Introduction
For many years, endovascular coiling or surgical clipping has been used in the treatment of intracranial aneurysms.4) However, the type of imaging studies required for the follow-up evaluation of these patients remains controversial. Conventional angiography and three- dimensional computed tomographic angiography (3D-CTA) are the methods mainly used for the imaging assessment of surgical clipping at follow up. Conventional angiography is the gold standard in the operative assessment of clip position. 3D-CTA is an easy alternative to conventional angiography, but it also has a number of limitations, including image quality and clip artifact.
In this study, conventional angiography was used for follow-up imaging of 45 patients who had undergone the clipping procedure. The objective of this study was to determine whether postoperative angiography conducted during the acute stage after aneurysm clipping was useful in patients with ruptured aneurysms.
Methods
During a 1.5-year period from May 2008 to November 2009, 57 patients were admitted to our surgical intensive care unit for subarachnoid hemorrhages (SAH). All SAHs and ruptured cerebral aneurysms were confirmed by computed tomography and conventional angiography and were surgically clipped; they represented 85% of all treated aneurysmal SAHs during that period. Among them, a consecutive series of 45 patients who underwent postoperative angiography were studied retrospectively. The parameters classified on postoperative angiography included incomplete clippings, vasospasms, vascular compromises (i.e. vessel stenosis and occlusion) and other aneurysms.
Results
The average age of the 45 investigated patients was 49.2 years and ranged from 18 to 72. There were 24 men and 21 women. The location of the aneurysms was mostly in the anterior circulation (Table 1). Anterior communicating artery aneurysms were the most common (36%). We have routinely performed postoperative digital subtraction angiography (DSA) on the seventh day after SAH. The average timing of the postoperative angiography after the onset of hemorrhage was 11.1 (±5.6) days.
Complete aneurysm closure was achieved in 42 patients (93%), whereas incomplete clippings were found in three (6.7%) patients, as presented in Table 2. Aneurysmal neck remnants were discovered in two patients and a fundus remnant was revealed in one patient. For the two patients with a neck remnant aneurysm, we considered that they did not need further treatment and thus, they were observed. A Guglielmi detachable coil embolization was performed in the patient with the fundus remnant, which indicated incomplete clipping. Twelve (27%) patients showed angiographic vasospasms and seven of them had either severe or symptomatic vasospasms that needed angioplasty. Chemical angioplasty was performed during angiography by intra-arterial nimodipine injection (Fig. 2). Four cases (9%) revealed parent artery stenosis or branch occlusions and two of them (4%) were clinically significant. Two cases showed aneurysms at another location, one of which was a ruptured aneurysm. Thus, an additional surgical clipping was performed in that case.
Overall, 21 (47%) patients showed significant findings in the postoperative angiography. Among them, vasospasm was the most common finding (Table 2). All patients were successfully imaged without procedural complications associated with transfemoral catheter angiography.
Discussion
The postoperative estimation of endovascular coils or vascular clips for the treatment of aneurysms is required in order to determine the efficiency of the initial procedure and to assess whether additional endovascular or surgical treatments are required.5)7) The choice of the best imaging examination is controversial. For vascular clip placement, the recommendations for postoperative evaluation are less well-defined, and follow-up conventional angiography or treatment may be more limited after vascular clip placement.2)8)
The detection of residual aneurysms and vasospasms is important. Despite the fact that small-sized residual aneurysms have been thought to create relatively little risk, incomplete clipping of an intracranial aneurysm may result in progressive enlargement of the residual portion and rupture at a weak point. The rates of residual aneurysms after initial clipping have been reported to be about 3.8 to 18%.4-6)8)10)11) These residual aneurysms can also present with neurologic symptoms from a local mass effect.5) The rebleeding rate of aneurysms with residual necks has been reported to be about 3.5 to 28%4)10)11) and aneurysm regrowth has been reported to occur in 3.5~15% of patients.4)10) Consequently, treatment of the residual aneurysm is mandatory, especially in patients of a young age.5) The rate of aneurysm re-rupture was reported to be about 2.7%, even after complete surgical clipping of the aneurysm.4)10) In this regard, a new multidisciplinary decision-making process has been proposed.11)
Much of the morbidity and mortality associated with SAHs in the days after the initial event is secondary to cerebral vasospasms.1) Angiographic vasospasm, usually visualized by conventional angiography or CTA, refers to stenosis in the cerebral arteries that is secondary to nearby subarachnoid blood products.9)13)14) The mainstays of vasospasm prevention and treatment include systemic administration of nimodipine and optimization of factors that affect the cerebral blood flow, including hemodynamic therapy.1)9)14) Endovascular therapies are typically used when conventional measures fail, and include angioplasty and selective intra-arterial vasodilator infusion.1)3)9) Vasospasms were frequently observed on 3D-CTA volume rendering images. However, 3D-CTA was less useful than two-dimensional DSA for the evaluation of vasospasms after SAHs.3)9)13)14) 3D-CTA, which is an alternative to conventional angiography, requires a comparison of the risks versus the benefits, including the procedural morbidity and mortality, radiation exposure and invasiveness.12)
According to Kaufmann et al., complications of conventional angiography have been well documented.6)13) They reported that the risk of transient ischemic attack was 2.09%, the risk of stroke with permanent disability was 0.14%, the risk of complications due to arterial puncture and catheter manipulation was 1.0%, the risk of hematoma was 4.2% and the risk of postoperative wound infection was 0.01%.2)6) The methods of 3D-CTA are easier than conventional angiography, and some authors have reported a high diagnostic accuracy of CTA (88.1%) in the detection of aneurysmal remnants. However, it also has a number of limitations, including image quality, clip artifact due to the number of clips, and hemodynamic spasm.12)13) Even though the scanning time of 3D-CTA is shortened by about 3 seconds, in the early periods of patients with SAHs, maintaining the patients’ status, including vital signs and mentality, are very important. However, there are risks in that the patient’s status cannot be monitored during the 3D-CTA evaluation.
It is well known that DSA is the golden standard in the postoperative assessment of clip position, but it also has some disadvantages, including its invasiveness. In this study, quite a large number of patients showed meaningful and positive findings in the postoperative angiography. If the postoperative angiography was not performed, these findings would be ignored, and the patients would not be given proper treatments. Thus, conventional angiography might be more valuable than CTA for the detection of vasospasms and incomplete clipping.
Conclusions
Our retrospective analysis revealed that postoperative angiography might be valuable in patients with ruptured aneurysms, especially in the acute stage after surgical clipping, in order to determine the presence of vasospasms, incomplete clippings, vascular compromises or other aneurysms that were missed at the initial cerebral angiography. However, intraoperative angiography and 3D-CTA can be alternatives to DSA in selected cases. This series, which had no selection bias, could be used as a basis to compare the immediate results of surgical clipping or endovascular coiling.
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