Peripheral nerve injuries/ palsies

Question 1

What is meant by peripheral nerve injury?

Answer 1

Injuries that result from systemic diseases (e.g. Diabetes or autoimmune disease) or localised damage(eg. trauma, compression, tumours) and manifest with neurological deficits distal to the level of the lesion.

Question 2

What are the different causes of PNI’s/ palsies?

Answer 2

1. Injury → from an accident can compress, crush or cut nerves
2. Medical Conditions → diabetes, guillain-barre syndrome, carpal tunnel syndrome
3. Autoimmune Disease → SLE, RA, sjogren’s syndrome

Question 3

What are the different types of nerve damage you can have?

Answer 3

1. Neuropraxia → compression injury causing temporary disruption of nerve conduction
2. Axonotmesis → axon is damaged but the perineurium and epineurium remain intact
3. Neurotmesis → complete nerve transection
4. Traumatic Neuroma → benign, painful nodular thickening caused by nerve regeneration at the site of different forms of nerve injury

Question 4

What are the presenting symptoms commonly seen with PNI’s/ palsies?

Answer 4

1. Motor Nerves → muscle weakness, painful cramps, uncontrollable muscle twitching
2. Sensory Nerves → paraesthesia in hands and feet (numbness + tingling), trouble sensing pain or changes in temperature, walking.
3. Autonomic Nerves → excessive sweating, changes in blood pressure, inability to tolerate heat, GI symptoms.

Question 5

What is Guillain-Barré syndrome?

Answer 5

• immune-mediated demyelination of the peripheral nervous system often triggered by an infection (campylobactur jejuni).
• Back/leg pain as initial symptom.
• Progressive, symmetrical weakness of all the limbs, weakness is classically ascending (limbs are first), reflexes are absent.
• LP will show rise in protein with normal WCC.
• Decreased motor nerve conduction velocity due to demyelination.

Question 6

What is carpal tunnel syndrome?

Answer 6

• compression of median nerve in the carpal tunnel.
• Causes include pregnancy, rheumatoid arthritis, oedema.
• Pins and needles in thumb, index and middle finger.
• Weakness of thumb adduction, wasting of thenar eminence, tinel’s sign (tapping causes paraesthesia), phalen’s sign (flexion of wrist causes symptoms).
• Tx with steroid injections and wrist spints at night.
• Surgical decompression if severe.

Question 7

What is foot drop?

Answer 7

• may be due to common peroneal/ fibular nerve lesion (most common) or L5 radiculopathy.
• Common peroneal nerve lesion occurs due to compression at neck of fibula.
• Weakness of foot dorsiflexion and eversion.
• Weakness of hip abduction suggests L5 radiculopathy.

Question 8

What investigations are used to diagnose/ monitor PNI’s/ palsies?

Answer 8

1. Imaging → plain x-ray or CT/MRI
2. Electromyography (EMG) or Nerve Conduction Studies

Question 9

How are PNI’s/ palsies managed?

Answer 9

1. Conservative Treatment → expectant management (allowing spontaneous recovery with close monitoring), activity modification, splinting, electrical stimulation, physiotherapy, analgesia
2. Surgery → nerve repair or nerve transfer (if injury not healing properly on its own or if open injuiry)