ARACHNOID GRANULATIONS, VENOUS SINUSES AND

HEADACHE, ARE THEY RELATED?

Quiñones Tapia D, Andreu Arasa C, and Viaño J.

Neuroradiology Hospital Nuestra Señora del Rosario,

Madrid SPAIN

THE AUTHORS HAVE NO DISCLOSURES TO MAKE

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

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.

Dural sinus and arachnoid granulationsAG 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”

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

Findings (N=120)A. In 4 cases AG were found

associated with venous thrombosisB. 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

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.

CASE 1: R transverse sinus thrombosis and AG

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

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.

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 AGThis patient’s HA did not worsen with valsalva or excercise

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

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

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

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

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

CASE 5: 30 yo male with HA and dizziness

Double posterior S. Sinus, and R hypoplastic Transverse sinus

CASE 6: 53 yo slim female. Headache and elevated CSF pressure, several LP (>21 cmH20)

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.

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?

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

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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