A 43-year-old female amateur marathon runner presented with a 3-year history of debilitating left calf pain and paraesthesia, which had gradually progressed to affect the anterior thigh and lumbar region. This was particularly apparent on running and was relieved entirely by rest. She had no relevant past medical history and no identifiable risk factors for vascular disease. A neurological opinion was sought; however, nerve conduction studies and spinal magnetic resonance imaging were unremarkable, so she was referred for a vascular opinion.