Functional Popliteal Artery Entrapment Syndrome: Poorly Understood and Frequently Missed? A Review of Clinical Features, Appropriate Investigations, and Treatment Options

Functional popliteal artery entrapment syndrome (PAES) is an important and possibly underrecognized cause of exertional leg pain (ELP). As it is poorly understood, it is at risk of misdiagnosis and mismanagement. The features indicative of PAES are outlined, as it can share features with other causes of ELP. Investigating functional PAES is also fraught with potential problems and if it is performed incorrectly, it can result in false negative and false positive findings. A review of the current vascular investigations is provided, highlighting some of the limitations standard tests have in determining functional PAES. Once a clinical suspicion for PAES is satisfied, it is necessary to further distinguish the subcategories of anatomical and functional entrapment and the group of asymptomatic occluders. When definitive entrapment is confirmed, it is important to identify the level of entrapment so that precise intervention can be performed. Treatment strategies for functional PAES are discussed, including the possibility of a new, less invasive intervention of guided Botulinum toxin injection at the level of entrapment as an alternative to vascular surgery. 1. Introduction Functional popliteal artery entrapment syndrome (PAES) is an important and possibly underrecognized cause of exertional leg pain. It shares many features with other causes of exertional leg pain, and more than one condition can be present at once, confusing the clinical picture. An understanding of the typical presenting features of the common causes of exertional leg pain is essential, allowing the clinician to determine those suggestive of PAES and requiring further investigation. Investigating functional PAES is fraught with potential problems and, if performed incorrectly, can result in false negative and false positive findings. The authors believe that currently accepted vascular investigations such as ankle-brachial indices and Doppler ultrasound performed at rest are not accurate in investigating functional PAES. Rather, a review of the literature would suggest that investigations such as provocative Doppler ultrasound and MRI angiography are performed as soon as possible after reproducing symptoms to “capture” the occlusion while it is occurring. Once the diagnosis of functional PAES is confirmed, there are a number of treatment strategies available. Until recently, definitive intervention was only available in the form of vascular surgery with variable myotomies and releases. We provide information on a Pilot study suggesting a new less invasive intervention of guided