Modified supraorbital craniotomy: technical note

'What's in a name', a systematic review of the pterional craniotomy for aneurysm surgery and its many modifications with a proposal for simplified nomenclature

BACKGROUND

The pterional or frontosphenotemporal craniotomy has stood the test of time and continues to be a commonly used method of managing a variety of neurosurgical pathology. Already described in the beginning of the twentieth century and perfected by Yasargil in the 1970s, it has seen many modifications. These modifications have been a normal evolution for most neurosurgeons, tailoring the craniotomy to the patients' specific anatomy and pathology. Nonetheless, an abundance of variations have appeared in the literature.

METHODS

A search strategy was devised according to the 2020 Preferred Reporting Items of Systematic Reviews and Meta-Analyses (PRISMA) statement. To identify articles investigating the variations in the pterional approach, the following search terms were applied: (pterional OR minipterional OR supraorbital) AND (approach OR craniotomy OR technique).

RESULTS

In total, 3552 articles were screened with 74 articles being read in full with 47 articles being included for review. Each article was examined according the name of the technique, temporalis dissection technique, craniotomy technique and approach.

CONCLUSION

This systematic review gives an overview of the different techniques and modifications to the pterional craniotomy since it was initially described. We advocate for the use of a more standardised nomenclature that focuses on the target zone to simplify the management approach to supratentorial aneurysms.

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.

[The orbitozygomatic approach. History, technique, and modifications]

The orbitozygomatic approach (OZA) has been used in neurosurgical practice since the 1980s. Many approach modifications have been proposed; anatomical and clinical developments have been conducted in many clinics. However, there is no algorithm for choosing an approach option, depending on the type and topographo-anatomical features of pathology.

MATERIAL AND METHODS

We searched for publications in the PubMed and Medscape databases using the keywords 'orbitozygomatic'.

RESULTS

A total of 447 publications matching the search terms were found. In most of them, the approach was either not actually orbitozygomatic or was mentioned in the description of a clinical case. One hundred and nineteen full text Russian or English papers were available for detailed analysis. Of these, we selected 72 most relevant publications.

DISCUSSION

There were no studies demonstrating disadvantages of the OZA compared to traditional craniotomies. Orbitozygomatic approaches are widely used in routine neurosurgical practice. Existing approaches are not without disadvantages. The publications are based on small material. The recommendations on choosing the optimal OZA option are based on the authors' opinion, i.e. they satisfy the minimum level of evidence. There are no studies comparing the efficacy of OZA options in different types and topographo-anatomical variants of neurosurgical pathology of the anterior and middle skull base.

CONCLUSION

The reasonability of using the orbitozygomatic approach in neurosurgical practice is obvious. There are a large number of orbitozygomatic approaches and their modifications. The modern literature lacks an algorithm for choosing the optimal OZA option for specific types and topographo-anatomical variants of the pathological process.

The supraorbital eyebrow approach for removal of craniopharyngioma in children: a case series

OBJECTIVE

Craniopharyngiomas can be a surgical challenge for the pediatric neurosurgeon. Ideally, total removal must be achieved. However, the need to reduce surgical morbidity and preserve quality of life has led to a number of neurosurgical approaches in order to attain this goal. The aim of this article is to present an alternative surgical approach to these lesions and to provide the rationale for this technique.

MATERIAL AND METHODS

Medical charts and operative records of eight pediatric patients harboring craniopharyngiomas who underwent surgical treatment using a supraorbital eyebrow approach (SOA) were reviewed from 2014 to 2016. Only patients younger than 18 years with a minimum follow-up of 12 months were included in this study. Using pre-operative magnetic resonance (MRI) scans, tumors were classified according to their degree of hypothalamic involvement. The surgical technique is also described in detail.

RESULTS

The study group included six males and two females with a mean age of 10 years (range, 2-16 years). The SOA was used successfully in elective surgery of eight craniopharyngiomas. The hypothalamus was displaced by the tumor in three patients and severely involved in five patients. Subtotal resection was undertaken in six patients, whereas gross-total resection was achieved in two. Endoscopic assistance was used after standard microscopic visualization in two out of eight cases. Cosmetic outcomes were excellent, and the complication rate related to the surgical procedure was quite low, apart from diabetes insipidus (which occurred in three out of the eight patients). In one patient, a large subdural collection needed surgery for evacuation. Mean follow-up was 23.2 months (range, 12-36 months). Additionally, no CSF leak or wound infection was identified.

CONCLUSIONS

The supraorbital eyebrow approach is an alternative route to operate on craniopharyngiomas in properly selected cases of all pediatric age ranges, from infants to teenagers. There is sufficient working space for the endoscope and all instruments, allowing for endoscopic assistance and bimanual surgical technique. Cosmetic results are excellent, and complications related to the approach are minimal.

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.

Management of infections complicating the orbitocranial approaches: Report of two cases and review of literature

BACKGROUND

The orbitocranial approaches are now indispensible for treating lesions of the skull base, providing access to lesions in the anterior and middle cranial fossae, as well as the upper clivus and anterior brainstem. The management of infectious complications of the orbitocranial approaches, however, has evaded the literature.

CASE DESCRIPTION

We present two cases of patients who underwent orbitocranial approach whose clinical course was complicated by wound infection and osteomyelitis. One patient was treated with antibiotics and then had a custom implant placed for cranioplasty. The other case was managed with removal of bone and wire-mesh cranioplasty.

CONCLUSION

Management of orbitocraniotomy infections can be difficult due to the complex geometry of the flap and to cosmetic considerations. Once the infection involves the bone, the bone can be replaced after cleaning or discarded and a cranioplasty performed. Cranioplasty can be performed with wire-mesh or a custom implant made by computer-assisted modeling.

Validity of the Lateral Supraorbital Approach as a Minimally Invasive Corridor for Orbital Lesions

BACKGROUND

Many approaches were recommended for surgical treatment of orbital lesions via either transorbital or transcranial routes. The frontolateral craniotomy through eyebrow skin incision (lateral supraorbital approach) is a combined cranio-orbital approach that could be used in different orbital lesions.

OBJECTIVES

To evaluate the efficacy and safety of the lateral supraorbital approach for resection of orbital lesions.

PATIENTS AND METHODS

Ten patients with different orbital lesions were treated by this minimally invasive technique. The technique is described in details. The postoperative outcome was evaluated with casting light on the specific parameters related to this approach.

RESULTS

This study included 6 females and 4 males, ranging in age from 2 years to 65 years with mean age of 37.3 years. Proptosis was the most common presenting complaint. Six patients were operated on via the right supraorbital approach, and 4 patients via the left supraorbital approach. Various pathological lesions were treated. The excision was total in 7 patients, subtotal in 1 patient, and partial in 2 patients. Two patients suffered transient supraorbital hypothesia, 1 patient showed temporary superficial wound infection with CSF leak and 1 patient died within 6 months.

CONCLUSION

The lateral supraorbital approach is a minimally invasive approach that provides excellent exposure of the superior, lateral, and medial orbit, as well as the orbital apex.

Technical note: Orbitozygomatic craniotomy using an ultrasonic osteotome for precise osteotomies

BACKGROUND

The orbitozygomatic craniotomy is a fundamental procedure in neurosurgery, allowing access to orbital and skull base pathology.

OBJECTIVE

Determine the feasibility of using an ultrasonic osteotome to safely perform orbitozygomatic osteotomies in patients with intracranial pathology.

METHODS

The medical records of patients undergoing orbitozygomatic craniotomy using an ultrasonic osteotome (Aesculap BoneScalpel™) for tumor resection at Johns Hopkins Hospital between November 2009 and March 2013 were retrospectively reviewed.

RESULTS

Six patients underwent orbitozygomatic craniotomy for tumor resection using an ultrasonic osteotome at the Johns Hopkins Hospital during the study period. All patients were female and the average age was 53.2 years. Patients were followed for an average of 375 days. There were two cases of transient diplopia. There were no cases of periorbital violation, orbital injury, enophthalmos, or orbital hematoma. Post-operative imaging showed the cuts were well opposed and no cosmetic issues were encountered.

CONCLUSION

Use of an ultrasonic osteotome allows for precise cuts under direct visualization with minimal risk to critical adjacent structures in our cohort of patients undergoing a two-piece orbitozygomatic craniotomy. This appears to be a safe instrument for osteotomy creation in skull base approaches.

The Supraorbital Keyhole Craniotomy through an Eyebrow Incision: Its Origins and Evolution

In the modern era of neurosurgery, the use of the operative microscope, rigid rod-lens endoscope, and neuronavigation has helped to overcome some of the previous limitations of surgery due to poor lighting and anatomic localization available to the surgeon. Over the last thirty years, the supraorbital craniotomy and subfrontal approach through an eyebrow incision have been developed and refined to play a legitimate role in the armamentarium of the modern skull base neurosurgeon. With careful patient selection, the supraorbital "keyhole" approach offers a less invasive but still efficacious approach to a number of lesions along the subfrontal corridor. Well over 1000 cases have been reported in the literature utilizing this approach establishing its safety and efficacy. This paper discusses the nuances of this approach, including the benefits and limitations of its use described through our technique, review of the literature, and case illustration.

Accessing the basilar artery apex: is the temporopolar transcavernous route an anatomically advantageous alternative?

The restricted operative field, difficulty of obtaining proximal vascular control, and close relationship to important anatomic structures limit approaches to basilar apex aneurysms. We used a cadaveric model to compare three surgical transcavernous routes to the basilar apex in the neutral configuration. Five cadaveric heads were dissected and analyzed. Working areas and length of exposure provided by the transcavernous (TC) approach via pterional, orbitozygomatic, and temporopolar (TP) routes were measured along with assessment of anatomic variation for the basilar apex region. In the pterional TC and orbitozygomatic TC approaches, the mean length of exposure of the basilar artery measured 6.9 and 7.2 mm, respectively (p = NS). The mean length of exposure in a TP TC approach increased to 9.3 mm (p < 0.05). Compared with the pterional and orbitozygomatic approaches, the TP TC approach provided a larger peribasilar area of exposure ipsilaterally and contralaterally (p < 0.05). The multiplanar working area related to the TP TC approach was 77.7 and 69.5% wider than for the pterional TC and orbitozygomatic TC, respectively. For a basilar apex in the neutral position, the TP TC approach may be advantageous, providing a wider working area for the basilar apex region, improving maneuverability for clip application, fine visualization of perforators, and better proximal control.

The frontotemporal-orbitozygomatic approach: reconstructive technique and outcome

BACKGROUND

The frontotemporal-orbitozygomatic (FTOZ) approach, also known as "the workhorse of skull base surgery," has captured the interest of many researchers throughout the years. Most of the studies published have focused on the surgical technique and the gained exposure. However, few studies have described reconstructive techniques or functional and cosmetic outcomes. The goal of this study was to describe the surgical reconstruction after the FTOZ approach and analyze the functional and cosmetic outcomes.

METHODS

Seventy-five consecutive patients who had undergone FTOZ craniotomy for different reasons were selected. The same surgical (one-piece FTOZ) and reconstructive techniques were applied in all patients. The functional outcome was measured by complications related to the surgical approach: retro-orbital pain, exophthalmos, enophthalmos, ocular movement restriction, cranial nerve injuries, pseudomeningocele (PMC) and secondary surgeries required to attain a reconstructive closure. The cosmetic outcome was evaluated by analyzing the satisfaction of the patients and their families. Questionnaires were conducted later in the postoperative period. A statistical analysis of the data obtained from the charts and questions was performed.

RESULTS

Of the 75 patients studied, 59 had no complications whatsoever. Ocular movement restriction was found in two patients (2.4 %). Cranial nerve injury was documented in seven patients (8.5 %). One patient (1.2 %) underwent surgical repair of a cerebrospinal fluid (CSF) leak from the initial surgery. Two patients (2.4 %) developed delayed postoperative pseudomenigocele. One patient (1.2 %) developed intraparenchymal hemorrhage (IPH). Full responses to the questionnaires were collected from 28 patients giving an overall response rate of 34 %. Overall, 22 patients (78.5 %) were satisfied with the cosmetic outcome of surgery.

CONCLUSION

The reconstruction after FTOZ approach is as important as the performance of the surgical technique. Attention to anatomical details and the stepwise reconstruction are a prerequisite to the successful preservation of function and cosmesis. In our series, the orbitozygomatic osteotomy did not increase surgical complications or alter cosmetic outcomes.

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.

Lateral orbital rim osteotomy in the treatment of certain skull base lesions

Quantitative data from a recent human cadaveric study suggested that removal of the lateral orbital rim alone may be sufficient to reach many targets for which the orbitozygomatic craniotomy has been used. Consequently, a lateral orbital rim osteotomy was substituted for an orbitozygomatic craniotomy in seven patients with a variety of pathologies located in the anterior, middle, and interpeduncular fossae. In each case, lateral orbitotomy provided a satisfactory surgical corridor for diagnosis and treatment. Compared with the orbitozygomatic craniotomy, the lateral orbital rim osteotomy offers several advantages: technical simplicity, shorter operating time, and a low risk of postoperative malocclusion. If, however, prolonged access to a wide expanse of the anterior portion of the middle fossa and inferotemporal area is needed, an orbitozygomatic approach is a better choice.

Transpalpebral orbitofrontal craniotomy: a minimally invasive approach to anterior cranial vault lesions

To describe a minimally invasive approach to anterior cranial vault pathology using a transpalpebral exposure with a miniorbitofrontal craniotomy.

DESIGN

Case series.

SETTING

Tertiary referral hospital with multidisciplinary skull base program. Participants include patients with intra-axial and extra-axial anterior skull base lesions who underwent the transpalpebral minicraniotomy approach.

MAIN OUTCOME MEASURES

Feasibility of the approach to permit adequate exposure of targeted lesion. We applied this approach in seven patients for the repair of persistent cerebrospinal fluid leaks, pneumocephalus, and the biopsy or resection of midline brain tumors along the anterior cranial base. The approach allowed bimanual instrumentation working with either endoscopic or microscopic visualization for tumor resection and repair of dural and cranial base defects. We measured an average working distance of 4 cm to the sella. The transpalpebral miniorbitofrontal craniotomy approach to the anterior cranial base is quick, adequate, and safe and should be considered as an alternative to extended bifrontal approaches and/or pterional craniotomies for select anterior cranial vault pathology.

Anatomo-radiological evaluation of lateral approaches to the skull base

Our objective is to correlate the anatomical exposure provided by complex skull base approaches to the lateral skull base with their CT and MRI scans counterparts and to introduce a modular concept emphasizing the derivation of complex skull base approaches from simpler ones.We executed 10 lateral approaches to the skull base in 20 embalmed cadaveric heads (40 sides). Each approach was executed a minimum of three times on each specimen. These approaches were the pterional and its modifications, the subtemporal and its modifications, and the suboccipital and its modifications. We correlated the approaches and the areas of the skull base exposed by scanning the surgical cavity filled with material imageable by CT and MRI and throughly surveying the operative field.Visualization of the area of the skull base exposed was excellent using our CT-MRI imageable cadaveric preparation. The topographic areas of the skull base exposed correlated well with their radiological counterparts.The areas of the skull base exposed by each of the complex surgical approaches to the skull base were clearly delineated by using our anatomo-radiological correlation. Complex approaches to the skull base are formed by simple neurosurgical approaches (building blocks) to which different modules are added.

Accessing the Orbital Roof via an Eyelid Incision: The Transpalpebral Approach

THIS ARTICLE OUTLINES A NEW SURGICAL TECHNIQUE FOR ACCESSING THE ORBITAL ROOF: the transpalpebral approach. It involves making an incision on the double fold of the upper eyelid, then dissecting the orbital septum and the orbicular muscle of the eye. This exposes the orbital roof and enables the surgeon to approach without a coronal incision of the scalp; the direct eyelid incision provides adequate workspace. We use this approach in three orbital roof fractures and one orbital hemangioma. This orbital approach offers a simpler surgical technique, a less invasive one, and still provides excellent exposure of the superior orbital cavity.

[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.

Extended endoscopic endonasal transsphenoidal approach to the suprasellar region: anatomic study and clinical considerations

The extended endoscopic endonasal approach to the suprasellar region was performed on 10 fresh adult cadavers to describe the anatomic landmarks and key surgical steps for safe performance of the surgical approach. The anatomic features and relationships of the sphenoidal ostia, sphenoidal sinus, and optic-carotid recess are described, as are four intradural suprasellar neurovascular structural areas, including the suprachiasmatic, subchiasmatic, retrosellar and ventricular regions. Various anatomic conditions may influence the use of the extended endoscopic endonasal approach. This approach provides a straight, midline approach to the suprasellar region and offers a multi-angled and close-up view of the relevant neurovascular structures. For clinical use, the most important surgery-related complications concern the management of operative bleeding and the prevention of postoperative cerebrospinal fluid leakage.

Sphenoorbital meningiomas: surgical limitations and lessons learned in their long-term management

OBJECT

Sphenoorbital meningiomas (SOMs) are complex tumors involving the sphenoid wing, orbit, and cavernous sinus, which makes their complete resection difficult or impossible. Sphenoidal hyperostosis that results in incomplete resection makes these tumors prone to high rates of recurrence with postoperative morbidity resulting in a nonfunctional globe. High-dose radiation therapy has often been described as the only treatment capable of achieving tumor control, although often at the expense of the patient's progressive visual deterioration.

METHODS

This series consisted of 25 patients who were retrospectively analyzed over a 12-year period. Visual function was evaluated pre- and postoperatively in all patients. A standardized surgical approach to a frontotemporal craniotomy and orbitozygomatic osteotomy with intra- and extradural drilling of the optic canal and all the hyperostotic bone was performed. Orbital and cranial reconstruction was performed in all patients. The follow-up period was 6 months to 12 years (average 5 years). The patients presented with the classic triad of SOM: proptosis (86%), visual impairment (78%), and ocular paresis (20%). A gross-total resection was achieved in 70% of patients with surgery limited by the superior orbital fissure and the cavernous sinus. Proptosis improved in 96% of patients with 87% improvement in visual function. Ocular paresis improved in 68%, although 20% of patients experienced a temporary ocular paresis postoperatively. There were no perioperative deaths or morbidity related to the surgical approach or reconstruction. Ninety-five percent of patients reported an improved functional orbit. There was tumor recurrence in 8% of patients; in one case recurrence was delayed for longer than 11 years.

CONCLUSIONS

Sphenoorbital meningiomas are a distinct category of tumors complicated by potentially extensive hyperostosis of the skull base. Successful resection requires extensive intra- and extradural surgery, necessitating drilling of the optic canal and an orbital osteotomy within anatomical limitations. The bone resection requires reconstruction with autograft, allografts, or alloplast for improved orbital function. All aspects of the clinical triad improved. A radical resection can be achieved with low morbidity, providing a significantly improved clinical outcome in the long-term period.

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.

Surgical technique of the supraorbital key-hole craniotomy

BACKGROUND

The enormous development of microsurgical techniques and instrumentation together with preoperative planning using the excellent preoperative diagnostic facilities available, enables neurosurgeons to treat more complicated diseases through smaller and more specific approaches.

METHODS

The technical details of the supraorbital key-hole craniotomy are described in this article as it has been evolving in our experience for more than 10 years. After an eyebrow skin incision with careful soft tissue dissection and single frontobasal burr-hole trephination, a supraorbital craniotomy is carried out with a diameter of about 1.5 x 2.5 cm. As a real frontolateral approach, the supraorbital craniotomy avoids removal of the orbital rim, the lesser sphenoid wing or the zygomatic arch.

RESULTS AND CONCLUSIONS

The supraorbital craniotomy allows wide intracranial exposure of the deep-seated supra- and parasellar region, according to the concept of key-hole approaches. The limited craniotomy requires minimal brain retraction thus significantly decreasing approach-related morbidity. In addition, the short skin incision within the eyebrow, the careful soft tissue dissection, and the single burr hole trephination result in a pleasing cosmetic outcome.

Surgical approaches to suprasellar and parasellar tumors

Uncommonly, pituitary tumors require a complex intracranial approach. In such instances of extensive para- and suprasellar involvement, an approach that incorporates basic techniques enhanced by developments in contemporary cranial base surgery is effective. Tumors with extensive invasion of the cavernous sinus unilaterally are generally best approached by a frontotemporal transcavernous strategy. Those with bilateral cavernous sinus involvement are better suited for a bifrontal transbasal type of approach. Supra-sellar tumors are best exposed by a strategy that affords the surgeon an adequate inferior-to-superior viewing angle, which is generally accomplished by removal of all or part of the orbital rim. These approaches yield benefits in decreased frontal lobe retraction, which may be particularly important in cases requiring a bilateral approach. Finally, some tumors with more modest extensions outside the bounds of the sella are now treated with a more minimalistic type of approach via a small incision in the eyebrow. This marks a move toward a "minimally invasive" type of strategy. Sound judgment based on adequate experience with these approaches must be exercised to ensure appropriate application of this strategy.

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.

Quantification of increased exposure resulting from orbital rim and orbitozygomatic osteotomy via the frontotemporal transsylvian approach

OBJECT

Use of orbital rim and orbitozygomatic osteotomy has been extensively reported to increase exposure in neurosurgical procedures. However, there have been few attempts to quantify the extent of additional exposure gained by these maneuvers. Using a novel laboratory technique, the authors have attempted to measure the increase in the "area of exposure" that is gained by removal of the orbital rim and zygomatic arch via the frontotemporal transsylvian approach.

METHODS

The authors dissected five cadavers bilaterally. The area of exposure provided by the frontotemporal transsylvian approach was determined by using a frameless stereotactic device. With the tip of a microdissector placed on targets deep within the exposure, the position of the end of the microdissector handle was measured in three-dimensional space as the microdissector was rotated around the periphery of the operative field. This maneuver was performed via the frontotemporal approach alone as well as with orbital rim and orbitozygomatic osteotomy approaches. After data manipulation, the areas of exposure corresponding to the polygons used to define these handle positions were calculated and directly compared. On average, the area of exposure provided by the frontotemporal transsylvian approach was increased 26 to 39% (p<0.05) by adding orbital rim osteotomy and an additional 13 to 22% (not significant) with removal of the zygomatic arch.

CONCLUSIONS

Significant and consistent increases in surgical exposure were obtained by using orbital osteotomy, whereas zygomatic arch removal produced less consistent gains. Both maneuvers may be expected to improve surgical access. However, because larger and more consistent gains were afforded by orbital rim removal, the threshold for removal of this portion of the orbitozygomatic complex should be lower.

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.

Supraorbital craniotomy by fracture of the anterior orbital roof. Technical note

The authors describe a new and rapid method to safely perform a supraorbital craniotomy. This technique can be used when tumor does not invade the orbital roof. Previous descriptions of the supraorbital craniotomy involved exposure of the frontal sinus by removing its anterior wall and using the Gigli saw to separate the orbital roof. This new approach avoids removal of the anterior sinus wall and separates the supraorbital bone flap from the calvaria by fracturing the anterior orbital roof forward. In addition, a method for harvesting a laterally based pericranium and muscle pedicle that contains a section of contralateral temporalis muscle is described. This vascularized pedicle can be used for repair of cerebrospinal fluid leaks or bone defects along the anterior fossa floor and orbit.