High-Flow and Low-Flow Cerebrovascular Malformations Syndromes Associated With Klippel-Trénaunay and Parkes-Weber Syndromes. A Systematic Review.

Klippel-Trénaunay syndrome (KTS) and Parkes Weber syndrome (PWS) are rare vascular disorders that share clinical features such as limb overgrowth and capillary malformations. However, they differ in the vascular flow dynamics. KTS is a low-flow malformation, while PWS is characterized by high-flow arteriovenous shunts. A systematic review of the literature was conducted following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, focusing on case reports and series describing patients with confirmed KTS or PWS and documented cerebrovascular or spinal vascular findings. Studies were analyzed for type and location of central nervous system lesions, and genetic data were reviewed where available. Forty studies comprising 76 patients met inclusion criteria. In KTS (61 patients), cerebrovascular anomalies were mostly venous in nature, including developmental venous anomalies, venous malformations, and cavernomas, with no spinal arteriovenous malformations reported. In contrast, PWS (n = 15) was exclusively associated with high-flow spinal arteriovenous malformations or fistulas, primarily affecting the thoracolumbar region. No cerebral lesions were identified in PWS. PIK3CA mutations were observed in KTS cases, while Ras GTPase-activating protein 1 mutations were more common in PWS. Cerebrovascular findings might offer valuable diagnostic insight into distinguishing KTS from PWS. These vascular recurrent findings, coupled with genetic testing, can enhance diagnostic precision and guide appropriate management strategies for these complex vascular syndromes.