The Avoidance of Microsurgical Complications in the Extradural Anterior Clinoidectomy to Paraclinoid Aneurysms

Abstract

Objective : Paraclinoid segment internal carotid artery (ICA) aneurysms have historically been a technical challenge for neurovascular surgeons. The development of microsurgical approach, advances in surgical techniques, and endovascular procedures have improved the outcome for paraclinoid aneurysms. However, many authors have reported high complication rates from microsurgical treatments. Therefore, the present study reviews the microsurgical complications of the extradural anterior clinoidectomy for treating paraclinoid aneurysms and investigates the prevention and management of observed complications. Methods : Between January 2004 and April 2008, 22 patients with 24 paraclinoid aneurysms underwent microsurgical direct clipping by a cerebrovascular team at a regional neurosurgical center. Microsurgery was performed via an ipsilateral pterional approach with extradural anterior clinoidectomy. We retrospectively reviewed patients' medical charts, office records, radiographic studies, and operative records. Results : In our series, the clinical outcomes after an ipsilateral pterional approach with extradural anterior clinoidectomy for paraclinoid aneurysms were excellent or good (Glasgows Outcome Scale : GOS 5 or 4) in 87.5% of cases. The microsurgical complications related directly to the extradural anterior clinoidectomy included transient cranial nerve palsy (6), cerebrospinal fluid leak (1), worsened change in vision (1), unplanned ICA occlusion (1), and epidural hematoma (1). Only one of the complications resulted in permanent morbidity (4.2%), and none resulted in death. Conclusion : Although surgical complications are still reported to occur more frequently for the treatment of paraclinoid aneurysms, the permanent morbidity and mortality resulting from a extradural anterior clinoidectomy in our series were lower than previously reported. Precise anatomical knowledge combined with several microsurgical tactics can help to achieve good outcomes with minimal complications.

The pneumatisation of anterior clinoid process is not associated with any predictors that might be recognised preoperatively

“…This is due to the fact that the process is pneumatised by the sphenoid, ethmoid, or both sinal origins [14]. Apart from rhinorrhoea, anterior clinoidectomies increase the rate of oculomotor nerve paresis, injuries of ICA, ophthalmic artery and cavernous sinus, or intraoperative aneurysm rupture [2,6,18,22]. However, in recently published cadaveric and radiographic studies pneumatised ACPs pertained to a minority of patients and ranged from 4% to 29% of investigated cases [1,4,5,14,20,21].…”

“…Intraoperative neural or vascular damage occurs more often in pneumatised ACP than in osseous examples. This is because the rotating drill may bore into the empty process with relatively high force and harm the surrounding structures, including the brain cortex, cranial nerves, ICA, orbital content, or cavernous sinus [2,22]. Preoperative evaluation of the ACP is omitted in several emergent cases of ruptured ICA aneurysms encountered in normal practice.…”

“…Furthermore, the decompression of the optic canal as well as enhancement of neurosurgical exposures to many surrounding structures in the approach is additionally facilitated by the removal the ACP [7,14]. Regardless of the multiple techniques in preforming an anterior clinoidectomy [6,8,25], cerebrospinal fluid (CSF) rhinorrhoea is a common complication in up to 40% of patients undergoing this procedure [22]. This is due to the fact that the process is pneumatised by the sphenoid, ethmoid, or both sinal origins [14].…”

“…Thus, attention to detail with regards to complication avoidance is up to date. Radiographic evaluation of air cell infiltrate into the ACP in all cases, including any of the previously mentioned indications, is recommended if bony destruction in the middle cranial fossa is considered preoperatively [10,14,22]. However, in emergent situations, such as patients with a ruptured aneurysm, the preoperative assessment of pneumatisation is occasionally abandoned.…”

“…The process projects posteriorly and medially in the middle cranial fossa and constitutes a boundary of the caroticoclinoid foramen if the ACP is merged with the top of the medial clinoid process [10]. The ACP is closely related to many vital neurovascular structures, including the internal carotid artery (ICA) adjacent to the medial and posterior aspect of the ACP [8,22]. The relationship between these structures can be pathologically affected by growing with expansion and lateral projection of an ophthalmic artery aneurysm or paraclinoid ICA aneurysm [18].…”