Keyhole Craniotomy Research Articles

Minimally Invasive Aneurysm Clipping: The Extent of the Supraorbital Approach

The supraorbital keyhole craniotomy is a well-established minimally invasive approach for the treatment of intracranial aneurysms. However, the surgical range of exposure using this technique for treatment of intracranial aneurysms has not been studied. We retrospectively reviewed the data of all clipped aneurysm cases using the supraorbital approach (SO) between 2006 and 2016 in our center. Most importantly, we determined the location of the treated aneurysms in the axial 2-dimensional plane, with the anterior clinoid process (ACP) as the point of reference: the ACP to aneurysm distance. Finally, we extracted data on patient age, aneurysm size, size of the craniotomy, length of hospital stay, and surgery-related complications. We included 142 patients for this series. A total of 170 aneurysms were clipped by means of the SO, and in 18 cases multiple aneurysms were treated during the same surgery. The mean aneurysm size was 7 mm (3.5-22 mm) and the mean craniotomy size was 28 mm (19-41 mm). The aneurysm location ranged from 14.4 mm medially to 35 mm laterally, measured with the ipsilateral ACP as the zero reference. Although the SO is conventionally used in the treatment of anterior circulation aneurysms, we were able to treat aneurysms over a range of 50 mm over the skull base. With its low complication risk, relatively short hospital stay, and excellent cosmetic results, SO remains a valuable treatment option for both young and aged patients.

Comparison of Supraorbital and Pterional Keyhole Approach for Clipping Middle Cerebral Artery Aneurysm: A Chinese Population-Based Study

Keyhole craniotomy is a minimally invasive approach for the treatment of middle cerebral artery (MCA) aneurysms. The aim of this study was to compare the clinical outcome between supraorbital keyhole approach and pterional keyhole approach (PKA) in Chinese patients with MCA aneurysm. Consecutive patients with MCA aneurysms were reviewed between January 2013 and December 2017. Efficacy and safety between PKA and supraorbital keyhole approach were compared. Poor outcome was defined as modified Rankin Scale score of 3-6 at discharge. This study enrolled 260 patients; 222 (85.4%) had ruptured aneurysm, and 183 (70.4%) received PKA. The distribution of PKA in unruptured and ruptured aneurysms showed no significant difference (P > 0.05). In subgroup analyses, PKA was more likely associated with poor outcome at discharge in patients with unruptured aneurysms (odds ratio= 5.500, 95% confidence interval= 1.013-29.850, P= 0.048), whereas approach selection was not an independent factor predicting poor outcome in patients with ruptured aneurysms (P > 0.05). In a Chinese population, supraorbital keyhole approach was superior to PKA in improving outcome in patients with unruptured MCA aneurysms, but the 2 approaches showed comparable outcomes at discharge in patients with ruptured aneurysms.

Key Hole Craniotomy for Microvascular Decompression for Trigeminal Neuralgia and Hemifacial Spasm: A Short Series of 4 Cases

Micro vascular decompression is performed as a common procedure in neurosurgical field for trigeminal neuralgia, hemi facial spasm, tinnitus etc. Regular craniotomy or craniectomy amounts to significant concerns in length of incision, size of craniotomy, postoperative stay in hospital, complications encountered and outcome. Keyhole craniotomy is an answer to all these concerns [1]. We present here our short series of key hole craniotomies done for micro vascular decompression for various indications and confirming the favorable outcome.

Frontal Keyhole Craniotomy for Resection of Low- and High-Grade Gliomas.

Minimally invasive techniques are increasingly being used to access intra-axial brain lesions. To describe a method of resecting frontal gliomas through a keyhole craniotomy and share the results with these techniques. We performed a retrospective review of data obtained on all patients undergoing resection of frontal gliomas by the senior author between 2012 and 2015. We describe our technique for resecting dominant and nondominant gliomas utilizing both awake and asleep keyhole craniotomy techniques. After excluding 1 patient who received a biopsy only, 48 patients were included in the study. Twenty-nine patients (60%) had not received prior surgery. Twenty-six patients (54%) were diagnosed with WHO grade II/III tumors, and 22 patients (46%) were diagnosed with glioblastoma. Twenty-five cases (52%) were performed awake. At least 90% of the tumor was resected in 35 cases (73%). Three of 43 patients with clinical follow-up experienced permanent deficits. We provide our experience in using keyhole craniotomies for resecting frontal gliomas. Our data demonstrate the feasibility of using minimally invasive techniques to safely and aggressively treat these tumors.

Minimally Invasive Alternative Approaches to Pterional Craniotomy: A Systematic Review of the Literature.

Minimally invasive alternatives to the pterional craniotomy include the minipterional and the supraorbital craniotomy (SOC). The latter is performed via either an eyebrow or an eyelid skin incision. The purpose of this systematic review was to analyze the type and the incidence of approach-related complications of these so-called "keyhole craniotomies". We review pertinent articles retrieved by search in the PubMed/Medline database. Inclusion criteria were all full-text articles, abstracts, and posters in English, up to 2016, reporting clinical results. A total of 105 articles containing data on 5837 surgeries performed via a minipterional or either of the 2 variants of the SOC met the eligibility criteria. Pain on mastication was the most commonly reported approach-related complication of the minipterional approach, and occurred in 7.5% of cases. Temporary palsy of the frontal branch of the facial nerve and temporary supraorbital hypesthesia were associated with the SOC eyebrow variant, and occurred in 6.5%, respectively in 3.6% of cases. Transient postoperative periorbital edema and transient ophthalmoparesis occurred in 36.8% and 17.4% of cases, respectively, when the SOC was performed via an eyelid skin incision. The risk of occurrence of the latter 2 complications was related to the removal of the orbital rim, which is an obligatory part of the SOC approach through the eyelid but optional with the SOC eyebrow variant. Each of the 3 keyhole approaches has a specific set and incidence of approach-related complications. It is essential to be aware of these complications to make the safest individual choice.

Anterior Skull Base Tumor Resection by Transciliary Supraorbital Keyhole Craniotomy: A Single Institutional Experience.

The prognosis and recurrence rate after resection of an anterior skull base lesion via transciliary supraorbital keyhole craniotomy depend on residual tumor volume. The extent to which pathology and size of tumor influence the resection rate using this approach is unknown. Sixty-two patients underwent a total of 64 operations using the supraorbital keyhole approach in this retrospective study. Meningioma was the most common tumor, followed by pituitary adenoma and craniopharyngioma. Age, sex, tumor volume, operative duration, blood loss, and complication rates were evaluated. Pre- and postoperative residual tumor volumes were measured using OsiriX software (medical image viewer system) based on magnetic resonance imaging. A 15-mL cut value divided the subjects into large versus small meningioma groups. The average resection rate for meningiomas was 95.2% compared with 83.9% for craniopharyngiomas and 53.2% for pituitary adenomas. The major complication rate (primarily blindness and hemiplegia) was 4.48% in all tumors. No operative-related deaths occurred. There were no surgical revisions to traditional large craniotomies. No significant differences in age, sex, postoperative volumes, resection rates, or recurrence rates were noted between small and large meningioma groups. However, longer operative times and hospital stays, and greater blood loss occurred in the large meningioma group. Transciliary keyhole craniotomy is a safe and effective approach for anterior skull base tumors, especially meningiomas. Excellent resection results were achieved even in cases of large meningiomas. Although longer operative times, longer hospital stays, and greater blood loss occurred in larger compared with smaller meningioma cases, recurrence rates were similar.

Minipterional and Supraorbital Keyhole Craniotomies for Ruptured Anterior Circulation Aneurysms: Experience at Single Center.

Keyhole craniotomy is a type of pterional craniotomy that involves a minimally invasive approach for the treatment of cerebral aneurysms. Currently, the minipterional keyhole craniotomy and supraorbital keyhole craniotomy procedures are frequently performed. We evaluated the feasibility and safety of supraorbital keyhole craniotomies and minipterional keyhole craniotomy for the clipping of ruptured intracranial aneurysms in the anterior cerebral circulation as an alternative to the pterional approach in a consecutive series of 25 patients. The rate of intraoperative aneurysmal rupture was 8% (2/25), and all ruptures were safely controlled. The success solely depends on careful selection of patients and the experience of the surgical team.

Endoscope-assisted repair of CSF otorrhea and temporal lobe encephaloceles via keyhole craniotomy.

OBJECTIVE Temporal lobe encephaloceles and cerebrospinal fluid otorrhea from temporal bone defects that involve the tegmen tympani and mastoideum are generally repaired using middle fossa craniotomy, mastoidectomy, or combined approaches. Standard middle fossa craniotomy exposes patients to dural retraction, which can lead to postoperative neurological complications. Endoscopic and minimally invasive techniques have been used in other surgeries to minimize brain retraction, and so these methods were applied to repair the lateral skull base. The goal of this study was to determine if the use of endoscopic visualization through a middle fossa keyhole craniotomy could effectively repair tegmen defects. METHODS The authors conducted a retrospective review of 6 cases of endoscope-assisted middle fossa repairs of tegmen dehiscences at a tertiary care medical center within an 18-month period. RESULTS All cases were successfully treated using a keyhole craniotomy with endoscopic visualization and minimal retraction. Surgical times did not increase. There were no major postoperative complications, recurrences of encephaloceles, or cerebrospinal fluid otorrhea in these patients. CONCLUSIONS Endoscopic visualization allows for smaller incisions and craniotomies and less risk of brain retraction injury without compromising repair integrity during temporal encephalocele and tegmen repairs.

Method for temporal keyhole lobectomies in resection of low- and high-grade gliomas.

OBJECTIVE The purpose of this study was to describe a method of resecting temporal gliomas through a keyhole lobectomy and to share the results of using this technique. METHODS The authors performed a retrospective review of data obtained in all patients in whom the senior author performed resection of temporal gliomas between 2012 and 2015. The authors describe their technique for resecting dominant and nondominant gliomas, using both awake and asleep keyhole craniotomy techniques. RESULTS Fifty-two patients were included in the study. Twenty-six patients (50%) had not received prior surgery. Seventeen patients (33%) were diagnosed with WHO Grade II/III tumors, and 35 patients (67%) were diagnosed with a glioblastoma. Thirty tumors were left sided (58%). Thirty procedures (58%) were performed while the patient was awake. The median extent of resection was 95%, and at least 90% of the tumor was resected in 35 cases (67%). Five of 49 patients (10%) with clinical follow-up experienced permanent deficits, including 3 patients (6%) with hydrocephalus requiring placement of a ventriculoperitoneal shunt and 2 patients (4%) with weakness. Three patients experienced early postoperative anomia, but no patients had a new speech deficit at clinical follow-up. CONCLUSIONS The authors provide their experience using a keyhole lobectomy for resecting temporal gliomas. Their data demonstrate the feasibility of using less invasive techniques to safely and aggressively treat these tumors.

Simultaneous Resection of Multiple Metastatic Brain Tumors with Multiple Keyhole Craniotomies.

The proper management of symptomatic patients with 2 or more brain metastases is not entirely clear, and the surgical outcomes of these patients undergoing multiple simultaneous craniotomies have not been well described. In this article, we describe patient outcomes after simultaneously resecting metastatic lesions through multiple keyhole craniotomies. We conducted a retrospective review of data obtained for all patients undergoing resection of multiple brain metastases in one operation between 2014 and 2016. We describe a technique for resecting multiple metastatic lesions and share the patient outcomes of this operation. Twenty patients with 46 tumor resections were included in the study. The primary site of metastases for the majority of patients was lung, followed by melanoma, renal, breast, colon, and testes. Nine of 20 (45%) patients had 2 preoperative intracranial lesions, and 11 (55%) had three or more. Karnofsky performance scales were calculated for 14 patients: postoperatively 10 of 14 (71%) scores improved, 2 of 14 (14%) worsened, and 2 of 14 (14%) remained unchanged. After surgery, 9 of 14 (64%) patients were weaned off steroids by 2-month follow-up. The overall median survival time from date of surgery was 10.8 months. We present patient outcomes after simultaneously resecting metastatic brain tumors through multiple keyhole craniotomies in symptomatic patients. Our results suggest comparable outcomes and similar surgical risk compared with those undergoing resection of a single brain metastasis. Resection of multiple brain metastases may improve Karnofsky Performance Scale scores in the early postoperative period and allow patients to be weaned from steroids.

Supraorbital Keyhole Craniotomy for Basilar Artery Aneurysms: Accounting for the "Cliff" Effect.

Treatment of basilar artery aneurysms is challenging. While endovascular techniques have dominated, there still remain circumstances where open surgical clipping is required or preferred. Minimally invasive "keyhole" approaches are being used more frequently to provide the durability of surgical clipping with a lower morbidity profile; however, careful patient selection is required. The supraorbital "keyhole" approach has been described for the treatment of basilar artery aneurysms, but careful assessment of the basilar exposure is necessary to ensure proper visualization of the aneurysm and ability to obtain proximal vascular control. Various methods of estimating the basilar artery exposure in this approach have been described, including the anterior skull base line and the posterior clinoid line, but both are unreliable and inaccurate. To propose a new method, the orbital roof-dorsum line, to simply and accurately predict the basilar artery exposure. CT angiograms for 20 consecutive unique patients were analyzed to obtain the anterior skull base line, posterior clinoid line, and the orbital roof-dorsum line. CT angiograms were then loaded onto a Stealth neuronavigation system (Medtronic, Minneapolis, Minnesota) to obtain "true" visualization lengths. A case illustration is presented. Pairwise comparison tests demonstrated that both the anterior skull base and the posterior clinoid estimation lines differed significantly from the "true" value ( P < .0001). Our orbital roof-dorsum estimation provided results that accurately predicted the "true" value ( P = .71). The orbital roof-dorsum line provides a simple and reliable method of estimating basilar artery exposure and should be used whenever considering patients for surgical clipping by this approach.

Quantification of Working Volumes, Exposure, and Target-Specific Maneuverability of the Pterional Craniotomy and Its Minimally Invasive Variants

Quantitative comparison of minimally invasive and standard cranial approaches remains a methodologic challenge. The aim of this study was to apply a new digital, navigation-based method to quantify multiple parameters of the pterional, supraorbital, lateral supraorbital and mini-pterional approaches and to describe a target-specific maneuverability score. Supraorbital, lateral supraorbital, mini-pterional, and standard pterional craniotomies were performed on 8 sides in 4 cadaver heads. The limits of superficial and deep exposure and surgical target points were registered with image-guidance (Medtronic Stealth). A custom software (Guided Therapeutics Eyes II Software [GTxEyesII]) calculated superficial and deep surface areas, working volumes, and target distances. Volumes were reconstructed digitally and visualized with GTxEyesII. Finally, we defined for each approach a target-specific maneuverability score based on surface exposure, target distance, target position, and anatomical obstacles. Surface exposure and volumes were significantly smaller for keyhole approaches compared with standard pterional craniotomy (P < 0.01). Maneuverability index scores showed the greatest values for standard pterional craniotomies, but nearly equally high scores could be achieved by one or several of the less-invasive approaches for most of the targets. The combination of a navigation-based measurement method with custom software (GTxEyesII) provides a powerful tool for visualization and quantification of surgical approaches. Compared with standard pterional craniotomy, alternative keyhole craniotomies offer comparable deep exposure with smaller working volumes and relatively high maneuverability for specific targets.

Clinical Application of Scalp Markers and Three-Dimensional Sliced Computed Tomography Reconstructions of the Skull Transverse-Sigmoid Sinus Groove in the Retrosigmoid Approach.

To explore the clinical value of bone flap creation and the sinus protection in the approach of retrosigmoid keyhole craniotomy with the guidance of three-dimensional (3D) sliced computed tomography (CT) reconstruction of the skull transverse sinus and sigmoid sinus groove. The scalp tracings of the transverse sinus and sigmoid sinus groove of 108 posterior fossa lesion patients were delineated by gentian violet, which relies on the relationship between its 3D reconstruction location and scalp marker. The craniotomy was executed with the guidance of its surface tracings. The intraoperative findings of exposure and damage of transverse sinus, sigmoid sinus, morphology, stability, complications, and postoperative appearance of bone flap restoration were evaluated. Morphological analysis of the transverse-sigmoid sinus groove showed right superiority, left superiority, and balanced type in 61, 18, and 29 cases, respectively and the relationship between the asterion and the transverse-sigmoid sinus groove showed that asterion sites were located in the upper portion, onto, and below the transverse and sigmoid sinus groove in 19, 68, and 21 cases, respectively. Good intraoperative exposure without damage of transverse sinus and sigmoid sinus, good stability and appearance of bone flap restoration, and no postoperative pseudomeningocele were obtained after using this method to locate the transverse sinus and sigmoid sinus. The 3D sliced CT reconstruction of the skull transverse sinus and sigmoid sinus groove was helpful in the approach of retrosigmoid craniotomy for sinus exposure, sinus protection, and the prevention of cerebrospinal fluid leakage and pseudomeningocele.

SUPRAORBITAL KEYHOLE CRANIOTOMY IN SURGERY OF INTRA- AND EXTRA-AXIAL BRAIN TUMORS

Background . Priority objectives of surgical neurooncology (diagnosis verification, tumor cytoreduction, and preservation of patient’s functional status) can be achieved both through traditional neurosurgical approaches and through the use of keyhole surgery. Keyhole surgery allows to minimize unnecessary, extended resection of the skull base and long-term static brain tissue retraction. Objective . The authors present preliminary results of the use of supraorbital keyhole craniotomy in intra- and extra-axial brain tumors. Materials and methods. In 2014–2016, 45 patients were operated through supraorbital craniotomy to treat intra- and extra-axial tumors. The majority of patients (n = 28) was diagnosed with anterior cranial fossa meningiomas. Gliomas of the frontal lobe were diagnosed in 12 patients. The average tumor size ranged from 3 to 3.5 cm. Results . Mortality, disability, or serious permanent access-related complications were not observed in our group. In all cases, the transition to the classical craniotomy was not required. Periorbital edema and transient hypoesthesia were observed in all patients. Permanent frontal hypoesthesia was observed in 3 patients (4 %) for a time period up to six months. According to postoperative MRI performed in all patients at the time of discharge, in the group of intra-axial brain tumor gross-total removal was observed in 8 patients (47 %), in 9 patients (53 %) the tumor was near-totally removed (more than 90 % of the tumor), in the group of meningiomas all 28 patients had gross-total removal. Conclusion. Supraorbital craniotomy can be an effective and safe alternative to classic approaches to treatment of extra-axial tumors of the anterior cranial fossa and intra-axial tumors of the frontal lobe. The approach requires a very careful selection of patients, individualization of surgery, and further critical evaluation.

The Extended Lateral Supraorbital Approach and Extradural Anterior Clinoidectomy Through a Frontopterio-Orbital Window: Technical Note and Pilot Surgical Series

Lateral approaches to treat anterior cranial fossa lesions have evolved since the first frontotemporal approach described by Dandy in 1918. We describe a less invasive approach to perform extradural anterior clinoidectomy through a lateral supraorbital (LSO) approach for anterior circulation aneurysms and anterolateral skull base lesions. The extended LSO approach involves performing a standard lateral supraorbital craniotomy followed by drilling of the sphenoid wing and lateral wall of the orbit through the frontal bony opening of the LSO approach, without any temporal extension of the craniotomy. This creates a frontopterio-orbital window exposing the periorbita; superior, medial, and anterior aspect of the temporal dura mater; and superior orbital fissure. After unroofing the superior orbital fissure, the meningo-orbital fold is cut, and the temporal dura mater is peeled from the lateral wall of the cavernous sinus to expose the anterior clinoid process allowing a standard opening of the optic canal and anterior clinoidectomy. The extended LSO approach and extradural anterior clinoidectomy allowed access to 4 sphenoid wing/anterior clinoidal meningiomas, 5 anterior circulation aneurysms, 2 temporomesial lesions, and 1 orbital/cavernous sinus abscess. Postoperatively, 2 patients had transient hemiparesis, 2 patients had transient third nerve palsy, and 1 patient had minimal visual field deterioration. All patients had a modified Rankin Scale score ≤1 at 8-week follow-up. The extended LSO approach opens a new route (frontopterio-orbital window) to perform extradural anterior clinoidectomy safely and increases surgical exposure, angles, and operability of a less invasive keyhole craniotomy (LSO approach) to treat anterior cranial fossa lesions.

Assessment of the effect of short-term factors on surgical treatments for hypertensive intracerebral haemorrhage

BackgroundHypertension is the most common cause of intracerebral haemorrhages (ICHs), yet the short-term impact factors associated with hypertensive intracerebral haemorrhages (HICHs) in patients who undergo different surgical treatments are still unknown. Materials and methodsAll consecutive patients with acute HICHs admitted to our hospital from January 2012 to March 2015 were enrolled in the study. Patients were either randomly divided or assigned according to their family’s preference into three groups (those undergoing minimally invasive aspiration, keyhole craniotomy or haematoma aspiration with extended pterional and decompressive craniotomy). Patients’ information and clinical characteristics were collected to identify risk factors influencing the short-term effects of the procedures. ResultsThere were significant differences among the groups: haematoma aspiration with extended pterional and decompressive craniotomy was the optimal method, resulting in fewer complications, higher Glasgow Outcome Scale (GOS) scores and better short-term outcomes. Surgical treatment, Glasgow Coma Scale (GCS) scores, haemorrhage volume and degree of midline shift were risk factors for the short-term effects associated with HICH. ConclusionsHaematoma aspiration with extended pterional and decompressive craniotomy is suitable for treating HICH patients. Surgical treatment, GCS score, haemorrhage volume and degree of midline shift influence the short-term effects observed following HICH surgery.

Keyhole Cisternal Navigational Resection of an Inner Falx Meningioma

Objective: The keyhole concept in neurosurgery has remained mostly limited to transcranial endoscope-assisted microsurgery or limited-sized keyhole craniotomies. In contrast, documentation of keyhole surgery, as described by Yaşargil, regarding no traumatization to the normal neural, arterial, and venous structures has appeared relatively less in the medical literature, under the term keyhole neurosurgery. Microsurgical resection of falcine meningiomas, although not infrequent, poses technical challenges related to the tumor’s anatomic relationships with the superior sagittal sinus, inferior sagittal sinus, callosomarginal arteries, pericallosal arteries, and neural structures of the medial aspects of the hemispheres. Case Description: A 35-year-old female patient with an anterior inner falcine meningioma and frontal multiple cortical veins draining into superior sagittal sinus is presented. The tumor was totally removed using a very small gap without scarifying any cortical vein. Postoperatively, the patient did very well. Conclusions: The microneurosurgical technique of navigation through aquatic cisternal corridors for surgical access is a minimally invasive technique permitting surgical manipulations through very small gaps and preserves normal neural and vascular structures.

Management of Intracranial Meningiomas Using Keyhole Techniques

Background: Keyhole craniotomies are increasingly being used for lesions of the skull base. Here we review our recent experience with these approaches for resection of intracranial meningiomas.Methods: Clinical and operative data were gathered on all patients treated with keyhole approaches by the senior author from January 2012 to June 2013. Thirty-one meningiomas were resected in 27 patients, including 9 supratentorial, 5 anterior fossa, 7 middle fossa, 6 posterior fossa, and 4 complex skull base tumors. Twenty-nine tumors were WHO Grade I, and 2 were Grade II. Results: The mean operative time was 8 hours, 22 minutes (range, 2:55-16:14) for skull-base tumors, and 4 hours, 27 minutes (range, 1:45-7:13) for supratentorial tumors. Simpson Resection grades were as follows: Grade I = 8, II = 8, III = 1, IV = 15, V = 0. The median postoperative hospital stay was 4 days (range, 1-20 days). In the 9 patients presenting with some degree of visual loss, 7 saw improvement or complete resolution. In the 6 patients presenting with cranial nerve palsies, 4 experienced improvement or resolution of the deficit postoperatively. Four patients experienced new neurologic deficits, all of which were improved or resolved at the time of the last follow-up. Technical aspects and surgical nuances of these approaches for management of intracranial meningiomas are discussed. Conclusions: With careful preoperative evaluation, keyhole approaches can be utilized singly or in combination to manage meningiomas in a wide variety of locations with satisfactory results.

Supraorbital keyhole craniotomy in surgery of anterior circle of willis aneurysms

The progress in surgical treatment of intracranial aneurysms is based on the introduction of modern minimally invasive techniques. Among the variety of keyhole approaches, supraorbital craniotomy is most often used in surgical treatment of anterior circle of willis aneurysms. The authors present the preliminary results of application of supraorbital keyhole craniotomy for anterior circle of willis aneurysms in 27 patients. Most of the patients had unruptured aneurysms (18 patients). Nine patients had SAH, and 4 of them were operated on in the acute period. The patients' condition was assessed as a grade 1-2 (Hunt-Hess scale) and grade 1-3 (Fisher scale). There were no intraoperative aneurysm ruptures, other serious complications, and deaths. Postoperative complications were assessed at 2 weeks and 6 months. The postoperative cosmetic outcome was assessed by patients as excellent.

Interfascial Dissection for Protection of the Nerve Branches to the Frontalis Muscles during Supraorbital Trans-Eyebrow Approach: An Anatomical Study and Technical Note.

Introduction Preservation of the temporal branches of the facial nerve during anterolateral craniotomies is important. Damaging it can inflict undesirable cosmetic defects to the patient. The supraorbital trans-eyebrow approach (SOTE) is a versatile keyhole craniotomy but still has a high rate of frontalis muscle (FM) palsy. Objective Anatomical study to implement the interfascial dissection during the SOTE to preserve the nerves to the FM. Methods Slight modification of the standard technique of the SOTE was performed in 6 cadaveric specimens (12 sides). Results Distal rami to the FM were exposed. The standard "u-shape" incision of the FM can cross over the nerves. Alternatively, an "l-shape" incision was performed until the superior temporal line (STL). An interfascial dissection was performed near to the STL and the interfascial fat pad was used as a protective layer for the nerves. Conclusion Various pathologies can be addressed with the SOTE. In the majority of the cases the cosmetic results are good, but FM palsy remains a drawback of this approach. The interfascial dissection may be used in an attempt to prevent frontalis rami palsy.