Diagnostic Approach to Sudden Onset Bilateral Lower Extremity Weakness

Critical Initial Assessment

The American College of Cardiology recommends checking for the "5 Ps plus temperature" (Pain, paralysis, paresthesias, pulselessness, pallor, and polar) to assess for limb-threatening ischemia 1
The American College of Radiology suggests assessing motor strength systematically, documenting hip flexion/extension, knee flexion/extension, ankle dorsiflexion/plantarflexion, and toe movements bilaterally 2
Measuring skin temperature gradient is important, as cool extremities suggest arterial insufficiency 3

The American College of Radiology recommends obtaining CT angiography (CTA) of the aorta and bilateral lower extremities with IV contrast immediately if pulses are absent or severely diminished bilaterally 2, 4
The guideline suggests that time is tissue, and delays beyond 4-6 hours increase the risk of permanent damage and limb loss 4, 3
Initiating systemic anticoagulation with heparin immediately while awaiting imaging is recommended to prevent thrombus propagation 4, 5

The American College of Cardiology notes that aortic saddle embolus can present with sudden onset, absent femoral pulses, and a history of atrial fibrillation or cardiac disease 1
Bilateral acute limb ischemia, classified as Rutherford Class IIb, requires emergency revascularization within 6 hours 4, 5

The American College of Cardiology recommends immediate vascular surgery consultation before completing imaging if limb-threatening signs are present 4
Starting unfractionated heparin bolus followed by infusion is suggested, as well as preparing for emergency revascularization (catheter-directed thrombolysis, thrombectomy, or surgical bypass) 4, 5
The presence of paralysis or motor weakness requires immediate surgical intervention, potentially before imaging 4

The Journal of Neurology, Neurosurgery and Psychiatry notes that functional neurological disorder should not be overlooked in the differential, but only after excluding life-threatening causes 6