1、CEREBRAL ARTERIOVENOUS MALFORMATIONS,AVM: a TLA for the CNS,Incidence,0.52% at autopsy Slight male preponderance (1.09 to 1.94) Congenital lesions (although rarely familial),Embryology,First half of third week of gestation epiblastic cells migrate to form mesoderm mesodermal cells differentiate to a
2、rterial and venous vessels on the surface of the embryonic nervous system,Embryology,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 v
3、essels sprout branches & penetrate developing brain reach the gray-white interface, either loop back to pial surface or traverse entire neural tube, thus epicerebral & transcerebral circn eventually connect arterial and venous systems by around the twelfth week,Pathology & Pathophysiology,absence of
4、 normal capillary system,Pathology & Pathophysiology,absence of normal capillary system usual function displaced,Pathology & Pathophysiology,absence of normal capillary system usual function displaced asymptomatic at birth,Pathology & Pathophysiology,absence of normal capillary system usual function
5、 displaced asymptomatic at birth vessels change with time may develop aneurysms,parenchymal changes within and around the lesion,Pathology & Pathophysiology,absence of normal capillary system usual function displaced asymptomatic at birth vessels change with time may develop aneurysms,parenchymal ch
6、anges within and around the lesion site frequency is proportional to brain volume,Pathology & Pathophysiology,absence of normal capillary system usual function displaced asymptomatic at birth vessels change with time may develop aneurysms,Clinical presentation,95% have symptoms by age of 70 years,Cl
7、inical presentation,95% have symptoms by age of 70 years peak presentation second to fourth decade,Clinical presentation,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, seizur
8、es, 2nd & 3rd,Clinical presentation,factors contributing to symptoms vessel walls, flow and pressures,Clinical presentation,factors contributing to symptoms vessel walls, flow and pressures enlargement and encroachment,Clinical presentation,factors contributing to symptoms vessel walls, flow and pre
9、ssures enlargement and encroachment dural sinuses,Clinical presentation,factors contributing to symptoms vessel walls, flow and pressures enlargement and encroachment dural sinuses ischaemia,Clinical presentation,factors contributing to symptoms vessel walls, flow and pressures enlargement and encro
10、achment dural sinuses ischaemia cardiac output,Clinical presentation,Hemorrhage,AVM rupture not a function of size,Aneurysm rupture related to aneurysm size,Hemorrhage,AVM rupture not a function of size no marked increase with exercise, pregnancy, trauma,Aneurysm rupture related to aneurysm size inc
11、rease with trauma exercise, end pregnancy,Hemorrhage,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,Hemo
12、rrhage,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%,Hemorrhage,A
13、VM 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 mor
14、tality 30-50% higher rebleed mortality rate (13%),Hemorrhage,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 inc
15、rease with trauma exercise, end pregnancy arterial, therefore more severe mortality 30-50% higher rebleed mortality rate (13%) vasospasm common,Hemorrhage - AVM,Nonetheless, risk of major, incapacitating, or fatal hemorrhage in untreated lesion is 40 to 50%,Hemorrhage - AVM,Nonetheless, risk of majo
16、r, 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,Spetzler & Martin Grading System,Criteria,Score,Size of Nidus,Small (3cm),1,Medium
17、 (3-6cm),2,Large (6cm),3,Eloquence of Adjacent Brain,No,0,Yes,1,Deep Vascular Component,No,0,Yes,1,Treatment Options,Surgical Resection,Treatment Options,Surgical Resection Endovascular Embolisation,Treatment Options,Surgical Resection Endovascular Embolisation Stereotatic Radiosurgery,Treatment Opt
18、ions,Surgical Resection Endovascular Embolisation Stereotatic Radiosurgery Multimodal Therapy,Treatment Options,Surgical Resection Endovascular Embolisation Stereotatic Radiosurgery Multimodal Therapy Conservative Management,Normal Perfusion Pressure Breakthrough Theory,R.F. Spetzler et al,Normal pe
19、rfusion pressure breakthrough theory,Loss of autoregulation and carbon dioxide reactivity in presence of large arteriovenous malformation.,Normal perfusion pressure breakthrough theory,Loss of autoregulation and carbon dioxide reactivity in presence of large arteriovenous malformation. Normal hemisp
20、heric vessels are chronically maximally dilated to attempt to divert flow from the AVM,Normal perfusion pressure breakthrough theory,Loss of autoregulation and carbon dioxide reactivity in presence of large arteriovenous malformation. Normal hemispheric vessels are chronically maximally dilated to a
21、ttempt 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,Normal perfusion pressure breakthrough theory,Loss of autoregulation and carbon dioxide reactivity in presence of large arteriovenous malform
22、ation. 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,Arterial inflow,Mathematical Models,Arterial inflow Nidus,Mathematical Models,Arterial inflow Nidus Venous Outflow,Mathematical Models,Anaesthesia Technique,
