The Natural History of Cerebral Aneurysms By: Ehsan Mohammad Hosseini Neurosurgery Resident at Isfahan University of Medical Science Advisor: Homayoun Tabesh M.D Assistant Professor of Neurosurgery

CEREBRAL ANEURYSMS Prevalence in general population: up to 2% Prevalence of aneurysmal SAH: 1 in 10000 85% anterior circulation. Occurs near branching vessels Can cause compressive cranial neuropathy (P.com aneurysm compressing CN III causing ptosis and pupil dilation) 3 types Saccular Fusiform Mycotic

Natural history is define as outcome of disease without any interventions. Unruptered Aneurysm & Ruptured Aneurysm

Overall mortality at 6 months: 40% - 50% 18% of patients expire before reaching the hospital; 25% within 24 hours. Only one third of those who survive have functional independent lives. Rebleed has a catastrophic morbidity : 48% to 78%.

Unruptered Aneurysm Prevalence

Rupture Rate of UIA

Risks factors for SAH in unruptured aneurysms Increased aneurysm size on serial imaging Aneurysm size > 10 mm Aneurysm between 6-9 mm in middle and young age group Posterior circulation aneurysms: especially basilar apex Previous SAH from another aneurysm Symptomatic aneurysms Females Cigarette smoking Binge alcohol drinking

Ruptured Aneurysm Short term; Hospitalization to 6 months after initial SAH Long term; After 6 months

Subarachnoid Hemorrhage:

MCA Larger in 70% ACA Ophthalamic Post communicating Anterior choroidal MCA Larger in 70% Pierces dura Hypophysial and meningial Carotid canal THE MAJORITY OF THE ANT. CER. ART. LIES WITHIN THE INTERHEMISPHERIC FISSURE AND TNE COLLOSAL CISTERN THIS SLIDE IS AN ANTERIOR VIEW OF A RIGHT CAROTID ART. ANGIOGRAM NOTE THE ICA SEGMENTS

Common patterns of aneurysms: branches and tortuous turns ICA system 85% are anterior (ICA) circulating aneurysms 15% are posterior (vertebrobasilar) circulating aneurysms Acom Artery aneurysms most common (30%) VB system

Intracranial superior view of the right sellar and parasellar region , AC: anterior clinoid process , ICA: internal carotid artery , LT: lamina terminalis , ON: optic nerve , OlN: olfatory nerve , SW: sphenoid wing , TS: tubercullum sellae

Frontal view of the anterior (carotid) intracranial circulation 15 A1 segment of anterior cerebral artery 32 lateral lenticulostriate arteries 16 medial lenticulostriate arteries 33 bifurcation/trifurcatio n of middle cerebral artery 1 internal carotid artery - cervical segment 17 recurrent artery of Heubner 2 internal carotid artery - vertical petrous segment 34 anterior temporal lobe branches of middle cerebral 18 A1-A2 junction anterior cerebral artery 3 internal carotid artery – horizontal petrous segment 43 sylvian point 19 anterior communicating artery 44 opercular branches of middle cerebral artery 4 presellar segment (C5) internal carotid artery 20 proximal A2 segment anterior cerebral artery 45 sylvian(insular) branches of middle cerebral artery 9 ophthalmic artery 21 callosomarginal branch of anterior cerebral artery 10 and 11 supraclinoid segment internal carotid artery 28 pericallosal branch of anterior cerebral artery 13 anterior choroidal artery 14 internal carotid artery bifurcation 31 M1 segment of middle cerebral artery

-Top down view (superior to inferior) of the skull base 35 orbitofrontal branch of MCA 45 sylvian(insular) branches of MCA BLACK KEY RED KEY 5 meningohypophyseal trunk 1 vertebral artery 6 horizontal (C4) intracavernous ICA 2 PICA 7 inferolateral trunk 3 basilar artery 9 ophthalmic artery 4 AICA 12 PCOM 5 superior cerebellar artery 13 anterior choroidal artery 6.1 P1 segment PCA 14 ICA bifurcation 6.2 P2 segment PCA 15 A1 segment of ACA 8 posterior temporal branch of PCA 19 ACOM 9 parieto-occipital branch of PCA 20 proximal A2 segment ACA 10 calcarine branch of PCA 21 callosomarginal branch of ACA 14 vertebral-basilar junction 28 pericallosal branch of anterior cerebral 16 pontine perforators 17 anterior spinal artery 31 M1 segment of MCA 33 bifurcation/trifurcation of MCA 34 anterior temporal lobe branches of MCA

-3D frontal view shows lobulated aneurysm arising from the tip of the basilar artery projecting posteriorly into the interpeduncular cistern 1 vertebral artery 2 PICA 3 basilar artery 4 AICA 5 SCA 6.1 P1 segment of (PCA) 6.2 P2 segment of (PCA) 7 PCOM 9 parieto-occipital branch of PCA 10 calcarine branch of PCA 14 vertebral basilar junction

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