Case 13: Acute leg symptoms
Wednesday, March 23rd, 2011Author: Dr Rupesh Amin
A 24 year old female presented to the E.D. with a left painful knee and numbness over her left toe. The pain was worsening over the past three days with mild knee swelling. She suffered no trauma and was able to weight bear. She had a background history of homocysteinuria, hyperoxaluria, medullary nephrocalcinosis and multiple PEs. She was not on warfarin and received dialysis four times weekly.
1. What is the diagnosis?
Click to see the answerThis patient has an acute ischaemic limb. This is defined as a sudden decrease in the arterial perfusion to a limb causing a threat to viability. Likely causes are separated into embolic (30%), thrombotic (60%) and other (10%). Important clues from the history of embolic occlusion are of a sudden deterioration, possible source (e.g. malignancy, atrial fibrillation), normal clinical findings in the contralateral limb and no history of previous claudication. Other causes include trauma, aortic dissection and Raynaud’s.
2. Name two findings on examination that would be consistent with the diagnosis.
Click to see the answerClassical signs and symptoms include the ‘6Ps’. Pallor, pain, perishing cold and pulselessness are earlier features. Paraesthesiae and paralysis are late signs of irreversible damage. Assessment in the E.D. should include close inspection, temperature, capillary refill time, neurovascular examination (including presence of bruits) and motor function.
3. What is the acute management and further treatment options available?
Click to see the answerThis is a surgical emergency, with a narrow margin of time for investigations. Doppler ultrasound can be used to assess the severity and level of obstruction however may not take into account the presence of a collateral circulation. Keeping the foot dependant, oxygen and immediate heparinisation assist blood flow and tissue perfusion. Correction of hypotension and cardiac anomalies e.g. atrial fibrillation will assist in the acute setting. Further specialist management may include imaging (CT/MR angiography with duplex studies) and options such as catheter related thrombolysis, embolectomy, surgical revascularisation and amputation depending on the likely aetiology and severity of ischaemia.
4. What uncommon predisposing factor does this patient highlight?
Click to see the answerHomocysteinuria is an autosomal recessive trait resulting in disordered metabolism of the amino acid methionine, commonly due to cystathionine beta synthase (CBS) deficiency. Homocysteinuria is an independant risk factor for atheroma formation, with higher total plasma homocysteine concentration being associated with increased risk of coronary artery disease, stroke, and venous thromboembolism. Other clinical features may include a Marfinoid habitus, ectopia lentis, glaucoma and seizures.