Unruptured middle cerebral artery aneurysm case series

Anatomy of the MCAs of 54 patients with unruptured middle cerebral artery aneurysms was retrospectively analyzed, as was that of 54 sex-, age-, and vessel side-matched control patients without MCA aneurysms. From medical records, Kliś et al., obtained each patient's medical history including previous and current diseases and medications. For each patient, they calculated the following tortuosity descriptors: relative length (RL), sum of angle metrics (SOAM), triangular index (TI), product of angle distance (PAD), and inflection count metric (ICM).

Patients with an MCA aneurysm had significantly lower RLs (0.75 ± 0.09 vs 0.83 ± 0.08, p < 0.01), SOAMs (0.45 ± 0.10 vs 0.60 ± 0.17, p < 0.01), and PADs (0.34 ± 0.09 vs 0.50 ± 0.17, p < 0.01). They also had significantly higher TIs (0.87 ± 0.04 vs 0.81 ± 0.07, p < 0.01) and ICMs (3.07 ± 1.58 vs 2.26 ± 1.12, p < 0.01). Female patients had significantly higher RLs (0.76 ± 0.11 vs 0.80 ± 0.09, p = 0.03) than male patients.

Middle cerebral artery aneurysm formation is strongly associated with blood vessel tortuosity parameters, which can potentially be used to screen for patients at risk for MCA aneurysm formation ¹⁾.

411 patients with single unruptured MCA aneurysms treated with simple microsurgical clipping were enrolled. Patients were divided into two groups based on the application of somatosensory evoked potential (SSEP) monitoring during surgery.

The Ischemic complications (ICs) rate was 0.9% and 5.6% in the SSEP and non-SSEP groups, respectively. Univariate analysis revealed that age≥62.5years, aneurysm size≥4.15mm, temporary clipping, history of hyperlipidemia and stroke, and no-SSEP monitoring were risk factors for ICs. Multivariate logistic regression analysis showed that age≥62.5years (odds ratio [OR]=7.7; 95% confidence interval [95% CI]=1.5-37.7; P=0.011), previous stroke (OR=26.8, 95% CI=2.4-289.2, P=0.007), and inversely SSEP monitoring (OR=0.14, 95% CI 0.02-0.72, P=0.019) were independent risk factors for ICs.

Clinicians should consider the possibility of IC during microsurgical clipping of unruptured MCA aneurysms in patient ≥ 62.5years and/or a history of stroke. Intraoperative SSEP monitoring is an effective and feasible tool for preventing IC ²⁾.

Fifty unruptured middle cerebral artery aneurysms were analyzed. Spatial and temporal maximum pressure (Pmax) areas were determined with a fluid-flow formula under pulsatile blood flow conditions. Intraoperatively, thin walled regions (TWRs) of aneurysm domes were identified as reddish areas relative to the healthy normal middle cerebral arteries; 5 neurosurgeons evaluated and divided these regions according to Pmax area and TWR correspondence. Pressure difference (PD) was defined as the degree of pressure elevation on the aneurysmal wall at Pmax and was calculated by subtracting the average pressure from the Pmax and dividing by the dynamic pressure at the aneurysm inlet side for normalization.

In 41 of the 50 cases (82.0%), the Pmax areas and TWRs corresponded. PD values were significantly higher in the correspondence group than in the noncorrespondence group (P = .008). A receiver-operating characteristic curve demonstrated that PD accurately predicted TWRs at Pmax areas (area under the curve, 0.764; 95% confidence interval, 0.574-0.955; cutoff value, 0.607; sensitivity, 66.7%; specificity, 82.9%).

A high PD may be a key parameter for predicting TWRs in unruptured cerebral aneurysms ³⁾.

416 patients treated between March 2003 and February 2014. All patients met the following criteria: 1) microsurgical clipping of an unruptured MCA bifurcation aneurysm was performed, and 2) clinical and radiographic follow-up data were available including preoperative digital subtraction angiography. The incidence of and risk factors for procedure-related complications were retrospectively evaluated.

Procedure-related complications occurred in 15 (3.6%) patients, including asymptomatic complications in 10 (2.4%) patients and symptomatic complications in 5 (1.2%) patients. Multivariate logistic regression analysis showed that posteroinferior projection of the aneurysm (odds ratio = 2.814, 95% confidence interval = 0.995-6.471, P = 0.042), distance between the internal carotid artery bifurcation and the MCA bifurcation (Dt) in a linear line (odds ratio = 1.813, 95% confidence interval = 0.808-6.173, P = 0.043), and horizontal angle between the vertical line to the base of the skull and Dt (odds ratio = 2.046, 95% confidence interval = 1.048-10.822, P = 0.048) were independent risk factors for procedure-related complications.

When performing clipping of unruptured MCA bifurcation aneurysms, the procedure-related complication rate was 3.6%. Patients with MCA bifurcation aneurysms with posteroinferior projection, shorter Dt, and larger horizontal angle may be at a higher risk of procedure-related complications when performing microsurgical clipping ⁴⁾.

Clinical and radiological data of 103 patients interdisciplinary treated for unruptured MCA aneurysms over a 5-year period were analyzed in endovascular (n = 16) and microsurgical (n = 87) cohorts. Overall morbidity (Glasgow Outcome Score <5) after 12-month follow-up was 9 %. There was no significant difference between the two cohorts. Complete or “near complete” aneurysm occlusion was achieved in 97 and 75 % in the microsurgical, respective endovascular cohort. A “complex” aneurysm configuration had a significant impact on complete aneurysm occlusion in both cohorts, however, not on clinical outcome. Treatment of unruptured MCA aneurysms can be performed with a low risk of repair using both approaches. However, the risk for incomplete occlusion was higher for the endovascular approach in this series ⁵⁾.

Individualized surgical simulation using three-dimensional (3D) imaging to allow safe performance of clipping surgery for unruptured middle cerebral artery (MCA) aneurysm via pterional keyhole mini-craniotomy was performed in 100 consecutive patients.

3D images were reconstructed of the skin, skull, cerebral arteries and veins, and aneurysm. The size, shape, and location of the scheduled keyhole and the patient's head position were individually optimized using this preoperative simulation system. The site of opening of the sylvian fissure was also preoperatively determined according to the spatial relationships between the aneurysm and sylvian veins. 110 pterional keyhole clipping surgeries were consecutively performed in 100 patients.

The mean diameter of the pterional keyhole was 25±2 mm. Magnetic resonance imaging detected lacunar infarction in 4 cases (3.6%) but no other abnormalities. 1 patient suffered a reversible ischemic neurological deficit and 1 patient (79 years old) showed mild dementia. The modified Rankin scale at 3 months after the operation was grade 0 in all cases except 1 patient with mild dementia (grade 1). Mini-mental state examination, Hamilton rating scale for depression, and Beck depression inventory were all significantly improved (p<0.01) after the operations.

Pterional keyhole clipping surgery based on careful surgical simulation with 3D images is a safe and less invasive means to treat relatively small unruptured MCA aneurysms ⁶⁾.