Symptom Laterality Concordance: Aortic Dissection Masquerading as Ipsilateral Lumbar Radiculopathy.

Introduction: Aortic dissection is a lethal vascular emergency that may present atypically as isolated limb ischemia. A specific diagnostic pitfall, termed "symptom laterality concordance," arises when these ischemic symptoms align with a preexisting, ipsilateral lumbar spinal pathology, creating a high risk of misdiagnosis. Case Report: We present a 64-year-old male with known right L4/5 lumbar disk herniation, initially diagnosed with radicular exacerbation due to right lower limb pain and sensory loss. The examination revealed right L5 radicular signs alongside a cool limb with a weakly palpable pulse. Vascular ultrasound showed right common iliac artery occlusion. Subsequent tearing chest pain led to a CTA diagnosis of Stanford type B aortic dissection. Despite emergent stenting, the patient succumbed to aortic rupture. Conclusion: This case highlights "symptom laterality concordance" as a critical cognitive trap, where a vascular catastrophe mimics an ipsilateral spinal condition. It underscores the need for clinicians to carefully consider vascular pathologies in all unilateral limb presentations. We advocate for a dual vascular-neurological assessment and propose a clinical algorithm to mitigate this risk.