The “focus on aneurysm” principle: Classification and surgical principles of management of concurrent arterial aneurysm with arteriovenous malformation causing intracranial hemorrhage

CONTEXT: Concurrent arterial aneurysms (AAs) occurring in 2.7-16.7% patients harboring an arteriovenous malformation (AVM) aggravate the risk of intracranial hemorrhage. AIM: We evaluate the variations of aneurysms simultaneously coexisting with AVMs. A classification-based management strategy and an abbreviated nomenclature that describes their radiological features is also proposed. SETTING: Tertiary care academic institute. STATISTICS: Test of significance applied to determine the factors causing rebleeding in the groups of patients with concurrent AVM and aneurysm and those with only AVMs. SUBJECTS AND METHODS: Sixteen patients (5 with subarachnoid hemorrhage and 11 with intracerebral/intraventricular hemorrhage; 10 with low flow [LF] and 6 with high flow [HF] AVMs) underwent radiological assessment of Spetzler Martin (SM) grading and flow status of AA + AVM. Their modified Rankin's score (mRS) at admission was compared with their follow-up (F/U) score. RESULTS: Pre-operative mRS was 0 in 5, 2 in 6, 3 in 1, 4 in 3 and 5 in 1; and, SM grade I in 5, II in 3, III in 3, IV in 4 and V in 1 patients, respectively. AA associated AVMs were classified as: (I) Flow-related proximal (n = 2); (II) flow-related distal (n = 3); (III) intranidal (n = 5); (IV) extra-intranidal (n = 2); (V) remote major ipsilateral (n = 1); (VI) remote major contralateral (n = 1); (VII) deep perforator related (n = 1); (VIII) superficial (n = 1); and (IX) distal (n = 0). Their treatment strategy included: Flow related AA, SM I-III LF AVM: aneurysm clipping with AVM excision; nidal-extranidal AA, SM I-III LF AVM: Excision or embolization of both AA + AVM; nidal-extranidal and perforator-related AA, SM IV-V HF AVM: Only endovascular embolization or radiosurgery. Surgical decision-making for remote AA took into account their ipsilateral/contralateral filling status and vessel dominance; and, for AA associated with SM III HF AVM, it varied in each patient based on diffuseness of AVM nidus, flow across arteriovenous fistula and eloquence of cortex. Follow up (F/U) (23.29 months; range: 1.5-69 months) mRS scores were 0 in 12, 2 in 2, 3 in 1 and 6 in 1 patients, respectively. CONCLUSIONS: Patients with intracranial AVMs should be screened for concurrent AAs. Further grading, management protocols and prognostication should particularly “focus on the aneurysm.”