Material and Method: We evaluated 17 patients with olfactory groove meningiomas undergoing the supraorbital eyebrow approach from February 2018 to November 2022. A retrospective analysis of patients was performed with eyebrow approaches of our database of 17 who had supraorbital craniotomy for olfactory groove meningioma removal. Patients were evaluated based on pathology, resection rate, complications, and cosmetic re-sults.

Results: Patients' grade with olfactory groove meningioma was World Health Organization grade 1, and the mean Ki-67 was 1.4. The resection grade was Simpson Grade 1. The satisfaction of patients with cosmetic outcomes was perfect. None of the patients underwent postoperative reoperation. Only one patient underwent rehospitalization in the postoperative period for evaluation due to a suspected wound infection.

Conclusion: Supraorbital eyebrow craniotomy is an effective keyhole approach for the surgery of olfactory groove meningiomas. Future surgical treatment of more types of anterior fossa lesions, with increasing patient numbers and multicenter studies, will employ this technique.

A variety of surgical approaches have been used to treat olfactory groove meningioma, including largely invasive, extended bifrontal, interhemispheric, orbi-tozygomatic, pterional, and nasal approaches^2-6. These approaches are generally sufficient. However, cosmetic results in these approaches can be a cause for concern. By combining the instruments used in narrower corridors with the microscope, researchers have developed various minimally invasive methods in transcranial pathologies^6,7. Among these, supraor-bital eyebrow mini-craniotomy (eyebrow approach) is used safely today^1,7-9.

Primarily, the eyebrow approach is effective in treating anterior fossa tumors, arachnoid cysts, and aneurysms¹⁰. The eyebrow approach allows for easy visualiza-tion of the ipsilateral frontal lobe, the medial part of the contralateral frontal and ipsilateral temporal lobes, the ipsilateral Sylvian fissure, the ipsilateral olfactory gro-ove, the cribriform plate region, the parasellar region, and the prepontine cistern in the surgical field^11,12.

We evaluated the results of olfactory groove meningiomas operated in our clinic with the supraorbital eyebrow minicraniotomy approach, together with the literature.

We obtained data from the patient's records and directly reviewed the imaging. Demographic and clinical characteristics included age, sex, vision impairment, and anosmia. Within 48 hours before surgery, we eva-luated the tumor characteristics and suitability for the surgical approach using computed tomography (CT) and magnetic resonance imaging (MRI).

Patients older than 18 years of age who had previously undergone olfactory meningioma surgery with the eyebrow approach and meningioma cases located mainly in the cavernous sinus, sella, diaphragm, and cli-noid were not included in the study.

There are no definitive indications for the supraorbital approach. However, we believe the following factors should be considered when evaluating the surgical approach: (1) If the tumor extends from the cribriform plate into the ethmoid sinus, the supraorbital approach alone may not be sufficient according to Simpson gra-de 1. (2) If the defect in the nasal sinuses cannot be adequately repaired during the supraorbital approach, another approach should be considered.

Surgical Technique
After general anesthesia, endotracheal intubation, and placement of a Foley catheter, the patient is fixed in a Mayfield three-pin head holder with two pins on the ipsilateral posterior cranium and the one-pin site on the contralateral frontal bone. We operated on patients with the head elevated to enhance jugular venous drainage, reflected the head backward to augment gravity-assisted brain retraction, and used no retractors.

Depending on the location of the lesion, it would be more appropriate to choose the non-dominant side so that the dominant frontal lobe is least damaged, especially to reach both sides.

ally to reach both sides. The skin incision was limited to the eyebrow starting from just 0.5-1 cm lateral to the supraorbital notch (Figure 1). The skin incision length was approximately 3-4 cm. For cosmetic concerns, the orbicularis oculi muscle was pushed down, and the frontalis muscle was cut flush with the skin incision. Placing the skin incision laterally to the supraorbital notch is crucial to prevent forehead numbness due to damage to the supraorbital nerve during surgery.

The pericranium was incised starting from the anterior end of the linea temporalis following retraction of the upper edge of the skin incision using fish hooks. A small D-shaped 3.0 by 1.5 cm craniotomy was perfor-med in the supraorbital area. The skin incision is made along the eyebrow without cutting the hair of the eyeb-row (Figure 1).

After the inner lip of the orbital rim and orbital promi-nences were drilled out, the dura was opened in a C-shaped fashion and reflected inferiorly. Following gentle retraction of the frontal lobe, cerebrospinal fluid (CSF) was aspirated till identification of the ipsilateral optic nerve and carotid artery (Figures 1, 2).

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Figure 1: A: The skin incision was limited to the eyebrow starting from just 0.5-1 cm lateral to the supraorbital notch, B: The sterile draping of the surgical field, C: Skin incision, D: Dural opening, E: Operation and hemostasis by bipolar cautery, F: Removal of the tumor.

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Figure 2: The MRI showing the tumor before surgery.

The medial part of the tumor was dissected until free-ing the tumor from the peripheral structures (Figure 1, 2). After the tumor was de-vascularized and debulked, the tumor was resected (Simpson Grade 1). The blee-ding was controlled and stopped. The dura was closed watertight. The bone flap was replaced and fixed with mini plates.

Routine follow-up MRI or CT were obtained regularly at 72 hours, 3, 6, and 12 months postoperatively (Figures 3, 4).

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Figure 3: The MRI showing postoperative surgical excision of the tumor.

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Figure 4: 3D CT showing the postoperative bony anatomy of the approach.

Statistical Analysis
Data were analyzed using both Microsoft Excel (Mic-rosoft, Redmond, Washington) and GraphPad Prism Version 6 (GraphPad Software Inc., La Jolla, Califor-nia, USA). One-way analysis of variance (one-way ANOVA) was used to evaluate differences in tumor volume.

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Table 1: Patients’characteristics.

At the time of discharge, 3/17 patients had graded frontalis palsy. It was observed that these improved in the controls within the first month. All of the patients reported that they were satisfied with the cosmetic results at the 3-month follow-up. The frontal sinus was entered in 2/17 patients and obliterated with adipose tissue. None of these patients had a cerebrospinal fistu-la, wound infection, forehead collapse, or a problem requiring reoperation in the early or late postoperative period (Table 2).

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Table 2: The surgical results.

None of the patients had eyebrow alopecia or temporal muscle atrophy. The patients reported no additional complaints regarding their chewing functions. None of our patients developed stroke, postoperative hematoma, a supraorbital pseudomeningocele, or a seizure. No additional preventive medical treatment for seizures was given. Anosmia developed in 1/17 of our patients postoperatively, and anosmia resolved in this patient's 2-month follow-up. The pathology results indicated that 15 patients had meningiomas classified as World Health Organization grade 1, while 2 patients had gra-de 2 meningiomas. The mean preoperative tumor vo-lume was 20.0±14.2 cm³ (range 2.2-45.9 cm³). All our patients underwent Simpson grade 1 olfactory groove meningioma resection, which involves the complete removal of the underlying bone and associated dura. Mean Ki-67 indexes were 1.4% (range: 1-3%). During the follow-up, no patient showed any signs of recurrence.

The average duration of the operation was 2.4 hours, during which we did not administer any additional blood elements or transfusions. We readmitted one of our patients, who had a frontal sinus entry, to the hos-pital for a skin infection evaluation one month after discharge, but we did not perform any additional pro-cedures or operations.

Only one patient underwent preoperative lumbar drai-nage for brain relaxation during dissection, and this was removed in the early postoperative period.

In our study, 17 olfactory groove meningioma patients were evaluated. Despite the absence of recurrence in our Simpson grade 1 resection patients and the absence of mortality in our postoperative follow-ups, we antici-pate satisfactory surgical outcomes, including cosmetic problems and short hospital stays.

Most surgeons avoid the supraorbital eyebrow mini-craniotomy approach due to the potential legal issues associated with an incision in a socially prominent facial area. However, for cosmetic results, the skin incision should be cut aesthetically, monopolar and bipolar bleeding should be avoided as much as possib-le, and these conditions can be managed with tampons and retractors. In our study, temporalis atrophy, eye alopecia, CSF fistula, and supraorbital pseudomenin-gocele were seen in 0/17 patients. In another study, high cosmetic results were reported¹⁴. In the study, cosmetic satisfaction among patients is high: in 1 study, 84% of patients rated their cosmetic outcome as “very pleasant,” and the rate of permanent frontalis palsy was 2.1%⁹. The rate of permanent forehead numbness was 3.4%¹³. Although it is necessary to be careful when dissecting the skin, subcutaneous, bone, and muscle in cosmetic results, we think the same situation should be maintained in closing the last part of the surgery and dressing.

In our study, we performed Simpson grade 1 resection on 17 patients with olfactory groove meningioma. The mean max tumor volume was 20.0±14.2 cm³ (range 2.2-45.9 cm³). Our patients did not affect the cavernous sinus, the optic apparatus, the carotid artery, and the pituitary infundibulum structures. If these structures are affected, our surgical view will be reduced with the supraorbital eyebrow mini-craniotomy approach, and we will not be able to dissect vascular and neurological structures. We believe that Simpson Grade 1 and 2 resections were successfully performed with this app-roach, as the tumors in our study patients were relati-vely small in volume and did not compress vital neuro-vascular structures.

Our mean follow-up period was 11.4±5 months. We did not have any additional recurrences during this period. Despite the request for a longer follow-up, we anticipate no recurrence, given our mean Ki-76 index of 1.4% (range: 1-3%), which includes total tumor resection. In this context, future studies can evaluate our tumor volume and degree of resection for potential recurrence.

Performing the surgery without entering the frontal sinus is essential regarding infection and CSF fistula. However, when we encounter this complication, it can be managed with classical frontal sinus-filling methods such as abdominal fat tissue and frontal sinus craniali-zation. In this study, the frontal sinus occurred in 2/17 (11.7%) patients. Other studies^3,4 have estimated this rate to be approximately 21.6%. Although these numerical data vary depending on the number of pati-ents and surgical technique, it is a manageable problem in general. The literature review identified CSF leakage and wound complications as the most common complications^5,15. It has been emphasized that olfactory groove meningiomas are located in the midline as CSF problems and that methods that prevent dura and CSF fistula may not be adequately performed during surgery. Although this is valid for giant meningiomas, our microsurgery and the tumor volume we applied could easily be seen on the recessed cribriform plate. In addi-tion, our lumbar drainage application in the preoperative period not only facilitated the dissection but also helped to prevent postoperative CSF fistula. The presence of CSF fistula and supraorbital pseudomeningo-cele 0/17 in our study may be related to this. Despite the potential for CFS fistula complications during the supraorbital eyebrow mini-craniotomy approach, a study found this problem to be more manageable and less common compared to the endoscopic method^2,14,16.

Our study had several limitations. This was a single-center study and, therefore, may have been subjected to selection bias. However, the use of this surgical tech-nique is becoming widespread, and the results will be more evident as all these study results are published soon. Hence, we instituted strict inclusion and exclusion criteria. Our sample size was small, and we performed a short-term follow-up. The general drawback of minimal cranial approaches is the loss of proximal control of arterial structures during surgery due to the small size of the surgical space. In our study, no serious complications were encountered due to our relatively small space. New approaches that are alternatives to classical surgical approaches are rightly always approached with hesitation. It is natural to have reser-vations about this approach. However, with increased technical skills, this approach may be an alternative to the different concerns and wishes of selected patient groups. Our results may guide future studies in similar groups.

Supraorbital eyebrow mini-craniotomy can be used in the treatment of many anterior fossae, from arachnoid cysts to aneurysms, and the approach that is likely to become routine in some selected cases should be mul-ticenter with a large number of patients. We evaluated the complications in our study and managed them using classical microsurgery solutions. The supraorbital eyebrow mini-craniotomy method is safe, gives good cosmetic results, and may have lower morbidity rates. It allows for good exposure, resection, and relea-se of neurovascular structures. Adding endoscopy, neuronavigation techniques, and imaging techniques during surgery will, of course, make it easier to remove more large tumors that affect neurovascular structures with fewer problems.

1) Czirják S, Szeifert GT. The role of the superciliary approach in the surgical management of intracra-nial neoplasms. Neurol Res 2006; 28:131-7.

2) Bitter AD, Stavrinou LC, Ntoulias G et al. The Role of the Pterional Approach in the Surgical Treatment of Olfactory Groove Meningiomas: A 20-year Experience. J Neurol Surg B Skull Base 2013; 74: 97-102.

3) Feigl GC, Staribacher D, Britz G, Kuzmin D. Mi-nimally Invasive Approaches in the Surgical Tre-atment of Intracranial Meningiomas: An Analysis of 54 Cases. Brain Tumor Res Treat 2024; 12: 93-9.

4) Fountas KN, Hadjigeorgiou GF, Kapsalaki EZ, Paschalis T, Rizea R, Ciurea AV. Surgical and functional outcome of olfactory groove meningiomas: Lessons from the past experience and strategy development. Clin Neurol Neurosurg 2018; 171: 46-52.

5) Roa Montes de Oca JC, Gonçalves Estella JM, Nieto-Librero AB et al. Olfactory Groove Menin-giomas: Comprehensive assessment between the different microsurgical transcranial approaches and the Endoscopic Endonasal Approaches, sys-tematic review and metanalysis on behalf of the EANS skull base section. Brain Spine 2022; 2: 101661.

6) Xie B, Qin C, Zhang S, Zhang C et al. A novel classification for guiding the surgical approach for cranio-orbital lesions: a single institution case se-ries of 45 cases and a literature review. Neurosurg Rev 2024; 47: 71.

7) Zador Z, Gnanalingham K. Eyebrow craniotomy for anterior skull base lesions: how I do it. Acta Neurochir (Wien) 2013; 155: 99-106.

8) Paladino J, Mrak G, Miklić P, Jednacak H, Mihal-jević D. The keyhole concept in aneurysm surgery--a comparative study: keyhole versus standard cra-niotomy. Minim Invasive Neurosurg 2005; 48: 251-8.

9) Park J, Woo H, Kang DH, Sung JK, Kim Y. Su-perciliary keyhole approach for small unruptured aneurysms in anterior cerebral circulation. Neuro-surgery 2011; 68: 300-9

10) Ansari SF, Eisenberg A, Rodriguez A, Barkhouda-rian G, Kelly DF. The Supraorbital Eyebrow Cra-niotomy for Intra- and Extra-Axial Brain Tumors: A Single-Center Series and Technique Modification. Oper Neurosurg (Hagerstown) 2020; 19: 667-77.

11) Li Y, Rey-Dios R, Roberts DW, Valdés PA, Co-hen-Gadol AA. Intraoperative fluorescence-guided resection of high-grade gliomas: a comparison of the present techniques and evolution of future stra-tegies. World Neurosurg 2014; 82: 175-85.

12) Sastry R, Bi WL, Pieper S et al. Applications of Ultrasound in the Resection of Brain Tumors. J Neuroimag 2017; 27: 5-15.

13) Reisch R, Perneczky A, Filippi R. Surgical tech-nique of the supraorbital key-hole craniotomy. Surg Neurol 2003; 59: 223-7.

14) Banu MA, Mehta A, Ottenhausen M et al. Endos-copeassisted endonasal versus supraorbital keyho-le resection of olfactory groove meningiomas: comparison and combination of 2 minimally inva-sive approaches. J Neurosurg 2016; 124: 605-20. 15. Ormond DR, Hadjipanayis CG. The Supraorbital Keyhole Craniotomy through an Eyebrow Inci-sion: Its Origins and Evolution. Minim Invasive Surg 2013; 2013: 296469.

16) Komotar RJ, Starke RM, Raper DM et al. Endoscopic endonasal versus open transcranial resection of anterior midline skull base meningiomas. World Neurosurg 2012; 77: 713-24.