**7. Treatment**

Management of blister aneurysms is associated with a high overall rate of mortality and morbidity [35]. The main causes for this include the small size and broad neck morphology along with the prominent fragility of such lesions, features that often lead to intraprocedural rupture when traditional surgical or endovascular techniques such as clipping or primary coiling are to be applied [6, 19]. Additionally, and even if an initial intervention proves successful, subsequent regrowth requiring further treatment has been commonly reported [9]. Other factors contributing to the grim prognosis of blister aneurysms include a commonly grave clinical presentation as well as delays in an appropriate diagnosis.

Given the lack of universal consensus in blister aneurysm treatment, a wide variety of approaches and methods has been employed up to date and will be discussed below. These have included both reconstructive and deconstructive surgical and endovascular techniques, with different authors competing for best results in an ever-changing field. In any case, attention should be given to specific measures to prevent rerupture while awaiting final treatment (tight arterial blood pressure control, cautious cerebrospinal fluid drainage in patients with a ventricular drainage in place and selective use of aminocaproic acid) [41]. The latter must be instituted as soon as possible to secure the aneurysm and to allow aggressive management of subarachnoid hemorrhage-related complications such as vasospasm and hydrocephalus.

The alternative treatment modalities for blister aneurysms are:

a.Reconstructive techniques


b.Deconstructive techniques

• Parent artery occlusion with surgical or endovascular means with or without bypass surgery

#### **7.1 Surgical treatment**

#### *7.1.1 Clipping procedures (primary clipping and wrap-clipping)*

#### *7.1.1.1 Technique*

Traditionally, surgical clipping has been the preferred mode of treatment for all forms of cerebral aneurysms, including blister lesions. In a typical case, the procedure starts with exposure of the cervical internal carotid artery to ensure

#### *Blister Aneurysms DOI: http://dx.doi.org/10.5772/intechopen.89284*

proximal control in case of an intraprocedural rupture. This is usually achieved with an incision along the medial border of the ipsilateral sternocleidomastoid muscle [42]. Subsequently, a standard pterional craniotomy with generous sphenoid ridge drilling is carried out, and through this, the Sylvian fissure is opened widely. Gentle retraction of the frontal lobe provides access to the supraclinoid internal carotid artery which, in most cases, is found to be prominently sclerotic [43]. The aneurysm itself is usually seen protruding from the dorsomedial carotid wall. Careful preparation of the aneurysmal dome is crucial. As a matter of fact, should the frontal lobe be attached to it, most authors propose a subpial dissection in order to minimize direct manipulation of the lesion [44]. Special care is needed to avoid removing the platelet plug that typically covers the aneurysm as this may result in a large wall defect and uncontrollable bleeding [4].

Direct clipping of a blister aneurysm is performed under temporary trapping and in such a way that the blades of a usually angled or curved Sugita clip are parallel to the longitudinal axis of the carotid artery [19, 45]. This has been shown to lower the risk of intraprocedural rupture [17]. Given that the underlying pathological process seems to extend well beyond the limits of the aneurysm itself, the surgeon should try, when closing the clip, to include part of the "normal" arterial wall outside the lesion in order to avoid breakage of the transitional zone found in between them [4]. A valid alternative is to envelope the entire diseased arterial segment with a wrapping material such as gauze, cotton or Gore-Tex on top of which the clip can be applied to obliterate the lesion [46]. Wrap-clipping not only reinforces the carotid wall as a whole but also helps avoid slippage of the clip, a complication not uncommonly seen in blister aneurysms surgery [47]. One yet alternative is to wrap the lesion after the clip has been applied (clip-wrapping). Whatever the exact technique, induced hypotension [11], burst suppression with desflurane or thiopental, cooling of the patient or even transient flow arrest with adenosine can all prove useful adjuncts [11, 24, 41, 48].
