Dementia is a loss of cognitive ability, such as loss of memory, concentration, language and problem solving. Dementia is seen in many neurodegenerative diseases including Alzheimer’s and Parkinson’s disease. Furthermore, cog fog is a common complaint among multiple sclerosis patients. Cog fog is simply a milder form of cognitive impairment compared to what is commonly considered to be dementia. In any case, dementia and cog fog may share similar causes.
The x-ray on the left is a lateral (side) view of a fairly normal cervical spine. The bones, cartilage and joints are all normal in size, shape and spacing. The gray spaces are the discs made of cartilage, and posterior to them are the facets or joints that separate the vertebral segments of the spine.
There are many different types of inherited disorders that can affect the normal design of the base of the skull and cervical spine and thus impair blood and cerebrospinal fluid (CSF) flow in the brain and cord. They fall into categories called: craniosynostosis, craniodyostosis and craniocervical junction abnormalities, which is the base of the skull and upper cervical spine. One of the first types of inherited disorders of connective tissues I studied when I began my research is a condition called craniocleidodysostosis. It is a very rare condition in which cartilage in an infant fails to turn into bone resulting in significant deformation of the skull, clavicals and spine among other things. I also grew up witnessing first hand the impact of severe rheumatoid arthritis on the upper cervical spine and the serious neurological consequences it can have. Both my mother and her mother, my grandmother died quite young due to complications including a slipped odontoid process of the second cervical vertebra (C2) called axis. Rheumatoid arthritis is also considered to be an inherited disorder of connective tissues. The inflammatory arthritides are a separate subject I cover at another time.
In addition to inherited disorders, even more people are affected by acquired disorders due to diseases such as rheumatoid arthritis mentioned above, psoriatic arthritis, lupus erythematosis and osteoarthritis to name just a few. Lastly, everyone is affected by degeneration of the spine due to injuries and aging. Diseases and trauma simply speed up the process and generally make it worse. Inherited disorders tend to show up early in life because of the design flaws. Conditions related to trauma show up later, in midlife, and conditions related to aging degeneration tend to show up late in life. In brief, I categorize all of the different conditions collectively under the umbrella term craniocervical syndromes. The list of craniocervical syndromes is long. Although the different types of craniocervical syndromes are rare by themselves, collectively they affect many people.
Degeneration of the cervical spine is called spondylosis. This lateral view x-ray of the neck shows spondylosis in the lower cervical spine. If you look at the gray spaces between the bones and compare it to the picture above you will see that they are much thinner. As mentioned above, the gray spaces are the cartilage or discs of the spine. The bones show distortion on the front side and are less square with pointed edges due to compression that caused their inner support structures to collapse.
When the bones, cartilage and connective tissues of the spine, such as the ligaments degenerate they sometimes bulge and buckle backward which invades the space of the spinal canal and outlets for the spinal nerves. Technically it’s called stenosis. Stenosis means narrowing. When it becomes severe enough stenosis can compress the nerve roots and cord causing neurological signs and symptoms. It may even lead to dementia.
More and more evidence is starting to link head injuries to Alzheimer’s disease, Parkinson’s disease and dementia. Controversy, likewise, continues to surround the role of trauma in multiple sclerosis. Research has come a long way in understanding traumatic brain injuries which occur immediately after the trauma. In contast to traumatic brain injuries that occur at the time of the accident the symptoms of cog fog and dementia start to show up many years, sometimes decades later even when they are from the same cause.
In this regard, head and neck injuries often occur together. Unless it is fractured, the skull is oftentimes undamaged. The bones, cartilage and connective tissues of the spine, however, are much more vulnerable to serious strains and sprains that can initiate the degenerative process. In contrast to nerves, the hard and soft tissues of the spine breakdown slowly over years, which leads to spondylosis.
The brain scan on the left is a perfect example of spondylosis. The cord is the long gray tube that drops down from the brainstem. The white area is blood and cerebrospinal fluid. If you look down at the lower cervical spine you can see that the white area is indented. The indentations are caused by degeneration of the bones, cartilage and connective tissues that spread into the spinal canal and if severe enough, compress the cord.
Oftentimes, however, spondylosis compresses the thecal sac of the cord without compressing the cord directly. But the thecal sac contains the vertebral veins of the cord so that compression can lead to what is called venous hypertension, which is an increase in venous pressure.
Acccording to a study done by Rutger’s University, vertebral venous hypertension is one of the most overlooked causes of ischemia of the arterial blood supply to the cord. The arterial blood supply to the cervical cord comes from the vertebral arteries. In this regard, the vertebral arteries also supply the lower inner lobes of the brain, thalamus, hypothalmaus, brainstem and cerebellum. Furthermore, the brain sits further upstream and above the level of the neck making it more susceptible to decreased blood flow from the vertebral arteries due to distance and gravity. Vertebral venous hypertension, that is, back pressure against the vertebral veins, can thus decrease blood flow to the brain the same way it decreases blood flow to the cord by decreasing the pressure gradient. It can also affect the drainage of the brain, as well as CSF flow in the brain and cord, which is closely connected to venous flow.
The health of the cervical spine is important to the health of the brain. Cervical spondylosis and stenosis may play a role in chronic edema, ischemia and normal pressure hydrocephalus. It may also play a role in cog fog and dementia.