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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.

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.

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

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

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.

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?

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.

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

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.

Open Peer Commentary

Brain cooling via emissary veins: Fact or fancy?

George L. Brengelmanna