signal
* Lumbar puncture for CSF - raised proteins

Question 5

Mx of GBS?

Answer 5

Supportive care
VTE prophylaxis (as PE is leading cause of death)
1st line: IV immunoglobulins (IVIG)
Plasmapheresis (IVIG alternative)

Question 6

What is bulbar palsy?

Answer 6

Subtype of LMN lesion impacting 9th (glossopharyngeal), 10th (vagus) and 12th (hypoglossal) CN.

The resultant impairments primarily involve mechanisms of speech (dysarthria) and swallowing (dysphagia).

Question 7

Causes of bulbar palsy

Answer 7

• MND - Progressive bulbar palsy
• Myasthenia gravis
• GBS
• Brainstem stroke

Question 8

Sx of bulbar palsy

Answer 8

Absent or normal jaw jerk reflex
Absent gag reflex
Flaccid, fasciculating tongue
Nasal speech, often described as “quiet”

Question 9

Ix for bulbar palsy

Answer 9

Neuro examination - asses CN
Electromyography (EMG) + nerve conduction studies
Bloods

Question 10

Mx of bulbar palsy?

Answer 10

Speech + swallowing therapy - manage dysarthria + dysphagia
Nutrition support
Tx of underlying cdtn

Question 11

What is muscular dystrophy? What are two different types of this disease?

Answer 11

A group of inherited genetic disorders characterised by progressive degeneration and weakening of body’s muscles.

Two Types:
1. Duchenne muscular dystrophy (DMD)
2. Becker muscular dystrophy

Question 12

What kind of genetic inheritence are muscular dystrophies?

Answer 12

X-linked recessive disorders, males are predominantly affected while females are usually carriers

Question 13

Sx in Duchenne’s muscular dystrohpy compared to Becker’s MD?

Answer 13

Duchenne:
* Early childhood
* Muscle wasting + weakness
* Children usually wheelchair bound before puberty and have resp failure by early twenties
* Hypertrophic calves (degenerated muscle replaced by fat)
* +ve Gower’s manoeuvre
* Difficulty lifting the child due to proximal muscle weakness

Becker’s:
* Later in childhood
* Muscle wasting + weakness
* Become wheelchair bound in teens and can survive into thirties

Question 14

Ix for Duchenne’s and Becker’s dystrophy?

Answer 14

GS - genetic testing
1st line - Creatine kinase

Question 15

Mx of muscular dystrophies?

Answer 15

• Glucocorticoids - slow muscle degeneration
• Physio - maintain mobility
• Genetic counselling for affected family members

Question 16

What are the main causes of mortality for muscular dystrophies like Duchenne’s?

Answer 16

Resp complications and dilated cardiomyopathy.

Question 17

What is myasthenia gravis?

Answer 17

Autoimmune disease marked by production of antibodies that target nicotinic acetylcholine receptors on muscle fibres. This reduces ability of acetylcholine to trigger muscle contraction resulting in muscle weakness.

Question 18

What are the drugs that can exacerbate Myasthenia Gravis?

Answer 18

Beta blockers
Lithium
Penicillamine
Gentamicin
Quinolones
Phenytoin

Question 19

Sx of Myasthenia Gravis?

Answer 19

• Limb muscle weakness
• Drooping eyelids or diplopia
• Difficulty smiling or chewing
• Change in speech or difficulty swallowing
• Myasthenic snarl
• Head droop
• Fatigable muscle weakness

Sx worsen w/prolonged movement or by end of the day

Question 20

Ix for myasthenia gravis?

Answer 20

Bloods - serum acetylcholine receptor antibody and muscle-specific tyrosine kinase antibodies
CT chest - thymoma (identify thymic hyperplasia)
EMG or nerve conduction studies

In myasthenic crisis - Spirometry

Question 21

Tx of Myasthenia Gravis?

Answer 21

• Acute cases - intravenous immunoglobulin (IVIG) or plasmapheresis in severe
• Immunosuppressive therapy (steroids)
• Anticholinesterase inhibitor (pyridostigmine or neostigmine)

If pts have thmic hyperplasia or thymoma - thymectomy