Issue link: https://www.massageandbodyworkdigital.com/i/621015
R Recent scientific breakthroughs in how we look at the lymph system and the circulation of cerebral spinal fluid are causing gradual shifts in massage therapy. Let's look briefly at the historical journey of our ongoing understanding of fluid dynamics, unveil some of the newest and most exciting discoveries concerning the circulation of lymph and cerebrospinal fluid (CSF), and then offer some effective manual therapy techniques for lymph drainage that can help facilitate the natural exchanges between these fluids. NEW AND OLD CSF HYDRODYNAMICS The lymphatic system was discovered somewhat late in history, 2 but the identification of CSF came even later. In ancient times, Hippocrates and Galen recognized fluids in the brain, but even at the time of French philosopher and scientist René Descartes (1596–1650), the brain was still considered to be merely a hydraulic pump moving fluid through the nerves to animate the muscles. The scientific discovery of CSF is attributed to Swedish scientist, philosopher, and visionary Emanuel Swedenborg (1688–1772). 3 His career was exceptionally prolific—he wrote approximately 40,000 pages on scientific and mystical topics throughout his life. In 1741, he described the expansion and contraction of the brain, and its production of an extremely refined substance, a "highly gifted juice," which he called the "spirituous essence," the "spirituous fluid," that was present in CSF. 4 He said this refined fluid traveled throughout the entire body and was returned to the blood by lymph. 5 In his description, Swedenborg may have made the first connection between CSF and the lymphatic system. He also stated, for the first time, that CSF is "secreted by the blood vessels in the brain," a concept that has just recently been confirmed by scientific investigations, as we will discuss later. A man ahead of his time, Swedenborg likely had an influence on the development of cranial osteopathy, potentially influencing W. G. Sutherland (1873–1954), the originator of cranial osteopathy, which is the foundation of craniosacral therapy. For more than 100 years, the classical understanding of the physiology of CSF has remained unchallenged, until recently. The Old Model: The Three Falling Pillars of CSF Physiology If you understand a little about CSF physiology, you know it has traditionally been based on three main points that experts universally accepted as the unquestioned truth: • Production. Since 1919, schools have taught that CSF is mainly formed by the choroid plexi inside the brain ventricles; it then circulates within the ventricular system, eventually to be passively absorbed into the venous sinuses, and/or into the lymph system. 6 • Circulation. In the classical model, it was also believed that CSF flows unilaterally (from the lateral ventricles to the third and fourth ventricles), eventually reaching the spaces around the brain. • Reabsorption. The old CSF model attributed the fluid's reabsorption only to the veins and lymphatics. In 1869, G. Schwalbe injected Berlin Blue dye into the most external cerebrospinal spaces (the subarachnoid space or SAS) of dogs and found that he could follow the dye from the central nervous system (CNS) into the lymph nodes of the neck. Schwalbe made the very first statement that the lymphatic pathways are the major pathways, outside of the CNS, for CSF reabsorption. 7 However, it was not clear exactly what pathway the blue dye took to get from the CSF to the nodes in the neck. A little later, in 1872, H. Quincke demonstrated that the CSF could leave the CNS through little spaces surrounding the cranial and spinal nerves. 8 Numerous researchers have demonstrated these pathways and shown that some constituents of the CSF drain into lymph nodes in the neck (cervical lymph nodes), using the lymph pathways to exit the CNS. 9 T. Brinker, and others, showed that at least 50 percent of CSF is reabsorbed through the lymphatics rather than the veins. 10 Today, these three pillars of the physiology of CSF are losing their ground as fundamental principles. Even though this is what most physiology and neurobiology books still describe today, recent research shows there is now little convincing evidence to support this exact model. 11 The New Scientific Model With the three main pillars of conventional CSF physiology—production, circulation, and reabsorption—being critically challenged, a reformulation of this old theory may change applications in research, as well as applications to manual treatments. Let's look at the changes in conventional thinking regarding CSF physiology. • Production. Today, researchers are finding that choroid plexi most likely have only a small role in CSF secretion; the major source of CSF production is in all probability the capillaries of the brain's cerebral tissue, 12 echoing the innovative 48 m a s s a g e & b o d y w o r k j a n u a r y / f e b r u a r y 2 0 1 6