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The Somatic Connection  |   January 2018
Lymphatic Vessels Found in the Brain—Osteopathic Considerations, Part 2: Now in Humans and Monkeys
Author Notes
  • University of California, San Diego School of Medicine 
Article Information
The Somatic Connection   |   January 2018
Lymphatic Vessels Found in the Brain—Osteopathic Considerations, Part 2: Now in Humans and Monkeys
The Journal of the American Osteopathic Association, January 2018, Vol. 118, 53. doi:https://doi.org/10.7556/jaoa.2018.012
The Journal of the American Osteopathic Association, January 2018, Vol. 118, 53. doi:https://doi.org/10.7556/jaoa.2018.012
Absinta M, Ha SK, Nair G, et al. Human and nonhuman primate meninges harbor lymphatic vessels that can be visualized noninvasively by MRI. eLife. 2017;6:e29738. doi:10.7554/eLife.29738 
Researchers at the National Institute of Neurological Disorders and Stroke have identified the existence of meningeal lymphatic vessels in human and nonhuman primates (common marmoset monkeys). This research follows research reviewed previously in The Somatic Connection describing meningeal lymphatic vessels in rats.1 Five human volunteers (3 women, 2 men, aged 28-53 years) and 3 marmoset monkeys were injected with 2 kinds of dyelike substances, both gadolinium-based compounds. One, gadobutrol, penetrates the blood-brain barrier, and the other, gadofosveset, binds to albumin and remains within blood vessels. 
On 3-dimensional rendering of subtraction magnetic resonance images, dural lymphatic vessels were seen in vivo running parallel to the dural venous sinuses, especially the superior sagittal and straight sinuses, and alongside branches of the middle meningeal artery. These vessels were seen only with gadobutrol and not gadofosveset, which confirmed they were lymphatic in nature. 
The ability to visualize the cerebral lymphatic system with these new techniques makes it possible to study how the brain removes waste products and circulates white blood cells. Furthermore, this technology allows the examination of lymphatic and blood circulation changes in the aging process and in disease. The procedures used in this study are breakthrough technological advances and will likely spawn further research in conditions in which cerebral lymphatic flow may play a part, such as movement disorders. 
These procedures may advance the knowledge of how osteopathic manipulative treatment (OMT) affects intracranial fluid dynamics, including immune system functions. A simple OMT technique such as anterior cervical lymphatic drainage facilitation may eventually be seen to have intracranial lymphatic flow effects (a likely prospect, in my opinion). 
Taken together with the preceding entry in The Somatic Connection on the nature of respiratory and cardiac functions on cerebrospinal fluid flow, a bigger picture begins to emerge on the possible impact of OMT on neurovascular immune functions verified by state-of-the-art imagery. I believe that the mechanisms of action for OMT, including osteopathic cranial manipulative medicine, will eventually be demonstrated and shown effective by virtue of these very advances in technology. 
References
King HH. Lymphatic vessels found in the brain—osteopathic considerations. J Am Osteopath Assoc. 2015;115(10):627. [CrossRef]