Surgical clipping of a dissecting aneurysm of the precommunicating segment of the anterior cerebral artery: a case report and review of the literature

A 20-year-old previously healthy Caucasian woman was admitted to a local hospital because of the sudden onset of severe headache and loss of consciousness. Computed tomography (CT) revealed diffuse subarachnoid hemorrhage (SAH) involving the basal cisterns and the anterior part of the interhemispheric fissure. The SAH was classified as group 3 according to the Fisher’s scale [19]. She was then referred to our hospital and, upon admission, a neurological examination showed severe headache and nuchal rigidity (Grade II of the Hunt and Hess scale).

Neuroradiological investigation by means of computed tomography angiography (CTA) disclosed a dissecting aneurysm of the A₁ segment of the right ACA (Figure 1A-C). Digital subtraction angiography confirmed the presence of the dissecting aneurysm of the A₁ segment of the right ACA originating from the parent vessel with a very acute angle (Figure 1D). No perforating arteries were clearly detected. Moreover, hypoplasia of the distal part of the right A₁ segment (that is, close to the anterior communicating artery) was highlighted. Both right and left postcommunicating segments (A₂) were perfused from the left ACA, and a balloon occlusion test of the right ICA was performed in order to validate this condition (Figure 1E).

Because of the characteristic angulation of the aneurysm and the non-accessibility from the opposite site through the anterior communicating artery – due to the hypoplasia of the distal part of the A₁ segment of the right ACA and to the vasospasm – it was not possible to perform an endovascular treatment (Figure 1F). Accordingly, surgery was chosen by means of clipping the right ACA through a right standard pterional craniotomy (Figure 2) [20]. Using a microsurgical technique the dura mater was opened and reflected anteriorly. Afterwards, with sharp arachnoid dissection the sylvian fissure was opened in a distal-to-proximal direction in order to achieve cerebrospinal fluid release and brain relaxation; these maneuvers allowed us to reduce brain retraction and to visualize the right ICA, with its bifurcation, and the homolateral optic nerve. Finally, a vascular clip was positioned at the origin of the right ACA.

Postoperatively, her headache progressively diminished and left-side weakness initially presented (Grade 3 of the Medical Research Council scale); her left-side weakness was relieved by medical therapy with dihydropyridine calcium channel blocker (nimodipine) and corticosteroids. No other medications were used.

CT scans, performed at postoperative days (PODs) 3 and 7, showed a right frontobasal hypodensity area – as per subacute ischemic stroke – and progressive resorption of the SAH (Figure 3A-B). Early postoperative CTA- magnetic resonance imaging scans (1 month) confirmed and characterized the right frontobasal subacute ischemia with regular flow of the anterior cerebral circulation (Figure 3C).

Neurologic examination remained otherwise unchanged and she was discharged on POD 24 without any new neurological defect.

A late postoperative angiography (3 months) showed the correct positioning of the clip, with regular perfusion of both right and left anterior postcommunicating cerebral arteries (Figure 3D).

Six months after surgical treatment she showed no clinical and/or neurological defects of new onset and resumed her ordinary life.

Written informed consent was obtained from the patient for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.