Bleeding Risk in Unruptured and Residual Cerebral Aneurysms - Angiographic Annual Growth Rate in Nineteen Patients

Abstract

Whether and when unruptured aneurysms or aneurysmal rests following incomplete surgery result in subsequent bleeding are major concerns for neurosurgeons. By calculating the annual growth rate of aneurysms in long-term follow-up angiography (partly supplemented with MR-imaging and/or MR-angiography), we attempted to determine the surgical indications for these aneurysms. Long-term follow-up angiography ranging from one to 20 years was carried out on five patients whose ruptured aneurysms had been incompletely occluded, six patients with multiple aneurysms, of which the ruptured ones had been completely obliterated at operation and the small unruptured aneurysms, missed or misdiagnosed, and eight patients with unruptured aneurysms which were asymptomatic or symptomatic. The correlation of annual aneurysm growth rate to subsequent bleeding was investigated. Four out of six fast-growing aneurysms with high annual growth rates (more than 8% increase per year) resulted in subsequent bleeding whereas none of the fourteen slow-growing aneurysms with low annual growth rates (less than 8% increase per year) led to bleeding (Fisher's exact test; p < 0.01). Hypertension, patient age and aneurysmal location showed no significant correlation to the annual growth rate (Fisher's exact test; p > 0.05). This study suggests that aneurysmal rests after incomplete surgery and missed or misdiagnosed multiple or incidental aneurysms which are fast growing have a high possibility of subsequent bleeding and should be operated on as soon as possible.

A theoretical model for fibroblast-controlled growth of saccular cerebral aneurysms

“…Even though the size of the aneurysm is currently used as an indicator to determine the risk of rupture, it has been suggested that the growth rate of the aneurysm may also be a strong indicator of the rupture risk (Imaizumi et al, 2002;Kamitani et al, 1999). The growth rate of the present model aneurysm depends strongly on the life-time of the collagen fibres.…”

“…Yamaki et al (1986), for example, report about a cerebral aneurysm that enlarged from 2 mm to 15 mm in only 24 days, whereas Imaizumi et al (2002) report of an aneurysm that grew from about 4 mm to 10 mm in one year. Kamitani et al (1999) study the growth rate of a large population of unruptured cerebral saccular aneurysms. They report growth rates ranging from 1% up to 120% of size increase per year.…”

Simulation of Clipping Position for Cerebral Aneurysms Using Three-dimensional Computed Tomography Angiography

“…1,4,19,20) Additionally, the infundibulum of the PCoA partly implanted into the neck may prevent complete obliteration. 20) Many cases of regrowth and rerupture have been reported after clipping of ICA-PCoA aneurysms, 4,11,16,19,21) although the incidence of aneurysm remnants at this location differs. 14,16,18,20) Third, the present study included a thorough search for aneurysm remnants using endoscopy during surgery, especially around the blind corner between the aneurysm and its parent artery.…”

“…24) Aneurysm remnants after clipping may regrow and lead to recurrent symptoms of hemorrhage or mass effect. 4,5,[7][8][9]11,14,[16][17][18][19][20][21]24) Therefore, aneurysm surgery should aim at complete circulatory exclusion of aneurysms, but this cannot be achieved in several circumstances including large necks, insufficient exposure, and mal-positioning of clips. 4,7,9,20) Aneurysm remnants can be classified into two groups, dog-ear and broad-based remnant.…”

What is the Role of Clipping Surgery for Ruptured Cerebral Aneurysms in the Endovascular Era? A Review of Recent Technical Advances and Problems to be Solved

“…75) The residual neck after surgical clipping sometimes carries the risks of enlargement and rupture. 9,27,37,64,69) The incidence of neck residuals in postoperative angiographic series has been reported as 5-9%. 9,62,69) Technical advances in diagnostic tools enable more precise postoperative evaluation of surgical clipping.…”