Limb pain differential and pathophysiology

Question 1

Limb pain differentials

Answer 1

-ALI
-MSK
-cauda equina
-DVT

Question 2

ALI presentations

Answer 2

6 P’s
-pain- sudden, severe
-pallor- pale, cold
-pulselessness
-paraesthesia- numbness/ tingling
-paralysis- weakness/ inability to move
-perishing cold to touch compared to other limb
Late stages
-mottling or cyanosis
-complete numbness
-severe pain followed by loss of sensation

Question 3

ALI pathophysiology

Answer 3

-sudden arterial occlusion due to an embolus that blocks an artery
-could also be due to trauma or arterial dissection
-causes a lack of oxygen so anaerobic respiration occurs
-lactic acid builds up
-cells become hypoxic -> increases vascular permeability and causes inflammation
-activates platelets causing worsening ischaemia

Question 4

Cauda equina presentations

Answer 4

-saddle anaesthesia
-loss of sensation in legs
-tingling, burning, numbness in lower extremities
-weakness in legs
-incontinence
-severe lower back pain

Question 5

Cauda equina pathophysiology

Answer 5

-herniated disc, tumour, infection, trauma compresses nerve roots
-disrupts blood flow causing ischaemia and nerve dysfunction
-nerve dysfunction causes motor, sensory and autonomic dysfunction

Question 6

DVT presentations

Answer 6

-unilateral leg swelling
-pain or tenderness
-redness or discolouration
-warmth over infected area
-dilated superficial veins
-homan’s sign (pain in calf when dorsiflexing foot)

Question 7

DVT pathophysiology

Answer 7

-occurs due to venous stasis, endothelial injury, hypercoagulability
-damage to vein wall, exposes lumen to platelets
-triggers clotting cascade
-clot grows and traps RBCS and platelets
-blood flow slows causing pain and swelling
-if clot breaks, forms embolus and block pulmonary arteries causing PE