Angiographically unrecognized microaneurysms: Intraoperative observation and operative technique

Abstract

Twenty operated cases of angiographically unrecognized microaneurysm (AUM) have been analysed with special reference to intra-operative observations and clipping-technique. Among the patients with intracranial aneurysms that the authors' facility has operated upon, the incidence of asymptomatic incidental AUM that was 2 mm or smaller amounted to 3.7%. Thirteen cases of AUM were found on the middle cerebral artery; four AUMs arose from the M1 portion, four from the bifurcation, and five from the second bifurcation. Sixty percent of AUMs were recognized on the parent arteries of ruptured aneurysms. In 90% of cases the AUMs were broad based in shape and in 70% of cases exhibited a thin-walled neck and a thin-walled fundus. Intra-operative findings revealed four reasons why AUMs were not visible in the pre-operative angiograms: (1) the AUM was sandwiched between two arteries; (2) the AUM was completely hidden by a contiguous large or giant aneurysm; (3) the AUM was diagnosed by pre-operative angiogram as a bleb of the contiguous aneurysm; (4) the AUM was not visible on angiograms because the height of the AUM was extremely low. Twelve cases of AUM were successfully clipped using four different clipping techniques; (1) clipping parallel to the bifurcation in four, (2) clipping parallel to the parent artery in four, (3) pinch-clipping in two of the cases, and (4) cross clipping in two of the cases. The other eight cases were wrapped and coated. AUMs may be present during the direct operation of intracranial aneurysms and in intravascular surgery. Neurosurgeons and neuroradiologists need to explain the possible existence of AUMs to patients and their families.

3D Rotational Angiography: The New Gold Standard in the Detection of Additional Intracranial Aneurysms

“…The phenomenon of angiographically occult additional aneurysms found during surgery of symptomatic aneurysms is well known in the surgical literature: Yaşargil 6 found, in his series of 1012 symptomatic aneurysms, 377 additional aneurysms, of which 169 (12.2% of all aneurysms) were 2 mm or smaller. Karasawa et al 5 and Inamasu et al 4 reported an incidence of 3.7% and 4.9% of angiographically occult microaneurysms of 2 mm or smaller. If technically possible, these microaneurysms were clipped or wrapped to prevent their growth and rupture.…”

“…[1][2][3] However, during surgery of symptomatic aneurysms, additional small angiographic occult aneurysms are commonly found with an incidence of 3.7%-12.2%. [4][5][6] Most neurosurgeons clip or wrap these additional microaneurysms to prevent their growth and rupture. Because the operative view during surgical exploration is restricted to part of the cerebral vasculature, it is likely that the incidence of these small additional aneurysms is higher than that reported in surgical series.…”

Current Treatment Strategies for Intracranial Aneurysms: An Overview

“…Microaneurysms ( Figure 1B ) are IAs with diameters smaller than 2 mm. 5 Most microaneurysms are chronic hypertension related, also known as Charcot-Bouchard aneurysms. They often occur in blood vessels smaller than 0.3 mm and prone to the microvessels in the basal ganglia.…”

Incidence, classification, and treatment of angiographically occult intracranial aneurysms found during microsurgical aneurysm clipping of known aneurysms

“…This incidence was comparable to two previously reported case series. 6,9 We included only patients with AO aneurysms with preoperative digital subtraction angiography (DSA); had we included patients with AO aneurysms without preoperative DSA, the 28% incidence in this group would have increased the overall incidence of AO aneurysms. AO aneurysms were located most frequently on the MCA and ACoA, and furthermore, there was a significantly higher incidence of AO aneurysms in the MCA and ACoA segments in patients with known MCA and ACoA aneurysms (5.2% vs 1.3% for MCA aneurysms [p < 0.0001] and 2.6% vs 0.6% for ACoA aneurysms [p < 0.0001] in patients with and without known aneurysms there, respectively).…”