[In search of the lymphatic system of the central nervous system]

Lymphatic flow in the brains and lymphatic vessels in the meninges are recognized through the intra-cerebral injection of a dye specific to the lymphatic system. The confluence of these two components can only be at the level of the cerebro spinal fluid (CSF), which lends support to the hypothesis that the CSF itself constitutes the lymph of the nervous system. The authors report the results of a study based on a necropsic investigation and an experimental animal model, contributing new facts in favor of this hypothesis. For a certain number of inflammatory diseases of the central nervous system (CNS) when the initial phase is still limited to the brain or to the spinal chord tissues, it is usually asymptomatic; only when it reaches the meninges, that clinical symptoms be seen: this can be explained by the presence of such lymphatic circulatory system. Stasis of the cerebral lymphatic circulation, should be regarded as a new etiologic factor in the onset of brain oedemas. This concept, already taken into account by some investigators, deserves consideration in the study of most CNS diseases.