An anatomicosurgical study of the temporal branch of the facial nerve

Identification of the anatomy of the deep temporal vein using computed tomography imaging: A retrospective cross-sectional review of patient imaging

PURPOSE

The deep temporal vein (DTV) can be used in free flap procedures when the superficial temporal vein is inadequate. Despite its potential utility, its branching patterns have only been examined in one small anatomic study. The purpose of this study was to examine computed tomography angiography (CTA) images to determine DTV location, variation, and suitability as a microvascular recipient, to provide surgeons with a guide for its use in head and neck defects.

METHODS

A retrospective chart review identified 152 patient CTA images (76 female; 76 male) in a single academic center imaging database, selected consecutively from January 2017 to April 2020. Patients under 19 years were excluded; ages ranged from 19 to 80 years (average 51.6 years). Reason for imaging, DTV caliber, laterality, distance to zygomatic arch (ZA [coronal and sagittal]), distance to lateral orbital rim (LOR), and branching pattern were recorded.

RESULTS

The predominant reason for imaging was to rule out cerebrovascular accident (96.2%). Average caliber was 3.46 ± 1.29 mm (95% confidence interval [CI] [3.32, 3.61]; range, 1.00-10.8). Bilateral DTVs were observed in 98.7% of patients. Average distance to landmarks were as follows: ZA (coronal), 13.8 ± 5.85 mm (95% CI [13.2, 14.5]; range, 2.7-33.8); ZA (sagittal), 15.1 ± 6.12 mm (95% CI [14.1, 16.1]; range, 2.8-47.2); LOR, 47.1 ± 9.09 mm (95% CI [46.0, 48.1]; range, 10.8-62.9). Seven branching patterns were identified, including a posterior vertical variant that bypasses the superficial temporal fat pad.

CONCLUSIONS

The DTV is a "lifeboat" option for head and neck reconstruction. Its average caliber is sufficient for use in microsurgery. Knowledge of both its typical and aberrant courses allow for efficient preoperative planning and surgical dissection. CTA is a useful adjunct when planning to use the DTV for free tissue transfer.

Cranio-Orbito-Zygomatic Approach: Core Techniques for Tailoring Target Exposure and Surgical Freedom

Background: The cranio-orbito-zygomatic (COZ) approach is a workhorse of skull base surgery, and each of its steps has a precise effect on target exposure and surgical freedom. The present study overviews the key techniques for execution and tailoring of the COZ approach, focusing on the quantitative effects resulting from removal of the orbitozygomatic (OZ) bar, orbital rim, and zygomatic arch. Methods: A PRISMA-based literature review was performed on the PubMed/Medline and Web of Science databases using the main keywords associated with the COZ approach. Articles in English without temporal restriction were included. Eligibility was limited to neurosurgical relevance. Results: A total of 78 articles were selected. The range of variants of the COZ approach involves a one-piece, two-piece, and three-piece technique, with a decreasing level of complexity and risk of complications. The two-piece technique includes an OZ and orbitopterional variant. Superolateral orbitotomy expands the subfrontal and transsylvian corridors, increasing surgical freedom to the basal forebrain, hypothalamic region, interpeduncular fossa, and basilar apex. Zygomatic osteotomy shortens the working distance of the pretemporal and subtemporal routes. Conclusion: Subtraction of the OZ bar causes a tremendous increase in angular exposure of the subfrontal, transsylvian, pretemporal, and subtemporal perspectives avoiding brain retraction, allowing for multiangled trajectories, and shortening the working distance. The COZ approach can be tailored based on the location of the lesion, thus optimizing the target exposure and surgical freedom and decreasing the risk of complications.

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.

Orbital Anatomy: Anatomical Relationships of Surrounding Structures

Advances in skull base and orbital surgery have led to an increased need to understand the anatomy of the orbit and surrounding structures to safely perform surgeries in this area. The purpose of this article is to review the surrounding anatomy of the orbit from a practical and operative point of view. We describe the orbit from an inferomedial endoscopic endonasal perspective (focusing on its inferior relationship with the maxillary sinus and related structures and its medial relationship with the ethmoid bone), from a posterior and superolateral intracranial perspective (describing the anatomy of the superior orbital fissure, optic canal, inferior orbital fissure, cavernous sinus, orbitofrontal cortex, and surrounding dura) and from an anterior perspective (focusing on the muscles, connective tissue, lateral and medial canthus, and relevant neurovascular anatomy). A deep knowledge of the critical neurovascular and osseous structures surrounding the orbit is necessary for adequately choosing and performing the most favorable orbital approach in every case.

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.

The extradural minipterional approach for the treatment of paraclinoid aneurysms: a cadaver stepwise dissection and clinical case series

Minipterional (MPT) craniotomy has recently been added to the neurosurgical armamentarium as a less invasive alternative to the pterional craniotomy for the treatment of parasellar lesions. However, its clinical applicability in the treatment of certain complex aneurysms, such as those arising in the paraclinoid region, remains unclear. To illustrate the microsurgical anatomy of a modified extradural MPT approach, which combines a classic MPT craniotomy with an extradural anterior clinoidectomy, and to demonstrate its clinical applicability in the treatment of complex paraclinoid aneurysms. A stepwise extradural MPT approach is illustrated in a cadaver study. Clinical outcome data from a series of 19 patients with 20 paraclinoid aneurysms treated surgically using the extradural MPT approach between 2016 and 2018 were retrospectively collected. In 95% of the cases, complete aneurysm occlusion was achieved. No aneurysm recurrences were seen during follow-up with a median length of 21 months. The outcome, according to the modified Rankin Scale, was 0 points in 12 patients (63%), 1 point in 6 patients (32%), and 2 points in 1 patient (5%). Four out of 6 patients (67%) with initial visual symptoms showed improvement following treatment, whereas in two (11%), vision became worse. The extradural MPT approach ensures a sufficiently large exposure of the paraclinoid region that is comparable with conventional approaches with the advantage of being minimally invasive. Our case series demonstrates the feasibility of this approach for the treatment of complex paraclinoid aneurysms.

Quantitative measurement of the surgical freedom for anterior communicating artery complex-a comparative study between the frontotemporal pterional and supraorbital craniotomy; a laboratory study

OBJECTIVE

To quantitatively measure surgical degree of freedom (SDF) to the anterior communicating artery (AComA) complex via removal of the orbital rim. Comparisons of SDF quadrants were made between a supraorbital and standard frontotemporal pterional craniotomy according to the surgeons' geometric microscope compass-based views.

METHODS

Eleven latex-injected formalin-fixed cadaveric heads; 14 sides (eight unilateral and three bilateral) were dissected. Standard frontotemporal pterional and subsequent supraorbital craniotomy approaches were conducted in each specimen. Point "0" was allocated as a point 1 cm distal to the ipsilateral A1 and A2 junction of AComA. The tip of a 10-cm long pointer was used to locate point 0. The base of the pointer stick was maneuvered outside the craniotomy in eight compass directions, with the most peripheral points expressed as target points 1-8. The center of this octagon was attributed point C. A pyramid was established by connecting the points 0, C, and 2 neighboring target points. A frameless stereotaxic instrument was used as a three-dimensional digitizer to measure pyramid volume. Each neighboring two pyramids form a hexagonal cone and was expressed as a surgical freedom quadrant (cm³). The quadrants are depicted counterclockwise (surgeons view) as orbital-nasal, vertex-nasal, vertex-temporal, and orbital-temporal.

RESULTS

Total SDF obtained via supraorbital and pterional approaches were 122.8 ± 109.66 and 159.94 ± 93.65, respectively (mean ± SD cm³; supraorbital < pterional by 30.2%). Supraorbital to pterional, in the orbital-nasal quadrant was 21.9 ± 35.5 and 13.04 ± 8.7, vertex-nasal 31.3 ± 28.5 and 16.7 ± 13.7, vertex-temporal 39.5 ± 42.14 and 60.4 ± 4.7, and orbital-temporal 30.14 ± 42.14 and 70.01 ± 42.14, respectively (mean ± SD cm³). In the vertex-nasal quadrant, the supraorbital approach provides a 47.3% increase in SDF compared to the standard frontotemporal pterional craniotomy approach.

CONCLUSION

Given that the AComA complex is located more nasally and the surgeon's view is more vertex, we propose that a supraorbital craniotomy allows a more contralateral portion of the AComA complex to be visualized during dissection.

Immersive Surgical Anatomy of the Frontotemporal-Orbitozygomatic Approach

The frontotemporal-orbitozygomatic (FTOZ) approach is widely used for accessing anterolateral lesions in skull base surgery. Many studies have described the technique and quantified the surgical exposure and freedom provided by the FTOZ approach. However, few studies have provided a detailed analysis of the technique and surgical landmarks using three-dimensional (3D) models. In this study, we aimed to create a collection of volumetric models (VMs) and stereoscopic media on the step-by-step surgical technique of the FTOZ approach using cadaveric dissections. The FTOZ approach was divided into eight major steps: positioning, incision of the skin, dissection of scalp flap, mobilization of the temporalis muscle, dissection of periorbita, craniotomy, drilling of basal structures, and dural opening. The MacCarty keyhole and inferior orbital fissure are major surgical landmarks that were referenced for the six bony cuts. Photogrammetry and structured light scanning were used to construct high-resolution VMs. We illustrated the two-piece FTOZ craniotomy, followed by the one-piece and three-piece FTOZ craniotomies. Stereoscopic images, videos, and VMs were produced for each step of the surgical procedure. In addition, the mini-orbitozygomatic (MOz) and orbitopterional (OPt) approaches were considered and described as possible alternatives to the FTOZ approach. Recent advances in 3D technology can be implemented in neurosurgical practice to further enhance our spatial understanding of neurovascular structures. Surgical approaches should be carefully selected and tailored according to the patient's unique pathology and needs.

Pure Endoscopic Lateral Orbitotomy Approach to the Cavernous Sinus, Posterior, and Infratemporal Fossae: Anatomic Study

Objective  The aim of this anatomic study is to describe a fully endoscopic lateral orbitotomy extradural approach to the cavernous sinus, posterior, and infratemporal fossae. Material and Methods  Three prefixed latex-injected head specimens (six orbital exposures) were used in the study. Before and after dissection, a computed tomography scan was performed on each cadaver head and a neuronavigation system was used to guide the approach. The extent of bone removal and the area of exposure of the targeted corridor were evaluated with the aid of OsiriX software (Pixmeo, Bernex, Switzerland). Results  The lateral orbital approach offers four main endoscopic extradural routes: the anteromedial, posteromedial, posterior, and inferior. The anteromedial route allows a direct route to the optic canal by removal of the anterior clinoid process, whereas the posteromedial route allows for exposure of the lateral wall of the cavernous sinus. The posterior route is targeted to Meckel's cave and provides access to the posterior cranial fossa by exposure and drilling of the petrous apex, whereas the inferior route gives access to the pterygopalatine and infratemporal fossae by drilling the floor of the middle cranial fossa and the bone between the second and third branches of the trigeminal nerve. Conclusion  The lateral orbitotomy endoscopic approach provides direct access to the cavernous sinus, posterior, and infratemporal fossae. Advantages of the approach include a favorable angle of attack, minimal brain retraction, and the possibility of dissection within the two dural layers of the cavernous sinus without entering its neurovascular compartment.

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.

One Piece Orbitozygomatic Approach Based on the Sphenoid Ridge Keyhole: Anatomical Study

The one-piece orbitozygomatic (OZ) approach is traditionally based on the McCarty keyhole. Here, we present the use of the sphenoid ridge keyhole and its possible advantages as a keyhole for the one-piece OZ approach. Using transillumination technique the osteology of the sphenoid ridge was examined on 20 anatomical dry skull specimens. The results were applied to one-piece OZ approaches performed on freshly frozen cadaver heads. We defined the center of the sphenoid ridge keyhole as a superficial projection on the lateral skull surface of the most anterior and thickest part of the sphenoid ridge. It was located 22 mm (standard deviation [SD], 0.22 mm) from the superior temporal line; 10.7 mm (SD, 0.08 mm) posterior and 7.1 mm (SD, 0.22 mm) inferior to the frontozygomatic suture. The sphenoid ridge burr hole provides exposure of frontal, temporal dura as well as periorbita, which is essential for the later bone cuts. There is direct access to removal of the thickest (sphenoidal) part of the orbital roof, after which the paper-thin (frontal) part of the orbital roof is easily fractured. The sphenoid ridge is an easily identifiable landmark on the lateral skull surface, located below the usual placement of the McCarty keyhole, with comparative exposure.

Effectiveness of Temporal Augmentation Using a Calvarial Onlay Graft during Pterional Craniotomy

Temporal hollowing occurs to varying degrees after pterional craniotomy. The most common cause of temporal hollowing is a bony defect of the pterional and temporal regions due to the resection of the sphenoid ridge and temporal squama for adequate exposure without overhang. The augmentation of such bony defects is important in preventing craniofacial deformities and postoperative hollowness. Temporal cranioplasty has been performed using a range of materials, such as acrylics, porous polyethylene, bone cement, titanium, muscle flaps, and prosthetic dermis. These methods are limited by the risk of damage to adjacent tissue and infection, a prolonged preparation phase, the possibility of reabsorption, and cost inefficiency. We have developed a method of temporal augmentation using a calvarial onlay graft as a single-stage neurosurgical reconstructive operation in patients requiring craniotomy. In this report, we describe the surgical details and review our institutional outcomes. The patients were divided into pterional craniotomy and onlay graft groups. Clinical temporal hollowing was assessed using a visual analog scale (VAS). Temporal soft tissue thickness was measured on preoperative and postoperative computed tomography (CT) studies. Both the VAS and CT-based assessments were compared between the groups. Our review indicated that the use of an onlay graft was associated with a lower VAS score and left-right discrepancy in the temporal contour than were observed in patients undergoing pterional craniotomy without an onlay graft.

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.

Modified pterional craniotomy without "MacCarty keyhole"

Pterional craniotomy is one of the most widely used approaches in neurosurgery. The MacCarty keyhole has remained the preferred means of beginning the craniotomy to achieve a low access point; however, the bone opening may result in a residual defect and an aesthetically unpleasant depression in the periorbital area. We present our modification of the traditional technique. Instead of drilling the keyhole in the frontoperiorbital area, the classical location, we perform a 5 × 15 mm strip craniectomy at the lowest accessible point in the infratemporal fossa, corresponding to the projection of the most lateral point of the sphenoid ridge. The anterior half of this opening exposes the basal frontal dura, while the posterior half brings the temporal dura into view. This modified technique was applied in 48 pterional craniotomies performed for removal of a variety of neoplasms during 2014-2015. There were no approach-related complications. Aesthetic outcomes and patient acceptance have been good; no patient developed skin depression in the periorbital area. In our experience, craniotomy for a pterional approach with the lowest possible access to the frontotemporal skull base may be performed by drilling a narrow oblong opening, without the use of any keyhole or burr hole, to create a smaller skull defect and achieve optimal aesthetic outcomes.

A Simple Method for Reconstruction of the Temporalis Muscle Using Contourable Strut Plate after Pterional Craniotomy: Introduction of the Surgical Techniques and Analysis of Its Efficacy

Objective

Pterional craniotomy (PC) using myocutaneous (MC) flap is a simple and efficient technique; however, due to subsequent inferior displacement (ID) of the temporalis muscle, it can cause postoperative deformities of the muscle such as depression along the inferior margin of the temporal line of the frontal bone (DTL) and muscular protrusion at the inferior portion of the temporal fossa (PITF). Herein, we introduce a simple method for reconstruction of the temporalis muscle using a contourable strut plate (CSP) and evaluate its efficacy.

Materials and Methods

Patients at follow-ups between January 2014 and October 2014 after PCs were enrolled in this study. Their postoperative deformities of the temporalis muscle including ID, DTL, and PITF were evaluated. These PC cases using MC flap were classified according to two groups; one with conventional technique without CSP (MC Only) and another with reconstruction of the temporalis muscle using CSP (MC + CSP). Statistical analyses were performed for comparison between the two groups.

Results

Lower incidences of ID of the muscle (p < 0.001), DTL (p < 0.001), and PITF (p = 0.001) were observed in the MC + CSP than in the MC Only group. The incidence of acceptable outcome was markedly higher in the MC + CSP group (p < 0.001). ID was regarded as a causative factor for DTL and PITF (p < 0.001 in both).

Conclusion

Reconstruction of the temporalis muscle using CSP after MC flap is a simple and efficient technique, which provides an outstanding outcome in terms of anatomical restoration of the temporalis muscle.

Preservation of the nerves to the frontalis muscle during pterional craniotomy

OBJECT

There continues to be confusion over how best to preserve the branches of the facial nerve to the frontalis muscle when elevating a frontotemporal (pterional) scalp flap. The object of this study was to examine the full course of the branches of the facial nerve that must be preserved to maintain innervation of the frontalis muscle during elevation of a frontotemporal scalp flap.

METHODS

Dissection was performed to follow the temporal branches of facial nerves along their course in 5 adult, cadaveric heads (n = 10 extracranial facial nerves).

RESULTS

Preserving the nerves to the frontalis muscle requires an understanding of the course of the nerves in 3 areas. The first area is on the outer surface of the temporalis muscle lateral to the superior temporal line (STL) where the interfascial or subfascial approaches are applied, the second is in the area medial to the STL where subpericranial dissection is needed, and the third is along the STL. Preserving the nerves crossing the STL requires an understanding of the complex fascial relationships at this line. It is important to preserve the nerves crossing the lateral and medial parts of the exposure, and the continuity of the nerves as they pass across the STL. Prior descriptions have focused largely on the area superficial to the temporalis muscle lateral to the STL.

CONCLUSIONS

Using the interfascial-subpericranial flap and the subfascial-subpericranial flap avoids opening the layer of loose areolar tissue between the temporal fascia and galea in the area lateral to the STL and between the galea and frontal pericranium in the area medial to the STL. It also preserves the continuity of the nerve crossing the STL. This technique allows for the preservation of the nerves to the frontalis muscle along their entire trajectory, from the uppermost part of the parotid gland to the frontalis muscle.

Techniques for Preservation of the Frontotemporal Branch of Facial Nerve during Orbitozygomatic Approaches

Background During orbitozygomatic (OZ) approaches, the frontotemporal branch (FTB) of the facial nerve is exposed to injury if proper measures are not taken. This article describes in detail the nuances of the two most common techniques (interfascial and subfascial dissection). Design The FTB of the facial nerve was dissected and followed in its tissue planes on fresh-frozen cadaver heads. The interfascial and subfascial dissections were performed, and every step was photographed and examined. Results The interfascial dissection is safe to be started from the most anterior part of the superior temporal line and followed to the root of the zygoma. The dissection is continued on the deep temporalis fascia (DTF), and the interfascial fat pad is elevated. With the subfascial dissection, both the superficial temporalis fascia and the DTF are elevated. The interfascial dissection exposes the zygomatic arch directly, whereas the subfascial dissection requires an additional cut on the DTF to expose the zygomatic arch. Proper subperiosteal dissection on the zygomatic arch is another important step in FTB preservation. Conclusion Detailed understanding of the complex relationship of the tissue planes in the frontotemporal region is needed to perform OZ exposures safely.

Combined subgaleal/myocutaneous technique for temporalis muscle dissection

Background The frontal branch of the facial nerve (FBFN) is the most susceptible neural structure to injury during frontotemporal craniotomies. The balance between adequate temporalis muscle mobilization and frontal branch protection with minimal anatomical alteration is the philosophy behind our approach to temporalis muscle dissection. Objective To describe a combined subgaleal/myocutaneous technique for dissection and mobilization of the temporalis muscle in anterolateral cranial approaches. Methods Interdisciplinary literature review of the anatomical course of the FBFN was performed. Retrospective analysis of anterolateral craniotomies performed at our institution in which the combined subgaleal/myocutaneous (CSGMC) technique was performed. Results A total of 71 cases of anterolateral craniotomies (excluding full variant orbitozygomatic) were performed with the successful application of a CSGMC technique (36 pterional, 31 orbitopterional, and 4 fronto-orbital). Partial frontalis weakness was transient in one case. Conclusion The CSGMC technique provides sufficient protection for the FBFN and allows for adequate mobilization for a variety of skull base exposures while minimally violating myofascial anatomy. This is the first reported technique that allows both adequate temporalis muscle mobilization with performance of the one-piece orbitofrontal and orbitopterional approaches, without disruption of the superficial/deep temporalis fascia and fat-pad complex.

[Transzygomatic pterional approach. Part 2: Surgical experience in the management of skull base pathology]

OBJECTIVES

To present our experience with the transzygomatic pterional approach in the treatment of neurosurgical pathology of the base of the skull located in the middle cranial fossa and surrounding areas.

METHOD

A retrospective study of pathological findings, surgical outcomes and complications in a series of 31 cases operated on between 2009 and 2011 using a transzygomatic pterional approach.

RESULTS

The lesions involved the sphenoid wing (25.9%), several regions due to invasive growth pattern (19.5%), the temporal lobe (16.1%) and cavernous sinus (12.9%). The others were located in the floor of the middle fossa, Meckel's cave, incisural space, cisterns and infratemporal region. The pathological nature of the lesions was: benign meningioma (42%), temporal lobe tumour (19.5%), vascular disease (12.9%), inflammatory lesions (6.4%), atypical meningioma (6.4%), epidermoid cyst (6.4%), neurinoma (3.2%) and poorly differentiated infratemporal carcinoma (3.2%). The approach was usually combined extra-intradural (58.1%) and, less frequently, just extradural (16.1%) or intradural (25.8%). Approach-related complications were minor: haematomas in the wound not requiring treatment (67.8%), superior transient facial paresis (9.7%), transient temporomandibular joint dysfunction (12.9%) and atrophy of the temporal muscle (16.2%). There were no hardware-related complications or cosmetic issues related to the osteotomy and posterior osteosynthesis of the zygomatic arch.

CONCLUSIONS

The pterional approach combined with osteotomy of the zygomatic arch allows mobilising the temporalis muscle away from the temporal fossa, consequently exposing its entire surface to complete the temporal craniotomy up to the middle fossa; it helps to access and treat pathology in this region or it can be used as a corridor to approach surrounding areas.

[Transzygomatic pterional approach. Part 1: anatomical study]

OBJECTIVE

Cadaveric study of the anatomical structures of the temporal region, as well as the technical aspects of the transzygomatic pterional approach.

MATERIAL AND METHODS

Six human formalin-fixed heads, whose arterial circulatory system was injected with red-dyed silicone, were studied (12 temporal regions). Dissections were performed using standard microsurgical techniques and instruments.

RESULTS

We confirm the existence of a double superficial and deep layer within the superficial temporal fascia, which makes possible to perform the zygomatic arch osteotomy without damaging the temporal muscle and the branches of the superficial temporal artery and the facial nerve. The shape and location of the osteotomies to preserve the témporo-mandibular joint and ligaments and to provide correct reconstruction of the bone flap are described. We compare the exposure of intracranial structures obtained by this approach with those obtained by the conventional pterional approach and the orbitozygomatic approach.

CONCLUSIONS

The transzygomatic pterional approach provides wide exposure of the temporal lobe for trans-sylvian, pre-temporal and/or subtemporal approaches in selected cases of neurosurgical pathology. A detailed anatomical knowledge of the temporal region is necessary to achieve the best surgical, functional and cosmetic results.

Supraorbital minicraniotomy

The recent use of neuroendoscopy combined to microsurgery allows new surgical approaches. We report our early experience with a supraorbital microcraniotomy. This technique is suitable for small lesions situated in the region of the anterior fossa, suprasellar cisterns, and Sylvian cistern. A 50-mm incision in the eyebrow and a supraorbital minicraniotomy are performed. We report on six patients with different lesions and good cosmetic results. We conclude that this approach is safe and useful in selected cases.

Fronto-orbito zygomatic approach: a technical modification

The fronto-orbito zygomatic approach is part of the surgical armamentarium of modern skull base surgery. As described in the literature, it requires costly technological tools such as powerful drills and saws, to be performed. In the present communication we describe a technical modification that allows the zygoma to be elevated "en bloc" together with the fronto-orbital bone flap by means of appropriate use of the Gigli's saw. Using this technique, adequate replacement of the craniotomy flap requires only two silk sutures. This technical modification, which was already successfully used in over 20 cases, would also allow this useful approach to be performed in those neurosurgical environments where modern costly technology for cranial base surgery is not available.

Giant cell tumor (osteoclastoma) of the petrous bone: case report

A case of a basal middle fossa giant cell tumor occurring in a 46-year-old man is described. The lesion appeared at the computed tomography (CT) scan examination as an hypodense mass with a peripheral "ring-like" enhancement, and no evident erosion of the skull base. The tumor, which infiltrated the basal temporal parenchyma, was removed via a temporal transzygomatic craniotomy, and extensive drilling of the petrous bone. Despite the occurrence, of significant postoperative complications, the patient ultimately showed a good clinical outcome, with no signs of recurrence at the 1-year follow-up CT scanning. The clinical and diageostic aspects and the management policy, of this rare lesion are discussed.

[Fronto-temporo-orbito-zygomatic approach - analysis of the surgical technique on cadaver simulations]

This paper presents consecutive stages of the fronto-temporo-orbito-zygomatic approach (FTOZA). Two simulations of FTOZA were performed on non-fixed human cadavers without any known pathologies in the head and neck. The consecutive stages of the procedure were documented with photographs and schematic diagrams. The starting point for FTOZA is a pterional craniotomy and osteotomy including the orbital rim, body of the zygomatic bone and zygomatic arch. In justified cases it is also possible to temporarily remove the upper and lateral walls of the orbit. Wide drawing apart of the Sylvian fissure is an important supplement of the approach. The fronto-temporo-orbito-zygomatic approach is a reproducible technique, which provides surgical penetration of the middle cranial fossa and related regions. This approach is particularly useful in the treatment of tumours of the above-mentioned anatomical areas as well as vascular malformation of the posterior part of the arterial circle of the brain.

A surgical modification for performing orbitozygomatic osteotomies: technical note

The addition of orbitozygomatic osteotomies to the fronto-temporo-sphenoidal craniotomy minimizes brain retraction required to reach deep seated pathology by allowing additional soft tissue dissection and strategic cranial bone removal. We report a modification of this technique in order to reduce soft tissue and cosmetic morbidity while increasing the efficiency with which this technique is performed. A two piece fronto-temporo-sphenoidal craniotomy combined with orbitozygomatic osteotomies was analyzed via cadaver dissection. The craniotomy and orbitozygomatic osteotomies were performed using the foot plate of the craniotome to facilitate the orbitozygomatic osteotomies. A similar technique was utilized in the operating room to safely create the two piece fronto-temporo-sphenoidal craniotomy and orbitozygomatic osteotomies in a series of patients. The illustrated technique was performed in cadavers and the results were analyzed in a series of 18 consecutive patients with minimum 3-month follow-up. Increased efficiency, good tissue preservation, and minimal soft tissue damage with no orbital injury were noted with a high rate of gross total lesional resection. With the added safety of a cutting instrument separated from the orbital soft tissues by a footplate, tissue trauma was minimized. Orbitozygomatic osteotomies are frequently added to the fronto-temporo-sphenoidal craniotomy in order to reach intracranial pathology that would previously have required excessive brain retraction to address. This manuscript details the use of a single drill system that can be used for both the craniotomy and the safe and efficient generation of orbitozygomatic osteotomies.

The work horse of skull base surgery: orbitozygomatic approach. Technique, modifications, and applications

Object

The aim of this study was to describe the microsurgical anatomy of the orbitozygomatic craniotomy and its modifications, and detail the stepwise dissection of the temporalis fascia and muscle and explain the craniotomy techniques involved in these approaches.

Methods

Nine cadaveric embalmed heads injected with colored silicone were used to demonstrate a stepwise dissection of the 3 variations of orbitozygomatic craniotomy. The craniotomies and dissections were performed with standard surgical instruments, and the microsurgical anatomy was studied under microscopic magnification and illumination.

Results

The authors performed 2-piece, 1-piece, and supraorbital orbitozygomatic craniotomies in 3 cadaveric heads each. Stepwise dissection of the temporalis fascia and muscle, and osteotomy cuts were shown and the relevant microsurgical anatomy of the anterior and middle fossae was demonstrated in cadaveric heads. Surgical case examples were also presented to demonstrate the application of and indications for the orbitozygomatic approach.

Conclusions

The orbitozygomatic approach provides access to the anterior and middle cranial fossae as well as the deep sellar and basilar apex regions. Increased bone removal from the skull base obviates the need for vigorous brain retraction and offers an improved multiangled trajectory and shallower operative field. Modifications to the orbitozygomatic approach provide alternatives that can be tailored to particular lesions, enabling the surgeon to use the best technique in each individual case rather than a “one size fits all” approach.

The relationship of the fronto-temporal branches of the facial nerve to the fascias of the temporal region: a literature review applied to practical anatomical dissection

The understanding of the course of the facial nerve and its relationship to the different connective tissue layers in the temporal area is paramount to preserving this nerve during surgery. But the use of different nomenclatures for anatomical structures such as for the different fascial layers or fat pads in the temporal region as well as the difference in description of the course of the fronto-temporal branches of the facial nerve in relationship to the fascial layers can lead to confusion. Therefore we have reviewed the literature about this topic and tried to apply the information to practical anatomical dissection.

Aesthetic issues in neurosurgery: a protocol to improve cosmetic outcome in cranial surgery

Nowadays, surgical interventions must treat with care the aesthetic impact on the patient, even when a malignant pathology or an patient's advanced age could give the aesthetic issue lower priority. The cranio-facial area is probably the most important anatomical region with regard to the harmony of the human body. Consequently, a step-by-step procedure, applicable regardless of the site and the nature of the lesion, is advisable to minimize the aesthetic impact. We prospectively analyzed 65 patients during a period of 2 years. At 1-year follow-up, all patients were invited to undergo a 3D-multislice CT and to complete a questionnaire with a subjective rating scale about aesthetic impact. The 3D-multislice CT scan didn't show dislocations, depressions or gaps of the bone flap. Nevertheless, five patients complained of some degree of aesthetic injury, or reported a psychological suffering from the aesthetic consequences of surgery. As a control group, we retrospectively reviewed 223 patients. The authors describe their surgical protocol and discuss it in the light of the results of their series.

Surgical repair of temple defects after Mohs micrographic surgery

BACKGROUND

It is typically recommended that linear surgical closures follow a relaxed skin tension line (RSTL). In the temple, these lines generally run parallel to the orbital rim. However, closures parallel to RSTLs are not feasible for many medium and large surgical defects because of anatomic constraints.

OBJECTIVES

We sought to describe our method of repairing temple defects and assess the cosmetic outcome of temple defects repaired perpendicular to the RSTLs.

METHODS

We performed a two-phase study of temple closures. In the first phase, a retrospective analysis was performed to assess the defect size and type of closure used for 99 consecutive temple defects. In the second phase, 27 of 86 patients who previously underwent linear surgical repairs in the temple that were designed perpendicular to the RSTLs were evaluated 12 to 24 months postoperatively to assess the cosmetic outcome. Results In the first phase of the study, there was an inverse correlation between the width of the postoperative defect and the ability to close the defect parallel to the RSTLs. The percentage of defects that could be repaired parallel to the RSTLs for defects up to 1 cm in width, 1.1 to 2 cm in width, and greater than 2 cm in width was 46%, 28%, and 8%, respectively. In the second phase of the study, 27 patients with temple defects repaired perpendicular to the RSTLs were evaluated an average of 1.7 years after operation. Most scars (83%) were clinically invisible or barely visible. There were no cases with residual standing cones (dog-ears) or hypertrophic scars.

CONCLUSION

The vast majority of temple defects can be repaired in a linear fashion. Smaller defects (width < 1 cm) can be repaired parallel to the RSTL. Those that are larger (width 1-3 cm) or more medially located can be repaired perpendicular to the RSTL, using loose cheek skin for the closure. Very large defects (width > 3-5 cm) or those with limited cheek mobility may require flaps or skin grafts for closure.

Innervation of the Corrugator Supercilii Muscle

The frowning forehead is unwanted, generally because it gives an impression of anger and displeasure. The frown is formed mainly by the repeated contraction of the corrugator supercilii muscle. We studied the relevant nerve supply to the muscle in detail to enhance selective neurotomy. A bicoronal incision extending downward to the preauricle was made and the subgaleal dissection proceeded in 19 hemifaces of cadavers. The temporal branch of the facial nerve was divided into 2 to 4 smaller branches at the zygomatic arch. There were commonly 3 branches. The temporal branch is located 10 mm lateral to the supraorbital notch or foramen 2.8 to 25 mm above the supraorbital rim. It contains 4 to 7 thin rami (5 on average). A plexus mainly from the inferior ramus partly from the middle ramus of the temporal branch of the facial nerve enters the corrugator supercilii muscle in the supraorbital area. Because the temporal branch had multiple interconnection among its own rami, selective blocking of the middle ramus cannot promise the elimination of the frown line.

Modifications to the orbitozygomatic approach. Technical note

The orbitozygomatic craniotomy is one of the workhorse approaches of skull base surgery, providing wide, multidirectional access to the anterior and middle cranial fossae as well as the basilar apex. Complete removal of the orbitozygomatic bar increases the angles of exposure, decreases the working depth of the surgical field, and minimizes brain retraction. In many cases, however, only a portion of the exposure provided by the full orbitozygomatic approach is needed. Tailoring the extent of the bone resection to the specific lesion being treated can help lower approach-related morbidity while maintaining its advantages. The authors describe the technical details of the supraorbital and subtemporal modified orbitozygomatic approaches and discuss the surgical indications for their use. Modifications to the orbitozygomatic approach are an example of the ongoing adaptation of skull base procedures to general neurosurgical practice.

The One-Piece Orbitopterional Approach

The orbitopterional approach is an anterior skull base extension of the pterional approach that provides greater exposure to the anterior cranial fossa, supra- and parasellar regions, and anterior communicating artery complex. We describe the surgical technique in a stepwise manner to create a one-piece orbitopterional craniotomy flap; keyholes for the bone cuts are the MacCarty burr-hole and the anterolateral portion of the inferior orbital fissure. This one-piece technique is less complicated than the two-piece orbitopterional craniotomy and eliminates the need for complex reconstruction of cosmetically important areas (i.e., the orbit and forehead).

Osteotomy design and execution

Craniofacial osteotomies are an integral part of contemporary neurosurgery because of their ability to provide substantially more exposure to deepseated lesions with reduced brain retraction. A systematic approach to the performance of these osteotomies coupled with meticulous bone work capitalizes on their advantages without producing any significant cosmetic defects. As their indications are progressively more clearly defined and familiarity and facility are gained by the surgeons performing them, operative time and morbidity should decrease. Lowering operative time and morbidity with excellent esthetic results is likely to be increasingly important when considering operative versus nonoperative management, particularly as nonsurgical modalities continue to develop.

Cosmetic considerations in cranial base surgery

Recent advances in the surgical techniques for the resection of cranial base tumors have allowed for improved degrees of tumor resection, functional outcomes, and esthetic results. If the resection and functional results are not compromised by procedures providing excellent cosmetic outcomes, there is no reason to ignore or compromise the esthetic aspect with regard to technical execution and planning. A thorough assessment of the patient's preoperative deficits and tumor anatomy and a working knowledge of the available cranial base approaches and their combinations permit the surgeon to design an approach that allows for optimal tumor resection with the best possible cosmetic result. In a time when alternative treatment options like radiosurgery exist for cranial base tumors, esthetic outcome is a significant quality-of-life issue that patients consider in their decision to choose surgery versus an alternative treatment.

[The temporal periosteum: anatomical study and surgical implications]

The periosteum of the temporal area is mentioned at different places in the literature: either against the osseous plane like everywhere in the human body, or between the deep and the superficial temporal fascia. The subperiosteal subtemporal approach in craniofacial surgery in children is in favour of a juxta-osseous localization of the periosteum. Ten premature still-born neonates and two adults cadavers have been dissected for this study and, permit anatomical and histological (with HES coloration) studies. With every specimen, the authors concluded that the temporal periosteum is against the outer table of the calvarium. It became thinner in adults because of direct insertions of the temporalis muscle in the calvaria. An anatomical description of the layers of the temporal area is realised and discussed with an extensive review of the literature. The authors have proposed a subperiosteal subtemporal approach in craniostenosis surgery.

Technique for fixing a temporalis muscle using a titanium plate to the implanted hydroxyapatite ceramics for bone defects

We devised a technique to fix the temporalis muscle to the transplanted hydroxyapatite implant by using a titanium plate, which is fixed to the hydroxyapatite ceramic implant by screws and achieves good clinical results. The size, shape, and curvature of the hydroxyapatite ceramic implants were determined according to full-scale models fabricated using the laser lithographic modeling method from computed tomography data. A titanium plate was then fixed with screws on the implant before implantation, and then the temporalis muscle was refixed to the holes at both ends of the plate. The application of this technique reduced the hospitalization time and achieved good results esthetically.

Cosmetic and functional reconstruction achieved using a split myofascial bone flap for pterional craniotomy. Technical note

Cosmetic deformities that appear following pterional craniotomy are usually caused by temporal muscle atrophy, injury to the frontotemporal branch of the facial nerve, or bone pits in the craniotomy line. To resolve these problems during pterional craniotomy, an alternative method was developed in which a split myofascial bone flap and a free bone flap are used. The authors have used this method in the treatment of 40 patients over the last 3 years. Excellent cosmetic and functional results have been obtained. This method can provide wide exposure similar to that achieved using Yaşargil's interfascial pterional craniotomy, without limiting the operative field with a bulky temporal muscle flap.

Subfascial and submuscular methods of temporal muscle dissection and their relationship to the frontal branch of the facial nerve. Technical note

The microsurgical anatomy of the temporal and zygomatic branches of the facial nerve are presented along with related local vasculature (frontal and parietal branches of the superficial temporal artery [STA]) as encountered when using subfascial and submuscular temporal muscle dissection techniques for anterolateral craniotomies. Twenty sides were studied in 10 cadaveric specimens that had been previously injected with latex. The rami of the temporal and zygomatic branches of the facial nerve and branches of the STA were dissected out through pterional and orbitozygomatic approaches by using a submuscular or subfascial temporal muscle dissection technique. The three rami of the temporal branch of the facial nerve (the auricularis, frontalis, and orbicularis) were found to run within the galeal plane of the scalp. The zygomatic branch of the facial nerve was found to course deeper than the most caudal extension of the galea, known as the superficial musculoaponeurotic layer. The frontal branch of the STA served as an important landmark for the subfascial or submuscular dissections because excessive reflection of the scalp flap inferior to the level of this vessel would inadvertently injure the frontalis branch of the facial nerve. Subfascial and submuscular dissections of the temporal muscle offer an alternative to the interfascial technique during anterolateral craniotomies. Scalp and temporal dissection performed with careful attention to anatomical landmarks (frontal branch of the STA and the suprafascial fat pad) provides a safe and expeditious alternative to the traditional interfascial technique.

Less invasive reconstruction of the temporalis muscle for pterional craniotomy: modified procedures

BACKGROUND

I developed a modified pterional craniotomy technique which is less invasive for both the facial nerve and the temporalis muscle.

METHODS

The keys to this procedure are subfascial dissection and reflection of the temporalis fascia without interfascial dissection, and posterior displacement of the temporalis muscle without muscular incision. The limited exposure from the bulky temporalis muscle can be avoided with this procedure. A small cuff of the fascia-periostium complex is left on a free bone flap along the superior temporal line to facilitate the subsequent muscle closure.

RESULT

Since the facial nerve and temporalis muscle are not injured with this procedure, the functional and cosmetic results are satisfactory.

CONCLUSION

To reduce functional and cosmetic complications, and the cost of pterional craniotomy, I believe that my procedure is recommended.

Orbitozygomatic craniotomy. Technical note

The orbitozygomatic approach provides wide, multidirectional access to the anterior and middle cranial fossae, as well as to the upper third of the posterior fossa and clivus. The authors describe technical details of the surgical approach as it has evolved over 3.5 years of experience in 83 consecutive cases. This modified technique eliminates the need for bone reconstruction of the orbital walls to prevent enophthalmos and minimizes the risk of injury to the frontal branch of the facial nerve. At a follow-up evaluation after a period averaging 14 months, all patients were pleased with the cosmetic results of this approach.