CEREBRAL ARTERIOVENOUS MALFORMATIONS Incidence Embryology Embryology Pathology & Pathophysiology Pathology & Pathophysiology Pathology & Pathophysiology Pathology & Pathophysiology parenchymal changes within and around the lesion parenchymal changes within and around the lesion site frequency is proportional to brain volume Clinical presentation Clinical presentation Clinical presentation Clinical presentation Clinical presentation Clinical presentation Clinical presentation Clinical presentation Clinical presentation Hemorrhage Hemorrhage Hemorrhage Hemorrhage Hemorrhage Hemorrhage Hemorrhage - AVM Hemorrhage - AVM Spetzler & Martin Grading System Treatment Options Treatment Options Treatment Options Treatment Options Treatment Options Normal Perfusion Pressure Breakthrough Theory Normal perfusion pressure breakthrough theory Normal perfusion pressure breakthrough theory Normal perfusion pressure breakthrough theory Normal perfusion pressure breakthrough theory Arterial inflow Arterial inflow Nidus Arterial inflow Nidus Venous Outflow Anaesthesia Technique Surgical Resection Endovascular Embolisation Stereotatic Radiosurgery Multimodal Therapy Surgical Resection Endovascular Embolisation Stereotatic Radiosurgery Multimodal Therapy Conservative Management R.F. Spetzler et al Loss of autoregulation and carbon dioxide reactivity in presence of large arteriovenous malformation. Loss 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 Loss 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 Loss 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 Mathematical Models Mathematical Models Mathematical Models * AVM: a TLA for the CNS 0.52% at autopsy Slight male preponderance (1.09 to 1.94) Congenital lesions (although rarely familial) First 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 system First 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 absence of normal capillary system absence of normal capillary system usual function displaced absence of normal capillary system usual function displaced asymptomatic at birth absence of normal capillary system usual function displaced asymptomatic at birth vessels change with time may develop aneurysms Pathology & Pathophysiology absence of normal capillary system usual function displaced asymptomatic at birth vessels change with time may develop aneurysms Pathology & Pathophysiology absence of normal capillary system usual function displaced asymptomatic at birth vessels change with time may develop aneurysms 95% have symptoms by age of 70 years 95% have symptoms by age of 70 years peak presentation second to fourth decade 95% 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 & 3rd factors contributing to symptoms vessel walls, flow and pressures factors contributing to symptoms vessel walls, flow and pressures enlargement and encroachment factors contributing to symptoms vessel walls, flow and pressures enlargement and encroachment dural sinuses factors contributing to symptoms vessel walls, flow and pressures enlargement and encroachment dural sinuses ischaemia factors contributing to symptoms vessel walls, flow and pressures enlargement and encroachment dural sinuses ischaemia cardiac output AVM rupture not a function of size Aneurysm rupture related to aneurysm size AVM rupture not a function of size no marked increase with exercise, pregnancy, trauma Aneurysm rupture related to aneurysm size increase with trauma exercise, end pregnancy AVM rupture not a function of size no marked increase with exercise, pregnancy, trauma arteriovenous, therefore less severe Aneurysm rupture related to aneurysm size increase with trauma exercise, end pregnancy arterial, therefore more severe AVM 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% AVM 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%) AVM 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 rare Aneurysm rupture related to aneurysm size increase with trauma exercise, end pregnancy arterial, therefore more severe mortality 30-50% higher rebleed mortality rate (13%) vasospasm common Nonetheless, risk of major, incapacitating, or fatal hemorrhage in untreated lesion is 40 to 50% Nonetheless, 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 Criteria Score Size of Nidus Small (<3cm) 1 Medium (3-6cm) 2 Large (>6cm) 3  Eloquence of Adjacent Brain No 0 Yes 1  Deep Vascular Component No 0 Yes 1 Surgical Resection Surgical Resection Endovascular Embolisation Surgical Resection Endovascular Embolisation Stereotatic Radiosurgery *