Les relations neurochirurgie — neuroradiologie interventionnelle

Development of a mechanical characterisation device for intracranial aneurysms: Calibration on polymeric phantom arteries

Intracranial aneurysm is a major health issue related to biomechanical arterial wall degradation. Currently, no method allows predicting rupture risk based on in vivo quantitative mechanical data. This work is part of a large-scale project aimed at providing clinicians with a non-invasive patient-specific decision support tool, based on the in vivo mechanical characterisation of the aneurysm wall. Thus, the primary objective of the project was to develop a deformation device prototype (DDP) of the artery wall and to calibrate it on polymeric phantom arteries. The deformations induced on the phantom arteries were quantified experimentally using a Digital Image Correlation (DIC) system. The results indicated that the DIC system was able to measure the small displacements generated by the DDP. We also observed that the flow mimicking the blood flow did not significantly disturb the measurements of the artery wall displacement caused by the DDP. Finally, a limit displacement value generated by the DDP was evaluated. This value corresponds to the lowest displacement value detectable by the clinical imaging system that will be tested on animals in the future (Spectral Photon Counting CT).

[Treatment of grade 0 intracranial aneurysms: Retrospective study of 79 cases]

AIM

Without precise international recommendations, despite the advances of the ISUAA study, the superiority of microsurgery or endovascular treatment for unruptured intracranial aneurysm (UIA) over the natural history of this disease has not been proved. In this context, the authors evaluate their experience with the aim of assessing the results and risks of the different therapeutics and comparing them with the natural risk of this disease.

MATERIAL AND METHOD

From January 1993 to July 2000, 79 patients harboring 110 UIAs were treated. These patients were divided retrospectively into two groups. Group A included 45 operated patients. Group B included 37 patients treated with endovascular coiling. The therapeutic choice was not randomized and was approved by a multidisciplinary neurovascular staff.

RESULTS

The two populations were homogeneous in terms of age and sex. In group A, 12 patients presented early complications (26.6 %), with one death. In group B, 15.6 % of the patients presented an ischemic complication. After 1 year of follow-up, morbidity was 11.4 % in group A and 4.8 % for group B. Angiography found a partial recanalization in 12.5 % of the operated patients and in 33 % of the patients treated with endovascular coiling.

DISCUSSION

Many factors are involved in the therapeutic decision: UIA location and size and individual risks. Progress in both surgery and interventional neuroradiology has led to good results conforming with the data reported in the literature but does not demonstrate the superiority of one technique over another.

Anévrismes intracrâniens non rompus : que proposer ?

Intracranial unruptured aneurysm (ICUA) has become a common condition for patient consultation. The mortality rate after fissuration is estimated to be between 52% and 85.7%. The final therapeutic decision results from a balance between the risk of rupture and risks related to the aneurysmal exclusion. Analysis of the risk of rupture risk enables a classification of risk factors. Depending on the circumstances of diagnosis, we considered the ICUA at high risk of rupture for incidental ICUA larger than 7 mm and in the event of associated aneurysms. Classifying by morphologic features, high-risk ICUA were located in the vertebrobasilar system (RR: 4.4; 95%CI: 2.7-6.8), those with a size between 7 and 12 mm (RR: 3.3; 95%CO: 1.3-8.2), larger than 12 mm (RR: 17; 95%CI: 8-36.1), those that were multilobular or a larger size and those ones with a index P/L superior to 3.4 (risk x20). Familial ICUA would expose to a major rupture risk (2 to 7 times sporadic ICUA). Some systemic factors were related to ICUA rupture: arterial hypertension (RR: 1.46; 95%CI: 1.01-2.11) and smoking addiction (RR: 3.04; 95%CI: 1.21-7.66). After microsurgical exclusion, the morbidity and mortality rates were 10% and 2% respectively. Some microsurgical morbidity factors were identified: age (32%>65 years), size (14%>15 mm), vertebrobasilar location and temporary occlusion. The rupture incidence after microsurgical exclusion was estimated 0.26%/year. After endovascular exclusion, the morbidity and mortality rates were 8% and 1% respectively. The complete exclusion rate varied between 47% and 67%. The rupture risk was estimated at 0.9%/year. Treatment recommendations were classified into 3 categories.