new emissary veins article

[Cece]

http://www.ncbi.nlm.nih.gov/pubmed/22127046

Neurosurgery. 2012 May;70(5):1312-8; discussion 1318-9.

Anatomy and pathology of the cranial emissary veins: a review with surgical implications.

Mortazavi MM, Tubbs RS, Riech S, Verma K, Shoja MM, Zurada A, Benninger B, Loukas M, Cohen Gadol AA.

Section of Pediatric Neurosurgery, Children's Hospital, Birmingham, Alabama, USA.

Abstract

Emissary veins connect the extracranial venous system with the intracranial venous sinuses. These include, but are not limited to, the posterior condyloid, mastoid, occipital, and parietal emissary veins. A review of the literature for the anatomy, embryology, pathology, and surgery of the intracranial emissary veins was performed. Detailed descriptions of these venous structures are lacking in the literature, and, to the authors', knowledge, this is the first detailed review to discuss the anatomy, pathology, anomalies, and clinical effects of the cranial emissary veins. Our hope is that such data will be useful to the neurosurgeon during surgery in the vicinity of the emissary veins.

This was just published last month. Dr. Sclafani mentioned awhile back that he's seen people with MS with either very small or very large emissary veins, both of which are abnormal. Your IR can only see these if he enters the venous sinuses to confirm that the jugular connects to the sinuses and to look for blockages there, which most IRs do not do. Dr. Schelling considers emissary veins of importance in MS. It's possible that the back of the brain headache (which I suffered today, and which goes away when I lie down) that some pwCCSVI have is due to dilatation of the emissary veins. The abstract mentions embrology of the emissary veins, and that is of interest, because in pwMS our abnormal emissary veins could only have developed while we were fetuses because the skull develops around the emissary veins leaving channels through the skull for these veins, thus meaning that abnormal emissary veins may be confirmation that our CCSVI and abnormal jugulars were present before birth. Anatomy, pathology, anomalies and clinical effects of the emissary veins are all of interest.

Here's a diagram of an emissary vein, if it helps to see how it travels through the skull from the venous sinuses of the brain: http://edutoolanatomy.wikispaces.com/fi ... 5B7%5D.jpg

[1eye]

Detailed descriptions of these venous structures are lacking in the literature, and, to the authors', knowledge, this is the first detailed review to discuss the anatomy, pathology, anomalies, and clinical effects of the cranial emissary veins.

Doesn't this just give you a warm feeling all over? Of course, anatomy of the human body is a well-known, boring, hackneyed topic. Way overdone; needs no further elaboration.

It makes me worry, about our ignorance of anything to do with recycling and reuse. Maybe we're too busy replacing, revising, and reinventing?

What else are we unaware of, I wonder?

[drsclafani]

http://www.ncbi.nlm.nih.gov/pubmed/22127046

Neurosurgery. 2012 May;70(5):1312-8; discussion 1318-9.

Anatomy and pathology of the cranial emissary veins: a review with surgical implications.

Mortazavi MM, Tubbs RS, Riech S, Verma K, Shoja MM, Zurada A, Benninger B, Loukas M, Cohen Gadol AA.

Section of Pediatric Neurosurgery, Children's Hospital, Birmingham, Alabama, USA.

Abstract

Emissary veins connect the extracranial venous system with the intracranial venous sinuses. These include, but are not limited to, the posterior condyloid, mastoid, occipital, and parietal emissary veins. A review of the literature for the anatomy, embryology, pathology, and surgery of the intracranial emissary veins was performed. Detailed descriptions of these venous structures are lacking in the literature, and, to the authors', knowledge, this is the first detailed review to discuss the anatomy, pathology, anomalies, and clinical effects of the cranial emissary veins. Our hope is that such data will be useful to the neurosurgeon during surgery in the vicinity of the emissary veins.

This was just published last month. Dr. Sclafani mentioned awhile back that he's seen people with MS with either very small or very large emissary veins, both of which are abnormal. Your IR can only see these if he enters the venous sinuses to confirm that the jugular connects to the sinuses and to look for blockages there, which most IRs do not do. Dr. Schelling considers emissary veins of importance in MS. It's possible that the back of the brain headache (which I suffered today, and which goes away when I lie down) that some pwCCSVI have is due to dilatation of the emissary veins. The abstract mentions embrology of the emissary veins, and that is of interest, because in pwMS our abnormal emissary veins could only have developed while we were fetuses because the skull develops around the emissary veins leaving channels through the skull for these veins, thus meaning that abnormal emissary veins may be confirmation that our CCSVI and abnormal jugulars were present before birth. Anatomy, pathology, anomalies and clinical effects of the emissary veins are all of interest.

Here's a diagram of an emissary vein, if it helps to see how it travels through the skull from the venous sinuses of the brain: http://edutoolanatomy.wikispaces.com/fi ... 5B7%5D.jpg

Thanks Cece.

Here is another article.

J Otolaryngol. 1989 Aug;18(5):232-5.
Objective tinnitus associated with abnormal mastoid emissary vein.
Forte V, Turner A, Liu P.
Source
Department of Otolaryngology, University of Toronto, Ontario, Canada.
Abstract
Tinnitus may be defined as the perception of sound in the absence of environmental input. It can be subjective. Objective tinnitus may be caused by clearly definable mechanical or vascular abnormalities, and as such may be amenable to specific management. We report a case of objective tinnitus associated with an abnormal mastoid emissary vein. A review of the literature identified only one other report of objective tinnitus associated with an emissary vein. That report involved a posterior condylar emissary vein. The venous drainage of the sigmoid sinus was studied on 50 human skulls demonstrating three possible emissary veins of each sigmoid sinus. The postauricular region was dopplered on 30 asymptomatic human subjects. None was found to have dopplered emissary vein flow.

I find it interesting that they were unable to detect emissary flow in 30 asymptomatic patients. Patients with MS very frequently have large emissary veins.

[Cece]

That would seem to indicate that the normal condition is no emissary flow. And very large emissary veins is either abnormal or a variant of normal.

My whooshing tinnitus that I used to hear every day is entirely gone now, since my second procedure. It never bothered me and I used to think it was normal, but I take its absence as a good sign.

[1eye]

Is what we're saying that emissary veins are necessary but not often used, such as when someone is upside-down, or has a jugular blocked?

[Cece]

Is what we're saying that emissary veins are necessary but not often used, such as when someone is upside-down, or has a jugular blocked?

I don't think so... You can't grow an emissary vein as an adult. Other veins can grow (collaterals, angiogenesis). But an emissary vein goes through the skull. You can't grow veins through skulls, you have to grow skulls around veins, which happens before we are born. If healthy controls have no emissary veins, as the research posted suggested, they must be unnecessary. They're an early fetal stage that, in normal people, seem to be gone before the skull is forming, but in people with blocked jugulars, the emissary veins persist and, as in my case, can become very large.

The question remains if they are merely a sign of other pathology (a very large emissary vein may indicate a congenitally blocked jugular) or if they are pathological in and of themselves (reflux through large emissary veins can go directly into the venous sinuses and the brain, instead of being dissipated perhaps by the junction between the sinuses and the jugulars).

That's my best understanding. Emissary veins in a healthy person would not be called into use when he goes upside down, because there would be no emissary veins to speak of, because the emissary veins would have only persisted past the fetal stage and the formation of the skull if there was a reason for them to persist.

[1eye]

Perhaps the existence of the reservoir of venous blood in emissary veins indicates a need to block refluxing blood, in those perhaps with bad or no working valves to block the reflux?

[Cece]

maybe we've seen this one before?
http://www.ajnr.org/content/22/6/1186.short

The Petrosquamosal Sinus: CT and MR Findings of a Rare Emissary Vein

BACKGROUND AND PURPOSE: Morphologic changes in the dural sinuses and emissary veins of the posterior fossa relate closely to the development of the brain. We report characteristic findings of imaging in six patients with a rare and forgotten emissary vein called the petrosquamosal sinus (PSS).

METHODS: From a larger group of patients with ear abnormalities, we selected six patients from three ENT imaging centers, because they had CT features suggestive of a PPS. This was the criterion for inclusion in this retrospective study. They were explored by high-resolution CT (HRCT) of the temporal bone. MR venography was performed in three patients to determine the presence and patency of the emissary vein.

RESULTS: The PPS was bilateral in two patients and unilateral in the other four. It affected mainly the left side (left:right ratio, 5:3). Three patients had associated inner ear (n = 2) or middle ear malformations (n = 1). Five of six patients had jugular vein hypoplasia, with development of emissary mastoid veins in three patients.

CONCLUSION: Petrosquamosal sinus can be identified on HRCT in a typical location. It is encountered more frequently in patients referred for congenital abnormalities of the skull base. This rare anatomic variant should be assessed before surgical treatment, because proper identification of these large venous channels would be of interest to the surgeon.

Five out of six patients with this rare petrosquamosal sinus emissary vein also had jugular vein hypoplasia.
Fits with the theory that impaired cerebrospinal drainage leads to persistent emissary veins.

[1eye]

Could this be a clinical indicator of probable CCSVI? Tied directly to congenital development?

[Cece]

Could this be a clinical indicator of probable CCSVI? Tied directly to congenital development?

I think I overstated the absence of emissary veins in healthy controls, and that there are still emissary veins but smaller and fewer than seen in pwCCSVI.

An imaging trial of pwMS and healthy controls, looking specifically at the emissary veins, could find differences between the two groups (pwMS and healthy controls), which would support the concept of CCSVI.

[1eye]

It would be quick and therefore less expensive than labour-intensive studies. I think the rubber would really hit the road if there were a test for CCSVI, if the explanation of it had nothing to do with auto-immunity, and was only indirectly related to jugulars.

Someday soon maybe researchers could stop using pw"MS" as test subjects for CCSVI. Its prevalence in the population generally may be somewhat higher than in only pw"MS". I think the real clincher would be finding CCSVI via emissary vein imaging. If you can treat some of pw"MS" with it, bonus!

I realize normal people have the emissaries but are they not much smaller or indeed non-existent, having never been required during development?

[Cece]

Here's a purpose for emissary veins in healthy people:
http://www.springerlink.com/content/y28j55527622m414/

Blood flow in the emissary veins of the human head during hyperthermia
M. Cabanac and H. Brinnel

Abstract
The direction of the blood flowing in the emissary veins (vena emissaria mastoidea and v. e. partietalis) was recorded in human subjects during moderate hyperthermia and hypothermia. During hyperthermia the blood flowed rapidly from skin to brain. During hypothermia either no flow could be detected or the blood flowed slowly from brain to skin. On two fresh cadavers the calvaria was removed with the scalp adhering. Gentle massaging of the scalp produced abundant drops of blood on the inner surface of the bone each time the scalp was massaged, thus showing that cutaneous blood can flow inward through the bone. These results support the hypothesis of selective brain cooling in hyperthermic humans by offering a possible mechanism.

Veins are so loosy goosy bidirectional. This wouldn't be so complicated if they were arterial.
When we're cold, blood flows out of the brain through the emissary veins. When we're hot, blood flows into the brain through the same veins.
It says the same here: http://www.springerlink.com/content/v1861422275n6l67/

So in our already congested brains, these emissary veins turn into incoming traffic when we get hot? If we have larger than average emissary veins, does that mean more than average blood flow entering the brain through these veins as part of selective cooling?

[1eye]

I would expect a reservoir of venous blood close to the skin might be cooler than the brain. Maybe the lower pressure means the blood goes downward, seeming to reverse flow, just because of convection and gravity, when we are overheated. A larger reservoir would mean more blood is available for this. Maybe we grow them bigger when we have too much cerebral vein pressure (from lower outflow) to allow the convection reversal to occur if the emissaries are too small.

When cooler, less or reversed convection, plus the heart pump may still give it some forward momentum. The fact that it is in a reservoir outside the skull means it will be cooler than what is inside, because it is closer to the air. This fails if the skull bone becomes so hot that the emissary blood and surrounding air cannot cool it enough that convection will carry it downward.

As an aside, could cooling/warming be among the reasons for less prevalence nearer the equator?

[Cece]

Open Peer Commentary

Brain cooling via emissary veins: Fact or fancy?

George L. Brengelmanna

http://journals.cambridge.org/action/di ... id=7238992

Reminds me of the titles on some of the CCSVI commentary!

Flow is definitely outward through the emissary veins when we are at normal temperature and inward when we are hyperthermic, in normal people. If we have higher pressure due to jugular outflow obstructions and the emissary veins are being used as outflow, would the inflow not get in?

[1eye]

I need a more precise definition of terms here. I think outflow obstructions cause higher pressure on the vein side of things (not to be confused with arterial hypertension). Inflow has to match outflow, or the head explodes or implodes. However the total flow may be slower if there is an outflow problem. I find if I have been too hot I shut right down and have no energy. I would think I might have a brain cooling difficulty, and right now I might blame it on my emissaries having slow flow inward, whether it is because of pressure, or lack of convection, or both. Cooling off provides some immediate relief, if I can manage it.