Peripheral Neuropathy

Question 1

What are the different fibre types in the peripheral nervous system?

Answer 1

• Large myelinated fibres: Motor nerves and sensory nerves carrying info on proprioception, vibration or light tough.
• Thinly myelinated fibres: light touch, pain and temperature.
• Small unmyelinated fibres (light touch, pain and temperature

Question 2

What is the clinical presentation of neuropathy?

Answer 2

• Muscle weakness/atrophy.
• If affecting large myelinated fibres presents with sensory ataxia loss of vibration sense +/- numbness and tingling.
• If affecting small (thinly myelinated/unmyelinated fibres) then impaired pin prick, temperature, painful burning/numbness and tingling.
  Automonic - Postural hypotension, erectile dysfunction, GI disturbances and abnormal sweating

Question 3

What is length dependant axonal neuropathy?

Answer 3

Occurs > 50y.
Neuropathy starts symmetrically in toes/feet and progresses slowly.
Causes include: diabetes, alcohol, nutritional deficiencies (B12/folate), metabolic/endocrine, rheumatological, drugs, infections, Charcot-Marie-tooth

Question 4

What is sensory ataxia?

Answer 4

Postural instability and incoordination due to loss of sensory input to control movement.

Question 5

What is Guillian Barre Syndrome?

Answer 5

• Post-infectious autoimmune disease which causes an acute inflammatory demyelinating neuropathy

Question 6

What are potential causes of Guillian-Barre and how does it present?

Answer 6

• Common causes are campylobacter but can be CMV, EBV.
• It presents with progressive ascending weakness over days with flaccid, quadraparesis and areflexia.
• May have respiratory/bulbar or autonomic involvement.
• Treated with IV immunoglobulins/apheresis (bind to autoantibodies)

Question 7

What is the treatment for chronic inflammatory demyelinating polymyopathy?

Answer 7

Steroids and IV immunoglobulins

Question 8

How can you determine whether a condition is axonal or demyelinating?

Answer 8

Nerve conduction studies. If axonal then the spikes will be smaller. If demyelinating then conduction will be slower

Question 9

What is mononeuritis multiplex and its causes?

Answer 9

• Development of neuropathy in 2+ nerves. It describes a cluster of conditions and is not a diagnosis itself.
• It is often caused by diabetes, vasculitis, rheumatological, infective, sarcoidosis or lymphoma.
• Commonly affects common peroneal, radial, axillary, median and sciatic nerve

Question 10

What are the symptoms of neuropathy in common peroneal nerve?

Answer 10

Weak ankle dorsiflexion and sensory disturbance on lateral aspect of calf and foot.

Question 11

What are the symptoms of neuropathy in the radial nerve?

Answer 11

Wrist/finger drop and sensory disturbance on dorsum of hand

Question 12

What are the symptoms of neuropathy in the axillary nerve

Answer 12

Weakness of shoulder abduction and C5 sensory disturbance

Question 13

What are the symptoms of neuropathy in the median nerve

Answer 13

• Weakness in 2 radial lumbricals, opponens brevis, abductor pollicis and flexor pollicis brevis. (muscular weakness)
• Sensory disturbance

Question 14

What are the symptoms of neuropathy in the femoral nerves

Answer 14

Weak hip flexion and knee extension and sensory disturbance over the lateral calf and dorsum of the foot

Question 15

What are the investigations and management of mononeuritis multiplex

Answer 15

• History and exam, nerve conduction studies and EMG, MRI or LP.
• Management is treatment is of the underlying cause

Question 16

What are symptoms of muscle disease?

Answer 16

• Proximal muscle weakness,
• Facial weakness (drooling)
• Ptosis or ophthalmoplegia (paralysis of ocular muscles)
• head drop (neck weakness)
• Breathlessness especially when laying flat.
• Exercise intolerance and palpitation (myocardium)

Question 17

What are some different muscle disease

Answer 17

• Muscular dystrophies eg, DMD or BMD
• Metabolic muscle disorders,
• Inflammatory muscle disorders eg, polymyositis or dermatomyositis,
• Myotonic dystrophies

Question 18

Explain the presentation, investigation and management of myasthenia gravis

Answer 18

• It is an autoimmune disease with antibodies against Ach receptors.
• Presents with fatigable weakness of ocular, bulbar, neck, respiratory and/or limb muscles
• Investigations is antibodies against ACh receptors. Can also to single fibre EMG.
• Treat with pyridostigmine (anti-acetylcholine esterases) and immunosuppressants