When it comes to cerebellar tonsillar ectopia (CTE) and race and gender, no one is spared. All races are equally susceptible due to the precarious position of the brainstem over the foramen magnum as a result of upright posture. When it comes to gender, however, females are more susceptible to cerebellar tonsillar ectopia than males.

Other neurological conditions are not the same. For instance, when it comes to multiple sclerosis (MS) the incidence of MS is higher in Europeans than it is Asian and African people. As in CTE, females, likewise, have a higher incidence than males. On the other hand, while they don’t get MS, Asian and African people due get a variant of MS called optic spinal multiple sclerosis and Devic’s disease.

In this regard race and gender affect the size and layout of the cranial vault which is the part of the skull that contains the brain which ultimately predisposes us to cerebellar tonsillar ectopia.

Cerebellar Tonsillar Ectopia and Gender

The picture below is of casts of human skulls. The pictures are used with permission from Bone Clones Inc. The skull on the left is of a mature European male. The skull on the right is a mature European female. The top of the cranial vault is removed from the female skull. The layout of the cranial vault is affected by the shape of the face and base of the skull, as well as the genetic design of the brain. In fact, the flat bones that cover the cranial vault grow inside a membrane of the brain and are called membranous bones.

Regardless of race, female skulls tend to be smaller overall. They are also smoother on the outside surface and have less “bossing,” which is a technical term for bumps and ridges that form on the skull bones where the muscles of the face, head and neck attach. The rougher surface of male skulls is caused by a stronger pull from larger muscles. In additon to smaller overall skull size, the average capacity of the female cranial vault is smaller compared to male averages.

The smaller cranial vault makes females more susceptible to cerebellar tonsillar ectopia than males.

It is possible that, in addition to MS and cerebellar tonsillar ectopia, also known as Chiari malformation, the design of the cranial vault may also play a role in optic spinal multiple sclerosis and Devic’s disease. Although, some experts strongly disagree, others suspect that both conditions may actually be variants of MS. I suspect the cause may be due to CTE causing compression of nerves and blood vessels within the holes and canals of the skull and spine. The difference in signs, symptoms and lesions seen in MS versus optic spinal multiple sclerosis or Devic’s may be due to the difference in design of the cranial vault and the way the brain reacts to trauma and inversion flows or backjets where fluid flows back into the brain during whiplash type injuries. In the different skull designs the backwards surge of venous blood flow will follow different courses depending on the layout of the cranial vault and dural sinuses.

When it comes to surgeries of the face, such as cleft palate for example, or straightening teeth in orthodontia, races are broken down into different categories. For practical purposes and for this discussion, there are basically just three major races to consider when it comes to the design of the face with many variations mixed in. Realistically speaking, the human race is more like a stew. Indeed, there are so many variations that many anthropologists prefer not to talk about it, at least not in polite company fearing it may provoke prejudice. Most consider it to be a vague term at best. They’re probably right.

On the other hand, for the rest of us mere mortals the difference is as plain to see as our hand in front of our face. In fact, the key telltale differences between the races is in the face. My sister-in-law is Chinese. Needless to say, her face and almond shaped brown eyes are easy to spot at a family party amongst the mostly round blue eyed Irish and English faces. Many people in the Americas have African mixed with European and the signs of both races are easy to see. Likewise, many indigenous South Americans have mixed with Europeans and have Asian features like their ancestors. On other continents, indigenous people are a mix of African and Asian races. In the far reaches of Russia the Europeans and Asians mix. India is a wildcard. My niece’s husband is all Indian. He has a large rounder head like an Asian but a more prognathic face with fine features that look very European. Nonetheless, a good anthropologist can tell the difference in most cases.

The face is a very important structure designed to deal with its environment. Like everything else in the body, it is a reflection of evolution and humankind’s adaptations to the environment. The face is used for sight, smell, sound, taste and touch. It is also used for communicating and chewing. It is closely connected to the brain and is used to communicate paralinguistically without speech or sound just as animals do. Without saying a word it can deliver obvious or very subtle messages. Developmentally speaking, the face is closely connected to the base of the skull and grows from the same primitive musculoskeletal tissues in the embryo. In this regard, the face has a large influence on the growth of the base of the skull and likewise, the base of the skull affects the growth of the face. Many things can go wrong and there are many different types of face and base deformities humans are susceptible to. I discuss them elsewhere on this site and will discuss them further as the site develops.

Cerebellar Tonsillar Ectopia and Race

The shape of the face and the base of the skull are intimately connected and grow together. Each has an equal impact on the development of the other. Together they also affect the shape of the cranial vault, as mentioned above. Consequently, they also affect the tendency to develop cerebellar tonsillar ectopia.

In contrast to the face and base, the cover over the cranial vault of the brain grows from connective tissues that are actually part of the outer membrane of the brain. The cranial vault thus develops along with the brain as the infant brain matures. Nonetheless, the layout of the cranial vault is affected by race as much as the face and the base of the skull. Among other things these factors influence the layout and pitch of the veins inside the brain. The layout of the cranial vault also affects the compartments of the brain and openings in the skull for the passage of nerves and blood vessels.

Although all people have roughly the same number of nerve cells in the brain regardless of whether they have big heads or small heads, how they fit eveything in the cranial vault varies between races, genders and individuals. Some people have large structures and some have smaller compact sizes. Some people have undersized spaces, called hypoplasia. Hypoplasia of the posterior fossa can cause cerebellar tonsillar ectopia.

Asians have the largest cranial capacity of the three races. The base of the skull also inclines upward due to natural head position or inclination, which is affected by upright posture and the face. As a result of the shape of their face and inclined base of the skull, Asians have tall towers that rise straight up over the hole in the base of the skull, called the foramen magnum, making them susceptible to cerebellar tonsillar ectopia. The tall tower also tends to stack the brain up higher in the vault and raises the center of gravity. On the other hand, the design of the in-line face makes Asian skulls more balanced on top of the cervical spine. It has been my experience that Asian males have less bossing at the external occipital protuberance (the knowlege bone). This is probably due to better balance and less strain on the ligamentum nuchae that helps hold the head upright. If anything, Asians tend to tip back slightly.

Europeans have a slightly smaller cranial vault compared to Asians and the face juts out prominently from the rest of the skull. This makes European faces heavy, which increases the strain on the ligamentum nuchae at the back of the skull, which causes bossing commonly called the knowledge bone. The base of the skull tends to incline upward similar to Asians. Thus Europeans tend to have tall towers similar to Asians, which, likewise, raises the center of gravity. The face is somewhat tighter in Europeans compared to Asians and Africans who have comparatively wider cheek bones and rounder nasal openings. More importantly, according to a fairly recent orthodontic study done in the UK, Europeans, also tend to have the shortest length in the base of the skull. The smaller size crams the brainstem and cerebellum in the posterior fossa compared to Asians and Africans. Moreover, the combination of a tall tower, a protruding face and a short base of the skull may further predispose European designs to problems due to whiplash injuries as well as inversion flows in the veins of the brain. It certainly predisposes them to cerebellar tonsillar ectopia. This will discussed further below.

Compared to Asians and Europeans, African skull designs have slightly smaller cranial vaults overall predisposing them to cerebellar tonsillar ectopia. On the other hand, they have a longer base compared to Europeans that is closer to Asian designs. This effectively increases the size of the posterior fossa, compared to European designs. Although on the surface, African faces appear rounder, more like Asians, the design of the African face is technically called brachycephalic. Brachycephalic means the face is more square or similar in height and width. Africans also have deeper faces measuring from the furthest point on the front of the face at the tip of the jaw to the furthest points in the back of the face behind the eyeballs and back of the mouth. The inclination of the base of the skull is also closer to level compared to Asians and Europeans.

The African skull design lowers the forehead and creates wider cheeks and arches for the teeth. Consequently, in contrast to a top heavy, ableit balanced tall tower seen in Asians, or tall tower with an imbalanced protruding face seen in European designs, African cranial vaults are lower and spread out. In contrast to Asian and European designs, this lowers the center of gravity making it more like a sports car in whiplash injuries and other types of truama that cause venous inversion flows into the brain.

Of the three designs the European skull may be more susceptible to inversion flows due to their cranial vault design, especially the posterior fossa and dural sinuses. On the other hand, all the races are susceptible to cerebellar tonsillar ectopia due to the design of the bent base of the skull, and females are more susceptible than males regardless of race. In this regard, cerebellar tonsillar ectopia may also play a role in optic neurtis and transverse myelitis and will be discussed further as this site develops.

In brief, while possibly playing a role buffering the negative impact of inversion flows into the brain during whiplash type injuries the tall tower design of the Asian and the compact design of the African cranial vault may actually increase their susceptibility to optic neuritis and transverse myelitis due to cerebellar tonsillar ectopia and displacement of the brain within the cranial vault.

The design of the cranial vault due to upright posture predisposes humans to neurodegenerative diseases such as Alzheimer’s, Parkinson’s and multiple sclerosis. There are many different types of inherited (genetic) disorders in the design of the cranial vault and of the base of the skull that can cause problems such as craniosynostosis and craniodysostosis and predispose individuals to cerebellar tonsillar ectopia.

The upper cervical spine is closely connected to the base of the skull and parts of it grow from the same primitive musculoskeltal tissue in the embryo. In addition to the cranial vault, there are many types of upper cervical problems that can cause problems with blood and CSF flow and subsequent neurodegenerative diseases. Some are inherited as design problems such Kleppel-Feil and fusion of the upper cervical vertebra of C1 and C2 to each other or to the base of the skull. Other conditons are acquired from aging, injuries and diseases such as rheumatoid arthritis. I refer to them colletively as craniocervical syndromes. Craniocervical syndromes can affect blood and CSF flow in the brain and cord.

The design of the cranial vault affects the spatial orientation of the brain, as well as the length, pitch and layout of the dural sinuses of the brain. It may play a role in optic neuritis and other cranial nerve signs. It may also play a role in the response of the brain to venous backjets and the formation of MS lesions. Upright cine MRI, brain scans, arteriograms (MRA) and venograms (MRV) are starting to show the effects of upright posture and the design of the cranial vault on brain, blood and CSF flow and their role in neurodegenerative condtions and diseases.