出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/10/08 06:17:31」(JST)
| Dural arteriovenous fistula | |
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This dural arteriovenous fistula of the superior sagittal sinus drains into subarachnoid veins and is classified as Borden type IIIb.
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| Classification and external resources | |
| DiseasesDB | 32954 |
A dural arteriovenous fistula (DAVF), not to be confused with dural arteriovenous malformation (DAVM), is an abnormal direct connection (fistula) between a meningeal artery and a meningeal vein or dural venous sinus.
The Borden Classification of dural arteriovenous malformations or fistulas, groups into three types based upon their venous drainage:[1]
Type I dural arteriovenous fistulas are suppied by meningeal arteries and drain into a meningeal vein or dural venous sinus. The flow within the draining vein or venous sinus is anterograde.
The distinction between Types Ia and Ib is somewhat specious as there is a rich system of meningeal arterial collaterals. Type I dural fistulas are often asymptomatic, do not have a high risk of bleeding and do not necessarily need to be treated.
The high pressure within a Type II dural AV fistula causes blood to flow in a retrograde fashion into subarachnoid veins which normally drain into the sinus. Typically this is because the sinus has outflow obstruction. Such draining veins form venous varices or aneurysms which can bleed. Type II fistulas need to be treated to prevent hemorrhage. The treatment may involve embolization of the draining sinus as well as clipping or embolization of the draining veins.
Type III dural AV fistulas drain directly into subarachnoid veins.[2] These veins can form aneurysms and bleed. Type III dural fistulas need to be treated to prevent hemorrhage. Treatment can be as simple as clipping the draining vein at the site of the dural sinus. If treatment involves embolization, it will only typically be effective if the glue traverses the actual fistula and enters, at least slightly, the draining vein.
The Cognard Classification[3] correlates venous drainage patterns with increasingly aggressive neurological clinical course.
Confined to sinus wall, typically after thrombosis.
IIa - confined to sinus with reflux (retrograde) into sinus but not cortical veins. IIb - drains into sinus with reflux (retrograde) into cortical veins (10-20% hemorrhage).
Drains direct into cortical veins (not into sinus) drainage (40% hemorrhage).
Drains direct into cortical veins (not into sinus) drainage with venous ectasia (65% hemorrhage).
Spinal perimedullary venous drainage, associated with progressive myelopathy.
One approach used for treatment is embolization.[4]
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| リンク元 | 「硬膜動静脈瘻」「脊髄硬膜動静脈瘻」 |
| 関連記事 | 「A」「AVF」「AV」「dural」 |
[★] 動静脈瘻 arteriovenous fistula, AV fistula, 動静脈シャント