Lower Limb Mononeuropathies

Question 1

The lateral cutaneous nerve of thigh lesions:

Causes:

• What is compression on exiting pelvis beneath inguinal ligament called?
• How does obesity or pregnancy cause this?

Where does pain and numbness occur?

What type of pain do they have?

Answer 1

Meralgia paraesthetica

Pressing down no inguinal ligament

Antero-lateral thigh pain and/or numbness

Question 2

Sciatic nerve lesions:

What is this also called?

What usually causes this?

It causes leg pain. Where else does it cause pain?

Where do the pain radiate to?

Motor features can occur but less commonly!

What 2 motor signs can you see?

Answer 2

Sciatica

Lumbar radiculopathy due to slipped disc, trauma, tumour etc.

Back pain

Radiates top to bottom

Foot drop
Weak hip abduction

Question 3

Common peroneal nerve lesions:

What is another name for the common peroneal nerve?

What nerve does it branch from?

What does the nerve divide into itself?

What can cause compression against the fibula of this nerve?

Answer 3

Lateral popliteal nerve
Common fibular nerve

Sciatic nerve - the common peroneal nerve goes into the anterior compartment

Deep and superficial peroneal nerve

Leg crossing or squatting
Fracture
Plaster casts

Question 4

Common peroneal nerve lesions:

Deep peroneal nerve lesions:

• Lesions mean muscles in the anterior compartment are weak. What 3 motor signs will you therefore see?
• Where will numbness occur?

Superficial peroneal nerve lesions:
-There is weak ankle eversion. Where does numbness occur?

Answer 4

Weak ankle dorsiflexion (Foot drop) - the commonest cause
Weak toe dorsiflexion
Weak foot eversion

First web space

Anterolateral lower leg and foot dorsum (except webspace)

Common peroneal nerve lesions present with a mixture of above

Question 5

Tibial nerve lesions:

What nerve does it branch from?

What causes compression behind the medial malleolus?

Lesions mean muscles in the posterior compartment are weak. What 3 motor signs will you therefore see?

Where will numbness occur?

Answer 5

Sciatic nerve - it goes into the anterior compartment

Tarsal tunnel syndrome

Weak ankle plantarflexion
Weak toe plantarflexion
Weak foot inversion

Sole of foot