Lower limb nerve injuries and compartment syndrome

Question 1

Differentiate between the pain severity and location of pain in cauda equina and conus medullaris

Answer 1

CAUDA EQUINA

• pain is more severe, radicular
• unilateral pain in perineum, thighs and legs

CONUS MEDULLARIS

• less severe pain
• bilateral pain in perineum, thighs

Question 2

Differentiate between sensory disturbance, sexual function and bowel/bladder involvement in cauda equina and conus medullaris

Answer 2

CAUDA EQUINA

• sensory distrubance is unilateral saddle shaped
• less impaired sexual function
• late bowel/bladder involvement

CONUS MEDULLARIS

• sensory disturbance bilateral saddle
• severely impaired sexual function
• early bladder/bowel involvement

Question 3

Differentiate between motor loss and reflexes in cauda equina and conus medullaris

Answer 3

CAUDA EQUINA

• Asymmetric motor loss with atrophy
• ankle and knee reflexes reduced

CONUS MEDULLARIS

• Symmetric motor loss
• Ankle reduced reflex

Question 4

What causes cauda equina

Answer 4

• disc herniation in L5/S1 region which compresses cauda equina
• spinal fracture
• tumour

Question 5

What causes conus medullaris

Answer 5

• disc herniation
• tumour
• inflammatory conditions (chronic inflammatory demyelinating, polyradiculopathy, sarcoidosis)
• infection (cmv, hsv, ebv, lyme, TB)

Question 6

What is sciatica?

• Location
• Causes
• Motor functions of sciatic nerve

Answer 6

Pain that radiates from buttocks down leg and can travel as far as to feet and toes
- L5/S1 nerve root impingement
(L5 n root exists between L5/S1 vertebral bodies, S1 n root between S1 and S2)

• Trauma, haematoma, piriformis syndrome (sciatic nerve compression), misplaced IM injections
• Hip flexion, knee extension, hip adduction (branches provide branches to all muscle groups in leg)