Surgical Management of Bilateral Middle Cerebral Artery Aneurysms via a Unilateral Supraorbital Key-Hole Craniotomy

Abstract

Introduction: Surgical management of multiple intracranial aneurysms may be difficult if located bilaterally. In the case of bilateral middle cerebral artery (MCA) aneurysms, surgical treatment through a unilateral approach is generally not recommended. In this study we describe the surgical technique and important factors that enable treatment of bilateral MCA aneurysms via a unilateral key-hole approach.

Patients and Methods: 15 patients (12 females, 3 males) with bilateral aneurysms of the MCA were surgically treated via a supraorbital key-hole approach. Age ranged from 37 to 60 years (mean: 47). 7 of the 15 patients presented with an acute subarachnoid hemorrhage (SAH). Cerebral angiography was performed in all patients pre- and postoperatively. Patients suffering from SAH were treated within the first 72 h. All 15 patients were planned to be operated via a unilateral supraorbital keyhole craniotomy using an eye-brow incision.

Results: In 10 of the 15 patients MCA aneurysms of both sides could be occluded completely through the unilateral approach. In 5 patients bilateral craniotomies had to be performed, in 1 of these patients during the same procedure. Factors necessitating a second craniotomy were brain swelling (1 patient with SAH), insufficient instruments (2 patients), and complex configuration of the contralateral aneurysm (2 patients). Permanent morbidity was anosmia in 1 patient and hyposmia and a mild visual field deficit in 1 further patient.

Conclusion: Bilateral aneurysms of the MCA may be treated sufficiently through a unilateral supraorbital key-hole approach in selected patients. This is also possible in patients presenting with SAH. Factors necessitating bilateral craniotomies were brain swelling and complex configuration of the contralateral aneurysm.

cerebral aneurysm - middle cerebral artery - bilateral aneurysm - unilateral approach - key-hole craniotomy

References

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Comments

“In this series Hopf and Reisch describe their series of 15 patients in whom an attempt was made to microsurgically clip bilateral middle cerebral artery aneurysms via a unilateral supraorbital eyebrow approach. Seven patients were treated in the context of subarachnoid hemorrhage and eight patients were treated electively. Ten of 15 patients were successfully clipped. Factors that prevented clipping were related to brain swelling in 1 case, inability to place the clip with the available instruments in 2 cases, and complex aneurysm morphology in 2 cases. Morbidity included anosmia in 1 case, contralateral subdural hematoma in 1 case, bilateral subdural hygromas in 1 case, and a visual fi eld defi cit in one case.

As the authors note, this technique has been discussed by others before. The value of this small series is to show that reasonably good results can be obtained when clipping bilateral MCA aneurysms via a unilateral approach and that in about a third of cases it is not technically feasible. Those surgeons who are familiar with this approach will be aware that the contralateral middle cerebral artery is actually quite accessible via a pterional, supraorbital, or orbitozygomatic craniotomy. Whether a contralateral aneurysm can be successfully clipped via this approach depends substantially on its morphology; in particular, the important factors are the length and confi guration of the distal internal cerebral artery and contralateral middle cerebral artery. Utmost attention should be dedicated to the preservation of the olfactory tracts, which are easily damaged in achieving this exposure. The desire to achieve a contralateral clipping should not compromise the need for proximal and distal control, just as for any aneurysm. When these criteria can be met, a unilateral approach off ers the patient the benefi t of a single craniotomy. Neurosurgeons contemplating clipping of patients with bilateral aneurysms should be familiar with this technique so as to be able to offer it as an option where appropriate.”

Peter Nakaji,
Phoenix, Arizona

In this article, the authors describe their experience with the surgical treatment of bilateral middle cerebral artery (MCA) aneurysms through a unilateral key-hole approach. Surgical management of multiple intracranial aneurysms can be difficult if located bilaterally and in the case of bilateral ("mirror") MCA aneurysms, surgical treatment usually is performed through two separate approaches , either at different times or during the same surgical procedure (1). Approaching these bilateral aneurysms through one single, unilateral approach has been rarely described before (2,3).

The authors carefully describe the diff erent steps, especially in the planning of such an endeavour, that are necessary and the technical difficulties that can be encountered. In doing this, they give an excellent example of the key-hole concept of minimally invasive neurosurgery, as it has been developed and advocated by their teacher, Prof. Axel Perneczky. It really changed some general unwritten laws of neurosurgery, e.g. look for the shortest route, right-sided lesions always will be approached from the right side, etc. The key-hole concept includes exact visualization of the individual anatomy of a patient pre-operatively, careful planning of the best approach based upon these data and performing the procedure with all technical possibilities that we have, like navigation, combining microscope and endoscope and intraoperative monitoring (4). This is what the authors exactly did. In this study they describe the surgical technique and important factors that enable treatment of bilateral MCA aneurysms via a unilateral approach. They have treated 15 patients with bilateral aneurysms of the MCA via a unilateral supraorbital keyhole approach. Successful treatment could be achieved in 10 out of 15 patients including 5 patients presenting with acute SAH.

In 10 of the 15 patients, MCA aneurysms of both sides could be sufficiently managed through the unilateral supraorbital keyhole craniotomy. In 1 of these patients, the craniotomy had to be slightly extended rostrally to suffi ciently control the contralateral MCA aneurysm. In the remaining 5 patients additional craniotomies were performed to deal with the contralateral aneurysm, in 1 patient during the same procedure. Factors necessitating bilateral approaches were insufficient control of the contralateral aneurysm due to size or complex confi guration of the aneurysm (2 patients) or inadequate microsurgical instruments (2 patients), i. e., too bulky and / or too short instruments, or unsuitable confi guration of available aneurysm clips. In 1 further patient, preparation of the contralateral aneurysm was thought to be too traumatic due to signifi cant brain swelling following acute SAH.

There was no mortality in this group of patients. Complications were seen in 3 out of 15 patients, in 2 patients leading to minor permanent morbidity. Complications were superfi cial wound infection, contralateral subdural hematoma, and anosmia in a single patient and bilateral subdural eff usions in another patient, both requiring surgical treatment. A third patient suff ered from hyposmia and a mild peripheral visual fi eld defi cit. There were no cerebral infarctions or other parenchymal lesions seen on the early postoperative CT scans that were related to surgery.

Nevertheless, the management of bilateral MCA aneurysms remains challenging and an approach through a unilateral approach can only be considered after a thorough preoperative analysis of the exact localization, size, and confi guration of all aneurysms. Based upon our own experience with surgical treatment of bilateral MCA aneurysms through a unilateral supraorbital key-hole approach (5), as we do since 2001, I can fully agree with the authors in their analysis of factors for successful clipping of the contralateral aneurysm and those situations in which such an approach is not advisable, e.g. more peripherally located MCA aneurysms and the large and complex ones are not well amenable, as are the cases with a long M1 segment. Also aneurysms pointing inferior are more difficult to control from the contralateral approach because the MCA regularly covers the neck region of the aneurysm and visualization of the perforating branches is poor.

In conclusion, it is an well-written report on an application of the key-hole concept to the treatment of bilateral MCA aneurysms and all the presented details should help others to make a sound decision in every case of such bilateral MCA aneurysms whether or not to treat it through a unilateral key-hole approach.

André Grotenhuis
Nijmegen, The Netherlands

1. Shin BG, Kim JS, Hong SC. Single-stage operation for bilateral middle cerebral artery aneurysms. Acta Neurochir (Wien) 2005; 147: 33–38

2. Martellotta N, Gigante N, Toscano S et al. Unilateral supraorbital keyhole approach in patients with middle cerebral artery (M1-M2 segment) symmetrical aneurysms. Minim Invas Neurosurg 2003; 46: 228–230

3. de Sousa AA, Filho MA, Faglioni Jr W et al. Unilateral pterional approach to bilateral aneurysms of the middle cerebral artery. Surg Neurol 2005; 63 (Suppl 1): 1–7

4. van Lindert E, Perneczky A, Fries G et al. The supraorbital keyhole approach to supratentorial aneurysms: concept and technique. Surg Neurol 1998; 49: 481–490

5. Menovsky T, Grotenhuis JA. Bilateral middle cerebral artery aneurysms. Acta Neurochir (Wien) 2005; 147: 1007

Correspondence