Making the Diagnosis
To accurately assess and diagnose this patient’s condition, the clinician needs to eliminate other possible causes of symptoms and rule out stroke. Unilateral leg numbness or weakness without arm involvement is rarely caused by a stroke. Sciatica is a possible diagnosis; however, it does not usually affect the entire leg as a stroke would. The differential diagnosis also should include deep vein thrombosis (DVT) and cellulitis. Deep vein thrombosis and cellulitis are unlikely in this case; although the patient had weakness, the leg was not very swollen, discolored, or painful. The correct diagnosis is acute limb ischemia.
Acute limb ischemia (ALI) typically presents with symptoms of unilateral lower extremity pain, numbness and/or weakness, diminished temperature, and sometimes pallor of the skin. The severity of symptoms may vary based on the location of the clot, degree of collateral circulation, and any pre-existing neuropathy. Signs often include asymmetric temperature to palpation of the legs/feet, pulse difference between legs, delayed capillary refill, and/or lower blood pressure in the affected leg.
More concerning signs include the 5 Ps: pallor, poikilothermia, pain with passive stretch, and pulse deficit. All of these signs and symptoms can be variable and not all patients with ALI will have all 5 Ps.
Testing for ALI should typically start with an ankle/brachial index comparing ankle and arm blood pressures. Normally, the ratio is greater than 1 but is considered normal as long as it is greater than 0.9; 0.9 to 0.5 is considered mild to moderate; less than 0.5 is considered severe; and less than 0.3 critical.
This should be followed by formal imaging either with arterial duplex or CT angiogram of the lower extremity, as well as routine laboratory workup and electrocardiogram. Severity of ALI can be stratified using the Rutherford classification (Table).
Table. Rutherford Classification for Acute Limb Ischemia
|Classification||Sensory Loss||Motor Loss||Doppler|
|IIa Threatened||Toes only||None||+/- audible|
|IIb Precarious||Beyond toes||Partial||Rarely audible|
Treatment typically consists of heparin therapy and intervention by either interventional radiology or vascular surgery. Vascular surgery can be consulted first.
The patient in this case was diagnosed with acute limb ischemia, which was thought to be due to his history of atrial fibrillation with a subtherapeutic INR of 1.7. He was treated with heparin followed by angioplasty and did well.
Brady Pregerson, MD, is an emergency physician at Tri-City Medical Center and Scripps Coastal Urgent Care both in Oceanside, California.
Pregerson DB. Vascular Surgery: Arterial. Emergency Medicine 1-Minute Consult. 5th ed. 2017;5. http://www.erpocketbooks.com/emergency_medicine_reference_books/quick-essentials-emergency-medicine/