S6 - Lower Nerve Conditions

Question 1

• *Nerve injuries**
• What can happen? (overview terms)

Answer 1

• Loss of function - motor, sensory, proprioception
• Neuroma formation leading to pain

Question 2

• *Neuroma**
• How is this formed

Answer 2

If severed ends are not surgically reapposed (sewn back together), unregulated, ineffective regeneration of the axon occurs.

The sprouting of axons from the severed ends of the nerve leads to the formation of a traumatic neuroma - this is extremely painful

Question 3

Summary:
Nerve lesions in the lower limb, damage to these nerve will…
- Nerve to psoas and ilacus
- Femoral
- Obturator
- Superior gluteal
- Inferior gluteal
- Sciatic
- Tibial
- Common Fibular
- Root compression

Answer 3

NERVE TO PSOAS AND ILIACUS:
– no pelvic swing on walking

FEMORAL:
– loss of hip flexion and knee extension, loss of sensation anterior thigh and medial calf

OBTURATOR:
– loss of adduction of thigh, loss of sensation inner thigh

SUPERIOR GLUTEAL:
– pelvic dip, loss of abduction thigh

INFERIOR GLUTEAL:
– loss of extension at hip, buttock wasting

SCIATIC:
– loss of all motor except adduction and flexion of the thigh and extension of knee, loss of sensation lower leg and foot

TIBIAL(HIGH):
– loss of flexion of toes and inversion of foot, loss of sensation of sole of foot, inferior aspect of toes and nail bed

COMMON FIBULAR(HIGH):
– loss of extension of toes and foot(foot drop), looss of sensation lateral lower leg and upper foot

ROOT COMPRESSION:
– prolapsed disc catches nerve at next intervertebral foramen and not one at same level of the disc, e.g L4/5 disc catches L5 nerve root

Question 4

• *Neuropathy**
• Define
• Causes

Answer 4

Neuropathy: Loss of motor and sensory function

Causes:
• Injury-stretch of nerve, complete division
• Extrinsic pressures-tumour, abscess..etc
• Medical conditions – Diabetes – Alcohol excess – Drugs
• Other rarer causes-nerve tumours…etc

Question 5

• *Piriformis sydrome**
• What happens
• Why does this happen?
• Describe the pain distribution
• Treatment

Answer 5

• Sciatica symptoms not originating from spinal roots and/or spinal disc compression, but involving the overlying piriformis muscle
• Overuse of muscle leads to spasm
• Diagnosis of exclusion and treatment is mostly about activity modification

Question 6

• *Meralgic paraethesia**
• What is this?
• Causes
• Symptoms
• Diagnostic confirmed
• Treatment

Answer 6

• Compression of the nerve as it passes through the inguinal ligament as it passes the fascia latta
• Causes: obesity (compression by abdominal fat), wearing a tight belt, tight clothing, pregnancy
• Symptoms: Burning or stinging in the antero-lateral aspect of the thigh, aggravated by lying down with hip flexed. Tenderness on palpation, reduced sensation
• Diagnosis confirmed: by absence of motor signs and by excluding pelvis and intra abdominal causes of irritation like a tumour
• Treatment: Stop wearing tight belts, corsets, potentially a local nerve block, surgery to free the nerve

Question 7

• *Foot drop**
• 1 possible cause

Answer 7

1 possible cause:
- Deep peroneal nerve and sensory loss in the 1st dorsal web space

Question 8

Which nerve is usually chosen for a vein harvest for bypass surgery?

Answer 8

Saphenous nerve inury