cranial meninges

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Cranial meninges

Cranial meningesRajasri ManimaranGroup 2

Protection of the BrainThe SkullCranial meningesCerebrospinal fluidBlood brain barrier

The Meninges

1. Dura Mater - Composed of two layers:a) Periosteal outer layer, attaches to bone.b) Meningeal inner layer, closer to brain.Cranial Meninges - 3 layer protective membraneTwo layers fused, except to enclose the dural sinuses3. Pia Mater - delicate, follows convolutions.2. Arachnoid Layer - spider web like.

Coronal section of the upper part of the headEndosteal layerMeningeal layerThey are closely united except along certain lines; they are separated to form venous sinusesSuperior sagittal sinus (Dural venous sinus)Dura mater Subdural spaceEndo ( outer) . Bilaminar layer5

Sagittal section showing the duramater1) Falx cerebri2) Tentorium cerebelli3) Falx cerebelli4) Diaphragma sellae6

Dural Nerve SupplyBranches of the trigeminal, vagus, and first three cervical nerves and branches from the sympathetic system pass to the dura.The dura is sensitive to stretching, which produces the sensation of headache.8Dural blood supplyThemiddle meningeal arterysupplies most of the blood for the dura mater, though the meningeal branches of theposteriorandanterior ethmoidal arteryalso contribute.Arachnoid mater

Subdural space Potential space between dura and arachnoid mater.Cranial Meningeal Spaces Epidural spacePotential space superior to dura. Subarachnoid spaceFilled with CSFContains the blood vessels supplying brain.

12Subaracnoid spaceRelatively narrow over the surface of cerebral hemisphere, but sometimes becomes much wider in areas at the base of the brain, the widest space is called subarachnoid cisterns.

Median sagittal section to show the subarachnoid cisterns & circulation of CSFSuperior cistern Interpeduncular cisternCerebellomedullary cisternChiasmatic cisternPontine cistern14Pia materPia mater functions to cover and protect thecentral nervous system(CNS), to protect the blood vessels and enclose the venous sinuses near the CNS, to contain the cerebrospinal fluid (CSF) and to form partitions with the skull.The CSF, pia mater, and other layers of the meninges work together as a protection device for the brain, with the CSF often referred to as the fourth layer of the meninges.

Pathology There are three types ofhemorrhageinvolving the meninges:Anepidural hematomaarise after an accident or spontaneouslyAsubdural hematomais ahematoma(collection of blood) located in a separation of thearachnoidfrom thedura mater. The small veins that connect thedura materand thearachnoidare torn, usually during an accident, and blood leaks into this areaAsubarachnoid hemorrhageis acute bleeding under the arachnoid; it may occur spontaneously or as a result of trauma.

Other medical conditions that affect the meninges includemeningitis(usually fromfungal,bacterial, orviralinfection) andmeningiomasthat arise from the meninges, or frommeningeal carcinomatoses(tumors) that form elsewhere in the body andmetastasizeto the meninges.

Cranial venous sinusesThedural venous sinuses(also calleddural sinuses,cerebral sinuses, orcranial sinuses) arevenous channels found between layers ofdura materin thebrain.They receivebloodfrom internal and externalveinsof the brain, receivecerebrospinal fluid(CSF) from thesubarachnoid space, and ultimately empty into theinternal jugular vein.NameDrains toInferior sagittal sinusStraight sinusSuperior sagittal sinusTypically becomes right transverse sinus or confluence of sinusesStraight sinusTypically becomes left transverse sinus or confluence of sinusesOccipital sinusConfluence of sinusesConfluence of sinusesRight and Left transverse sinusesSphenoparietal sinusesCavernous sinusesCavernous sinusesSuperior and inferior petrosal sinusesSuperior petrosal sinusTransverse sinusesTransverse sinusesSigmoid sinusInferior petrosal sinusSigmoid sinusSigmoid sinusesInternal jugular veinARTERIES to specific brain areasCorpus striatumMiddle & lateral striateAnterior & Middle cerebral arteryInternal capsuleThalamus PComA, basilar, PCAMidbrain PCA, supCerebellarA, basilarPons Basilar, Ant, inf, supCerebellarA,Medulla oblongataVertebral, ASA,PSA,PICA, basilarCerebellum supCerebellar, AICA,PICA22Blood Supply of The BrainVERTEBRALBasilarPosterior cerebral arteryINTERNAL CAROTIDMiddle cerebralAnterior cerebralAnterior communicating arteryPosterior communicating artery

CIRCLE OF WILLIS23

Subarachnoid hemorrhage6/8/2013 2009, American Heart Association. All rights reserved.

Aneurysm26

symptomsHeadache (sudden onset, greater severity)Nausea and vomittingLoss or impairment of consciousness (may progress to coma and death)Confusion and irritabilityMeningial irritation and nuchal rigidity (stiff neck)Focal neurological deficits (may indicate site of lesions).Differential diagnosisMeningitisMigraineIntracerebral hemorrhageIschemic stroke

GradeSigns and symptomsSurvival1Asymptomaticor minimal headache and slight neck stiffness70%2Moderate to severe headache; neck stiffness; noneurologicdeficit exceptcranial nerveplasy60%3Drowsy; minimal neurologic deficit50%4Stuporous; moderate to severe hemiparesis; possibly earlydecerebrate rigidityand vegetative disturbances20%5Deep coma;decerebrate rigidity;moribund10%Hunt and Hess classification Scale of severity34Treatment Stabilizing patient.Prevention of rebleeding by obliterating the bleeding source.prevention of a phenomenon known asvasospasm and,prevention and treatment of complications.Preventing Re-bleedingUp to 14% of SAH patients may experience re-bleeding within 2 hours of the initial hemorrhageRe-bleeding was more common in those with a systolic blood pressure >160mm HgAnti-fibrinolytic therapy may reduce re-bleeding but has not been shown to improve outcomes

6/8/2013 2009, American Heart Association. All rights reserved.Surgical and Endovascular Management of SAHSurgery clip aneurysm baseEndovascular coilingShould be performed within 2 days of hemorrhage.6/8/2013 2009, American Heart Association. All rights reserved.SAH outcome is mostly defined by the severity of the initial hemorrhage. Thus, procedural complications are better delineated in studies of unruptured aneurysms. The 30-day mortality in the International Study of Unruptured Intracranial Aneurysms was 2% after coiling and disability was 7.4%. The 2-month combined endovascular mortality and disability was 25.4% in the International Subarachnoid Aneurysm Trial (ISAT) of patients with ruptured aneurysms. 1. Brilstra EH, Rinkel GJ, van der Graaf Y, van Rooij WJ, Algra A. Treatment of intracranial aneurysms by embolization with coils: a systematic review. Stroke. 1999;30(2):470-476.2. Wiebers DO, Whisnant JP, Huston J, 3rd, Meissner I, Brown RD, Jr., Piepgras DG, Forbes GS, Thielen K, Nichols D, O'Fallon WM, Peacock J, Jaeger L, Kassell NF, Kongable-Beckman GL, Torner JC. Unruptured intracranial aneurysms: natural history, clinical outcome, and risks of surgical and endovascular treatment. Lancet. 2003;362(9378):103-110.3. Molyneux A, Kerr R, Stratton I, Sandercock P, Clarke M, Shrimpton J, Holman R. International Subarachnoid Aneurysm Trial (ISAT) of neurosurgical clipping versus endovascular coiling in 2143 patients with ruptured intracranial aneurysms: a randomised trial. Lancet. 2002;360(9342):1267-1274.

6/8/2013 2009, American Heart Association. All rights reserved.

Clipping

38Left image arrow -Angio with Large aneurysmRight image arrow Angio showing aneurysm post clipping

6/8/2013 2009, American Heart Association. All rights reserved.

Angio Image Courtsey: The University of Texas Health Science Center at San Antonio Department of NeurosurgerySurgical and Endovascular Management of SAHCombined morbidity and mortality was significantly greater in surgically treated patients than in those treated with endovascular techniques (30.9% vs. 23.5%; absolute risk reduction 7.4%)During the short follow-up period, the re-bleeding rate for coiling was 2.9% versus 0.9% for surgeryThere have been no randomized comparisons of coiling versus clipping for unruptured aneurysms

6/8/2013 2009, American Heart Association. All rights reserved.6/8/2013 2009, American Heart Association. All rights reserved.

Coiling

41Coil system embolization: immediate result

6/8/2013 2009, American Heart Association. All rights reserved.

Angio showing large ICA aneurysmSame aneurysm - Post GDC CoilingAngio Image Courtsey: The University of Texas Health Science Center at San Antonio Department of Neurosurgery

Preventing vasospasmThe use ofcalcium channel blockers, thought to be able to prevent the spasm of blood vessels by preventingcalciumfrom entering smooth muscle cells, has been proposed for the prevention of vasospasm.The oral calcium channel blockernimodipineimproves outcome if administered between the fourth and twenty-first day after the hemorrhage.Preventing other complicationsIf medication dont help, then angiography may be attempted to identify the sites of vasospasms and administer vasodilatormedication (drugs that relax the blood vessel wall) directly into the artery.Angioplasty(opening the constricted area with a balloon) may also be performed.Summary and ConclusionsThe current standard of practice calls for microsurgical clipping or endovascular coiling of the aneurysm neck whenever possible

Treatment morbidity is determined by numerous factors, including patient, aneurysm, and institutional factors6/8/2013 2009, American Heart Association. All rights reserved.Summary and ConclusionsFavorable outcomes are more likely in institutions that treat high volumes of patients with SAH, in institutions that offer endovascular services, and in selected patients whose aneurysms are coiled rather than clipped

Optimal treatment r