脑动静脉畸形

nullnullCEREBRAL ARTERIOVENOUS MALFORMATIONSAVM: a TLA for the CNSnullIncidence0.52% at autopsy Slight male preponderance (1.09 to 1.94) Congenital lesions (although rarely familial)nullEmbryologyFirst half of third week of gestation epiblastic cells migrate to form mesoderm mesodermal cells differentiate to arterial and venous vessels on the surface of the embryonic nervous systemnullEmbryologyFirst half of third week of gestation epiblastic cells migrate to form mesoderm mesodermal cells differentaite to arterial and venous vessels on the surface of the embryonic nervous system Seventh gestational week vessels sprout branches & penetrate developing brain reach the gray-white interface, either loop back to pial surface or traverse entire neural tube, thus epicerebral & transcerebral circ'n eventually connect arterial and venous systems by around the twelfth week nullPathology & Pathophysiologyabsence of normal capillary systemnullPathology & Pathophysiologyabsence of normal capillary system usual function displacednullPathology & Pathophysiologyabsence of normal capillary system usual function displaced asymptomatic at birthnullPathology & Pathophysiologyabsence of normal capillary system usual function displaced asymptomatic at birth vessels change with time may develop aneurysmsnullparenchymal changes within and around the lesionPathology & Pathophysiologyabsence of normal capillary system usual function displaced asymptomatic at birth vessels change with time may develop aneurysmsnullparenchymal changes within and around the lesion site frequency is proportional to brain volumePathology & Pathophysiologyabsence of normal capillary system usual function displaced asymptomatic at birth vessels change with time may develop aneurysmsnullClinical presentation95% have symptoms by age of 70 yearsnullClinical presentation95% have symptoms by age of 70 years peak presentation second to fourth decadenullClinical presentation95% have symptoms by age of 70 years peak presentation second to fourth decade high output failure, neonate, vein of Galen hydrocephalus, first decade headache, hemorrhage, seizures, 2nd & 3rdnullClinical presentationfactors contributing to symptoms vessel walls, flow and pressuresnullClinical presentationfactors contributing to symptoms vessel walls, flow and pressures enlargement and encroachmentnullClinical presentationfactors contributing to symptoms vessel walls, flow and pressures enlargement and encroachment dural sinusesnullClinical presentationfactors contributing to symptoms vessel walls, flow and pressures enlargement and encroachment dural sinuses ischaemianullClinical presentationfactors contributing to symptoms vessel walls, flow and pressures enlargement and encroachment dural sinuses ischaemia cardiac outputnullClinical presentationnullHemorrhageAVM rupture not a function of sizeAneurysm rupture related to aneurysm sizenullHemorrhageAVM rupture not a function of size no marked increase with exercise, pregnancy, traumaAneurysm rupture related to aneurysm size increase with trauma exercise, end pregnancynullHemorrhageAVM rupture not a function of size no marked increase with exercise, pregnancy, trauma arteriovenous, therefore less severeAneurysm rupture related to aneurysm size increase with trauma exercise, end pregnancy arterial, therefore more severenullHemorrhageAVM rupture not a function of size no marked increase with exercise, pregnancy, trauma arteriovenous, therefore less severe mortality 6 to 13.6%Aneurysm rupture related to aneurysm size increase with trauma exercise, end pregnancy arterial, therefore more severe mortality 30-50%nullHemorrhageAVM rupture not a function of size no marked increase with exercise, pregnancy, trauma arteriovenous, therefore less severe mortality 6 to 13.6% lower rebleed mortality rate (1%)Aneurysm rupture related to aneurysm size increase with trauma exercise, end pregnancy arterial, therefore more severe mortality 30-50% higher rebleed mortality rate (13%)nullHemorrhageAVM rupture not a function of size no marked increase with exercise, pregnancy, trauma arteriovenous, therefore less severe mortality 6 to 13.6% lower rebleed mortality rate (1%) vasospasm rareAneurysm rupture related to aneurysm size increase with trauma exercise, end pregnancy arterial, therefore more severe mortality 30-50% higher rebleed mortality rate (13%) vasospasm commonnullHemorrhage - AVMNonetheless, risk of major, incapacitating, or fatal hemorrhage in untreated lesion is 40 to 50% nullHemorrhage - AVMNonetheless, risk of major, incapacitating, or fatal hemorrhage in untreated lesion is 40 to 50% Yearly risk of initial hemorrhage ~3% Rebleed in first subsequent year 6-18%, reducing to ~3% again thereafter Pediatric prognosis worse than adult nullSpetzler & Martin Grading System Criteria Score Size of Nidus Small (<3cm)1Medium (3-6cm)2Large (>6cm)3 Eloquence of Adjacent Brain No0Yes1 Deep Vascular Component No0Yes1nullTreatment OptionsSurgical ResectionnullTreatment OptionsSurgical Resection Endovascular EmbolisationnullTreatment OptionsSurgical Resection Endovascular Embolisation Stereotatic RadiosurgerynullTreatment OptionsSurgical Resection Endovascular Embolisation Stereotatic Radiosurgery Multimodal TherapynullTreatment OptionsSurgical Resection Endovascular Embolisation Stereotatic Radiosurgery Multimodal Therapy Conservative ManagementnullNormal Perfusion Pressure Breakthrough TheoryR.F. Spetzler et alnullNormal perfusion pressure breakthrough theoryLoss of autoregulation and carbon dioxide reactivity in presence of large arteriovenous malformation. nullNormal 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 AVM nullNormal 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 AVM Obliteration of the AVM diverts all flow to these maximally dilated vessels which have lost their normal control mechanisms nullNormal 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 AVM Obliteration of the AVM diverts all flow to these maximally dilated vessels which have lost their normal control mechanisms Results in loss of protection of the capillary bed, with edema and hemorrhage nullArterial inflowMathematical ModelsnullArterial inflow NidusMathematical ModelsnullArterial inflow Nidus Venous OutflowMathematical ModelsnullAnaesthesia Technique