Anterior Clinoidectomy Technique Research Articles

Optic Foraminotomy for Clipping of Superior Carotid-Ophthalmic Aneurysms.

Background: Carotid-ophthalmic aneurysms usually cause visual problems. Its surgical treatment is challenging because of its anatomically close relations to the optic nerve, carotid artery, ophthalmic artery, anterior clinoid process, and cavernous sinus, which hinder direct access. Despite recent technical advancements enabling risk reduction of this complication, postoperative deterioration of visual function remains a significant problem. Therefore, the goal of preserving and/or improving the visual outcome persists as a paramount concern.Objective: We propose optic foraminotomy as an alternative microsurgical technique for dorsal carotid-ophthalmic aneurysms clipping. As a secondary objective, the step by step of that technique and its benefits are compared to the current approach of anterior clinoidectomy.Methods: We present as an example two patients with superior carotid-ophthalmic aneurysms in which the standard pterional craniotomy, transsylvian approach, and optic foraminotomy were performed. Surgical techniques are presented and discussed in detail with the use of skull base dissections, microsurgical images, and original drawings.Results: Extensive opening of the optic canal and optic nerve sheath was successfully achieved in all patients allowing a working angle with the carotid artery for correct visualization of the aneurysm and further clipping. Significant visual acuity improvement occurred in both patients because of decompression of the optic nerve.Conclusion: Optic foraminotomy is an easy and recommended technique for exposing and treating superior carotid-ophthalmic aneurysms and allowing optic nerve decompression during the first stages of the procedure. It shows several advantages over the current anterior clinoidectomy technique regarding surgical exposure and facilitating visual improvement.

Anterior Clinoidectomy: Intradural Step-by-Step En Bloc Removal Technique

Anterior clinoidectomy is an important and essential skill for skull base and cerebrovascular neurosurgeons. We present a 1-piece intradural anterior clinoidectomy, providing a step-by-step description of the technique, independently of anatomic variations. Between 2014 and 2020, 128 patients (119 women and 9 men; average age, 54.6 years) underwent intradural anterior clinoidectomy during microsurgical clipping of carotid-ophthalmic aneurysms. The anterior clinoid process continues medially with the planum sphenoidale, over the optic nerve, laterally with the lesser wing of the sphenoid bone, and inferiorly with the optic strut, which is always found anteriorly to the clinoid segment of the internal carotid artery, and separates the optic canal from the superior orbital fissure. The proposed anterior clinoidectomy followed, one after the other, these 3 fixation points for the detachment of the anterior clinoid process. The main indication for intradural anterior clinoidectomy was the management of vascular lesions around paraclinoid (clinoidal and ophthalmic) segments of the internal carotid artery. Complications of the procedure included injury to the internal carotid artery or the ophthalmic artery, thermal damage to the optic nerve, and invasion of the sphenoid sinus or a pneumatized anterior clinoid process, which could lead to postoperative cerebrospinal fluid leakage. The anterior clinoidectomy technique described here minimizes the drilling surface for detachment of the anterior clinoid process and reduces operative time as well as the amount of bone dust produced by drilling. It also precisely delineates the localization of the optic strut, preventing carotid or optic nerve damage.

Intradural “limited drill” technique of anterior clinoidectomy and optic canal unroofing for microneurosurgical management of ophthalmic segment and PCOM aneurysms—review of surgical results

To evaluate the safety and efficacy of intradural "limited drill" technique (ILDT) of anterior clinoidectomy (AC) and optic canal unroofing (OCU) for microneurosurgical management of ophthalmic segment and posterior communicating artery (PCOM) aneurysms. All the patients with ophthalmic segment and PCOM aneurysms who underwent AC and OCU by ILDT for microneurosurgical management of ophthalmic segment and PCOM aneurysms during 4-year period (2013-2016) at our Institute were included in this study. In ILDT of AC and OCU, the use of power drill is restricted to AC only and OCU is done exclusively with 1-mm Kerrison punch. AC and OCU by ILDT were done in 24 patients with 29 ophthalmic segment and 7 PCOM aneurysms. AC and OCU by ILDT helped in mobilization of optic nerve/internal carotid artery (ICA) and provided excellent exposure for all these aneurysms. There was no injury to ICA or optic nerve during drilling. AC and OCU facilitated clip ligation of 34 of these aneurysms. Remaining 2 aneurysms were considered not suitable for clipping. Check angiogram done for 33 aneurysms revealed complete obliteration of 26 aneurysms, very small residual neck in 5 aneurysms, and small residual aneurysm in 2 aneurysms. Deterioration in vision was noted in 1 patient (4.1%). In 6 patients with preoperative visual deficits, significant improvement in vision was noted in 4 patients (4/6-66.6%) after surgery. Good outcome (MRS < 2) was noted in 91.6% (22/24) of these patients. ILDT is a safe and effective technique of AC and OCU which provide good exposure for ophthalmic segment and PCOM aneurysms.

How I do it : Anterior clinoidectomy and optic canal unroofing for microneurosurgical management of ophthalmic segment aneurysms

Power drilling commonly used for anterior clinoidectomy and optic canal unroofing can result in thermal injury to the optic nerve. The authors describe an intradural "limited drill" technique of anterior clinoidectomy and optic canal unroofing for microneurosurgical management of ophthalmic segment aneurysms, where optic canal unroofing is done with 1 mm Kerrison punch and the use of the power drill is restricted to anterior clinoidectomy to avoid thermal injury to the optic nerve. The optic nerve, internal carotid artery (ICA), and aneurysm are covered with wet gelfoam pieces to prevent any inadvertent contact with the drill. "Limited drill technique" is a safe and effective technique of anterior clinoidectomy and optic canal unroofing. • Anterior clinoidectomy and optic canal unroofing is an important skull base technique required for safe clipping of the majority of ophthalmic segment aneurysms • Power drilling commonly used for optic canal unroofing can cause thermal injury to optic nerve • More than 2 mm free space is available around the optic nerve in the optic canal • Foot plate of 1 mm Kerrison punch can be safely introduced within a normal optic canal without causing mechanical injury to the optic nerve • Reflection of posteriorly based dural flap acts as a dural barrier, preventing direct contact of drill bit to optic nerve, internal carotid artery and aneurysm during drilling • Entanglement of cottonoids to rotating drill bit is a major problem in intradural anterior clinoidectomy • Wet gelfoam pieces do not get entangled to the rotating drill bit • Structures surrounding the area of drilling can be covered with wet gel foam pieces to prevent direct contact of the drill to neurovascular structures • Opened cisterns can be covered with wet gelfoam pieces during drilling to prevent deposition of bone dust in the subarachnoid space • "Limited drill technique" of anterior clinoidectomy and optic canal unroofing is a safe and effective technique for the exposure of ophthalmic segment aneurysms.

The “No-Drill” Technique of Anterior Clinoidectomy: A Skull Base Approach to the Paraclinoid and Parasellar Region

The “No-Drill” Technique of Anterior Clinoidectomy: A Skull Base Approach to the Paraclinoid and Parasellar Region

THE “NO-DRILL” TECHNIQUE OF ANTERIOR CLINOIDECTOMY

A high-speed power-drilling technique of anterior clinoidectomy has been advocated in all publications on paraclinoid region surgery. The entire shaft of the power drill is exposed in the operative field; thus, all neurovascular structures in proximity to any portion of the full length of the rotating drill bit are at risk for direct mechanical and/or thermal injury. Ultrasonic bone removal has recently been developed to mitigate the potential complications of the traditional power-drilling technique of anterior clinoidectomy. However, ultrasound-related cranial neuropathies are recognized complications of its use, as well as the increased cost of device acquisition and maintenance. A retrospective review of a cerebrovascular/cranial base fellowship-trained neurosurgeon's 45 consecutive cases of anterior clinoidectomy using the "no-drill" technique is presented. Clinical indications have been primarily small to giant aneurysms of the proximal internal carotid artery; however, in addition to ophthalmic segment aneurysms, selected internal carotid artery-posterior communicating artery aneurysms and internal carotid artery bifurcation aneurysms, and other large/giant/complex anterior circulation aneurysms, this surgical series of "no-drill" anterior clinoidectomy includes tuberculum sellae meningiomas, clinoidal meningiomas, cavernous sinus lesions, pituitary macroadenomas with significant suprasellar extension, other perichiasmal lesions (sarcoid), and fibrous dysplasia. A bony opening is made in the mid-to posterior orbital roof after the initial pterional craniotomy. Periorbita is dissected off the bone from inside the orbital compartment. Subsequent piecemeal resection of the medial sphenoid wing, anterior clinoid process, optic canal roof, and optic strut is performed with bone rongeurs of various sizes via the bony window made in the orbital roof. No power drilling was used in this surgical series of anterior clinoidectomies. Optimal microsurgical exposure was obtained in all cases to facilitate complete aneurysm clippings and lesionectomies. There were no cases of direct injury to surrounding neurovascular structures from the use of the "no-drill" technique. The surgical technique is presented with illustrative clinical cases and intraoperative photographs, demonstrating the range of applications in anterior and central cranial base neurosurgery. Power drilling is generally not necessary for removal of the anterior clinoid process, optic canal roof, and optic strut. Rigorous study of preoperative computed tomographic scans/computed tomographic angiography scans, magnetic resonance imaging scans, and angiograms is essential to identify important anatomic relationships between the anterior clinoid process, optic strut, optic canal roof, and neighboring neurovascular structures. The "no-drill" technique eliminates the risks of direct power-drilling mechanical/ thermal injury and the risks of ultrasound-associated cranial neuropathies. The "no-drill" technique provides a direct, time-efficient, and efficacious approach to the paraclinoid/ parasellar/pericavernous area, using a simplified mechanical route. This technique is applicable to any neurosurgical diagnosis and approach in which anterior clinoidectomy is necessary. It is arguably the gentlest and most efficient method for exposing the paraclinoid/parasellar/pericavernous region.

The No-Drill Technique of Anterior Clinoidectomy—A Skull Base Approach Tailored to Pathology

The No-Drill Technique of Anterior Clinoidectomy—A Skull Base Approach Tailored to Pathology

The No-Drill Technique of Anterior Clinoidectomy—A Skull Base Approach Tailored to Pathology

Introduction: Published articles describe a power drilling technique for anterior clinoidectomy. The entire “shaft” of the power drill is exposed in the operative field; thus all neurovascular structures in proximity to the full length of the rotating drill bit are at risk of direct mechanical and thermal injury. Ultrasonic bone removal has been recently developed to mitigate these risks. However, ultrasound-related cranial neuropathies are recognized complications of its use, in addition to its increased cost for the ultrasonic bone curettage device.

The No-Drill Technique of Anterior Clinoidectomy—A Skull Base Approach Tailored to Pathology

The No-Drill Technique of Anterior Clinoidectomy—A Skull Base Approach Tailored to Pathology