For long the CNS had been considered to lack lymphatics. The last few years have been spotted with works conflicting the immune-privilege status of CNS. Experimental evidence has assured the presence of lymphatics in the meninges, the meningeal lymphatic vessels (mLVs), along the venous sinuses carrying the immune cells along with drainage of cerebrospinal fluid (CSF). This article aims to explain the findings of multiple studies indicating the existence and clinical importance of the mLVs along with the controversies that refute the concept. A total of 30 studies were included after the search for literature was conducted in three major databases: PubMed, Scopus and Google scholar till through May 2020, with appropriate MESH terms like CNS, lymphatics, meninges, drainage, and glymphatics. Despite evidence supporting the existence of functional lymphatics in CNS, there has been conflict in opinion about the clearance by glymphatic system. Few have countered the CSF clearance mechanism, stating that those experiments showing such finding were performed on post-mortem tissue. The discovery of mLVs emphasizes a re-evaluation of fundamental neuroimmunology theory while enlightening a shift in the aetiology of neuro-inflammatory and neurodegenerative disorders accompanying the dysfunctional immune system.
Adil Asghar, Ravi K. Narayan, Ashutosh Kumar
Department of Anatomy, AIIMS Patna, India
Eur. J. Anat.
ISSN 2340-311X (Online)