The Anatomy and Physiology of the Glymphatic System and Its Role in Craniectomies and Syndrome of the Trephined

Abstract

Background: The glymphatic system, a relatively recently discovered system for transport of cerebrospinal fluid (CSF) and waste products in the central nervous system, has been implicated in several neurologic disorders. Altered CSF dynamics are seen after decompressive craniectomy, suggesting this procedure may impact glymphatic function. We aimed to systematically review the current literature to understand the effect of the glymphatic system on patients with decompressive craniectomies and Syndrome of the Trephined (SoT). Methods: PubMed and Embase were searched for preclinical and clinical studies investigating the glymphatic system and craniectomy, cranioplasty, or SoT in years 2012 to 2023. Results: Sixty-three studies were identified for review. Intracranial oscillations, cerebral perfusion, and arterial pulsations have been identified as major drivers of glymphatic influx. Each of these processes are diminished following craniectomy, suggesting craniectomy may impair glymphatic function. Reductions in brain pulsatility and alterations in glymphatic drainage after craniectomy were accompanied by impaired functional outcomes, as seen in SoT. Radiologically, CSF flow alterations are seen after craniectomies, which improve with cranioplasty. Conclusions: Glymphatic system dysfunction after craniectomy and in SoT may be a potential therapeutic target for patients with iatrogenically altered cranial vault anatomy.