“How will I know if I need another patch? How will I know if this one doesn’t work?” I ask him, and he says it’s too early to tell. My head is now a balloon, ready to pop, and the headache is everywhere, and I am giving it time, but time seems to be colluding with the mystery of this thing to draw out the suspense. I wait for it all to settle as I grapple with the new contours of my pain, trying to ignore the dread that settles in instead that even though I am supposed to be fixed, I am not fixed, and perhaps not fixable.
10
All of us have a kind of primordial ocean in our heads, keeping our brains aloft on its current. This ocean of cerebrospinal fluid is generated continuously in the depths of our brains, produced by the choroid plexuses within the third and fourth ventricles. It suffuses and surrounds our brains, providing buoyancy, and bathes our spinal cords, lubricating the entirety of the central nervous system. Like the deep ocean, much of this has been nearly impossible to observe firsthand. The history of cerebrospinal fluid has been centuries of murky guesswork, increasingly deeper dives, usually by solo divers, revealing glimpses of an alien landscape, the dark waters of a humanoid ocean floor patrolled by impossible creatures, the hulls of failed ships transformed into coral reefs, nature reclaiming its space.
There is cerebrospinal fluid within us before we even technically have either a brain or a spine. It comes before thought, before mind, before brain, before even the development of those choroid plexuses in the ventricles of the brain that will eventually take over the process of circulating and generating this fluid, before any of us are recognizable as human. It exists in three-week-old embryos in the form of fluid within the neural tube that will eventually become the brain and central nervous system; by the fourth week, the first choroid plexus, a network of blood vessels and cells, develops in the fourth ventricle. Eventually this structure begins to produce and release cerebrospinal fluid continuously, as it will for the rest of our lives.
This isn’t a thing that we can consciously control. Like the deep ocean, it is its own mystery. There are tides to cerebrospinal fluid production, peaks in its manufacture during the day and night to which none of us will ever likely be sensitive, unless something, mysteriously, goes wrong. Like the deep ocean, it used to be thought that this water in our brains was just water, and not something teeming with life, with its own purpose. And yet, like the deep ocean, it has also been the subject of myths and legends, with speculation about its mystical properties, assertions that this magical fluid might actually be the river of life, the source of consciousness, the place where the soul resides. We understand more now about the anatomy and structure and purpose of the brain and central nervous system; we have a more fleshed-out understanding than we did in the days where notions of these things were like maritime maps with drawings of dragons and mermaids and other fantastical creatures to mark spots of danger and obscurity. But in some ways the reality of what lies in its depths is stranger than anything we imagined; like the ocean, no dragons or mermaids, but instead merely the weirdness of furry-clawed crabs living 5,000 feet deep in hydrothermal vents, blind lobsters, light-producing deep-sea anglerfish, giant squid, bioluminescent octopi, isopod crustaceans, and other creatures that have been inhabiting this world, unbeknownst to us, for longer than humans have existed. It’s only recently that we have learned there’s more to cerebrospinal fluid than just providing a cushion to our brains, allowing them to float, acting as a link to our distant, primeval beginnings of life in the sea billions of years ago.
The earliest documentation of cranial cerebrospinal fluid was discovered on a papyrus fragment found in 1862 by the Egyptologist Edwin Smith. When the papyrus was finally translated in the 1930s, it revealed a medical history written by the Egyptian physician Imhotep around 3000 BC, detailing an account of a patient with open head trauma. According to Imhotep’s report, the patient’s skull fracture and meningeal rupture “[broke] open his fluid in the interior of his head.”
Other ancient physicians observed this brain fluid but did not always agree about its purpose—or even its existence. While Hippocrates (460–375 BC) described “water” surrounding the brain, the anatomist Galen (AD 130–200) noted the presence of “excremental liquid” in the ventricles of the brain, but dismissed it, believing those cavities to primarily contain not fluid but a gas-like spiritus animalis that provided energy throughout the body and was the key to human consciousness.
Andreas Vesalius, a sixteenth-century anatomist from the Netherlands considered the founder of modern human anatomy, described the cerebral ventricles and choroid plexus, and noted the presence of “brain water,” estimating that its volume was as much as one-sixth the volume of the brain. (Modern MRI studies have revealed that cerebrospinal fluid accounts for 18 percent of total brain volume.) He also, strikingly, broke with the Aristotelian tradition of believing the heart to be the center of the soul, and the source of feelings and emotions in the body: He posited that the brain and nervous system was where the mind was, and was the originator of emotion, and made
