Posterior fossa veins: Embryology, anatomy, variations and pathology

Transcription

1 Posterior fossa veins: Embryology, anatomy, variations and pathology Poster No.: C-2668 Congress: ECR 2010 Type: Educational Exhibit Topic: Neuro Authors: S. Nair, D. B. Sarkar, J. J. Bhattacharya, M. A. De Miquel ; Glasgow/UK, Barcelona/ES Keywords: Posterior fossa, Veins, Skull base DOI: /ecr2010/C-2668 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 25

2 Learning objectives Learning Objectives: 1. To understand posterior fossa venous embryology and anatomy. 2. To describe various nomenclatures used according to its relation to adjacent brain structure. 3. To illustrate variations in venous drainage. 4. To discuss common and uncommon posterior fossa venous pathology. Background Veins of posterior fossa principally drain into three main confluence namely galenic (superior confluent), torcular (posterior confluent) and petrosal (anterior confluent). The venous draining pattern can be highly variable. They are closely related to the hindbrain surface hence named according to the structures it's overlying. We describe the venous embryology, anatomy and common and rare pathology such as developmental venous anomalies, arterio-venous malformations, arterio-venous fistulas, vein of galen malformations and venous thrombosis. Imaging findings OR Procedure details With recent advances in CT and MR techniques, most of the posterior fossa venous drainage is easily identifiable however catheter angiogram is still helpful to assess the venous draining pattern. In this pictorial review we demonstrate a step wise approach to identify posterior fossa veins and we also describe a variety of venous pathologies. Posterior fossa veins anatomy. Posterior fossa veins drain into 3 main confluents (1) -names derived from hindbrain structure to which it is closely applied-: - Galenic (superior confluent) mainly draining towards the Vein of Galen, including the mesencephalic and superior brainstem drainage, and cranial aspect of the cerebellum (Figure 1 &2) Page 2 of 25

3 Superior vermian vein Pre-central vein Lateromesencephalic vein - Torcular (posterior confluent) towards the torcular and lateral sinuses, draining the posteroinferior aspect of the cerebellum (Figure 3) Inferior vermian vein Hemispheric veins (great horizontal fissure) - Petrosal (anterior confluent) draining the rest of the brainstem, cranial nerves, and anterior cerebellum. (Figure 4) Petrosal vein (draining into the superior petrosal sinus) Anterior hemispheric vein (primary fissure) Veins of the brainstem (variable) The inferior petrosal sinus sometimes receives also the vein of the lateral recess of the IV ventricle. Embryology The primitive mesencephalic and metencephalic pia-arachnoidal veins are the main drainage for the mesencephalon and metencephalon (future cerebellum) in the early foetus. Later in development venous drainage diverts to the three main confluents described below. A perpendicular pattern of venous connections appears to be the main scheme for venous evolution to cover the drainage needs of the developing cerebellum and brainstem (2). (Figure 5) Superior Group The primitive dorsal mesencephalic vein contributes via its anterior branches to the drainage of the mesencephalon and either gets incorporated into the basal vein of Rosenthal or adopts an independent course towards the vein of Galen. The veins that drain the superior region of the vermis & cerebellar hemispheres converge towards the straight sinus & vein of Galen in the superior vermian veins and pre-central vein, because in the relatively late stage when the cerebellum develops (up to 70 mm) the venous precursor of the vein of Galen has still a plexal arrangement. Posterior Group Carried primarily by vessels derived from the dorsal mesencephalic vein. Page 3 of 25

4 Secondary vermian venous drainage include the vein of the choroid plexus of the fourth ventricle A variable number of tentorial sinuses may be observed on each side, usually 1-2. Anterior Group Superior petrosal sinus is the derivative of one of the five main encephalic veins of the embryo: the pia-arachnoidal metencephalic vein. Petrosal vein is intradural in foetal life, and is partially related to the lateral aspect of the choroid plexus. It also receives venous drainage from the neighbouring cranial nerves. The veins of the archicerebellum & veins that drain the lateral region of the th choroid plexus of the 4 ventricle are first to appear. Brainstem venous development show multiple perpendicular anastomoses connecting anterior & superior confluents. Common Pathology Arterio Venous Malformation Abnormal direct arterio-venous connection without intervening capillaries (nidus) Usually seen in the supratentorial compartment, <15% infratentorial More likely to present with haemorrhage and/or progressive neurological deficits, in the posterior fossa Greater morbidity & mortality than supratentorial AVMs due to confines of the posterior fossa & proximity to crucial structures Annual rupture rate of 11.6% in first 5 years after presentation and 6.7% overall (3) Examples: Case : PICA feeding right hemispheric and vermian AVM draining towards precentral vein (Arrow) and superior petrosal sinus (arrow heads).note PICA aneurysm (arrow) (Figure 6, 7, 8) Case: PICA feeding a posterior superior AVM draining into superior vermian vein. Note PICA aneurysm (Figure 9) Case: AVM draining into inferior vermian vein and vein of lateral recess of fourth ventricle draining into inferior petrosal sinus. (figure 10) Page 4 of 25

5 Vein of Galen Malformation True VoG malformation is not a posterior fossa malformation. It is related to persistence of embryonic prosencephalic vein of Markowski which is a supratentorial vein draining towards the superior saggital plexus (later sinus). (figure 11, 12) Develops between 6-11 weeks of foetal life Fed by anterior cerebral, anterior & posterior choroidal, lenticulostriate and thalamic perforating arteries Results in high output heart failure, cerebral ischaemia, progressive paresis, mass effects, hydrocephalus, rarely causing haemorrhage Dural AV Fistula (figure 13 &14) Dural lesions with abnormal direct connections between arteries & venous sinuses / leptomeningeal veins Can occur anywhere within intracranial dura, normally close to the venous sinuses Represent 10-15% of intracranial vascular anomalies Aetiology generally proposed to be acquired, with venous sinus thrombosis a common thread Morbidity/mortality % per annum Symptoms vary with location from mild & non-specific (eg tinnitus) to severe (haemorrhage) Vascular Tumours Glomus Tumour: (Figure 15 & 16) F>M sixth decade Insidious onset Slowly growing, Hypervascular tumour within jugular foramen Locally invasive Metastasis: uncommon Presentation: conductive deafness, vertigo, headache, cranial nerve involvement Case: Angiogram showing glomus jugulare tumor draing into jugular vein, cavernous sinuses and both inferior petrosal sinuses. Page 5 of 25

6 Haemangioblastomas Von Hippel Lindau Syndrome Autosomal dominant Associated with clear cell renal carcinoma, cystadenomas, pheochromocytomas HGBLs in VHL are multiple, involves cerebellum in 35-40% Angiogram shows intensely vascular mass Case: Angiogram showing intensely enhancing mass within the cerebellum draining through the inferior vermian vein (arrow) Figure 17 & 18 Venous Sinus Thrombosis Very infrequent to affect only posterior fossa veins Uncommon cause of stroke (postulated 1 case for every 62.5 cases of arterial stroke) Incidence increasing as less severe cases are being diagnosed Untreated mortality 13-48% with 25-30% experiencing full recovery Predisposing factors include hypercoagulable state, dehydration, pregnancy, infection, trauma and tumour Symptoms include headache, altered consciousness, seizure, neurological deficit and visual disturbance. Images for this section: Page 6 of 25

7 Fig. 1: Lateral view vertebral artery angiogram showing 1. Pre central vein 2. Superior vermian vein Page 7 of 25

8 Fig. 2: lateral vertebral artery angiogram showing precentral vein (arrow) Page 8 of 25

9 Fig. 3: AP view vertebral angiogram showing anterior and posterior confluence 1. Tentorial sinus 2. Superior petrosal sinus 3. Hemispheric vein 4. Inferior vermian vein Arrow head: Petrosal vein Page 9 of 25

10 Fig. 4: Lateral Vertebral artery angiogram showing Anterior Confluent Small single Arrow: Anterior pontomesencephalic vein Single Arrow head: Anterior medullary vein Double arrow head: Lateral pontomesencephalic vein Three arrow head: Transverse pontine vein Long arrow: Petrous vein Two long arrow: Superior petrosal sinus Page 10 of 25

11 Fig. 5: 50 mm CR length embryo showing the venous plexus, precursor of the vein of Galen within the primitive dural mesh between the falx and the primordium of the tentorium. 1: Cerebral hemispheres 2: Dural mesh 3: Venous plexus Page 11 of 25

12 Fig. 6: Lateral view: vertebral artery angiogram showing PICA aneurysm (arrow head) Page 12 of 25

13 Fig. 7: Lateral view: Vertebral artery angiogram showing PICA feeding right hemispheric and vermian AVM draining towards precentral vein (Arrow) and superior petrosal sinus (arrow heads). Page 13 of 25

14 Fig. 8: AP View: PICA feeding right hemispheric and vermian AVM draining towards precentral vein (Arrow) Page 14 of 25

15 Fig. 9: Lateral View: PICA feeding a posterior superior AVM draining into superior vermian vein. Note PICA aneurysm. Page 15 of 25

16 Fig. 10: Lateral view vertebral angigram showing AVM draining into 1. Inferior vermian vein 2. Vein of lateral recess of fourth ventricle draining into inferior petrosal sinus. Page 16 of 25

17 Fig. 11: Complex Vein of Galen and Spinal AVM 1. medullary vein 2. lateral pontomesencephalic vein 3. Joining vein of Galen Page 17 of 25

18 Fig. 12: Complex Vein of Galen and Spinal AVM 1. medullary vein 2. lateral pontomesencephalic vein 3. Joining vein of Galen Page 18 of 25

19 Fig. 13: Lateral veiw vertebral angiogram showing fistula point at tentorial sinus Page 19 of 25

20 Fig. 14: Lateral View vertebral angiogram showing Arrow: Hemispheric vein Long arrow: anterior confluent small arrow heads: Dilated cerebellar veins Page 20 of 25

21 Fig. 15: AP view angiogram showing glomus jugulare tumour draing into jugular vein, cavernous sinuses and inferior petrosal sinuses. Coronary sinus joining both cavernous sinuses (arrow) Page 21 of 25

22 Fig. 16: lateral view angiogram AP view angiogram showing glomus jugulare tumour draing into jugular vein, cavernous sinuses and inferior petrosal sinuses. Coronary sinus joining both cavernous sinuses (arrow) Page 22 of 25

23 Fig. 17: AP View Angiogram showing intensely enhancing mass within the cerebellum draining through vermian vein (arrow) Page 23 of 25

24 Fig. 18: Lateral view Angiogram showing intensely enhancing mass within the cerebellum draining through vermian vein (arrow) Page 24 of 25

25 Conclusion The posterior fossa venous drainage is highly variable but constant pattern can be recognised. The knowledge and understanding the posterior fossa venous drainage is important for planning neurosurgical and endovascular management. Personal Information S. Nair, D. B. Sarkar, J. J. Bhattacharya, M. A. De Miquel ; Glasgow/UK, 2 Barcelona/ES References Newton TH, Potts DG. Radiology of the skull and brain. Embryogenesis of the veins of the posterior fossa: An overview. (1996) Maria Angeles de Miquel, Jose Maria Domenech Mateu, Victoria Cusi, Thomas P Naidich. Surgery of the Intracranial Venous System. Ed. by A Hakuba, Springer Verlag Tokyo, Arnaout et al (2009) Posterior fossa arteriovenous malformations, Neurosurgical Focus, 26(5): E12 Hernesniemi et al (2008) Natural history of brain arteriovenous malformations: A long term follow-up study of risk of haemorrhage in 238 patients, Neurosurgery, 63: Daif et al (1995) Cerebral venous thrombosis in adults. A study of 40 cases from Saudi Arabia, Stroke, 26)7): Page 25 of 25