Cranial and Craniosacral
CRANIAL OSTEOPATHY treats TMJ and other disorders using light manual pressure to manipulate the skull in order to free up perceived blockages to a delicate rhythmic pulsing that involves each of the skull bones in its own individual movement pattern. Over the years I've seen many credible patients who have reported that the treatment has relieved any of wide range of diverse symptoms. I believe them. I just don't believe the explanation for why the relief occurred or the basis for determining the types and locations of manipulations that are needed.
CRANIAL RESPIRATION, the theory that forms the basis for manipulating each of the cranial bones to ensure that it moves with the rest of the cranium, proposes a detailed system of oscillating rhythmic movement that was hypothesized more than a century ago when an osteopath named William Sutherland looked at the intimate way the cranial sutures fit together and concluded that they must be designed to support movements that circulate cerebrospinal fluid through the brain. He and his followers developed a complex system of specific rotations and displacements that each cranial bone should undergo according to the rhythym, and a series of manipulations to correct cranial bones which were not moving freely according to the rhythym. That system formed a basis for an entire philosophy of treatment.
Decades later, high precision ultrasound and other technologies supported the concept that cranial manipulation was at least possible. They showed that the skull is not a rigid container but a dynamic living system. It changes shape when a person simply bends down, and responds to arterial pulsing as well as functional muscular forces.
CRANIOSACRAL THERAPY became a popular extension of cranial work that grew out of studies which showed that bending the spine produces changes in CSF pressure. This finding should come as no surprise, because the spinal column is enclosed in the same cerebrospinal fluid reservoir as the cranium. Some practitioners reasoned that, since the spinal column should be subject to the same blockages of cerebrospinal circulation that occur in the cranium, it should be manipulated together with the skull to relieve blockages.
RECENT RESEARCH showed that the circulation of CSF is much more complex than envisioned by the elegant but oversimplified century old concept of cranial respiration. In the last couple of decades, researchers developed tools that can measure and track actual CSF dynamics. In the 1990s, they showed a pulsing unidirectional CSF flow at a frequency that corresponded to heart rate. In the 2000's, they found links between CSF flow and the lymphatic system. They described a glymphatic system of tiny vessels which worked to clean by-products from the glial cell activity in the brain and move them into circulation much like the lymphatic system cleans by products from cellular metabolism. In 2013, using a technique called 2 photon microscopy, researchers showed that CSF responded directly to arterial pulsation. Finally, in the February 2015 Journal of Neuroscience, a group of researchers used a real time high temporal and spatial resolution MRI to show all the details of the movement of CSF. They found movement in synchrony with the vascular pulse in agreement with previous studies, but they also found that an even more important cause of CSF fluid movement was the change in thoracic pressure due to breathing. They found no other pattern to CSF flow.
The intricate fit of the cranial sutures was designed to allow the cranium to deform while passing through the birth canal and rebound later. Occasionally one of the sutures gets damaged during this process and later fails to expand with the surrounding cranial bones. This locking together of sutures is called synostosis. When recreated experimentally by stapling sutures together in animals, craniosynostosis disturbs the growth of all the cranial bones in the area. In some of our patients, it may also occur in mild forms that we are not yet able to identify. If such partial synostoses do occur, they could have many effects on health. The cranial bones may move in small amounts that we cannot yet measure and for reasons that we do not yet understand. However, there is just no evidence that they move according to a unique rhythym separate from the heart or the breath. Indeed a unique and distinct cranial respiratory rhythym due to production of CSF would require some structure that moves with the same frequency, and there is no such structure in the system.
In regards to cranial manipulation, any change in cranial bone configuration that could be produced by light manual pressure would surely be dwarfed by the effects of chewing and swallowing, which spread very large forces over the front of the cranium hundreds of times each day. Forceful biting bends the entire cranium in monkeys, separating its two halves at the suture running along the top of the skull. Pre-industrial humans with strong jaw muscles have a thick ridge of bone at that same suture. Modern humans have weaker jaw muscles, but we also have thinner skulls, and they are probably also bent by functional forces. Studies have shown that chewing stimulates cerebral circulation. The distribution of biting forces in modern human skulls was recorded by researchers using stress sensitive paint, as shown below.
Today, in the name of craniosacral therapy, many practitioners manipulate the spine in a manner that increases its range of motion and removes blockages to physiologic movement patterns. Such manipulatons can be very helpful, because joint health is dependent on the range of motion, and anything that increases the range of motion at a joint is likely to help it heal. However the belief that the treatment is restoring a unique cranial rhythymic CSF circulation pattern to the cranium or spinal column seems highly unlikely.