CEREBRALARTERIOVENOUS MALFORMATIONSAVM: a TLA for the CNSIncidencen0.52%at autopsynSlight male preponderance (1.09 to 1.94)nCongenital lesions (although rarely familial)EmbryologynFirst half of third week of gestationepiblastic cells migrate to form mesodermmesodermal cells differentiate to arterial and venous vessels on the surface of the embryonic nervous systemEmbryologynFirst half of third week of gestationepiblastic cells migrate to form mesodermmesodermal cells differentaite to arterial and venous vessels on the surface of the embryonic nervous systemnSeventh gestational weekvessels sprout branches & penetrate developing brainreach the gray-white interface, either loop back to pial surface or traverse entire neural tube, thus epicerebral & transcerebral circneventually connect arterial and venous systems by around the twelfth week Pathology & Pathophysiologynabsence of normal capillary systemPathology & Pathophysiologynabsence of normal capillary systemnusual function displacedPathology & Pathophysiologynabsence of normal capillary systemnusual function displacednasymptomatic at birthPathology & Pathophysiologynabsence of normal capillary systemnusual function displacednasymptomatic at birthnvessels change with timenmay develop aneurysmsnparenchymal changes within and around the lesionPathology & Pathophysiologynabsence of normal capillary systemnusual function displacednasymptomatic at birthnvessels change with timenmay develop aneurysmsnparenchymal changes within and around the lesionnsite frequency is proportional to brain volumePathology & Pathophysiologynabsence of normal capillary systemnusual function displacednasymptomatic at birthnvessels change with timenmay develop aneurysmsClinical presentationn95%have symptoms by age of 70 yearsClinical presentationn95%have symptoms by age of 70 yearsnpeak presentation second to fourth decadeClinical presentationn95%have symptoms by age of 70 yearsnpeak presentation second to fourth decadehigh output failure, neonate, vein of Galenhydrocephalus, first decadeheadache, hemorrhage, seizures, 2nd & 3rdClinical presentationnfactors contributing to symptomsvessel walls, flow and pressuresClinical presentationnfactors contributing to symptomsvessel walls, flow and pressuresenlargement and encroachmentClinical presentationnfactors contributing to symptomsvessel walls, flow and pressuresenlargement and encroachmentdural sinusesClinical presentationnfactors contributing to symptomsvessel walls, flow and pressuresenlargement and encroachmentdural sinusesischaemiaClinical presentationnfactors contributing to symptomsvessel walls, flow and pressuresenlargement and encroachmentdural sinusesischaemiacardiac outputClinical presentationHemorrhagenAVMrupture not a function of sizenAneurysmrupture related to aneurysm sizeHemorrhagenAVMrupture not a function of sizeno marked increase with exercise, pregnancy, traumanAneurysmrupture related to aneurysm sizeincrease with trauma exercise, end pregnancyHemorrhagenAVMrupture not a function of sizeno marked increase with exercise, pregnancy, traumaarteriovenous, therefore less severenAneurysmrupture related to aneurysm sizeincrease with trauma exercise, end pregnancyarterial, therefore more severeHemorrhagenAVMrupture not a function of sizeno marked increase with exercise, pregnancy, traumaarteriovenous, therefore less severemortality 6 to 13.6%nAneurysmrupture related to aneurysm sizeincrease with trauma exercise, end pregnancyarterial, therefore more severemortality 30-50%HemorrhagenAVMrupture not a function of sizeno marked increase with exercise, pregnancy, traumaarteriovenous, therefore less severemortality 6 to 13.6%lower rebleed mortality rate (1%)nAneurysmrupture related to aneurysm sizeincrease with trauma exercise, end pregnancyarterial, therefore more severemortality 30-50%higher rebleed mortality rate (13%)HemorrhagenAVMrupture not a function of sizeno marked increase with exercise, pregnancy, traumaarteriovenous, therefore less severemortality 6 to 13.6%lower rebleed mortality rate (1%)vasospasm rarenAneurysmrupture related to aneurysm sizeincrease with trauma exercise, end pregnancyarterial, therefore more severemortality 30-50%higher rebleed mortality rate (13%)vasospasm commonHemorrhage - AVMnNonetheless, risk of major, incapacitating, or fatal hemorrhage in untreated lesion is 40 to 50% Hemorrhage - AVMnNonetheless, risk of major, incapacitating, or fatal hemorrhage in untreated lesion is 40 to 50%nYearly risk of initial hemorrhage 3%nRebleed in first subsequent year 6-18%, reducing to 3% again thereafternPediatric prognosis worse than adult Spetzler & Martin Grading SystemCriteriaScoreSize of Nidus Small (6cm)3Eloquence of Adjacent Brain No0Yes1Deep Vascular Component No0Yes1Treatment OptionsHSurgical ResectionTreatment OptionsHSurgical ResectionHEndovascular EmbolisationTreatment OptionsHSurgical ResectionHEndovascular EmbolisationHStereotatic RadiosurgeryTreatment OptionsHSurgical ResectionHEndovascular EmbolisationHStereotatic RadiosurgeryHMultimodal TherapyTreatment OptionsHSurgical ResectionHEndovascular EmbolisationHStereotatic RadiosurgeryHMultimodal TherapyHConservative ManagementNormal Perfusion Pressure Breakthrough TheoryR.F. Spetzler et alNormal perfusion pressure breakthrough theoryLoss of autoregulation and carbon dioxide reactivity in presence of large arteriovenous malformation.Normal perfusion pressure breakthrough theoryLoss of autoregulation and carbon dioxide reactivity in presence of large arteriovenous malformation.Normal hemispheric vessels are chronically maximally dilated to attempt to divert flow from the AVMNormal perfusion pressure breakthrough theoryLoss of autoregulation and carbon dioxide reactivity in presence of large arteriovenous malformation.Normal hemispheric vessels are chronically maximally dilated to attempt to divert flow from the AVMObliteration of the AVM diverts all flow to these maximally dilated vessels which have lost their normal control mechanismsNormal perfusion pressure breakthrough theoryLoss of autoregulation and carbon dioxide reactivity in presence of large arteriovenous malformation.Normal hemispheric vessels are chronically maximally dilated to attempt to divert flow from the AVMObliteration of the AVM diverts all flow to these maximally dilated vessels which have lost their normal control mechanismsResults in loss of protection of the capillary bed, with edema and hemorrhagenArterial inflowMathematical ModelsnArterial inflownNidusMathematical ModelsnArterial inflownNidusnVenous OutflowMathematical ModelsAnaesthesia Technique