CSF and blood are pumped into the brain under pressure similar to a bicycle pump filling a tire tube. The pressure of the pump comes from the heart and lungs. Since the brain is housed inside a closed container, which is filled to capacity, the increase in blood volume must be offset by a decrease in venous blood and cerebrospinal fluid (CSF). This is accomplished by pushing a proportionate amount of blood and CSF out through the large opening in the base of the skull called the foramen magnum and into the spinal canal.
Typically, when a radiologist views x-rays or MRI’s of the spine they don’t consider misalignments of the upper cervical spine or degeneration and changes in the normal curves of the lower spine to be a problem unless it causes contact with the spinal cord. This disregards the impact on the vertebral veins that are located between the spinal canal and cord. As the heart contracts blood and CSF are pushed into the spinal canal at the same time and thus compete for available space.
Humans use the occipital marginal sinus and emissary veins to drain the brain during upright posture. These veins empty into the vertebral veins of the spine. Misalignments of the upper cervical spine can affect blood and CSF flow as it passes between the cranial vault and spinal canal. Likewise, spondylosis (degenerative changes), stenosis (narrowing of the spinal canal) and scoliosis (abnormal curves) in the lower spine can also affect blood and CSF flow between the cranial vault and spinal canal.
The picture on the left is used with permission from Johan Linder of Clapotis Sea Kayak in Sweden. The pumping of the heart causes CSF waves to form in the brain and spinal cord. Respiration further increases the size of the waves. More than the heartbeat or respiration, upright posture significantly increases the pressure of the waves that form at the bottom of the cranial vault. (To see the affects of upright posture venous pressure inside the skull see my previous posts with pictures of the sutures).
When waves collide they cause standing waves called clapotis. If waves of blood and CSF from the brain collide with waves in the cervical spine they will cause inversion (reverse) flows and standing waves to form in the cisterns that surround the brainstem and cerebellum. Chronic standing waves may lead to compression and subsequent malfunction and degeneration of the structures they surround. Increased CSF volume, backjets (inversion flows) and standing waves in the CSF may play a role in neurodegenerative diseases.
Multisystem atrophy (MSA) is a variant of Parkinson’s disease associated with dysautonomia and cerebellar signs. Dysautonomia is dysfunction (malfunction) of the autonomic (vegetative) nervous system which regulates all the vital and internal functions of the body. The cerebellum is important to posture, coordination, balance and gait (walking). Many neurodegnerative diseases are similarly associated with dysautonomia and cerebellar signs.
There is a variant of MSA formerly referred to as olivopontocerebellar atrophy. It is associated with dysautonomia. It is also associated with atrophy, which means a decrease in the size of the brainstem and cerebellum. I suspect the atrophy is due to obstruction of CSF flow between the brain and cord that eventually erodes the brainstem and cerebellum similar to the impact of relentless pounding of waves of the Atlantic against the northeast coastline of North America.
The relentless pounding of waves can tear apart rocks. They can similarly compress and erode the brain. For further information on CSF, cisterns, atrophy of the brainstem, dysautonomia, cerebellar signs and Parkinsonism visit my website at www.upright-health.com or click on the link above.