CCSVI, Brain Cooling and Blood Flow

The upper cervical spine plays an important role in the venous drainage system of the brain, brain blood flow and brain cooling. Back pressure against the vertebral venous outlets in the upper cervical spine can thus be a cause of CCSVI, decreased blood flow and decreased cooling capacity of the brain. An overview of the cranial veins will make the connection clear.

The cranial veins include the veins of the face and scalp, the diploic veins, the emmisary veins and the dural sinues. The diploic veins, seen in the picture above, and mentioned in the previous post, sit between the inner and outer plates of the membranous bones of the skull that cover the cranial vault.

The dural sinuses seen in the pictures below are the main drainage routes of the brain inside the cranial vault. They are called dural sinues because they are not true veins. Instead they are tunnels formed by the outer coat of the brain itself, the dura mater. The inside walls of the dural sinuses are lined with the inner walls of veins. The dura mater, which means tough mother or material, makes the dural sinus drainage system much stronger than typical veins. As a result, they are better able to withstand stress and resist deformation from the pressure and movement of the brain, which sits on top of and presses down against them.

The cranial veins of the face and scalp, diploe and dural sinuses are all interconnected by the emissary veins. In contrast to the rest of the body, none of the cranial veins have valves to check or prevent reverse flows. That’s an important fact when it comes to discussing MS lesions, which I won’t go into here.

If you click on the picture to the left and look closely, you will see that the dural sinuses are depicted by stripes inside the skull. You will also see little black semicircles on the top and the bottom of the skull. The semicircles represent emissary veins, which link the face and scalp veins to the diploic veins and to the dural sinues.

The emissary veins play an important role in draining the head and brain. The ones located toward the back and bottom of the skull seen behind the outline of the ear, drain into the vertebral veins of the spine. In addition to drainage, the emissary veins also play a critical role in cooling the brain. They do so by delivering blood, that has been cooled by conduction and sweat evaporation at the surface of the face and scalp, to the diploe and to the dural sinues.

Besides cooling the diploe and dural sinuses, the brain also uses two counter current heat exchanger tunnel systems in the dural sinuses to cool incoming arterial blood before it enters the brain. The two cavernous (dural) sinuses are located inside the cranial vault. If you click on the picture to the right you will see the internal carotid depicted passing through the cavernous sinus before it enters the brain.

The other tunnel is called the suboccipital cavernous sinus, which is also known as the atlantooccipital membrane as depicted in the picture below. The suboccipital cavernous sinus is located just outside the skull between the first cervical vertebra and the occipital bone at base of the skull.

Even though it is outside the skull, studies have shown that the suboccipital cavernous sinus is constructed of nearly identical materials, in the same way and serves the same function as the cavernous sinus. For this reason, some scientists now consider it to be part of the dural sinuses of the brain. The suboccipital cavernous sinus contains and cools the two vertebral arteries before they enter the brain.

Thus, the brain is surrounded by cooled venous blood in the cranium and incoming arterial blood keeping the brain about two to three degrees cooler than the rest of the body. Some physical anthropologists attribute the extra large size of the human brain more to its exceptional cooling capacity than to the increase in arterial blood flow that comes with upright posture. Anthroplogists refer to human encephalization due to enhanced cooling capacity as the “radiator theory.”

Both the cavernous and suboccipital cavernous sinuses also play a role in maintaining blood flow and pressure in the brain. Their inner walls contain pressure sensors called baroreceptors that detect pressure in the tunnels. When pressure goes up they send signals that cause the muscles in the incoming arteries to constrict and decrease blood flow. When pressure drops they signal the blood vessels to open up and increase blood flow. Technically it is called the “neurovascular myogenic autoregulatory reflex mechanism.” As an aside, similar important pressure receptors and blood flow regulators are located in the carotid sinuses near the Adams apple of the throat.

The cranial veins drain into two extracranial venous drainage routes. One route is the jugular veins. The other is the vertebral veins. Interestingly, in contrast to the jugular veins, the vertebral veins have no valves making them similar to the cranial veins. Thus, back pressure against the vertebral veins can affect both the drainage and cooling capacity of the brain. This is interesting in light of the fact that in addition to evidence of CCSVI, MS patients often experience symptoms of heat intolerance.

An increase in pressure in the suboccipital cavernous sinus can also decrease blood flow through the vertebral arteries that pass through it before supplying the inner rear and lower most parts of the brain. It can do so by either direct compression of the vertebral arteries, or by stimulating the pressure sensors in the sinus walls thereby causing the arteries to constrict.

Decreased blood flow through the vertebral arteries can cause a wide variety of symptoms such as fatigue, dizziness, loss of balance and coordination to name a few. The complete list of symptoms is too long to discuss here so I will save it for future posts.


About uprightdoctor

I am a sixty year old retired chiropractor with considerable expertise in the unique designs of the human skull, spine and circulatory system of the brain due to upright posture, and their potential role in neurodegenerative diseases of the brain and cord. I have been writing about the subject for well over two decades now. My interests are in practical issues related to upright posture and human health.
This entry was posted in ccsvi, multiple sclerosis, physical anthropology. Bookmark the permalink.

19 Responses to CCSVI, Brain Cooling and Blood Flow

  1. Nice article about the change in direction of the blood from the face where it flows into the intracranium through the ophthalmic veins when a human becomes hyperthermic. When this change in direction of flow is hampered due to CCSVI this can have a large impact on heat-intollerance and maybe especially start giving eye problems to those people. People having MS are oftenly diagnosed with Optic-Neuritis, but it could also be a venous problem after all….

  2. alexandre galvao says:

    Who would be able to treat me in South Africa?

  3. AC says:

    Hi Dr Flanagan,

    Can you recommend any chiropracters in Australia that do the Atlas-Axis realignment or at least have a sound understanding of the blood and CSF circulatory issues that can be raised through a subluxation of this part of the neck?

  4. Shelia says:

    This is very interesting information. I want to know if there are any studies being done to find out why the African Americans that are diagnosed with Devic’s Disease, tend to have a poorer prognosis? Why the ones that do tend to go into remission take so long? For example, it has been nearly two years since my daughter was diagnosed and she has yet to regain her sight in her right eye nor can she walk. There is nothing to suggest she has any damage to her spine that dictates she will not walk. Yet I know people who have had three, four and even six attacks of Optic Neuritis and Transverse Myelitis yet they are walking and most can see.

  5. New discovery how to measure brain temperature -no invasion
    Also Brain tunnel provide cooling/heation of the brain -no invasion
    Zijad Sabovic,MD

  6. Brain tunnel provide noninvasive measurement of brain temperature.
    It provide also heating/cooling of the brain, no invasion.
    Webs site
    Zijad Sabovic , MD

  7. Elle says:

    I have MS for 21 yrs. and have always been athletic. I was swimming last week, very hot, humid and I was walking arm and arm to the pool with my husband. Got into the pool and did 20 laps. A man walks up to my husband and says whats wrong with your wife? She walks like she’s had a stroke and then she does 20 laps? Was she faking that Walk?

    • Good for you Elle. You can’t beat exercise and making it a habit early in life helps you better cope with all types challenges later on. Keep me posted about your condition. Dr. F

  8. Raza says:

    Excellent info Doc. I was diagnosed with MS in late 2008. Even before that, I had often observed my head temperature going up even with little exercise and heavy sweating from my head on treadmill. Unfortunately, none of the doc here pays any heed to it. Moreover, whenever I smoke, sweating from my head starts with increase in spasticity in my right arm (My main symptom of MS). Doc, Is there any way I could quantify this by measuring temperature of my head or any other test.

    • Hello Raza,

      Excess sweating is an autonomic sign. This could be due to increased CSF pressure in the cisterns or decreased blood flow to the hypothalamus of the autonomic nervous system. The fact that you have increased spasticity of your arm along with excess sweating when you smoke makes me suspect decreased blood flow to the brainstem from the vertebral arteries.

      You could do thermograms of the head and neck to check temperature changes but they wouldn’t be that helpful or accurate. It would also be difficult to do the thermograms as needed when the condition occurs. A brain MRI with blood and CSF flow studies would be much more productive. A cervical MRI would also be helpful to check for degenerative changes in the neck potentially causing pressure on the cord. Upright MRIs of the brain and cervical spine would be even better.

      Dr. F

      • Raza says:

        Thank you very much for your prompt response. Doc, as part of investigations for CCSVI, I had my MRV (my pics are posted at which showed stenosis of my both IJVs at C2 level. Further, during investigations (CT Venogram), I was told that I have a rare case of Eagle Syndrome. Despite this, I went for liberation treatment but as per my IR, he did not observe any significant stenosis of my IJVs or Azygous. I did not go for MRA since I was looking for CCSVI. My MRI does not show any herniated disc or any other problem except one lesion in C2 area and few in brain. But I have a strong feeling that my present symptoms especially spasicity in right hand are somehow related to hemodynamics as with changing posture from supine to standing or smoking a cigarette (bad habit-trying to quit) gives an immediate response.
        As advised, I will have MRA done for my neck and head since MRI in upright position facility is not available here and will update u. Last but not the least, I had met an accident back in 1997 which caused severe pressure on my neck without any physical trauma. May be this has any link to this. Thanks once again for your time.

      • Drs Flanagan says:

        Hello Raza,

        Eagle syndrome is caused by extra-long, oversized styloid processes,which are part of the temporal bone close to the ear canal. Their location next to the ear canal can cause tinnitis. The styloid process is also located on the outside edge of the jugular foramen for the IJs. Moreover, the jugular foramen is next to the foramen lacerum, which contains the internal carotid arteries. Eagle sydrome is associated with arterial symptoms especially with head movements such as rotation. The degree of deformation in your IJs is significant. On top of that you have arterial symptoms. I strongly suspect the styloid process may be the problem. You should consider getting plain view x-rays of your cervical spine, including specific upper cervical views to check for misalignments as they will further contribute to the deformation caused by the styloid processes. You should also consider consulting with a specialist as the styloid process may need to be surgically removed.

        Dr. F

  9. Jason Elder says:

    Good stuff…and in terms I can understand. Dad has some sort of cerebral basil artery insufficiency…so I’ll be visiting again. Thanks doc.

  10. Peggy Carter says:

    When I drink something cold or even icey I get really cold but can move better, so does brain freeze temporarily cool the brain?

    • Hi Peggy,
      You can definitly chill the brain with a cold drink. It is interesting that you can move better. More than cooling the brain you may be decreasing inflammation and pressure in the brain.

  11. Debbie says:

    Hi Doctor. I had an MRA in May and the result was ” Severely atretic versus absent distal-most left vertebral artery. The right vertebral artery is dominant with a patent basilar artery.” I believe I had read somewhere that the vertebral artery is very hard to perform surgery on. For years my face becomes beet red when I exercise or exposed to heat for even a little while. Is this the cause? It gets so red people look at me as though I’m going to pass out. I was dxed with MS in 2007 but have had it for about 30 years. I do not tolerate the heat well at all, in fact, I get full body tremors from my MS and the heat really exacerbates these symptoms.

    • Hi Debbie,
      You have interesting signs and symptoms. Both the internal carotid arteries and the vertebral-basilar arteries are cooled by a surrounding jacket of outgoing venous blood in the cavernous and suboccipital cavernous sinus respectively. The undersized left vertebral-basilar artery in you case can decrease the cooling capacity of the brain. The other point to consider is that the vertebral-basilar arteries suppy the hypothalamus of the brain, which is the control center for thermoregulation. I suspect it plays a role in heat intolerance in MS. MS is also associated with sluggish venous outflow and sluggish CSF flow, which can further reduce the cooling capacity of the brain.

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