The combined treatment of stenting and surgery in a giant unruptured aneurysm of the middle cerebral artery.

BACKGROUND: This case study reports on a combined therapy of stenting and surgery for a giant unruptured middle cerebral artery (MCA) aneurysm with the aim of preserving the patency of the vessel during surgery. CASE DESCRIPTION: A 51-year-old male presented with a sudden onset of moderate left hemiparesis and dysarthria. Neuro-radiological evaluations showed a giant right unruptured MCA aneurysm without subarachnoid hemorrhage (SAH). The cerebral angiography confirmed the presence of such an aneurysm producing compression of both M2 branches with consequent slowing of the blood flow. Two weeks later, the patient underwent the positioning of an Enterprise stent and inside this, a flow diverter Silk stent. They were placed across the aneurysm and in one of the two M2 branches with the aim of protecting them during surgical manipulation. The patient went immediately to surgery, where the aneurysm was resected and both M2 branches decompressed.
CONCLUSION: The combined placement of the stents allowed safe and successful surgical dissection of the M2 branches and clipping of the aneurysm without interrupting the blood flow.

INTRODUCTION

The endovascular treatment of intracranial aneurysms is well-defined in neurosurgery and its role is becoming increasingly preeminent, thanks to continuous technical improvements.[13949] We present the case of a right giant unruptured middle cerebral artery (MCA) aneurysm treated with a combined procedure of first stenting and then immediate clipping of the aneurysm. The reason for positioning a stent across the neck of the aneurysm and along the main branch of the MCA was to guarantee the patency of the vessel during dissection of the sac and the maneuvers of clipping. Furthermore, considering the preexistent critical blood perfusion it seemed mandatory to avoid any temporary closure of the MCA. To our knowledge, this is a novel approach where a preliminary stenting has been performed with the aim of making the surgical procedure of resecting a giant aneurysm in the same morning safe.

CASE DESCRIPTION

Clinical history and baseline data

A 51-year-old male was hospitalized in our department following sudden onset of a left hemiparesis. The cerebral computed tomography (CT) and the computed tomographic angiogram (CTA) scans, carried out at admission, showed a right giant MCA aneurysm without subarachnoid hemorrhage (SAH) but with mass effect [Figure 1]. The baseline cerebral angiography confirmed the presence of a giant aneurysm (about 20 × 30 mm with the largest perpendicular diameters in the anteroposterior projection) at the MCA bifurcation. The vascular flow through the MCA was very slow and its contrast opacification was delayed with respect to the ipsilateral anterior cerebral artery (ACA) by 1.75 s [Figure 2]. No embolic occlusions were seen. Angiographic images of the left carotid artery and vertebro-basilar complex were normal. At admission, an antiedema therapy with dexamethason was administered, which favoured the almost complete recovery of the symptoms within a few days.

Figure 1

(a,b,c) The CT and CTA carried out at admission showed a right giant unruptured MCA aneurysm

Figure 2

(a,b) The baseline cerebral angiography showed a giant right MCA aneurysm with the largest perpendicular diameters at the anteroposterior projection of about 20 × 30 mm. Note the delayed and reduced contrast opacification (a and b, black arrows) of the MCA distal to the aneurysm. (c) The slowing of the blood flow (c, black arrow) was well-evident in venous phase

Therapeutic strategy and clinical neuroradiological follow-up

With the aim of avoiding any interruption of the bood flow, we decided to perform a combined therapeutic strategy with stenting and surgery. The stenting would protect the MCA and its branches during the surgical maneuvers of dissection and clipping of the aneurysm.

On the day of surgery under general anesthesia in the radiology unit, an Enterprise stent (4.5 × 37 mm) (Cordis Neurovascolar, Miami Lakes, Florida, USA) was first placed from the right carotid dichotomy to the proximal M2 segment of the inferior trunk. Afterwards a flow diverter Silk stent (2.5 × 15 mm) (Balt, Montmorency, France) from the distal M1 segment to the proximal M2 segment of the inferior trunk was placed to complete the coverage of the aneurysmal neck. No stent was placed in the M2 superior thinner trunk of the right MCA. At the end of the endovascular procedure, an angiogram was performed, which showed a major staunching of blood within the sac, patency of the MCA, and the correct position of both stents [Figure 3]. At this point, the patient was moved to the neurosurgical operating room, where a standard pterional approach was performed. Once the sylvian fissure was opened, the aneurysm was immediately visible. Both the M2 trunks of the MCA were seen firmly adhered to the sac. The inferior trunk was larger and the flow diverter Silk stent was visible through the transparency of the arterial wall. Stenting had made the vessel stiffer [Figure 4a and b], easing significantly surgical manipulation during the dissection and also preventing arterial spasms. After freeing the M2 superior trunk [Figure 4c], the aneurysmal neck has been exposed and multiple clips were applied. Because of the consistency of the neck, the first clip tended to slip on the neck, wich in effect was protected by the stent. Three clips and the opening of the aneurysm were necessary to collapse the sac, which was then resected [Figure 4d]. Despite the previous stenting, abundant bleeding occurred during the emptying of the sac. As expected, the patency of the vessels ramained protected by the stents during the entire surgical phase.

Figure 3

(a,b,c) The right carotid artery injection on the day of combined treatment just before surgery. It was clearly visible the flow diverter SILK stent (b, black arrow) allocated from the distal M1 to the proximal M2 for a length equal to 15 mm

Figure 4

(a,b) The M2 inferior branch was sharply dissected from the wall of the giant aneurysm with a microblade, the vessel kept his steadiness facilitating the dissection and the branch of the MCA maintained the shape thanks to the Silk stent (b, black continued arrow) and the Enterprise stent (b, black interrupted arrow). (c) The dissection of the M2 superior branch with the exposure of adequate working-space around neck aneurysm for clipping. (d) Note the clipping of the aneurysm with three clips and patency of the protected neck

After surgery the patient remained in the intensive care unit for 2 days. Upon awakening, he showed a moderate left hemiparesis, which improved 3 weeks after surgery. A postoperative CT showed hypodensity around the surgical field [Figure 5].

Figure 5

(a,b) The CT performed 2 days after the combined treatment showed hypodensity in the surgical field

Cerebral angiography monitoring at 1-year showed the complete exclusion of the aneurysmal sac, no delay in the venous phase was seen while optimal flow through both M2 branches was noted [Figure 6].

Figure 6

(a) The cerebral angiography performed 1 year after the combined treatment showed a normal blood flow through the M1 segment and both M2 trunks. (b) Note the allocation of the more proximal clip that runs along the wall of MCA being protected from stents

Anticoagulant and antiplatelet therapy management

An important issue is the management of the anticoagulant/antiplatelet therapy. We use a standard protocol for stenting alone or with coiling as follows: 5 days of double antiplatelet theraphy before the procedure with acetylsalicylic acid (100 mg once daily) and clopidrogel (75 mg once daily), a bolus of 5000 UI of heparin at benning of the treatment followed by 1000 UI of heparin hourly during the procedure. After that, we administer both antiplatelet drugs for the first 3 months and then only acetylsalicylic acid for the following 2 months after the procedure at dosages reported in the pretreatment regimen.

In this case, we decided to modify the standard therapy on the days before and on the day of combined treatment.

Three days before the combined treatment, prophylaxis with heparin, started at admission, was interrupted and antiplatelet therapy only with acetylsalicylic acid (100 mg once daily) was administered orally. On the day of combined treatment, a double pharmacological antiplatelet therapy was administered. Acetylsalicylic acid (100 mg once daily) was administered before the stenting and clopidrogel (75 mg once daily) just after closing the duramater. No bolus of heparin was administered at the beginning of endovascular procedure. However, as in all endovascular procedures, all pressure washing systems were fully heparinized. One day after surgery, the patient started with the standard therapy with both antiplatelet drugs for the first 3 months and then with acetylsalicylic acid only for the following 2 months at the usual dosages. No particular problems of immediate or later bleeding with the wound was managed in this case.

DISCUSSION

Intracranial giant aneurysms are severe neurovascular lesions, which should be treated aggressively considering their poor natural history.[1226] Most frequently, giant aneurysms are localised at MCA bifurcation, with an incidence of about 4–7%.[1241] They are characterized by intraluminal thrombi, mural calcifications, fusiform aspect, incorporation of M1 tract-M2 branches into the base or dome becoming consequently challenging for either surgical clipping or coiling alone.[41] Due to the anatomical variability of such aneurysms, several surgical strategies have been performed for these complex cases, as aneurysm thrombectomy with clip reconstruction,[16414550] aneurysm exicision with an in situ bypass,[314041] Hunterian proximal MCA occlusion[610144150] and surgical trapping[71014374150] both with or without cerebral rivascularization. Many vascular neurosurgeons actually prefer safe alternatives to surgery, as endovascular parent artery sacrifice with possible surgical extracranial–intracranial bypass.[924344148] More recently, Kato et al.[12] have treated two giant MCA aneurysms combining multiple arterial reimplantation, Nakajima et al.[26] cured 13 giant MCA aneurysms with clipping (4), trapping and removal of sac (1), and microvascular reconstruction techniques (8); not lastly, Shi et al.[41] managed nine giant MCA aneurysms with incorporated branches performing partial endovascular coiling alone or in combination with extracranial bypass.

Moreover, among different surgical strategies documented in the literature, direct clipping[264450] or eventually reconstructive neck clipping[323850] of giant MCA aneurysms have been suggested, when the morphology of the aneurysm, its location and hemodynamic features are favorable. Furthermore we have to underline that the majority of the above-mentioned strategies have included temporary or permanent parent vessel occlusion.

In our case, the main problem was insufficient vascular blood flow distally to the giant MCA aneurysm due to the aneurysmal mass effect on M2 branches. The situation was clear with the CTA at admission, and later it was confirmed by the angiogram. Esteban et al.[8] described already that perfusion abnormalities due to arterial stenoses or occlusions may be suspected even from angio CT. In spite of the collateral vessel formation at the baseline angiogram after right carotid injection, the blood flow was not adequate to prevent the onset of a left hemiparesis and dysarthria. Vascular flow through the MCA was delayed with the respect to the ipsilateral ACA of 1.75 s. In effect, Kim et al.[13] have showed a correlation between angiographic collateral flow, infarct volume and outcome in patients with MCA occlusion highlighting that leptomeningeal collateral flow may be insufficient to sustain cerebral perfusion without recanalization.

In the reported case, the aneurysmal compression on the M1 tract-M2 branches was persistent and likely also affected the lenticulostriate arteries around the MCA bifurcation. For this reason we have considered at risk any strategy that would accept any form of even temporary proximal occlusion of MCA. Consequently, despite the devolopment of endovascular technology,[1322232829394749] we did not consider safe enough the possibility of stenting alone or in combination with coiling, as this would probably increase the compression on M1 tract-M2 branches further reducing blood flow.

In this case, we also retained that direct clipping of the aneurysm would also create the risk of spasm and damage to the M2 branches during their dissection. Furthermore, the clipping itself, due to the thickness of the wall, would increase the risk of losing the patency of MCA at the level of the neck during the surgical maneuvers. We did not trust the possibility of a compensatory blood pressure augmentation and burst suppression as we would probably need them for a longer period.

Evaluating then the strategy of revascularization with high-flow bypass, the compressed recipient M2 vessels, partially hidden by the aneurysmal sac, would be too thin to build a safe and patent bypass, apart from the usual well known problem of the temporary occlusion of a M2 branch. Neither did we consider a low-flow bypass sufficient. The low-flow bypass could be anyway inadequate or, in any case, would need a longer time to become functionally helpful, while the clinical situation required more urgent therapeutical management.

We decided finally to adopt a combined strategy that would keep the vascularization during the entire procedure. In the literature, a combined treatment approach for the same aneurysm has been described in the following different situations: (i) Delayed endovascular[2417] or surgical treatment[215171933] after previously unsuccessful surgical or endovascular treatment; (ii) temporary endovascular parent artery occlusion during clipping,[27424346] and (iii) microsurgical revascularization followed by endovascular parent artery occlusion and flow-redirection techniques.[91730] In our experience,[42] we have previously treated a series of eight giant paraclinoid and four vertebro-basilar aneurysms in combination with the neuroradiologist, where an adequate flow allowed a temporary occlusion. However, according to our knowledge, such a combined treatment in the same morning has never been described and represents a novel strategy in the exclusion of giant aneuysms. Reinforcing with stents the MCA at the level of the aneurysmal neck and the main M2 branch has allowed to keep the patency of vessels during surgery giving to the surgeon the time to perform in safety all the surgical maneuvers to resect the aneurysm and free the M2 branches. The first stent was used with the aim of allowing a better expansion and adhesion of the flow-diverter stent to the wall, thus reducing the risk of dislocation.[20] Both types of stents were chosen by the neuroradiologist due to his own experience. In his opinion, the Enterprise stent is easier to use in positioning, navigability and it has a good radial force, while the Silk stent is more adaptable inside another stent and has a wide range of measures, which makes it very versatile.

Another issue in this case was the antiplatelet and heparinic anticoagulant drug therapy before, during, and after the combined treatment. According to several authors,[5111821253536] this therapy is commonly established by the administration of dual antiplatelet therapy pre- and poststenting phase, usually acetylsalicylic acid and clopidrogel. If necessary, heparin may be administered during the endovascular procedure and even some variability in dosages and timing might be considered. However, no data is available concerning variations of antiplatelet/anticoagulant therapy in advance of early surgery. In this case, no bolus of heparin was administered at beginning of the stenting but as in any endovascular procedures all the pressure washing systems were fully heparinized. Furthermore, to speed all the procedure the patient and the operating room were prepared for surgery, so about 2 h after stenting, the aneurysm was already clipped and the dura closed, thus allowing the administration of clopridogel.

CONCLUSION

The combined treatment of a giant aneurysm with stenting, followed by immediate clipping, may be taken into consideration, whenever it is necessary to protect and strengthen the arterial walls during surgical maneuvers. Selected neoplastic lesions might also benefit from this strategy.