Abstract
Background Skull base approaches are utilized to improve microsurgical treatment of cerebral aneurysms. Advantages include early proximal and distal control, increased visualization, and minimal brain retraction. Orbitozygomatic (OZ) craniotomies via pterional incision are commonly used for the treatment of anterior communicating artery (ACoA) aneurysms. A smaller, less invasive OZ craniotomy performed through an eyebrow incision may provide several advantages over a standard OZ approach.
Objective We compare surgical outcomes of the standard and eyebrow OZ for the treatment of ACoA aneurysms.
Design All patients who underwent microsurgical treatment for ACoA aneurysms by a single surgeon over an 8-year period were included in this retrospective analysis. Patient demographics and clinical data were collected.
Participants Thirty-seven consecutive patients were identified, with 15 receiving eyebrow OZ and 22 receiving standard OZ.
Main Outcome Measures Data were collected on patient demographics, pathology, intraoperative and perioperative data, and 30-day morbidity.
Results A total of 100% of the eyebrow OZ group and 95.5% of the standard OZ group had complete aneurysmal occlusion. Four eyebrow OZ and six standard OZ patients had an intraoperative rupture. All were managed without complication. Two eyebrow OZ and one standard OZ patient died within 30 days of surgery. No patients in either group had aneurysm recurrence, required retreatment, or were limited intraoperatively by exposure.
Conclusions The OZ approach via an eyebrow incision has similar outcomes to a standard OZ approach and is a safe option for the treatment of ACoA aneurysms.
Keywords: eyebrow craniotomy, orbitozygomatic craniotomy, supraorbital craniotomy, cerebral aneurysm, intracranial aneurysm, anterior communicating artery aneurysm, microsurgical clipping
Introduction
The anterior communicating artery (ACoA) is the most common location for both ruptured and unruptured intracranial aneurysms. 1 2 3 Standard, traditional techniques for microsurgical clipping of these aneurysms involve large craniotomies and fixed retraction. Skull base approaches reduce the need for brain manipulation and are utilized to improve the microsurgical treatment of intracranial aneurysms. 4 5 Other advantages include early proximal and distal control, increased range of operative view, and a better trajectory to the target lesion with multidirectional access. 4 5 6 Given its location along the medial anterior skull base, ACoA aneurysms are well suited for treatment using different skull base approaches.
The orbitozygomatic (OZ) craniotomy is one such approach commonly used for microsurgical treatment of ACoA aneurysms. Many modifications of the OZ have been reported. Usually, this involves a pterional craniotomy plus removal of varying amounts of the orbit, zygomatic process of the frontal bone, and/or zygoma, tailored to the specific needs of the patient and pathology treated. 6 7 8 This is typically performed as a one-, two-, or three-piece craniotomy through a pterional incision. 6 7 8 However, a smaller, mini-OZ keyhole craniotomy through an eyebrow incision is also described and has several advantages compared with a standard OZ approach. 6 9 10 This involves a small incision in or just above the eyebrow that allows removal of the lateral orbital rim, the zygomatic process of the frontal bone, the lateral orbital roof, and supraorbital frontal bone in a one-piece craniotomy. Critics suggest that the eyebrow mini-OZ adds more risk than benefit in the treatment of ACoA aneurysms, particularly in the setting of subarachnoid hemorrhage. 11
In this retrospective study, we compare surgical outcomes using the mini-OZ through an eyebrow incision to the standard OZ for the microsurgical treatment of ACoA aneurysms. We discuss operative technique, outcomes, and complications with each approach and compare strengths and weaknesses.
Methods
All patients who underwent microsurgical treatment for ACoA aneurysm by the senior author (S.D.W.) over an 8-year period are included in this retrospective analysis of patients' medical records. All patients had immediate postoperative imaging with computed tomography (CT) angiogram. Patients with multiple aneurysms were treated with a standard OZ approach. Otherwise, the approach was chosen based on surgeon preference, which has become more eyebrow preferential over time. If a patient had significant ventricles and it appeared that the brain could be well relaxed intraoperatively with an external ventricular drain (EVD), then the eyebrow mini-OZ approach was chosen. If the brain appeared full and not easily decompressed on preoperative imaging, the standard OZ was chosen to allow a wider operative corridor. Data were collected on patient demographics, pathology treated, operative details, perioperative, modified Rankin Score, and 30-day morbidity. Fisher's exact test was used for all comparisons of incidence and t -test was used for all comparisons of continuous variables.
The standard OZ operative approach utilized in this series of patients was a modified two-piece OZ craniotomy through a pterional incision. A small pterional craniotomy is completed. Then, prior to dural opening, a bone scalpel (Misonix, Inc. Farmingdale, New York, United States) and osteotomes are used to remove the orbital rim and the zygomatic process of the frontal bone in one piece, completing the two-piece craniotomy. Fig. 1 shows the standard OZ used in this series. We have previously described our technique for the eyebrow mini-OZ. 12 Briefly, a small incision is made completely within the eyebrow. A burr hole is placed at the keyhole and craniotome is used to turn a small supraorbital cut. The flap is completed with orbital cuts using the bone scalpel and osteotomes to crack out the orbital rim, roof, and the zygomatic process of the frontal bone in one piece. Fig. 2 describes this technique. Fixed brain retractors were not used in any case for either approach. For both approaches, there was a low threshold for EVD placement for early cerebrospinal fluid (CSF) diversion if good brain relaxation cannot be achieved with opening of cisterns. Fig. 3 shows images of the intradural anatomical views obtained with our standard OZ and eyebrow mini-OZ.
Fig. 1.
( A ) Right-sided standard orbitozygomatic (OZ) prior to dural opening. The two-piece craniotomy includes a pterional craniotomy plus removal of the orbital roof and zygomatic process of the frontal bone. ( B ) The dura is opened and retracted anteriorly over the periorbita. Removal of the orbital roof allows better visualization and reduces need for brain manipulation. ( C ) Reconstructed bone flap for the right-sided standard OZ just prior to replacement at the end of the case.
Fig. 2.
( A ) Incision is completely within the eyebrow. The head is extended and then rotated approximately 20 degrees to the contralateral side. ( B ) Incision is opened and a small amount of temporalis muscle is dissected off the superior temporal line, exposing the keyhole. ( C ) Burr hole is drilled at the keyhole and craniotome is extended superiorly and medially, forming the supraorbital part of the craniotomy. ( D ) Bone scalpel is used to cut the lateral part of the orbit, near the frontozygomatic suture and connecting to the keyhole burr hole. It is then used to make the medial part of the orbital cut. Osteotomes are then used to crack the bone flap out in one piece. ( E ) Both the frontal dura and periorbita are exposed. ( F ) One-piece bone flap involves the supraorbital frontal bone, orbital rim, orbital roof, and zygomatic process of the frontal bone. ( G ) Intraoperative image after bone flap removal. ( H ) Intraoperative image at the end of the case after microsurgical clipping. ( I ) Staples are used for skin closure and are removed on postoperative day 7.
Fig. 3.
Relevant surgical anatomy from a right-sided eyebrow orbitozygomatic (OZ). ( A ) The opticocartoid cisterns are opened and the frontal lobe is dissected free from the skull base. Ipsilateral optic nerve (ON), internal carotid artery (ICA), optic chiasm (OC), and contralateral ON are then identified. ( B ) Further dissection reveals the lamina terminalis (LT) and ipsilateral anterior communicating artery (ACoA) cross over the optic chiasm. ( C ) Further dissection laterally reveals the ICA bifurcation, clearly exposing the origin of the middle cerebral artery (MCA) and ACoA. ( D ) The anatomy of the ACoA complex is visualized. A1, A2, recurrent artery of Heubner (RAH), and orbitofrontal (OF) branches of the ACoA are visible bilaterally. ( E ) Intraoperative surgical anatomy from a left standard OZ with wide sylvian fissure split. A1, A1 segment of anterior cerebral artery; A2, A2 branch of anterior cerebral artery; ATA, anterior temporal artery; CN3, oculomotor nerve; M1, M1 segment of middle cerebral artery.
Results
Thirty-seven consecutive patients with ACoA aneurysms were treated, 15 with eyebrow OZ and 22 with standard two-piece OZ. Table 1 summarizes the clinical data. There was no significant difference between age, direction of dome projection, size of aneurysm, side of approach, or Hunt–Hess grade between the two groups. The standard OZ group did have a significantly higher number of patients with multiple aneurysms, as would be expected considering that we do not use the eyebrow OZ approach for patients with multiple aneurysms. There was no significant difference between frequency of intraoperative rupture, complete aneurysm occlusion, postoperative infection, length of stay, or discharge disposition. The eyebrow OZ group did have a significantly higher rate of frontal sinus violation compared with the standard OZ group. A subgroup analysis removing patients who were treated electively (unruptured) and removing patients who had multiple aneurysms was also performed. These data are summarized in Table 2 .
Table 1. Summary of clinical data.
| Eyebrow OZ | Standard OZ | p -Value | |
|---|---|---|---|
| Patients | 15 | 22 | |
| Age: mean, range | 52.3, 29–76 | 50.5, 13–80 | 0.733 |
| Multiple aneurysms | 0 | 7 | 0.028 |
| Primary dome projection | 0.882 | ||
| Inferior | 5 | 9 | |
| Superior | 5 | 6 | |
| Anterior | 5 | 6 | |
| Posterior | 0 | 0 | |
| Max diameter (mm): mean, range | 5.5, 3–9 | 5.6, 2–10 | 0.831 |
| Side of approach: right, left | 13, 2 | 17, 5 | 0.677 |
| Hunt–Hess grade | 0.774 | ||
| 0 (unruptured) | 2 | 1 | |
| 1–2 | 7 | 10 | |
| 3 | 4 | 8 | |
| 4 | 2 | 3 | |
| Intraop rupture | 4 | 6 | 0.967 |
| Frontal sinus violation | 8 | 4 | 0.025 |
| Complete aneurysm occlusion | 15 | 21 | |
| Infection | 0 | 1 | |
| LOS (d): mean, range | 18.4, 7–34 | 16.7, 6–40 | 0.581 |
| Discharge disposition | 0.328 | ||
| Home | 11 | 14 | |
| Rehab | 2 | 7 | |
| Death | 2 | 1 | |
| Follow-up | |||
| No follow-up after discharge | 1 | 1 | |
| Mean, range (mo) | 21.7, 1–56 | 16.0, 1–55 | 0.205 |
| Recurrence or retreatment | 0 | 0 | |
| Modified Rankin Score at last follow-up | 0.057 | ||
| 0 | 9 | 6 | |
| 1 | 3 | 13 | |
| 2 | 1 | 0 | |
| 3 | 0 | 2 | |
| 4–5 | 0 | 0 | |
| 6 | 2 | 1 |
Abbreviations: Intraop, intraoperative; LOS, length of stay; Oz, orbitozygomatic.
Table 2. Subgroup analysis: elective/unruptured and multiple aneurysm patients removed.
| Eyebrow OZ | Standard OZ | p- Value | |
|---|---|---|---|
| Patients | 13 | 14 | |
| Age: mean, range | 51.6, 29–76 | 50.1, 13–80 | 0.407 |
| Primary dome projection | 0.484 | ||
| Inferior | 4 | 7 | |
| Superior | 5 | 5 | |
| Anterior | 4 | 2 | |
| Max diameter (mm): mean, range | 5.3, 3–9 | 6.0, 2–10 | 0.171 |
| Side of approach: right, left | 12, 1 | 11, 3 | 0.315 |
| Hunt–Hess grade | 0.406 | ||
| 1–2 | 7 | 4 | |
| 3 | 4 | 7 | |
| 4 | 2 | 3 | |
| Intraop rupture | 3 | 4 | 0.745 |
| Frontal sinus violation | 7 | 3 | 0.081 |
| Complete aneurysm occlusion | 13 | 14 | |
| Infection | 0 | 0 | |
| LOS (d): mean, range | 18.4, 7–34 | 15.8, 6–40 | 0.222 |
| Discharge disposition | 0.476 | ||
| Home | 9 | 9 | |
| Rehab | 2 | 5 | |
| Death | 2 | 0 | |
| Follow-up | |||
| No follow-up after discharge | 1 | 1 | |
| Mean, range (mo) | 24.9, 2–56 | 19.0, 1 - 55 | 0.243 |
| Recurrence or retreatment | 0 | 0 | |
| Modified Rankin Score at last follow-up | 0.091 | ||
| 0 | 7 | 4 | |
| 1 | 3 | 9 | |
| 2 | 1 | 0 | |
| 3 | 0 | 1 | |
| 4–5 | 0 | 0 | |
| 6 | 2 | 0 |
Abbreviations: Intraop, intraoperative; LOS, length of stay; Oz, orbitozygomatic.
A total of 100% of the eyebrow mini-OZ group and 95.5% of the standard OZ group had complete occlusion of the aneurysms. Four patients in the eyebrow OZ cohort had an intraoperative rupture, and all were managed without complication. Table 3 compares outcomes of all patients who had an intraoperative rupture, comparing standard with OZ groups. No significant difference was seen in the outcomes of these groups.
Table 3. Outcomes for patients with intraoperative rupture.
| Eyebrow OZ | Standard OZ | p -Value | |
|---|---|---|---|
| Patients with intraoperative rupture | 4 | 6 | |
| Age: mean, range | 59.3, 32–56 | 42.2, 13–70 | 0.286 |
| Preop Hunt–Hess grade | 0.517 | ||
| 0 (unruptured) | 1 | 0 | |
| 1–2 | 1 | 3 | |
| 3 | 1 | 2 | |
| 4 | 1 | 1 | |
| Complete aneurysm occlusion | 4 | 6 | |
| Infection | 0 | 1 | |
| LOS—excluding Hunt Hess 0 patient—(d): mean, range | 25.0, 11–32 | 16.7, 6–40 | 0.059 |
| Discharge disposition | 0.933 | ||
| Home | 2 | 3 | |
| Rehab | 2 | 2 | |
| Death | 0 | 1 | |
| Follow-up | |||
| No follow-up after discharge | 0 | 1 | |
| Mean, range (mo) | 14.7, 1–56 | 21.0, 2–46 | 0.1338 |
| Recurrence or retreatment | 0 | 0 | |
| Modified Rankin Score at last follow-up | 0.572 | ||
| 0 | 3 | 2 | |
| 1 | 0 | 3 | |
| 2 | 1 | 0 | |
| 3–5 | 0 | 0 | |
| 6 | 0 | 1 |
Abbreviations: LOS, length of stay; Oz, orbitozygomatic; preop, preoperative.
Two patients died within 30 days of surgery in the eyebrow OZ group. One patient, age 75, Hunt–Hess 3, did not significantly improve postoperatively and died from medical complications worsened by her subarachnoid hemorrhage. The second patient, age 76, Hunt–Hess 1, presented after an motor vehicle accident and his death was due to his multiple traumatic injuries. One patient in the standard OZ group, age 30, Hunt–Hess 2, died from gram negative intracranial infection. No patients in either group have had aneurysm recurrence or required retreatment at last follow-up. Regardless of the chosen approach, exposure was never a limiting factor when clipping the aneurysm or dealing with intraoperative rupture.
Discussion
For ruptured anterior circulation aneurysms, the International Subarachnoid Aneurysm Trial (ISAT) shows superior outcomes for endovascular coiling of ruptured aneurysms compared with microsurgical clipping at 1 year 1 ; however, the Barrow Ruptured Aneurysm Trial shows equivalent long-term outcomes with a much lower risk of aneurysm recurrence in the microsurgical clipping group. 13 14 A variety of explanations for the ISAT results have been proposed. Among the most common criticisms is a lack of surgical expertise in the microsurgical treatment arm. 2 14 Excessive brain manipulation is another hypothesis to explain some the difference in outcomes seen in the ISAT trial. 9 This hypothesis claims that the large approaches that were standard during the study combined with lack of surgical expertise contributed to excessive brain manipulation. Multiple studies have demonstrated that brain retraction causes significant intraoperative damage to brain tissue. 9 15 16 Outcomes could be improved with a greater emphasis on using techniques that minimize intraoperative brain manipulation.
The OZ craniotomy is an important tool for the skull base surgeon treating pathology of the anterior and middle cranial fossa. Compared with standard pterional craniotomy, it provides better access and significantly less need for brain retraction. 17 18 There are many variations and modifications that can allow the approach to be tailored to the needs of each individual patient. 6 18 19 A key principle of skull base surgery is that improved exposure and less brain manipulation can often be accomplished through optimal bone removal. However, this benefit must be considered against the risk for potential for unfavorable cosmetic outcome, CSF leak, infection, or any other complication that may be associated with increased bone removal. 6 19
The principles of “keyhole” or “minimally invasive” surgery has gradually evolved and increased in popularity over the past 30 years. 9 20 21 Since the earliest days of neurosurgery, it has been widely regarded that exposing large areas of brain cortex for long surgeries increases the risk of iatrogenic tissue damage through exposure to air, irrigation, potential sources of infection, and direct tissue trauma from surgical instruments. 22 Proponents of keyhole craniotomies believe that small craniotomies are the best way to minimize this risk. 9 23
The eyebrow OZ approach that we describe is a keyhole modification of the standard OZ approach. It utilizes a small incision within the eyebrow and cosmetic results are excellent. 24 Compared with the standard OZ approach, the incision, size of craniotomy, and amount of exposed brain cortex are all much smaller. While we do not use fixed retractors for either approach, the eyebrow OZ approach utilizes a direct anterior to posterior trajectory to the aneurysm beneath the frontal lobes that minimizes brain manipulation. 3 Fig. 2 shows relevant anatomy of the ACoA complex from a right eyebrow OZ approach. Downsides to this approach are a smaller and deeper operative field. 9 17 In the setting of subarachnoid hemorrhage and significant brain swelling, these disadvantages are more significant, and the procedure becomes more technically challenging. Preoperative or intraoperative EVD for CSF diversion is required to provide brain relaxation. For these reasons, preference in our series was given to the standard OZ approach if the patient had both small ventricles and a large amount of subarachnoid hemorrhage with a full brain on the preoperative CT that was determined to not be easily relaxed with placement of an EVD. However, as the senior author gained more experience with the eyebrow OZ, this became the preferred approach unless the patient had multiple aneurysms.
There was no significant difference in age, aneurysm size, aneurysm dome projection, or Hunt–Hess grade in our groups, suggesting similar population groups. There was no significant difference in occlusion rates, discharge disposition, or postoperative complications. Four patients in the eyebrow OZ group had an intraoperative rupture, and all were managed without difficulty. Both patients that died in the eyebrow OZ group were elderly patients with significant comorbidities. The one death in the standard OZ group was a young patient who developed postoperative intracranial infection. One significant difference is that the eyebrow OZ group had higher rates of entry into the frontal sinus. Some authors propose using bone wax to close the frontal sinus. 10 We have previously described our novel technique for frontal sinus repair during an eyebrow OZ, and we have had no infections, mucoceles, or delayed CSF leaks with our method. 12 If recognized and properly addressed intraoperatively, unintentional opening of the frontal sinus does not add significant risk.
There are several limitations to this study. First, retrospective studies cannot definitively establish one treatment as superior to another. Both approaches, as chosen for these patients in this institution, appear to be safe and reasonable treatments. Second, the standard OZ approach was selectively chosen for patients with multiple aneurysms and for patients where significant brain edema was expected based on preoperative imaging. This creates differences between cohorts that may represent selection bias, which could influence our reported outcomes, presumably creating a higher risk cohort of patients treated with the standard OZ approach. Our subgroup analysis in Table 2 attempted to remove some of the selection bias coming from patients with multiple aneurysms and who were unruptured preoperatively.
Both the standard OZ and eyebrow OZ can be utilized effectively for the treatment of ACoA aneurysms. Our results with both methods compare favorably to large published series of microsurgical treatment of anterior circulation aneurysms. While it is hard to specifically quantify the amount of brain manipulation that becomes detrimental, the best policy for microsurgical treatment of aneurysms is to minimize brain manipulation as much as possible.
Conclusion
The OZ approach via an eyebrow incision has similar outcomes to a standard OZ approach and is a safe option for the treatment of ACoA aneurysms. The eyebrow OZ had higher rates of entry into the frontal sinus, but this did not result in higher complication rates. The best policy for microsurgical treatment of aneurysms is to minimize brain manipulation as much as possible.
Conflict of Interest None declared.
Ethics Approval and Consent to Participate
This retrospective chart review involving human patients was under the ethical standards established by the 1964 Helsinki Declaration. Institutional Review Board approval at the Atrium Health Carolinas Medical Center Hospital was obtained. Written informed consent by the patients was deemed not applicable since there was no information of the participants in the article that compromise anonymity.
References
- 1.International Subarachnoid Aneurysm Trial (ISAT) Collaborative Group Molyneux A J, Kerr R S, Yu L Met al. International Subarachnoid Aneurysm Trial (ISAT) of neurosurgical clipping versus endovascular coiling in 2143 patients with ruptured intracranial aneurysms: a randomised comparison of effects on survival, dependency, seizures, rebleeding, subgroups, and aneurysm occlusion Lancet 2005366(9488):809–817. [DOI] [PubMed] [Google Scholar]
- 2.McDougall C G, Spetzler R F, Zabramski J M et al. The Barrow Ruptured Aneurysm Trial. J Neurosurg. 2012;116(01):135–144. doi: 10.3171/2011.8.JNS101767. [DOI] [PubMed] [Google Scholar]
- 3.Chen J, Li M, Zhu X et al. Anterior communicating artery aneurysms: anatomical considerations and microsurgical strategies. Front Neurol. 2020;11:1020. doi: 10.3389/fneur.2020.01020. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Origitano T C, Anderson D E, Tarassoli Y, Reichman O H, al-Mefty O. Skull base approaches to complex cerebral aneurysms. Surg Neurol. 1993;40(04):339–346. doi: 10.1016/0090-3019(93)90148-t. [DOI] [PubMed] [Google Scholar]
- 5.Bowles A P, Kinjo T, Al-Mefty O. Skull base approaches for posterior circulation aneurysms. Skull Base Surg. 1995;5(04):251–260. doi: 10.1055/s-2008-1058923. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 6.Lemole G M, Jr, Henn J S, Zabramski J M, Spetzler R F. Modifications to the orbitozygomatic approach. Technical note. J Neurosurg. 2003;99(05):924–930. doi: 10.3171/jns.2003.99.5.0924. [DOI] [PubMed] [Google Scholar]
- 7.Campero A, Martins C, Socolovsky Met al. Three-piece orbitozygomatic approach Neurosurgery 201066(suppl_1):E119–E120. [DOI] [PubMed] [Google Scholar]
- 8.Tanriover N, Ulm A J, Rhoton A L, Jr, Kawashima M, Yoshioka N, Lewis S B.One-piece versus two-piece orbitozygomatic craniotomy: quantitative and qualitative considerationsNeurosurgery 2006;58(4, Suppl 2):ONS-229–ONS-237, discussion ONS-237 [DOI] [PubMed]
- 9.Reisch R, Fischer G, Stadie A, Kockro R, Cesnulis E, Hopf N.The supraorbital endoscopic approach for aneurysms World Neurosurg 201482(6, Suppl):S130–S137. [DOI] [PubMed] [Google Scholar]
- 10.Bhattarai R, Liang C, Chen C et al. Supraorbital eyebrow keyhole approach for microsurgical management of ruptured anterior communicating artery aneurysm. Exp Ther Med. 2020;20(03):2079–2089. doi: 10.3892/etm.2020.8909. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11.Choi J H, Kang M J, Huh J T. Influence of clinical and anatomic features on treatment decisions for anterior communicating artery aneurysms. J Korean Neurosurg Soc. 2011;50(02):81–88. doi: 10.3340/jkns.2011.50.2.81. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 12.Peters D R, Payne C, Wait S D. Orbitozygomatic craniotomy via an eyebrow incision: management of the opened frontal sinus. J Neurol Surg B Skull Base. 2021;82 03:e190–e195. doi: 10.1055/s-0039-3402025. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 13.Macdonald R L. Editorial: clip or coil? Six years of follow-up in BRAT. J Neurosurg. 2015;123(03):605–607. doi: 10.3171/2014.11.JNS142261. [DOI] [PubMed] [Google Scholar]
- 14.Spetzler R F, McDougall C G, Zabramski J M et al. Ten-year analysis of saccular aneurysms in the Barrow Ruptured Aneurysm Trial. J Neurosurg. 2019;132(03):771–776. doi: 10.3171/2018.8.JNS181846. [DOI] [PubMed] [Google Scholar]
- 15.Yokoh A, Sugita K, Kobayashi S.Clinical study of brain retraction in different approaches and diseases Acta Neurochir (Wien) 198787(3–4):134–139. [DOI] [PubMed] [Google Scholar]
- 16.Andrews R J, Bringas J R.A review of brain retraction and recommendations for minimizing intraoperative brain injury Neurosurgery 199333061052–1063., discussion 1063–1064 [DOI] [PubMed] [Google Scholar]
- 17.Filipce V, Pillai P, Makiese O, Zarzour H, Pigott M, Ammirati M.Quantitative and qualitative analysis of the working area obtained by endoscope and microscope in various approaches to the anterior communicating artery complex using computed tomography-based frameless stereotaxy: a cadaver study Neurosurgery 200965061147–1152., discussion 1152–1153 [DOI] [PubMed] [Google Scholar]
- 18.Seçkin H, Avci E, Uluç K, Niemann D, Başkaya M K. The work horse of skull base surgery: orbitozygomatic approach. Technique, modifications, and applications. Neurosurg Focus. 2008;25(06):E4. doi: 10.3171/FOC.2008.25.12.E4. [DOI] [PubMed] [Google Scholar]
- 19.Cohen-Gadol A. The orbitozygomatic craniotomy and its judicious use. Oper Neurosurg (Hagerstown) 2020;18(05):559–569. doi: 10.1093/ons/opz246. [DOI] [PubMed] [Google Scholar]
- 20.Gandhi S, Cavallo C, Zhao X et al. Minimally invasive approaches to aneurysms of the anterior circulation: selection criteria and clinical outcomes. J Neurosurg Sci. 2018;62(06):636–649. doi: 10.23736/S0390-5616.18.04562-9. [DOI] [PubMed] [Google Scholar]
- 21.Perneczky A, Fries G.Endoscope-assisted brain surgery: part 1–evolution, basic concept, and current technique Neurosurgery 19984202219–224., discussion 224–225 [DOI] [PubMed] [Google Scholar]
- 22.Wilson D H. Limited exposure in cerebral surgery. Technical note. J Neurosurg. 1971;34(01):102–106. doi: 10.3171/jns.1971.34.1.0102. [DOI] [PubMed] [Google Scholar]
- 23.Teo C.The concept of minimally invasive neurosurgery Neurosurg Clin N Am 20102104583–584., v [DOI] [PubMed] [Google Scholar]
- 24.Gazzeri R, Nishiyama Y, Teo C. Endoscopic supraorbital eyebrow approach for the surgical treatment of extraaxial and intraaxial tumors. Neurosurg Focus. 2014;37(04):E20. doi: 10.3171/2014.7.FOCUS14203. [DOI] [PubMed] [Google Scholar]