SUPERIOR SAGITTAL SINUS(SSS) - Radioloksabha

SUPERIOR SAGITTAL SINUS(SSS) - Radioloksabha

CEREBRAL VENOUS ANATOMY AND VENOUS INFARCTS Dr MONICA PATIL Venous anatomy Causes of venous infarct Imaging of venous infarct

VENOUS ANATOMY VENOUS ANATOMY DURAL SINUSES CEREBRAL

VEINS: - DEEP CEREBRAL - SUPERFICIAL CORTICAL DURAL VENOUS SINUSES Posterosuperior group

1. Superior Sagittal Sinus 2. Inferior Sagittal Sinus 3. Straight Sinus 4. Transverse sinus 5. Sigmoid sinus & jugular bulb 6. Confluence(torcular herophili) Anteroinferior group 1. Cavernous sinus

2. Superior and inferior petrosal sinus 3. Clival plexus 4. Sphenoparietal sinus SUPERIOR SAGITTAL SINUS(SSS) Originates from ascending frontal veins anteriorly

Runs in midline at the union of calvaria and falx cerebri Tributaries from superficial cortical veins, vein of Trolard and venous lakes in diploic space On cor-seen as a triangular channel

between dural leaves of falx cerebri On sag-sickle shaped Normal variants-absence of anterior segment(sinus begins at coronal suture) and off midline position INFERIOR SAGITTAL SINUS(ISS) Smaller and inconstant Lies at the bottom of falx cerebri and

above corpus callosum and cingulate gyrus Terminates at falcotentorial junction where it joins vein of galen to form straight sinus STRAIGHT SINUS Formed by junction of ISS and VOG at the

falcotentorial apex Numerous small tributaries from falx cerebri, tentorium cerebelli and adjacent brain Terminates by joining at the confluence which is often asymmetric with septations and intersinus channels SS variant- persistent falcine sinus which connects

ISS or VOG directly to SSS. 2/3 of these patients have absent or rudimentary SS TRANSVERSE SINUS Contained between attachments of tentorium cerebelli to the inner table of skull Anatomic variations are the rule

rather than the exception Asymmetrical with R>L Hypoplastic and atretic segments SIGMOID SINUSES AND JUGULAR BULB Inferior continuation of the TS descending behind the petrous temporal bone and becoming jugular bulbs Jugular bulb is focal dilatation between

sigmoid sinus and extracranial portion of IJV Jugular bulb pseudolesions with flow asymmetry should not be mistaken for real masses(schwannoma, paraganglioma). Jugular foramen is intact, not eroded or remodelled CAVERNOUS SINUS

Irregularly shaped and heavily trabeculated venous sinuses that lie along sides of sella turcica extending from superior orbital fissure anteriorly to clivus and petrous apex posteriorly Contain ICA and VI n. III, IV, V1 and V2 are within lateral dural wall Tributaries-superior and inferior ophthalmic veins, sphenoparietal sinuses

Communicate with each other via intercavernous venous plexus Drains inferiorly through foramen ovale into clival plexus and superior and inferior petrosal sinuses Lateral walls are straight or concave(not convex) and venous blood enhances uniformly

SUPERIOR AND INFERIOR PETROSAL SINUS Superior petrosal sinus courses posteriorly along top of petrous temporal bone from CS to sigmoid sinus Inferior petrosal sinus courses above petrooccipital fissure from inferior

aspect of clival venous plexus to jugular bulb CLIVAL PLEXUS Extends along clivus to foramen magnum Connects cavernous and petrosal sinuses with each other and with

suboccipital veins around foramen magnum. SPHENOPARIETAL SINUS Courses around lesser wing of sphenoid at rim of middle cranial fossa It receives superficial veins from the

anterior temporal lobe and drains CS or inferior petrosal sinus SUPERFICIAL CORTICAL VEINS SUPERIOR CORTICAL VEINS- -8-12 unnamed, drain into SSS - Vein of Trolard (Sylvian fissure to SSS) MIDDLE CORTICAL VEINS-

-Begins over the Sylvian fissure and collects small tributaries from frontal, parietal and temporal opercula that overhang lateral cerebral fissure. -Superficial middle cerebral vein. -Drain into CS or sphenoparietal sinus. INFERIOR CORTICAL VEINS- -Vein of Labbe (sylvian fissure to TS)

DEEP CEREBRAL VEINS Medullary veins Subependymal v thalamostriate & septal veins Deep paramedian v.(Internal cerebral veins) Brainstem/ Posterior Fossa veins

MEDULLARY VEINS Unnamed veins, begin 1-2 cm below the cortex course straight through the white matter towards the ventricle Terminate into the subependymal veins Inapparent until they converge near the ventricle

SWI best depicts the vessels as the deoxygenated blood is paramagnetic SUBEPENDYMAL VEINS Most important named veins are the septal veins and the thalamostriate veins Course under the ventricular ependyma and collect blood

from the basal ganglia and deep white matter(via the medullary veins) Septal veins curve around the frontal horns of lateral ventricles, then course posteriorly along septum pellucidi. Thalamostriate veins receive tributaries from caudate nuclei and thalami curving medially to unite with septal veins near foramen of Monro to form 2 internal cerebral veins.

BRAINSTEM/POSTERIOR FOSSA VEINS SUPERIOR/GALENIC GROUP- -Drain into vein of galen. -Precentral cerebellar v-single midline v. -Superior Vermian v. -Anterior pontomesencephalic v. ANTERIOR/PETROSAL GROUP-

-Petrosal v.-large venous trunk lying in the CP angle cistern, receives tributaries from cerebellum, medulla and pons. POSTERIOR/ TENTORIAL GROUP- -Inferior vermian v-paired paramedian v. VENOUS DRAINAGE Peripheral or brain surface pattern (drain centrifugally)- cortical veins and SSS

Deep or central pattern (drain centripetally)- VOG and internal cerebral v. Inferolateral or perisylvian pattern-superficial middle cerebral v.=>sphenoparietal sinus=>CS Posterolateral or temporoparietal pattern- superior petrosal sinus and anastomotic v. of labbe into transverse sinus.

ETIOPATHOGENESIS PREDISPOSING FACTORS Pregnancy, peurperium Infection: Sinusititis, mastoiditis, otitis media,

meningitis

Trauma Prothrombotic conditions Dehydration Oral contraceptives Coagulopathies Trauma AVM IBD PNH Paraneoplastic syndrome

VENOUS INFARCT Cerebral venous thrombosis is an important cause of stroke especially in children and young adults. Clinically patients with cerebral venous thrombosis present with

variable symptoms ranging from headache to seizure and coma in severe cases. PATHOLOGY Venous thrombosis High venous pressure due to restricted flow Vasogenic edema in the white matter of the affected area due to

hydrostatic displacement of fluid from capillaries to extracellular spaces as a result of breakdown of BBB. May lead to infarction Cytotoxic oedema develops VENOUS INFARCT Venous thrombosis begins in dural

sinus. Then progresses to bridging veins. Petechial perivascular hemorrhages & cortical venous infarctions occur. VENOUS INFARCT Most commonly involved sinus: tranverse

Then -SSS -Sigmoid -Cavernous Most commonly involved veins: Superficial cortical veins that drain SSS. VENOUS INFARCT

Internal cerebral vein thrombosis is less common but devastating. Involves vein of Galen or straight sinus. May lead to bilateral venous infarcts in deep grey matter nuclei & upper midbrain.

IMAGING IN VENOUS INFARCT IMAGING IN VENOUS INFARCT IMAGING IN VENOUS INFARCT Empty delta sign Pseudo-delta sign Dense clot sign Cord sign

MR & veno findings CT IMAGING IN VENOUS INFARCT EMPTY DELTA SIGN: -Seen on contrast study - Hypodense sinus due to thrombus. - Surrounding cavernous spaces,

meningeal venous tributaries, venous channels enhance on CECT. CT IMAGING IN VENOUS INFARCT DENSE CLOT SIGN Seen on plain scan Hyperdense thrombus in dural sinus

It is also called as delta sign CT IMAGING IN VENOUS INFARCT CORD SIGN: Thrombosed cortical veins seen as linear high density areas. CT IMAGING IN VENOUS INFARCT

Hemorrhagic infarction in the temporal lobe. Dense transverse sinus due to

thrombosis. CT IMAGING IN VENOUS INFARCT Deep cerebral vein thrombosis seen asHyperdense thrombus in deep veins, vein of Galen or straight sinus. Secondary changes seen are

bilateral low density basal ganglia with or without associated petechial hemorrhages. MR IMAGING IN VENOUS INFARCT Infarct that does not follow the distribution of an expected arterial occlusion.

MRI is more sensitive for detection of venous thrombi than CT. The absence of a flow void & presence of altered signal intensity in the sinus is a primary finding of sinus thrombosis on MR images. MR IMAGING IN VENOUS

INFARCT ACUTE THROMBUS : Isointense with cortex on T1WI LATE ACUTE : Hyper on T1WI Hypo on T2WI SUBACUTE : Hyper on both T1 and T2WI CHRONIC:-T1 iso -T2 hyper

-Chronically thrombosed sinuses undergo fibrosis, develop significant vascularity and enhances strongly on T1 C. -Frayed or shaggy appearance MR IMAGING IN VENOUS INFARCT

T2-weighted image with normal flow void in the right sigmoid sinus. On the left there is abnormal high signal as a result of thrombosis.

MR IMAGING IN VENOUS INFARCT GRE - Thrombus hypointense, "blooms" Tl C+ - Acute-Peripheral enhancement MRV

- Absence of flow in occluded sinus on 2D TOF MRV -"Frayed" or "shaggy" appearance of venous sinus MR IMAGING IN VENOUS INFARCT Axial T2WI shows

replacement of signal void by thrombus in superior sagittal sinus. MR IMAGING IN VENOUS T2WI showing an INFARCT

area of increased signal intensity consistent with diffusion restriction along the cortex of the right parietal lobe. High-signal-

intensity thrombus in the superior sagittal sinus MR IMAGING IN VENOUS INFARCT T1WI shows an area of

isointense signal s/o thrombus in the right transverse sinus. GRE image shows

blooming in that area. MR VENO IN VENOUS INFARCT TOF MR venography is most commonly used for the diagnosis of cerebral venous thrombosis. 2D TOF techniques are used to

evaluate the intracranial venous system because of their excellent sensitivity to slow flow. MR VENO IN VENOUS INFARCT The left sigmoid sinus and

left IJV has no signal due to thrombosis. CAVERNOUS SINUS THROMBOSIS Communicate with veins of orbit, face and neck so infection from here can easily spread to CS.

When thrombosis is accompanied by infection thrombophlebitis S. aureus is most imp pathogen C/F-headache, fever and orbital symptoms(dirty orbital fat, periorbital oedema, chemosis) IMAGING CT

Lateral CS margins are convex and not flat or convex Proptosis, dirty orbital fat, periorbital swelling and sinusitis

MRI Non enhancing filling defects within the enhancing dural walls of CS and thrombosed orbital veins on T1C Rare- inflammation of the ICA can cause stenosis or pseudoaneurysm formation VENOUS OCCLUSION MIMICS SINUS VARIANTS FLOW ARTIFACTS

ARACHNOID GRANULATIONS SDH POLYCYTHEMIA AND LEFT TO RT SHUNT UNMYELINATED BRAIN DIFFUSE CEREBRAL OEDEMA CONDITIONS MIMICKING VENOUS INFARCT

PSEUDODELTA SIGN: In infants -hypointensity of the unmyelinated brain and the physiologic polycythemia resulting in high density of the blood in the sagittal sinus. MIMIC OF EMPTY DELTA SIGN (CT in head trauma) Unclotted blood in SSS creates low

density area surrounded by hyperdense SAH or SDH THANK YOU

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