Page 1 of 1

Warm skull due to venous insufficiency?

Posted: Wed May 05, 2010 5:54 pm
by Donnchadh
One of my constant "MS" symptoms is the perception that the top of my skull is warm. And this problem quickly resolved after my liberation procedure. I found this study which tends to confirm that venous insufficiency can be the cause for the development of manifold problems.

Donnchadh

QUOTE:

http://www.anthro.fsu.edu/research/falk/concepts.html

Updating the Radiator Hypothesis

By Dean Falk

Florida State University

During a workout (e.g., while running, doing aerobics, or kickboxing), the face becomes flushed as vessels dilate and perspiration increases and evaporates against the air. This cools the blood in the vessels of the face and in the vast network of tiny veins that riddle the bones of the skull ­ the cranial "radiator" (Fig. 1). As Michel Cabanac and Heiner Brinnel have shown, the radiator kicks-in and delivers cooled blood into the braincase when humans are over-heated (hyperthermic). Such "selective brain cooling" helps maintain the temperature of the brain (which is exquisitely heat-sensitive) within acceptable limits. This is a good thing too, because "it may be that the temperature of the brain is the single most important factor limiting the survival of man and other animals in hot environments" (Mary Ann Baker (1979:136).


Image


Figure 1. The existence of a vast network of veins that serves to cool the brain in hyperthermic humans was controversial until 1996, when Wolfgang Zenker and Stefan Kubik demonstrated the anatomical basis. This photograph of the cranial radiator is from their landmark paper (1996:4).



A few of the larger vessels in the radiator penetrate through recognized holes in the skull -- known as emissary foramina. Well-known examples include the parietal and mastoid emissary veins (Fig. 2), which occur in relatively high frequencies in humans (Hauser & De Stefano, 1989) compared to apes (Falk, 1986;Falk & Gage, 1998). The frequencies of the parietal and mastoid emissary foramina increased dramatically as brain size increased from Australopithecus africanus to Homo sapiens (Fig. 3). If one views the emissary veins that penetrate these foramina as a "window" into the wider network of cranial veins, it appears that the cranial radiator increased in complexity as brain size increased during the course of hominin evolution. According to the radiator hypothesis, evolution of the cranial radiator released a thermal constraint that previously kept brain size within ape ranges. Since larger brains are associated with greater cooling needs, they were selected for in conjunction with elaboration of a vascular mechanism for keeping brain temperature within safe limits. In a sense, the human brain (like the engine of a car) has a radiator that prevents overheating (Falk, 1990).

Image

Figure 2. The parietal (P) and mastoid (M) emissary veins penetrate the skull through foramina of the same names. The named emissary veins (there are others) are relatively large compared to the vessels pictured in Fig. 1, but contribute to the same widespread network of veins that participate in selective brain cooling when humans are over-heated. The named emissary veins also have the advantage of penetrating named foramina that may be scored in the fossilized skulls of our ancestors.

UNQUOTE.

Posted: Wed May 05, 2010 7:29 pm
by cheerleader
Beautiful! Marie (Mrhodes) has written about the emissary veins on here and how venous insufficiency would mess up the heating/cooling of the brain. But this is a fabulous illustration (with pictures, too!)
Glad your brain isn't cooking anymore, Donnchadh!

Jeff came home from a long mountain bike ride this afternoon, drenched in sweat and smiling. One of the benefits of his procedure is his ability to sweat and cool again. He couldn't take the heat for five minutes a year ago. No more heat intolerance.
cheer