Transorbital Approach Clipping of Middle Cerebral Artery Aneurysm: A Virtual Reality Morphometric Anatomic Study

BACKGROUND

The transorbital approach (TOA) has a unique advantage to the more common lateral approaches as it provides direct access to the anterior middle fossa and medial sylvian fissure (SF) without significant dissection or retraction. However, when to use the TOA for surgical treatment of middle cerebral artery (MCA) aneurysms remains unclear. This study details the feasibility of clipping unruptured MCA aneurysms via the TOA by highlighting the anatomic features that either facilitate or hinder the approach.

METHODS

Virtual reality (VR) models of 25 MCA aneurysms from computed tomography angiograms of actual patients were rendered with the relevant anatomic structures, including the neighboring temporal lobe and SF. TOA was performed on the models in VR and the globe was translated medially and inferiorly, replicating retraction used intraoperatively. Anatomic data, including the area of surgical freedom (AOF) at the aneurysm, were recorded. Trials of aneurysm clipping were conducted in VR and each aneurysm was classified as "possible" or "impossible" candidates for clipping via TOA. Separately, the relationship between surgical view and SF visualized was analyzed.

RESULTS

Sixteen aneurysms were eliminated as candidates for TOA treatment either through VR clip trial and/or because the SF was inaccessible. The remaining 9 (36%) were candidates for TOA. Comparing the details of these 2 aneurysm categories with Mann Whitney U tests, there was a statistically significant difference in the AOF of the TOA approach and the width of the aneurysm dome. A clinical case report is also provided highlighting the VR rehearsal similarity with surgery.

CONCLUSIONS

Given the minimally invasive, technically challenging approach, the feasibility and safety of TOA for MCA aneurysms must be evaluated before wide clinical adoption. This study identified AOF, aneurysm width, and SF accessibility as three features that may significantly impact the possibility of clipping MCA aneurysms via TOA.

Exploring optimal microscopic keyhole access to the skull base: an anatomical evaluation of transciliary supraorbital and transpalpebral orbitofrontal craniotomy approaches

PURPOSE

The past two decades have witnessed the rise of keyhole microscopic minimally invasive surgeries, including the transciliary supraorbital approach (TCA) and transpalpebral approach (TPA), commonly known as the transorbital approach. This study aims to elucidate the nuances, specific indications, and advantages of each approach.

METHODS

A series of dissections were conducted on five formalin-fixed, alcohol-preserved cadaver heads. The TCA was performed on one side, and the TPA on the other. Virtual measurements of working angles for both approaches were recorded. Additionally, three clinical cases were presented to illustrate the practical application of the techniques.

RESULTS

For TCA, the craniotomy dimensions were 1.7 cm x 2.5 cm (Cranial-Caudal (CC) x Lateral-Lateral (LL)), while for TPA, they measured 2.1 cm x 2.9 cm (CC x LL). The measurements of anterior clinoid processes (ACP) were obtained and compared between approaches. In the TCA, the mean ipsilateral ACP measurement was 62 mm (Range: 61 -63 mm), and the mean contralateral ACP measurement was 71.2 mm (Range: 70 -72 mm). In TPA, these measurements were 47.8 mm (Range: 47 -49 mm) and 62.8 mm (Range: 62 -64 mm), respectively. TCA exhibited an average cranial-caudal angle of 14.9°, while TPA demonstrated an average of 8.3°.

CONCLUSION

The anterior cranial fossa was better exposed by a TCA, which also featured shorter operative times, enhanced midline visualization, and a quicker learning curve. Conversely, the middle fossa was better exposed by a TPA, making it an excellent option for middle fossa pathologies, including those in the anterior temporal lobe. After sphenoid bone wing drilling, the TPA offers superior visualization from the lateral to the medial aspect and enhances the CC angle. Additionally, the TPA reduces the risk of postoperative frontalis palsy based on anatomic landmarks. However, the TPA requires a greater cranial osteotomy, and due to unfamiliarity with eyelid anatomy, the learning curve for most neurosurgeons is lengthier for this procedure.

'What's in a name', a systematic review of the pterional craniotomy for aneurysm surgery and its many modifications with a proposal for simplified nomenclature

BACKGROUND

The pterional or frontosphenotemporal craniotomy has stood the test of time and continues to be a commonly used method of managing a variety of neurosurgical pathology. Already described in the beginning of the twentieth century and perfected by Yasargil in the 1970s, it has seen many modifications. These modifications have been a normal evolution for most neurosurgeons, tailoring the craniotomy to the patients' specific anatomy and pathology. Nonetheless, an abundance of variations have appeared in the literature.

METHODS

A search strategy was devised according to the 2020 Preferred Reporting Items of Systematic Reviews and Meta-Analyses (PRISMA) statement. To identify articles investigating the variations in the pterional approach, the following search terms were applied: (pterional OR minipterional OR supraorbital) AND (approach OR craniotomy OR technique).

RESULTS

In total, 3552 articles were screened with 74 articles being read in full with 47 articles being included for review. Each article was examined according the name of the technique, temporalis dissection technique, craniotomy technique and approach.

CONCLUSION

This systematic review gives an overview of the different techniques and modifications to the pterional craniotomy since it was initially described. We advocate for the use of a more standardised nomenclature that focuses on the target zone to simplify the management approach to supratentorial aneurysms.

Transpalpebral Eyelid Approach for Supraorbital Frontal Craniotomy and Access to the Anterior Cranial Fossa

SUMMARY

The transpalpebral eyelid approach is an innovative alternative to traditional incisions for exposure of the anterior cranial fossa for neurosurgery. However, there is a paucity of data on this surgical technique in the plastic surgery literature for accessing the anterior cranial fossa. A retrospective review was performed of patients who underwent supraorbital frontal craniotomy using an anterior skull base approach with transpalpebral exposure over 8 years by a single plastic surgeon. Surgical techniques, medical comorbidities, intraoperative complications, and long-term complications were assessed. Twenty patients (mean age 52 ± 12 years, 55% male, 45% female) underwent supraorbital frontal craniotomy using an anterior skull base approach with upper transpalpebral exposure. Operative indications included the following: 75% had anterior communicating aneurysms, with a mean aneurysm size of 5.36 ± 1.91 mm; 10% had meningiomas; 10% had dural fistulas; and 5% had an orbital hemangioma. A total of 60% of patients had a smoking history. No intraoperative complications were encountered, and no cases required conversion to a traditional open approach. Mean length of hospital stay was 3.2 ± 1.5 days. Postoperative imaging revealed no residual or recurrent pathology. Mean follow-up time was 62.2 ± 30.6 months. No long-term neurologic or ophthalmologic complications or infections occurred. No forehead paresthesias, brow ptosis, or brow paralysis were noted. The transpalpebral technique is a safe, minimally invasive method to approach lesions of the anterior cranial fossa. Successful application may require appropriate management of the frontal sinus and supraorbital nerve. This approach does not limit neurosurgical access or results and led to no neurosurgical complications.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

MISIAN (Minimally Invasive Surgery for Treatment of Unruptured Intracranial Aneurysms): A Prospective Randomized Single-Center Clinical Trial With Long-Term Follow-Up Comparing Different Minimally Invasive Surgery Techniques with Standard Open Surgery

BACKGROUND

Unruptured intracranial aneurysms (UIAs) are increasingly diagnosed but treatment is still controversial. Although the descriptions and use of minimally invasive surgery (MIS) have increased, comparative studies with standard approaches are rare.

OBJECTIVE

MISIAN (Minimally Invasive Surgery for Treatment of Unruptured Intracranial Aneurysms) is a prospective randomized single-center clinical trial with long-term follow-up comparing different MIS techniques with standard open surgery for treatment of UIAs.

METHODS

We randomly allocated a standard pterional approach (PtA) or MIS (1:2) to 111 patients with UIAs of the anterior circulation (mean dome diameter, 6.4 mm; range, 3-20 mm). Patients selected for MIS underwent a second randomization between a transeyelid approach (TelA) or nanopterional approach (NPtA) (1:1).

RESULTS

Forty-one patients were randomized to and treated with the PtA, 36 with the TelA, and 34 with the NPtA. Only patients treated with PtA had permanent facial nerve palsy (n = 4 [10%]; P = 0.032). MIS cosmetic results were considered better than those of PtA by independent observers (P < 0.001), and less temporal atrophy in the MIS group was also observed (P = 0.0034). The proportion of excellent results was higher in the TelA group than in the NPtA group (86% vs. 67.6%; P = 0.039). Patients undergoing MIS also reported consistently higher satisfaction and quality-of-life scores (P < 0.001).

CONCLUSIONS

MIS is superior to standard PtA for microsurgical clipping of small UIAs of the anterior circulation in terms of cosmetic, satisfaction, and quality-of-life outcomes. The TelA or NPtA for UIAs did not show significant outcome differences at 12-18 months.

The Transpalpebral Versus the Transciliary Variant of the Supraorbital Keyhole Approach: Anatomic Concepts for Aneurysm Surgery

BACKGROUND

The supraorbital craniotomy (SOC) is classically performed through a skin incision in the patient's eyebrow. A variant with a skin incision in the patient's eyelid has become increasingly popular in recent years.

OBJECTIVE

To compare the transpalpebral and the transciliary variants of the SOC with regard to their potential role in aneurysm surgery.

METHODS

We carried out cadaveric dissections and virtual craniotomies on computerized tomography datasets. The skin incision, the craniotomy location and size, the working angles, and the achievable exposure of neurovascular structures were assessed and compared for both variants of the SOC.

RESULTS

The skin incision measured 4 cm for the transpalpebral and 3 cm for the transciliary variant. The skin could be retracted 1.5 cm upward from the lower edge of the orbital rim with the transpalpebral and 2.5 cm upward with the transciliary variant. The craniotomy size was 2.5 × 1.5 cm for both variants, given that the transpalpebral variant included an orbital osteotomy. The bony opening in the transpalpebral variant was 1 cm more caudal; this restricted the craniocaudal working angles and, thereby, limited the achievable exposure of neurovascular structures in the paraclinoid area and along the sphenoid ridge.

CONCLUSION

If the orbital rim and the anterior aspect of the orbital roof are removed, then the transpalpebral variant of the SOC enables a bony opening that is just as large as that of the transciliary variant. Nonetheless, the more caudal location of the bony opening alters the available working angles and may impede exposure of key structures during aneurysm surgery.

Transpalpebral Approach "Eyelid Incision" for Surgical Treatment of Intracerebral Aneurysms: Lessons Learned During a 10-Year Experience

BACKGROUND

The classic pterional, pretemporal, and orbitozygomatic approaches achieve large areas of exposure with easy maneuverability. In select cases (eg, some anterior circulation aneurysms), the minimally invasive fronto-orbital craniotomy can yield adequate exposure that must be balanced with its risk of frontalis injury.

OBJECTIVE

To detail a 10-yr experience using the transpalpebral approach, characterized by an incision whose camouflage is the natural eyelid crease, notably the effectiveness and outcomes of this exposure for anterior circulation aneurysms.

METHODS

In this retrospective review, 82 patients with 88 aneurysms underwent a supraorbital frontal minicraniotomy via the eyelid incision performed by a single neurosurgeon and closure by an oculoplastic surgeon (2007-2016). Incision of the orbiculi oculi developed a plane between the muscle and orbital septum superiorly. Outcomes recorded included aneurysm occlusion or residual, treatment modality (clipping/wrapping), postoperative hemorrhage or stroke, postoperative wound healing, and overall cosmesis.

RESULTS

Of 85 (97%) aneurysms treated by clipping, postoperative and follow-up imaging showed complete obliteration in 81 (95%) aneurysms and residuals in 4 (5%). Cosmetic outcomes for the eyelid incision were excellent: 81 (99%) patients noted excellent wound healing at follow-up and no scarring; 1 patient developed significant temporalis wasting and upper eyelid scarring after posterior communicating artery aneurysm clipping. Overall, 13 minor and 8 major complications affected 19 patients.

CONCLUSION

Our findings confirm the versatility of the eyelid supraorbital frontal minicraniotomy for common anterior circulation aneurysms. This large series found that postoperative complication risks were similar to traditional techniques and cosmetic results were excellent.

Transblepharo-Preseptal Modified Orbitozygomatic Approach for the Treatment of Ruptured Proximal Anterior Circulation Aneurysms

BACKGROUND

Minimally invasive skull base approaches, including the cosmetically optimal transblepharo-preseptal modified orbitozygomatic (TBMOZ) technique, have been described to treat proximal anterior circulation aneurysms. The use of minimally invasive techniques for previously ruptured aneurysms is rare because of perceived technical challenges in controlling intraoperative ruptures. Herein, we determine the utility of the minimally invasive TBMOZ approach for the treatment of ruptured proximal anterior circulation aneurysms.

METHODS

A retrospective analysis of an institutional review board-approved, prospective database was performed to identify patients with ruptured anterior circulation aneurysms treated with a TBMOZ approach. Patient demographics, aneurysm characteristics, temporary clip time, intra-operative ruptures, and neurologic outcomes were recorded.

RESULTS

Fifteen patients (9 females, 6 males; average age, 53.6 ± 12.2 years) underwent a TBMOZ craniotomy following subarachnoid hemorrhage for clipping of 17 aneurysms (12 anterior communicating, 3 posterior communicating, and 2 carotid terminus). Four of 15 patients (26.6%) experienced intraoperative rupture, which was easily controlled in all patients and did not affect clinical outcomes. All patients had complete aneurysm ablation confirmed on postoperative cerebrovascular imaging. Good neurologic outcomes (Glasgow Outcome Score [GOS] of 5) were achieved in 73.3% (n = 11) of patients at time of hospital discharge; the remaining patients had a GOS of 3-4. No patients experienced frontalis muscle weakness or facial nerve injuries, and all patients had acceptable cosmetic outcomes. One patient (6.6%) experienced a surgery-related complication: postoperative versus vasospasm-induced perforator infarcts.

CONCLUSIONS

The TBMOZ approach provides a minimally invasive option for the safe treatment of previously ruptured proximal anterior circulation aneurysms.

Endoscopic transorbital route to the petrous apex: a feasibility anatomic study

BACKGROUND

While the subtemporal approach represents the surgical module milestone designed to reach the petrous apex, a novel ventral route, which is the superior eyelid endoscopic transorbital approach, has been proposed to access the skull base. Accordingly, we aimed to evaluate the feasibility of this route to the petrous apex, providing a qualitative and quantitative analysis of this relatively novel pathway.

METHODS

Five human cadaveric heads were dissected at the Laboratory of Surgical NeuroAnatomy of the University of Barcelona. After proper dissection planning, anterior petrosectomy via the endoscopic transorbital route was performed. Specific quantitative analysis, as well as dedicated three-dimensional reconstruction, was done.

RESULTS

Using the endoscopic transorbital approach, it was possible to reach the petrous apex with an average volume bone removal of 1.33 ± 0.21 cm³. Three main intradural spaces were exposed: cerebellopontine angle, middle tentorial incisura, and ventral brainstem. The first one was bounded by the origin of the trigeminal nerve medially and the facial and vestibulocochlear nerves laterally, the second extended from the origin of the oculomotor nerve to the entrance of the trochlear nerve into the tentorium free edge while the ventral brainstem area was hardly accessible through the straight, ventral endoscopic transorbital trajectory.

CONCLUSION

This is the first qualitative and quantitative anatomic study concerning details of the lateral aspect of the incisura and ventrolateral posterior fossa reached via the transorbital window. This manuscript is intended as a feasibility anatomic study, and further clinical contributions are mandatory to confirm the effectiveness of this approach, defining its possible role in the neurosurgical armamentarium.

Supraorbital vs Endo-Orbital Routes to the Lateral Skull Base: A Quantitative and Qualitative Anatomic Study

BACKGROUND

Various extensions of the supraorbital approach reach the lateral and parasellar middle cranial fossa regions by removing the orbital rim and greater/lesser sphenoid wings. Recent proposals of a purely endoscopic ventral transorbital pathway to these regions heighten the need to compare these surgical windows.

OBJECTIVE

To detail the lateral and parasellar middle cranial fossa regions and quantify exposures by 2 surgical windows (transcranial and transorbital) through anatomic study.

METHODS

In 5 cadaveric specimens (10 sides), dissections consisted of 3 stages: stage 1 began with the supraorbital approach via the eyebrow; stage 2, endo-orbital approach via the superior eyelid, continued with removal of lesser and greater sphenoid wings; and stage 3, extended supraorbital, re-evaluated the gains of stage 2 from the perspective of stage 1. Operative working areas were quantified in Sylvian, anterolateral temporal, and parasellar regions; bone removal volumes were measured at each stage (nonpaired Student t-test).

RESULTS

Visualization into the anterolateral temporal and Sylvian areas, though varied in perspective, were comparable with either eyelid or transcranial routes. Compared with transcranial views through a supraorbital window, the eyelid approach significantly increased exposure in the parasellar region with wider angle of attack (P &lt; .01) and achieved comparable bone removal volumes.

CONCLUSION

Stage 2’s unique anatomic view of the lateral and parasellar middle cranial fossa regions paves the way for possible surgical application to select pathologies typically treated via transcranial approaches. Disadvantages may be the surgeon's unfamiliarity with the anatomy of this purely endoscopic, ventral route and difficulties of dural and orbital repair.