Preservation of the nerves to the frontalis muscle during pterional craniotomy

Use of a Monopolar Stimulator to Preserve the Frontotemporal Branches of the Facial Nerve During a Pterional Approach: 2-Dimensional Operative Video

Preservation of the frontotemporal branches of the facial nerve is essential to obtain good cosmetic outcomes after anterolateral cranial base approaches.1,2 Since the description of the interfacial dissection, most nerve injuries are due to retraction of the nerve fibers and not direct transection.3-5 In this video, we showcase the use of a monopolar stimulator to guide the placement of hook retractors and assess no undue retraction is applied to the nerve fibers during a pterional craniotomy. This simple tool can help in preserving frontalis function after anterolateral skull base craniotomies. Institutional review board approval was not required; the patient consented to the procedure and to the publication of his/her image.

A Prospective Comparison Between Soft Tissue Dissection Techniques in Pterional Craniotomy: Functional, Radiological, and Aesthetic Outcomes

BACKGROUND AND OBJECTIVES

Given the complex anatomy of the operative region and individual surgeon preferences, some techniques for soft tissue dissection before pterional craniotomy have gained more popularity than others. This prospective study used subjective and objective measurements to compare the functional, radiological, and aesthetic outcomes of 3 such dissection techniques.

METHODS

This multicenter prospective cohort study included all patients who underwent elective pterional craniotomy between 2018 and 2020 at 3 centers in Riyadh, Saudi Arabia. All patients underwent 1 of 3 soft tissue dissection techniques: myocutaneous flap, interfascial, and subfascial dissection techniques. Clinical and radiological assessments were performed upon discharge and at the 3- and 6-month follow-ups.

RESULTS

We included 78 patients, with a mean age of 44.9 ± 16.3 years. Myocutaneous flap, interfascial, and subfascial dissections were performed in 34 (43%), 24 (30%), and 20 patients (25%), respectively. The myocutaneous flap method had the shortest opening ( P = .001) and closure ( P = .005) times; tenderness was more evident in this group than in the others ( P = .05). The frontalis muscle was most affected in the interfascial dissection group ( P = .05). The frontalis nerve function was similar in all groups after 6 months ( P = .54). The incidence of temporomandibular joint dysfunction was highest in the myocutaneous flap group (29%). Decreased temporalis muscle thickness at the 6-month postoperative follow-up was most severe in the subfascial dissection group (12.6%), followed by the myocutaneous flap (11.9%) and interfascial dissection (9.9%) groups, with no significant difference ( P = .85). Temporal hollowing was more prominent in the myocutaneous flap group ( P = .03). Cosmetic satisfaction was highest in the interfascial dissection group, with no significant difference ( P = .4).

CONCLUSION

This study provides important information for neurosurgeons in weighing the benefits and risks of each technique for their patients.

Frontotemporal craniotomy with skin incision along the superior temporal line outside the hairline in bald male patients with temporal gliomas

A head skin incision is inevitable in neurosurgical procedures and is usually concealed within the hairline. Androgenetic alopecia (AGA) is a progressive hair loss disorder or baldness highly prevalent in men. Therefore, if bald male patients require neurosurgical procedures, skin incisions cannot be concealed, but this subject is yet to be discussed in the literature. This study presents a frontotemporal craniotomy using a skin incision along the superior temporal line, ignoring the hairline in bald male patients. Thirty-three patients with temporal gliomas underwent surgical removal between 2015 and 2022. They were divided into three groups: bald male patients with skin incisions not concealed in the hairline (minimum group, n = 13), bald and non-bald male patients with skin incisions concealed in the hairline (male group, n = 11), and female patients with skin incisions concealed in the hairline (female group, n = 9). In the minimum group, patients had no complaints regarding the incision scar. Cosmetic outcome was excellent, and no cases showed surgical site infection or peripheral facial nerve palsy. Compared with the male and female groups, the minimum group had the shortest skin incision length; however, the craniotomy size and extent of resection were similar. Skin incision for frontotemporal craniotomy cannot be hidden in bald male patients, and the preferred location for the incision is unknown. The skin incision along the superior temporal line is a cosmetically favorable, feasible, and safe procedure.

"The Double S" Technique: Subfascial Dissection and Temporalis Muscle Splitting to Prevent Cerebrospinal Fluid Leak and Maximize Surgical Exposure

BACKGROUND

Middle cranial fossa surgery commonly is approached either performing a subtemporal or a pterional craniotomy. To maximize a basitemporal region exposure, an adjunctive bone drilling could be required. In these cases, a watertight dura and temporalis muscle closure are mandatory.

OBJECTIVE

To describe a modified temporalis muscle dissection in middle cranial fossa surgery to increase basitemporal region exposure while assuring a safe and effective closure thus avoiding cerebrospinal fluid (CSF) leakage.

METHODS

A total of 8 patients have been enrolled. Five pterional and 3 subtemporal approaches were performed. In all cases, the novel subfascial muscle dissection and temporalis muscle splitting technique named "the double S technique," was performed to cut up the temporal muscle.

RESULTS

In all cases, a subgaleal drainage was used and removed within 48 hours. No cases of postoperative CSF leak or hematoma collection were reported.

CONCLUSIONS

The double S technique is a safe and effective alternative to enhance the basitemporal region exposure while avoiding the potential, common risk of CSF leak.

Key role of microsurgical dissections on cadaveric specimens in neurosurgical training: Setting up a new research anatomical laboratory and defining neuroanatomical milestones

Introduction

Neurosurgery is one of the most complex surgical disciplines where psychomotor skills and deep anatomical and neurological knowledge find their maximum expression. A long period of preparation is necessary to acquire a solid theoretical background and technical skills, improve manual dexterity and visuospatial ability, and try and refine surgical techniques. Moreover, both studying and surgical practice are necessary to deeply understand neuroanatomy, the relationships between structures, and the three-dimensional (3D) orientation that is the core of neurosurgeons' preparation. For all these reasons, a microsurgical neuroanatomy laboratory with human cadaveric specimens results in a unique and irreplaceable training tool that allows the reproduction of patients' positions, 3D anatomy, tissues' consistencies, and step-by-step surgical procedures almost identical to the real ones.

Methods

We describe our experience in setting up a new microsurgical neuroanatomy lab (IRCCS Neuromed, Pozzilli, Italy), focusing on the development of training activity programs and microsurgical milestones useful to train the next generation of surgeons. All the required materials and instruments were listed.

Results

Six competency levels were designed according to the year of residency, with training exercises and procedures defined for each competency level: (1) soft tissue dissections, bone drilling, and microsurgical suturing; (2) basic craniotomies and neurovascular anatomy; (3) white matter dissection; (4) skull base transcranial approaches; (5) endoscopic approaches; and (6) microanastomosis. A checklist with the milestones was provided.

Discussion

Microsurgical dissection of human cadaveric specimens is the optimal way to learn and train on neuroanatomy and neurosurgical procedures before performing them safely in the operating room. We provided a “neurosurgery booklet” with progressive milestones for neurosurgical residents. This step-by-step program may improve the quality of training and guarantee equal skill acquisition across countries. We believe that more efforts should be made to create new microsurgical laboratories, popularize the importance of body donation, and establish a network between universities and laboratories to introduce a compulsory operative training program.

Modified Lateral Orbitotomy Approach to Lesions of the Orbital Apex, Superior Orbital Fissure, Cavernous Sinus, and Middle Cranial Fossa

BACKGROUND

The lateral orbitotomy approach (LOA) provides minimally invasive access to the orbit, cavernous sinus region, and middle cranial fossa. Orbital retraction with this approach can nonetheless injure orbital structures, causing unnecessary morbidity.

OBJECTIVE

To describe our clinical experience with the modified LOA (mLOA), wherein the medial aspect of the lateral orbital wall posterior to the orbital rim is preserved.

METHODS

This is a retrospective, single-institution case series of patients undergoing a mLOA for lesions of the orbital apex, superior orbital fissure, cavernous sinus, and middle cranial fossa. The dimensions and variance of selected anatomic parameters relevant to this approach (orbital rim-superior orbital fossa depth, lateral orbital wall angle) were also analyzed using computed tomography scans from 30 adult patients.

RESULTS

Eight patients underwent a mLOA (mean age 54.0 ± 19.6 years; 3 males). Surgical targets included the superior orbital fissure (2; cavernoma and meningioma), sphenoid wing with or without the orbital apex (2; meningioma), cavernous sinus (2; rule out carcinoma and smooth muscle tumor), and anterior/mesial temporal lobe (2; cavernoma). Visual acuity/fields and diplopia was stable or improved in all patients postoperatively. One patient experienced a cerebrospinal fluid leak. On computed tomography analysis, the relevant bony anatomy displayed limited variability, with a mean orbital fossa depth of 42.7 ± 2.8 mm and a lateral orbital wall angle of 44.4° ± 2.7°.

CONCLUSION

The mLOA can provide safe, minimally invasive access to select lesions of the orbital apex, superior orbital fissure, cavernous sinus, and middle cranial fossa. The operative corridor has relatively consistent bony anatomy.

Surgical technique of temporal muscle resuspension during cranioplasty for minimizing temporal hollowing: A case series

Background

Temporal hollowing is a common but often overlooked complication following cranioplasty. To minimize temporal hollowing caused by temporal muscle contraction, we present the novel technique for temporal muscle resuspension during cranioplasty.

Methods

This is a retrospective case series which were done by a single surgeon at our university tertiary-A hospital between January 2019 and February 2020. The surgical technique was performed according to the forms of temporal muscle based on preoperative 3-D reconstruction and intraoperative images. All patients were followed up and evaluated on esthetic and functional outcomes.

Results

17 patients with an average age of 39.35 years, frontotemporoparietal cranial defect size of 78.85 cm², and median follow-up of 7 months were included. The main cause of decompressive craniectomy was trauma (n = 15). Techniques of temporal muscle augmentative resuspension were performed. The follow-up esthetic and functional outcome evaluation showed that all patients had good postoperative results. No revision surgery was found among the patients.

Conclusions

This study proposes methods of temporal muscle augmentative resuspension based on forms of the muscle. We believe this might be of use in minimizing temporal hollowing after cranioplasty.

Surgical Experience of Transcranial Approaches to Large-to-Giant Pituitary Adenomas in Knosp Grade 4

Pituitary adenomas in Knosp grade 4 are difficult to resect completely and are generally involved in poor prognosis, because of the close relationship between the tumor and internal carotid. In this study, the authors retrospectively reviewed the outcome of different transcranial approaches in the management of large-to-giant pituitary adenomas in Knosp grade 4. A total of 42 patients with large-to-giant pituitary adenomas in Knosp grade 4, who underwent craniotomy in the Pituitary Disease Subdivision, Department of Neurosurgery, Beijing Tiantan Hospital, between March 2012 and March 2015 were included in this study. Clinical characteristics, surgical methods, complications, and outcomes were evaluated. The median age was 45 years (range, 19-73 years old), and 42.9% of the enrolled cases were men. The mean tumor diameter was 43.6 mm, and the mean volume was 30.9 cm³. 26 patients underwent the frontolateral approach, while 16 cases accepted the frontotemporal approach. Gross total resection was achieved in 11 patients (26.2%), near total in 26 (61.9%), and subtotal in 5 (11.9%). The adenomas were larger, and the distance of the tumor extending to the lateral skull base was also further in the frontotemporal approach cases. The surgical time was shorter, and the bleeding volume was less in the frontolateral approach cases. Subsellar extension was associated with incomplete resection in pituitary macroadenomas of Knosp grade 4. The craniotomy is still an effective treatment for pituitary macroadenomas in Knosp grade 4.

Effects of Modified Osteoplastic Pterional Craniotomy on Temporal Muscle Volume and Frontal Muscle Nerve Function

Introduction  Pterional craniotomy is a surgical approach frequently used in aneurysm and skull base surgery. Pterional craniotomy may lead to cosmetic and functional problems, such as eyebrow drop due to facial nerve frontal branch damage, temporal muscle atrophy, and temporomandibular joint pain. The aim was to compare the postoperative effects of our modified osteoplastic craniotomy with classical pterional craniotomy in terms of any change in volume of temporal muscle and in the degree of frontal muscle nerve damage. Materials and Methods  Aneurysm cases were operated with either modified osteoplastic pterional craniotomy or free bone flap pterional craniotomy according to the surgeon's preference. Outcomes were compared in terms of temporal muscle volume and frontal muscle nerve function 6 months postoperatively. Results  Preoperative temporal muscle volume in the modified osteoplastic pterional and free bone flap pterional craniotomy groups were not different ( p  > 0.05). However, significantly less atrophy was observed in the postoperative temporal muscle volume of the osteoplastic group compared with the classical craniotomy group ( p  < 0.001). In addition, when comparing frontal muscle nerve function there was less nerve damage in the modified osteoplastic pterional craniotomy group compared with the classical craniotomy group, although this did not reach significance ( p  > 0.05). Conclusion  Modified osteoplastic pterional craniotomy significantly reduced atrophy of temporal muscle and caused proportionally less frontal muscle nerve damage compared with pterional craniotomy, although this latter outcome was not significant. These findings suggest that osteoplastic craniotomy may be a more advantageous intervention in cosmetic and functional terms compared with classical pterional craniotomy.

Suprafascial dissection for pterional craniotomy to preserve the frontotemporal branch of the facial nerve with less temporal hollowing

Background:

To protect the frontotemporal branch of the facial nerve (FTFN) when performing pterional craniotomy, several reports suggest the subfascial or interfascial dissection technique. However, the reports of postoperative frontalis paralysis and temporal hollowing, which are common complications, were relatively limited. This study reports the incidence of postoperative frontalis paralysis and temporal hollowing after pterional craniotomy using the suprafascial and interfascial techniques.

Methods:

Patients who underwent pterional craniotomy, using the suprafascial technique (leaving the muscle cuff and not leaving the muscle cuff) and the interfascial technique, between November 2015 and September 2018 were retrospectively evaluated for postoperative frontalis paralysis and temporal hollowing using Chi-squared/ Fisher exact test.

Results:

Seventy-two patients underwent pterional craniotomy, using the suprafascial technique in 54 patients (leaving the muscle cuff in 21 patients and not leaving the muscle cuff in 33 patients) and the interfascial technique in 18 patients. Eleven patients (20.4%) in the suprafascial group and 1 patient (5.6%) in the interfascial group developed transient frontalis paralysis (P = 0.272). No permanent frontalis paralysis was observed. Obvious temporal hollowing occurred in 18.2% of patients in the suprafascial group without the muscle cuff, in 64.3% of patients in the suprafascial group with the muscle cuff, and in 72.7% of patients in the interfascial group (P = 0.003).

Conclusion:

The suprafascial dissection technique does not cause permanent injury of the FTFN, and this approach results in a significantly lower incidence of postoperative temporal hollowing than interfascial dissection, especially without leaving a temporalis muscle cuff.

Safe Zone for Dissection in Frontotemporal Region to Avoid Injury to the Temporal Branch of Facial Nerve

ABSTRACT

The objective of this study is to provide a reliable roadmap for temporal branch of the facial nerve, in order to minimize, the risk of injury to the nerve during surgical dissections. A literature search was conducted on temporal branch of facial nerve. The date search range was 1950 to 2017. Databases searched included Medline, Web of science, Biosis, SciELO, Data Citation, and Zoologic Records. Data were collected on, author specialty, date of publication, and the relationship of the temporal branch of facial nerve to various landmarks in the frontotemporal region reported in human anatomic studies. Among the 48 studies reviewed, a total of 3477 anatomic dissections were performed in the craniofacial region. Temporal branch of facial nerve was located between 2.5 and 3 cm from lateral orbital rim. In relation to the zygomatic arch, it was found anywhere from the midpoint of the arch to 1 finger breath posterior to the arch. For the plane, it was most commonly described as being under the superficial temporal fascia (STF) or within the loose areolar tissue. Most anatomic dissections found 2 to 4 twigs of the temporal branch of facial nerve. In relation to the lateral canthus, it was found to be 2.85 +/- 0.69 cm superior and 2.54 +/- 0.43 cm lateral to the lateral canthus. Our study suggests consolidated data on surgical landmarks in order to ensure safe dissection in temporal region and prevent injury to the temporal branch of facial nerve.

Autologous Temporalis Subfascial Fat Graft for Skull Base Repair: A Novel Technique

BACKGROUND

Autologous abdominal fat grafts are occasionally used in the repair of skull base exposures. This surgical procedure typically requires an additional surgical site and may have unexpected postoperative complications.

OBJECTIVE

To describe an operative technique for harvesting subfascial fat from the temporal extension of the buccal fat pad for the repair of skull base defects.

METHODS

We review the pertinent anatomy of the temporalis subfascial fat pad and discuss the technique used to harvest the subfascial fat component in a clinical presentation.

RESULTS

A pretemporal approach was performed for clip ligation of an anterior circulation aneurysm. A standard frontotemporal incision was made with an interfascial flap to preserve the frontalis branches of the facial nerve. The subfascial fat was inspected and determined to be adequate for harvesting. Monopolar cauterization was carefully utilized to remove the fat. During closure, the graft was used to repair a pneumatized clinoid sinus and for the dural repair of the pretemporal exposure. The patient did not have any postoperative complications.

CONCLUSION

Autologous temporalis subfascial fat graft is a viable and safe technique for skull base dural and sinus repair during frontotemporal approaches in select patients. This technique avoids an additional surgical procedure and potential complications that may be associated with it.

Microsurgical Anatomy of the Anterior Circulation of the Brain Adjusted to the Neurosurgeon's Daily Practice

The study of cerebrovascular anatomy can be difficult and may take time due to its intrinsic complexity. However, it can also be difficult for the following reasons: the excessive description of neuroanatomy making articles hard to read, the unclear clinical application of what is written, the use of simplified or intricate schematic drawings that are not always appropriate for effective teaching, the poor quality of neuroanatomy dissections and the use of unusual views of figures that are not strictly related to the most frequent neuroimages to be interpreted in daily practice. Because of this, we designed an article that incorporates original and accurate anatomical dissections in an attempt to improve its comprehensibility. Five formalin-fixed adult cadaveric heads, whose vessels were injected with a colored silicone mixture (red for arteries and blue for veins), were dissected and examined under a microscope with magnifications from 3× to 40×. Special emphasis has been placed on correlating topographic anatomy with routine neuroimaging studies from computed tomographic angiography (CTA) and digital subtraction angiography (DSA). The essential surgical anatomy in a neurosurgeon’s daily practice is also described. The cadaveric dissections included in this study contribute to the understanding of the cerebrovascular anatomy necessary for the neurosurgeon’s daily practice.

The extradural extended eyebrow approach: A cadaveric feasibility study

INTRODUCTION

Extradural anterior clinoidectomy (eAC) is key to expose the paraclinoid region. Several authors have pointed limitations of performing an eAC through a supraorbital craniotomy. In this article, we aim to provide educational material and discuss the technical nuances to successfully perform an eAC throughout a modification of the supraorbital approach, the extradural extended eyebrow approach (xEBA+eAC).

METHODS

Four embalmed heads were used for anatomic dissection and perform the xEBA+eAC. Additionally, one head was used for a video demonstration of the surgical approach.

RESULTS

The anterior clinoid process was successfully removed, and the ophthalmic artery and paraclinoid region were exposed in all specimens. Drilling the sphenoid wing until exposing the meningo-orbital band and further interdural dissection are vital steps to expose the anterior clinoid process. Removal of the anterior clinoid process can be simplified in 3 osteotomies, including the optic canal unroofing, detachment from the lateral pillar, and drilling of the optic strut. Sectioning of the distal dural ring facilitates the mobilization of the internal carotid artery and the surgical exposure of the ophthalmic artery.

CONCLUSIONS

xEBA+eAC is a technically feasible approach that provides exposure to the paraclinoid region, along with anterior and middle cranial fossa.

The Supraorbital Eyebrow Craniotomy for Intra- and Extra-Axial Brain Tumors: A Single-Center Series and Technique Modification

BACKGROUND

The supraorbital (SO) eyebrow craniotomy provides minimally invasive access to the anterior and middle fossae and parasellar region.

OBJECTIVE

To present a series of patients treated with the SO approach to assess outcomes, the impact of endoscopy, and describe a modified pericranial flap aimed at reducing postoperative frontalis paresis and hypesthesia.

METHODS

A retrospective analysis was undertaken of our prospective database of patients who underwent SO craniotomy for tumor/cyst removal. Patients were evaluated based on pathology, utility of endoscopy, extent of resection, complications, and functional/esthetic recovery.

RESULTS

From 2007 to 2018, 129 operations were performed in 117 patients (54% women; mean age 60 ± 16.5 yr). The most common lesions were meningiomas (43%), gliomas (15%), and metastases (15%). Prior surgery and/or radiation had been performed in 37% and 26% of patients, respectively. Endoscopy was used in 76 (61%) operations and allowed more complete tumor removal in 38 (50%). For first-time operations, gross-total removal was achieved in 78%. Major complications included stroke (3%), cranial nerve deficit (3%), acute hematoma (1%), and cerebrospinal fluid leak (1%). The modified pericranial flap technique used in 18 recent patients resulted in a shorter duration of transient frontalis paresis and forehead hypesthesia with complete functional recovery in all 18.

CONCLUSION

The SO craniotomy is an effective keyhole approach for intra- and extra-axial tumors. Endoscopic assistance may allow additional tumor removal in almost 30% of the cases. The modified pericranial flap appears to accelerate functional recovery, although additional patients and follow-up are required to better assess this technique.

Minipterional craniotomy for surgical clipping of anterior circulation aneurysms: compatibility between the feasibility, safety and efficiency

Objective

The aim of this study was to assess the feasibility, safety and efficiency of minipterional craniotomy (MPT) for surgical clipping of anterior circulation aneurysms.

Methods

A retrospective study was conducted to compare the MPT from Jan 2015 to Dec 2018 and conventional pterional craniotomy (CPT) from Jan 2012 to Dec 2013 in unruptured intracranial aneurysms (UIA) and ruptured intracranial aneurysms (RIA). The feasibility and safety of MPT and CPT were assessed by analyzing medical records, radiologic imaging, and clinical outcomes. The efficiency of MPT and CPT were based on a survey research of temporomandibular dysfunction, facial nerve paralysis, and facial asymmetry.

Results

Total 628 patients who underwent 458 MPT (UIA:313, RIA:145) and 170 CPT (UIA: 106, RIA: 64) with anterior circulation aneurysms were included in this study. The baseline characteristics between MPT and CPT had no difference (p>0.05). There was no difference in the incidence of postoperative hemorrhage or ischemic lesions between MPT and CPT (p>0.05). The incidence of surgical wound infection was lower in MPT (0.4%) than CPT (3.5%) (p=0.002). More than 90% of postoperative pain disappeared faster in MPT (14.25±4.83 days) than CPT (27.59±10.35 days), and the feeling of facial asymmetry in surgical side was also lower for MPT (1.7%) than CPT (7.6%) (p<0.001). In the MPT, no patients presented with progress to chronic pain, masticatory disability, discomfort of maximal mouth opening or permanent facial palsy.

Conclusions

We suggest that MPT and CPT had similar clinical outcomes, and MPT showed better functional and cosmetic outcomes than CPT in terms of temporomandibular dysfunction, facial nerve paralysis, and facial asymmetry. Therefore, MPT for surgical clipping of anterior circulation aneurysms can be a compatible technique that satisfies the feasibility, safety and efficiency.

Same viewing angle, minimal craniotomy enlargement, extreme exposure increase: the extended supraorbital eyebrow approach

The supraorbital eyebrow approach (SEa) has been commonly used as a straightforward route to reach lesions located in the anterior cranial fossa. The reduced surgical exposure provided by this approach limits its applicability. A modification of the SEa, the extended supraorbital eyebrow approach (X-SEa), allows use of the transylvian corridor to approach parasellar lesions, while maintaining most of the aesthetic advantages of the SEa. To quantify the surgical exposure and maneuverability provided by the X-SEa using a cadaveric study. Eleven heads were used to obtain all stereotactic measurements. Surgical exposure and maneuverability were measured by means of the area of exposure and the angles of attack along key representative points in the anterior circulation. The horizontal angle of attack at the middle cerebral artery provided by the X-SEa was larger than that provided by the SEa (32.6 vs 18.4°, p = 0.009). The X-SEa afforded broader vertical angles of attack at all targets in the anterior circulation (p < 0.05). The total area of exposure provided by the X-SEa was significantly larger than that provided by the SEa (1272 vs 978 ± 156 mm², p = 0.003). The area of exposure in the ipsilateral trigon and in the midline quadrangle was also significantly larger for the X-SEa (paramedian 195 vs 121 mm², p = 0.01; midline 1310 vs 778 mm², p = 0.002). The X-SEa increases the exposure and surgical maneuverability along the anterior and middle cranial fossa when compared to the standard SEa.

The extended eyebrow approach a cadaveric stepwise dissection

BACKGROUND

The eyebrow incision supraorbital approach is limited by the lack of exposure of the sylvian fissure exposure. By extending the skin incision 15 mm posteriorly and the supraorbital craniotomy beneath the superior temporal line, proximal sylvian dissection is achievable, and the surgical exposure is drastically improved.

METHODS

Throughout a cadaveric stepwise dissection and a pertinent anatomical analysis, we describe in detail the surgical technique of the extended eyebrow approach (xEBA). We additionally highlight main anatomical elements involved in this approach and provide technical nuances to avoid complications.

CONCLUSION

xEBA is a versatile technique that uses the pretemporal, transylvian, and subfrontal corridor to enhance surgical exposure around the anterior cranial fossa.

Facial Nerve Preservation for Supraorbital Approaches: Anatomical Mapping Based on Consistent Landmarks

BACKGROUND

The supraorbital keyhole approach (SOKA) provides a safe and advantageous access to the anterior cranial fossa. The implemented skin incision varies depending on surgeon's preferences and requirements. Facial nerve (FN) injury might appear in up to 5.6% of patients. There is a lack of validated tenets for avoiding FN injury.

OBJECTIVE

To define a safety area for FN preservation during a SOKA.

METHODS

Ten dried skulls and 5 injected cadaveric heads (10 sides) were used. A Cartesian frame was created with its horizontal axis at the level of the supraorbital notch and the vertical axis just lateral to the frontozygomatic junction (FZj). FNs were dissected and points along their course were registered and transferred to the Cartesian frame.

RESULTS

Ten microscopic dissections of the FN were performed preserving all branches. A safety area could be defined 8 mm superior and 10 mm inferior to the FZj extending medially to the supraorbital notch and beyond. A 20 mm2 area superior and lateral to the FZj provided low probability (≤10%) of injuring the FN. Similarly, starting 4 mm inferior to the FZj, a lateral safety area was also found. A probabilistic colored heat map was built to represent the results.

CONCLUSION

We provide a "safety zone" for a SOKA incision in which the probability to encounter the FN is low. Clinical studies following our method may validate our findings and add evidence to the tenets for minimizing morbidity related to the SOKA incision.

Interfascial approach for pterional craniotomy: technique and adjustments to prevent cosmetic complications

BACKGROUND

Interfascial dissection for pterional craniotomy is one of the main techniques to expose the pterional region.

METHOD

A step-by-step optimized method of interfascial dissection to avoid three main esthetic complications of the pterional approach-upper facial nerve palsy, temporal muscle atrophy, and retro-orbital depression. A video of the interfascial dissection and three artistic drawings are provided in support of this technique.

CONCLUSION

A safe method of interfascial dissection, respecting anatomy, and avoiding cosmetic complications has been proposed.

Supraorbital keyhole approach for suprasellar arachnoid cyst: how I do it

BACKGROUND

Keyhole approaches have lately sparked strong interest because these approaches address skull base pathologies as reported by Eroglu et al. (World Neurosurg, 2019); Hickmann, Gaida, and Reisch (Acta Neurochir (Wien) 159:881-887, 2017); Jallo and Bognar (Neurosurgery, 2006); and Poblete et al. (J Neurosurg 122:1274-1282, 2015), minimizing brain retraction and improving cosmetic results. We describe the step-by-step surgical technique to drain a suprasellar arachnoid cyst by a supraorbital approach.

METHOD

The eyebrow incision is a direct route to expose the supraorbital corridor and even if it is smaller than a pterional approach, it permits to open the cisterns and to visualize neurovascular structures. The arachnoid cyst could be safely drained and a T-tube is placed.

CONCLUSION

This technique represents a suitable option for suprasellar arachnoid cyst, avoiding more extended and invasive approaches.

Immersive Surgical Anatomy of the Pterional Approach

The pterional approach (PA) is a versatile anterolateral neurosurgical technique that enables access to reach different structures contained in the cranial fossae. It is essential for neurosurgical practice to dominate and be familiarized with its multilayer anatomy. Recent advances in three-dimensional (3D) technology can be combined with dissections to better understand the spatial relationships between anatomical landmarks and neurovascular structures that are encountered during the surgical procedure. The present study aims to create a stereoscopic collection of volumetric models (VM) obtained from cadaveric dissections that depict the relevant anatomy and surgical techniques of the PA. Five embalmed heads and two dry skulls were used to record and simulate the PA. Relevant steps and anatomy of the PA were recorded using 3D scanning technology (e.g. photogrammetry, structured light scanner) to construct high-resolution VM. Stereoscopic images, videos, and VM were generated to demonstrate major anatomical landmarks for PA. Modifications of the standard PA, including the mini-pterional and two-part pterional approaches, were also described. The PA was divided into seven major steps: positioning, incision of the skin, dissection of skin flap, dissection of temporal fascia, craniotomy, drilling of basal structures, and dural opening. Emphasis was placed on preserving the temporal branches of the facial nerve and carefully dissecting the temporalis muscle. The interactive models presented in this article allow for clear visualization of the surgical anatomy and windows in 360-degrees and VR. This new modality of recording neuroanatomical dissections renders a closer look at every nuance of the topography experienced by our team in the laboratory. By accurately depicting essential landmarks, stereoscopy and VM can be valuable resources for anatomical education and surgical planning.

Surgery of the lateral skull base: a 50-year endeavour

Disregarding the widely used division of skull base into anterior and lateral, since the skull base should be conceived as a single anatomic structure, it was to our convenience to group all those approaches that run from the antero-lateral, pure lateral and postero-lateral side of the skull base as “Surgery of the lateral skull base”. “50 years of endeavour” points to the great effort which has been made over the last decades, when more and more difficult surgeries were performed by reducing morbidity. The principle of lateral skull base surgery, “remove skull base bone to approach the base itself and the adjacent sites of the endo-esocranium”, was then combined with function preservation and with tailoring surgery to the pathology. The concept that histology dictates the extent of resection, balancing the intrinsic morbidity of each approach was the object of the first section of the present report. The main surgical approaches were described in the second section and were conceived not as a step-by-step description of technique, but as the highlighthening of the surgical principles. The third section was centered on open issues related to the tumor and its treatment. The topic of vestibular schwannoma was investigated with the current debate on observation, hearing preservation surgery, hearing rehabilitation, radiotherapy and the recent efforts to detect biological markers able to predict tumor growth. Jugular foramen paragangliomas were treated in the frame of radical or partial surgery, radiotherapy, partial “tailored” surgery and observation. Surgery on meningioma was debated from the point of view of the neurosurgeon and of the otologist. Endolymphatic sac tumors and malignant tumors of the external auditory canal were also treated, as well as chordomas, chondrosarcomas and petrous bone cholesteatomas. Finally, the fourth section focused on free-choice topics which were assigned to aknowledged experts. The aim of this work was attempting to report the state of the art of the lateral skull base surgery after 50 years of hard work and, above all, to raise questions on those issues which still need an answer, as to allow progress in knowledge through sharing of various experiences. At the end of the reading, if more doubts remain rather than certainties, the aim of this work will probably be achieved.

Evaluation of temporal muscle trophism in relation to the manipulation time and infiltration of 0.5% isobaric bupivacaine through a pterional approach

INTRODUCTION

There are different techniques for the reconstruction of the temporal muscle (TM) in the pterional approach (PA) in order to avoid and reduce atrophy, it has not been able to avoid it in its entirety. The administration of bupivacaine generates regeneration of muscle fibres. There are no studies in the medical literature that evaluate the time of TM manipulation and the use of bupivacaine for the treatment of atrophy after pterional approach, the present investigation aim is to describe the effects of these variables.

PATIENT AND METHODS

Longitudinal study, including patients from 18-80 years old with pterional approach at 2016-2017. We evaluated the effects of the TM manipulation times and the administration of 0.5% bupivacaine on the trophism and function of TM.

RESULTS

Twenty-nine patients underwent a PA; 16(55.17%) count with criteria for 0.5% bupivacain infiltration. We found a negative correlation between manipulation times and trophism, with no statistically significance (p>.05). We evaluated presurgical and postsurgical index of Helkimo and Fonseca's index, finding an increase of disfunction with statistically significance (p<.05). In patients who were infiltrated with 0.5% bupivacaine we observed a mean difference in the TM's trophism of 0.275±1.18mm, in contrast with no infiltrated which was 2.39±1.30mm (t[27] = -5.118, p=.0001).

CONCLUSIONS

The manipulation of the TM during a pterional approach conditioned an impact on the quality of life according to the disfunction indexes, due to atrophy. This investigation exhibits that de administration of 0.5% bupivacaine during surgery offers a decrease in the TM atrophy.

The microneurosurgical anatomy legacy of Albert L. Rhoton Jr., MD: an analysis of transition and evolution over 50 years

The authors chronologically categorized the 160 original articles written by Dr. Rhoton and his fellows to show why they selected their themes and how they carried out their projects. The authors note that as neurosurgery progresses and new techniques and approaches are developed, accurate and safe treatment will depend upon continued clarification of microsurgical anatomy.

Comparative analysis on microsurgical removal of craniopharyngioma via lateral supraorbital approach and standard pterional approach

Background

Craniopharyngioma is a kind of intracranial benign tumor that is primarily treated with surgery. At present, a variety of surgical approaches are used for tumor resection. We have conducted a comparative analysis of the two approaches most used in our department.

Methods

The study retrospectively analyzed the clinical data from 65 patients with craniopharyngioma surgically treated by the two approaches mentioned above. Among these patients, 24 were treated by lateral supraorbital (LSO) approach and 41 by standard pterional approach. Indicators including, but not limited to, length of incision, operation time, postoperative pituitary function, urine volume, visual function improvement, and hospitalization were used to compare these two groups of patients.

Results

The data shows that there was no significant difference in total tumor resection rate (P = 0.54), postoperative visual field improvement (P = 0.68) and postoperative function of endocrine. However, the LSO approach significantly reduced the operative incision (P = 0.001), shortened the operation time (P = 0.001) and operative complexity, while reducing the incidence of postoperative complications (P = 0.04).

Conclusions

In surgical treatment of craniopharyngioma, LSO approach has similar surgical effect with standard pterional approach, but it can significantly shorten the operation time, reduce surgical trauma and the incidence of complications. Therefore, LSO provides another alternative to surgical approach for microsurgical removal of craniopharyngioma.

Supraorbital approach through eyebrow skin incision for aneurysm clipping: how I do it

BACKGROUND

Surgery has been in a huge development where the aim is to achieve same or better results with less complication in a less invasive way; these minimal approaches can be applied in a very safe way to aneurysmal neurosurgery.

METHOD

Images are studied to optimize the patient positioning and the surgical roadmap. After the positioning, the skin incision, craniotomy, and dura incision are performed and intradural lesion is reached. A watertight closure is performed under the microscope.

CONCLUSION

The keyhole approach requires some adaption from the side of the surgeon and can be performed only in cases envisioned to have no increased risk for the patient.

Distal transsylvian keyhole approach for unruptured anterior circulation small aneurysms

Background

To reduce complications associated with conventional pterional craniotomy, a transsylvian keyhole approach for unruptured small anterior circulation aneurysms is proposed.

Methods

A 7-cm linear scalp incision is made along the hairline, beginning at the zygoma, followed by minimal temporal muscle dissection. Two burr holes are drilled out at McCarty’s point and the temporal bone, and a 3-cm equilateral triangle bone flap is made, whose apex is located above the sylvian point. After the sphenoid ridge is drilled off, aneurysms are exposed and clipped with conventional microsurgical instruments.

Conclusions

This approach permits access to aneurysms via the transsylvian corridor with a smaller area of potential injury of superficial structures.

Electronic supplementary material

The online version of this article (10.1007/s00701-017-3378-7) contains supplementary material, which is available to authorized users.

Quantitative anatomical analysis and clinical experience with mini-pterional and mini-orbitozygomatic approaches for intracranial aneurysm surgery

OBJECTIVE

The aim of this investigation was to modify the mini-pterional and mini-orbitozygomatic (mini-OZ) approaches in order to reduce the amount of tissue traumatization caused and to compare the use of the 2 approaches in the removal of circle of Willis aneurysms based on the authors' clinical experience and quantitative analysis.

METHODS

Three formalin-fixed adult cadaveric heads injected with colored silicone were examined. Surgical freedom and angle of attack of the mini-pterional and mini-OZ approaches were measured at 9 anatomical points, and the measurements were compared. The authors also retrospectively reviewed the cases of 396 patients with ruptured and unruptured single aneurysms in the circle of Willis treated by microsurgical techniques at their institution between January 2006 and November 2014.

RESULTS

A significant difference in surgical freedom was found in favor of the mini-pterional approach for access to the ipsilateral internal carotid artery (ICA) and middle cerebral artery (MCA) bifurcations, the most distal point of the ipsilateral posterior cerebral artery (PCA), and the basilar artery (BA) tip. No statistically significant differences were found between the mini-pterional and mini-OZ approaches for access to the posterior clinoid process, the most distal point of the superior cerebellar artery (SCA), the anterior communicating artery (ACoA), the contralateral ICA bifurcation, and the most distal point of the contralateral MCA. A trend toward increasing surgical freedom was found for the mini-OZ approach to the ACoA and the contralateral ICA bifurcation. The lengths exposed through the mini-OZ approach were longer than those exposed by the mini-pterional approach for the ipsilateral PCA segment (11.5 ± 1.9 mm) between the BA and the most distal point of the P2 segment of the PCA, for the ipsilateral SCA (10.5 ± 1.1 mm) between the BA and the most distal point of the SCA, and for the contralateral anterior cerebral artery (ACA) (21 ± 6.1 mm) between the ICA bifurcation and the most distal point of the A2 segment of the ACA. The exposed length of the contralateral MCA (24.2 ± 8.6 mm) between the contralateral ICA bifurcation and the most distal point of the MCA segment was longer through the mini-pterional approach. The vertical angle of attack (anteroposterior direction) was significantly greater with the mini-pterional approach than with the mini-OZ approach, except in the ACoA and contralateral ICA bifurcation. The horizontal angle of attack (mediolateral direction) was similar with both approaches, except in the ACoA, contralateral ICA bifurcation, and contralateral MCA bifurcation, where the angle was significantly increased in the mini-OZ approach.

CONCLUSIONS

The mini-pterional and mini-OZ approaches, as currently performed in select patients, provide less tissue traumatization (i.e., less temporal muscle manipulation, less brain parenchyma retraction) from the skin to the aneurysm than standard approaches. Anatomical quantitative analysis showed that the mini-OZ approach provides better exposure to the contralateral side for controlling the contralateral parent arteries and multiple aneurysms. The mini-pterional approach has greater surgical freedom (maneuverability) for ipsilateral circle of Willis aneurysms.

The Infrazygomatic Segment of the Superficial Temporal Artery: Anatomy and Technique for Harvesting a Better Interposition Graft

BACKGROUND

The superficial temporal artery (STA) is underutilized as an interposition graft because current techniques expose and harvest STA above the level of the zygoma. This technique yields a diminutive arterial segment in both length and diameter, which limits its use for extracranial-intracranial bypass.

OBJECTIVE

To introduce a safe and efficient technique for harvesting of the infrazygomatic segment of the STA.

METHODS

Scalp layers, STA, and the facial nerve were studied in 18 specimens. The length of the STA segment harvested below the superior border of the zygomatic arch was measured. Safety of this technique was assessed by measuring the distance between the facial nerve and the STA.

RESULTS

The galea and subgaleal fat pad were the only anatomical planes found between the facial nerve and the STA below the zygomatic arch. A dense subcutaneous band of galea contained the STA and allowed proximal dissection of the artery without exposing the facial nerve. The average length of the artery harvested between the zygomatic arch and the parotid gland was 20 mm.

CONCLUSION

Subcutaneous dissection within the galea below the level of the zygomatic arch and preservation of the dense subcutaneous band surrounding the STA avoids transecting the facial nerve branches while providing increased STA exposure. This anatomical knowledge may increase the use of STA as an interposition graft in cerebrovascular bypass procedures and reduce the need to harvest grafts through additional incisions at remote sites.

Microsurgical Anatomy of the Interfascial Vein. Its Significance in the Interfascial Dissection of the Pterional Approach

BACKGROUND: The pterional approach (PA), together with its variants, is still one of the most common methods used by surgeons to reach the anterior and middle cranial base. A highly important technical detail during a PA is the preservation of the frontotemporal branch of the facial nerve, which can be achieved through an interfascial dissection.

OBJECTIVE: To describe the anatomy of the interfascial vein (IFV), highlighting its recognition as a significant anatomic reference to perform an interfascial dissection (IFD).

METHODS: Eight adult cadaveric heads, fixed with formaldehyde and injected with colored silicone, were studied. In 6 heads, an IFD was performed, simulating a PA. In the 2 remaining heads, the IFV was dissected. In addition, an IFD was performed in 10 patients, studying the IFV anatomy.

RESULTS: In the 6 cadaveric heads in which the PA with an IFD was performed, and in the 10 patients who underwent a PA with an IFD, the IFV was found. If the interfascial space is divided into thirds, in all cases, the IFV was located within the middle third of the interfascial fat pad. On the 2 cadaveric heads in which the IFV was anatomically dissected, the IFV was also located within the middle third of the interfascial space.

CONCLUSION: Recognizing the IFV in the interfascial space is of great help as an anatomic landmark to confirm that one is actually between both layers of the superficial temporal fascia.

Technical nuances of subtemporal approach for the treatment of basilar tip aneurysm

Background:

Basilar tip aneurysms are one of the most complex vascular lesions to treat surgically because of their location, depth of the approach, and close proximity of vital neurovascular structures such as the mesencephalon, cranial nerves, perforating arteries to the thalamus. There are different surgical approaches utilized to reach basilar tip aneurysms, namely, pterional, pretemporal, orbitozygomatic, subtemporal, and anterior petrosectomy. Each of them has its advantages and limitations.

Methods:

In this paper, we present our personal experience with the use of subtemporal approach. The technique is described in detail including its nuances and potential pitfalls.

Results:

The subtemporal approach is indicated for basilar tip aneurysms located at the level of the floor of the sella turcica to 1 cm above the dorsum sellae.

Conclusion:

Subtemporal approach offers good surgical corridor for the management of these complex vascular lesions.

Postoperative temporal hollowing: Is there a surgical approach that prevents this complication? A systematic review and anatomic illustration

BACKGROUND

Temporal hollowing is a common complication following surgical dissection in the temporal region. Our objectives were to: (1) review and clarify the temporal soft tissue relationships - supplemented by cadaveric dissection - to better understand surgical approach variations and elucidate potential etiologies of postoperative hollowing; (2) identify if there is any evidence to support a surgical approach that prevents hollowing through a systematic review.

METHODS

Cadaveric dissection was performed on six hemi-heads. A systematic review of the literature was undertaken to identify surgical approaches with a decreased risk of postoperative hollowing.

RESULTS

A total of 1212 articles were reviewed; 19 of these met final inclusion criteria. Level I and II evidence supports against the use of a dissection plane beneath the superficial layer of the deep temporal fascia or through the intermediate temporal fat pad. Level II evidence supports preservation of the temporalis muscle origin - no evidence is available to support other temporalis resuspension techniques. For intracranial exposure, refraining from temporal fat pad dissection (Level I Evidence) and use of decreased access approaches such as the minipterional craniotomy (Level I Evidence) appear to minimize temporal soft tissue atrophy.

CONCLUSIONS

This study highlights the significance of preservation of the temporal soft tissue components to prevent hollowing. Preserving the temporalis origin and avoiding dissection between the leaflets of the deep temporal fascia or through the intermediate temporal fat pad appear to minimize this complication.

Fronto-temporal branch of facial nerve within the interfascial fat pad: is the interfascial dissection really safe?

BACKGROUND

The study was conducted to clarify the presence or absence of fronto-temporal branches (FTB) of the facial nerve within the interfascial (between the superficial and deep leaflet of the temporalis fascia) fat pad.

METHODS

Eight formalin-fixed cadaveric heads (16 sides) were used in the study. The course of the facial nerve and the FTB was dissected in its individual tissue planes and followed from the stylomastoid foramen to the frontal region.

RESULTS

In the fronto-temporal region, above the zygomatic arch, FTB gives several small twigs running anteriorly in the fat pad above the superficial temporalis fascia and a branch within the temporo-parietal fascia (TPF) to the muscles of the forehead. There were no twigs of the FTB within the interfascial fat pad.

CONCLUSIONS

No branches of the FTB are found in the interfascial (between the superficial and deep leaflet of the temporalis fascia) fat pad. The interfascial dissection can be safely performed without risk of injury to the FTB and potential subsequent frontalis palsy.

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.