1. Quiñones Tapia D, Andreu Arasa C, and Viaño J. Neuroradiology Hospital Nuestra Señora del Rosario, Madrid SPAIN

2. THE AUTHORS HAVE NO DISCLOSURES TO MAKE

3. PURPOSE Arachnoid granulations (AG) are involved in CSF resorbption and increase with age Cystic arachnoid granulations are often detected inside dural venous sinuses Nowadays, submilimeter resolution in CT and MRI permit in vivo visualization of arachnoid granulations and intracranial venous sinuses AG may partially obstruct venous outflow, and thus could be related to some types of headaches or predispose to venous thrombosis

4. Approach/Method: A retrospective review of MRI and CT reports with the diagnosis of “prominent arachnoid granulation” was made from the last 3 years in an Imaging Center. 128 cases were reviewed 27 cases had venous MRA 40% of cases were obtained to study headaches related to valsalva or exertion. We tend to report AG when they are larger than 1cm or they obstruct aprox. 70% of the V sinus.

5. Dural sinus and arachnoid granulations AG are normal Cystic and vascular structures that may be located inside dural sinuses. They colect CSF returning fluid to the venous system. With age AG increase in size and number AG are also know as Pacchioni granulations. When they erode bone they are called “arachnoid pits”

6. Arachnoid Granulations on MRI Are always located adjacent to dural sinuses may erode bone and be intradiploic (arachnoid pits) May be completely inside the dural sinus, with a cystic non enhancing component and some small enhancing veins, and in these cases they may partially obstruct venous outflow saggital axial coronal

7. Findings (N=120) A.In 4 cases AG were found associated with venous thrombosis B.28 patients studied for headaches (HA) had AG obstructing mayor dural sinuses (20 SSS or dominant transverse) or in the Straight Sinus 8 C.Venous variants with small dural sinuses were detected in 15 patients studied with VMRA for HA associated with exertion or Valsalva D.2 patients had small cephaloceles into the AG and HA with Valsalva

8. A. AG associated with venous thrombosis (4 cases) In 4 cases of cerebral venous thrombosis we noticed prominent AG obstructing over 70% of a mayor venous sinus (related to the site of venous outflow) The A.G. may contribute for thrombosis to occur by decreasing venous flow. Predisposing factors such as dehydration and abnormal coagulation concur.

9. CASE 1: R transverse sinus thrombosis and AG CASE 1: R transverse sinus thrombosis and AG

10. A CASE1: VENOUS INFARCT/THROMBOSED TORCULA A CASE1: VENOUS INFARCT/THROMBOSED TORCULA 36 year old man with right side sensory deficit. Imaging findings: CT: Brain is normal, except for a large arachnoid granulation in the torcula (low attenuation on CT) and R hiperdense transverse S. MRI: on the following day Bright cortical-subcortical left medial occipital lobe lesion with slightly restricted diffusion (venous infarct) Large arachnoid granulation inside the torcula Abnormal content in the posterior sagital sinus (thrombus) Left transverse sinus is hypoplasic James L. Leach, Robert B. Fortuna, Blaise V. Jones, and Mary F. Gaskill-Shipley. Imaging of Cerebral Venous Thrombosis: Current Techniques, Spectrum of Findings, and Diagnostic Pitfalls. Radiographics October 2006 26:suppl 1 S19-S41; doi:10.1148/rg.26si055174

11. Cefaleas 49 patients with ICHD-II criteria for HA, 41 complete imaging with Venous Gd angioRM (Headache related to 20 sexual intercourse, 10 cough, and 11 on exertion). Transverse Sinus stenosis in 43%, 37% y 20% and 0 in Control group.

12. B. AG inside mayor Venous Sinus: Headache and Giant AG in S.Saggital Sinus Bone remodeling is present and the SSS is split by the AG This patient’s HA did not worsen with valsalva or excercise

13. Pacchioni granulations in the Straight Sinus (3/8 different cases studied for headache) This location has been reffered by some anatomists as “Galen’s Ampulla” and hypothetically attributed a valve mechanism for regulation of deep venous cerebral flow This anatomic disposition was found in 5 cases with HA on exertion

14. CASE 2: 53 yo female. L side tinnitus and HA. L transverse Sinus hiperintensity in FLAIR due to slow venous flow in the non-dominant sinus which has a partially obstructing AG

15. C CASE 3: 43 yo female with HA increasing with valsalva. L transverse Sinus AG/+ encephalocele  The dura and brain herniate inside the left transverse sinus (red arrow), possibly at a dural defect related to an arachnoid granulation. The venous outflow reduction may be related to her headaches

16. CASE 4: 73 yo male chronic headache CASE 4: 73 yo male chronic headache Venous sinus thrombosis suspected. Imaging findings:  Rounded cystic structure in the proximal right transverse sinus Isointense to CSF in all sequences and No enhancement (arachnoid G.)  Filling defect on post contrast images, the lateral R tranv sinus enhances  R transverse sinus decreased flow hiperintense T2w (not detected 3D PC MRA) James L. Leach, Robert B. Fortuna, Blaise V. Jones, and Mary F. Gaskill-Shipley. Imaging of Cerebral Venous Thrombosis: Current Techniques, Spectrum of Findings, and Diagnostic Pitfalls. Radiographics October 2006 26:suppl 1 S19-S41; doi:10.1148/rg.26si055174

17. D: Venous Variants on VMRA Abnormal development of dural sinuses in 15/27 cases with chronic HA and Venous MRA Hypoplasic/agenetic transverse sinuses and infratentorial suboccipital sinuses may be unusually small Intracranial Hipertension is related to small/ compressed venous sinuses Agenesis of the proximal portion of the non-dominant L Tranverse Sinus

18. CASE 5: 30 yo male with HA and dizziness Double posterior S. Sinus, and R hypoplastic Transverse sinus

19. CASE 6: 53 yo slim female. Headache and elevated CSF pressure, several LP (>21 cmH 2 0) MRI: normal ventricles and sulci. The torcula is small. Partially empty sella. Small collapsed cavernous sinuses. 3D PC non enhanced MRA: Abnormal bilateral hypoplastic transverse sinuses. Enlarged Saggital sinus.

20. Case 6 DSA: Abnormal torcula and proximal transverse sinuses are hypoplastic. Variant of suboccipital sinus comunicating the straight sinus with the Right internal yugular bulb. No trombus. Restricted venous outflow?

21. CASE 7: male with exertional headache, V. variants CASE 7: male with exertional headache, V. variants MRI and 3D PC MRA (no Gd) Vertical tentorium. Infratentorial occipital sagital sinus and left transv. hypoplasic sinus originating from the straight sinus. All the sinuses, have normal flow but are quite small

22. Summary / Conclusions In our series of HA with Valsalva/exertion 40% had reported AG obstructing (>70%) of mayor venous sinuses, but medical implications and treatment are unclear Arachnoid granulations, considered normal intracranial structures, may sometimes by size or location produce restricted cerebral venous outflow Looking at the veins and sinuses is mandatory in the evaluation of headache to exclude thrombosis, intracranial hypertension or hypotension, or to detect venous sinus hypoplasia in exertional headache. 55% of chronic HA with exertion had venous variants on VMRA Interventional treatment with venous stents should only be considered after clear relation with HA or increased intracranial pressure and demonstration of a venous pressure gradient in the affected venous sinus. Contact: dquinones@rmrosario.com

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