Optic Nerve Decompression through a Supraorbital Approach

Parasellar region meningiomas with optic canal (OC) invasion: Correlation between the degree of decompression of the OC and the improvement of visual acuity

PURPOSE

To evaluate the correlation between the degrees of circumferential decompression of the optic canal (OC) and the improvement of visual acuity in patients with parasellar meningiomas (PMs) with optic canal invasion.

METHODS

This is a monocentric retrospective study conducted at author's institution. The visual acuity was evaluated preoperative and at 3-months after surgery with Snellen acuity test. The degree of decompression of the OC was calculated through postoperative multiplanar CT-scan reconstructions in coronal plane at intraorbital opening (IOO), intracranial opening (ICO) and middle point between them (MP). OC was then divided in two segments (anterior and posterior).

RESULTS

29 consecutive patients were identified. Improvement of visual acuity was observed in 18 patients (62 %). Mean decompression achieved at ICO, MP and IOO was 226.2°± 43.6° (range: 68.7°-297.1°), 217.5°± 37.2° (range: 75.3°-268.7°) and 204.6°± 41.2° (range: 67.3°-252.6°) respectively. A decompression > 90° of the anterior segment of the OC, a decompression > 180° of the posterior segment and a full-length decompression > 90° were associated visual acuity improvement at univariate analysis (p = 0.010, p = 0.002 and p < 0.001, respectively). A decompression > 180° of the posterior segment and a full-length decompression > 90° of the OC maintained statistical significance at multivariate analysis (p = 0.030 and p = 0.035, respectively).

CONCLUSION

Anterior segment decompression > 90° and posterior segment decompression > 180° were associated with improvement of visual acuity at 3 months after surgery. A full-length decompression of the optic canal > 90° showed better visual outcome, while a full-length decompression > 180° did not seem to be related to significative improvements in visual acuity.

Optic nerve decompression through pterional and supraorbital approaches in the treatment of severe traumatic optic neuropathy

To investigate the effectiveness of optic nerve decompression (OND) in the treatment of severe traumatic optic neuropathy (TON) through pterional and supraorbital approaches, and to identify the prognostic factor for postoperative visual acuity (VA) following OND. Patients with severe TON treated with OND through either pterional or supraorbital approach in our institute from September 2019 to June 2022 were retrospectively reviewed in this study. Demographic information, trauma factors, the interval between trauma and complete blindness, the interval between trauma and surgery, and the associated craniofacial traumas were recorded. Hospitalization days and the postoperative VA of patients in two groups were compared. There were 54 severe TON patients with NLP included in this study; 21 patients underwent OND through the pterional approach, and the other 33 underwent the supraorbital approach. Respectively, in groups of pterional and supraorbital approaches, the average hospitalization days were 9.8 ± 3.2 and 10.7 ± 2.9 days (p = 0.58), the mean durations of follow-up were 18.9 ± 4.3 and 20.8 ± 3.7 months (p = 0.09), and the average circumference of OND were 53.14 ± 15.89 ◦ (range 220 ◦ -278◦) and 181.70 ± 6.56◦ (range 173 ◦ -193◦) (p<0.001). The overall improvement rates of pterional and supraorbital approaches are 57.1% and 45.5% (p = 0.40), respectively. Optic canal fracture (OCF) was revealed to be significantly associated with postoperative VA in the supraorbital approach (Binary: p = 0.014, CI: 1.573-57.087; Ordinal: p = 0.003, CI: 1.517-5.503), but not in the pterional approach. In the group of supraorbital approach, patients with OFC had a higher rate of a better outcome (78.6%) than those without (21.4%). Patients with severe traumatic TON may benefit from OND through either the pterional or supraorbital approach. OCF is a potential prognostic factor for postoperative VA following OND through the supraorbital approach.

Navigation-guided transcaruncular orbital optic canal decompression in indirect traumatic optic neuropathy: long-term outcomes

PURPOSE

To determine the surgical outcomes using navigation-guided transcaruncular orbital optic canal decompression (NGTcOCD) and investigate the relationship between visual prognosis. visual evoked potential (VEP), association with DeLano type of optic canal and Onodi cells in patients with indirect traumatic optic neuropathy (TON).

DESIGN

Prospective observational.

METHODS

Fifty-two consecutive patients with indirect TON unresponsive to steroid therapy were divided into three groups where Group I comprised of cases with optic canal fracture who underwent NGTcOCD, Group II without optic canal fracture who underwent NGTcOCD and Group III, no-decompression group who chose not to undergo NGTcOCD. An improvement in visual acuity (VA) at 1 week, 3 months and 1 year and amplitude and latency of VEP at 1 year were considered as primary and secondary outcomes, respectively.

RESULTS

The mean VA improved from 2.55±0.67 and 2.62±0.56 LogMAR at presentation to 2.03±0.96 and 2.33±0.72 LogMAR at final follow-up among Group I and Group II patients, respectively (p<0.001 and p=0.01). Statistically significant improvement observed among both the Groups in VEP amplitude (p=<0.01) and among Group II in VEP latency (p<0.01). Both Group I and Group II patients have better outcomes than patients in no-decompression group. VA at presentation and Type 1 DeLano optic canal were observed as significant prognostic factors.

CONCLUSIONS

NGTcOCD serves as a minimally invasive transcaruncular route to the optic canal which enables ophthalmologists to perform decompression from the anterior-most orbital end under direct visualisation. Patients with indirect TON with or without optic canal fracture and unresponsive to steroid therapy when managed with NGTcOCD have shown comparable and superior outcomes.

Anterolateral Routes to the Skull Base-The Frontotemporal Approaches and Exposure of the Sellar and Parasellar Regions

Surgical approaches to the sellar and parasellar regions are highly challenging due to the densely packed nature of the traversing neurovasculature. The frontotemporal-orbitozygomatic approach offers a wide angle of exposure for the management of lesions involving the cavernous sinus, parasellar region, upper clivus, and adjacent neurovascular structures. It combines the pterional approach with different osteotomies that remove the superior and lateral walls of the orbit and zygomatic arch. Extradural exposure and preparation of the periclinoid region, whether as initial preparation for a combined intraextradural approach to deep-seated skull base targets or as the main avenue of surgical exposure, can substantially enlarge surgical corridors and minimize the need for brain retraction in this very confined microsurgical space. We provide a stepwise description of how we perform the fronto-orbitozygomatic approach and an associated series of surgical maneuvers and techniques that can be utilized in a variety of anterior and anterolateral approaches, either alone or in combination, to tailor exposure to a given lesion. These techniques are not limited to traditional skull base approaches and represent a valuable addition to every neurosurgeon's armamentarium as enhancements to common surgical approaches.

Tailored Surgical Access to the Cavernous Sinus and Parasellar Region: Assessment of Cavernous Sinus Entry Corridors and the Periclinoid and Pericavernous Surgical Maneuvers

BACKGROUND

Lesions involving the cavernous sinus (CS) represent some of the most challenging pathologies of the skull base owing to the dense traversing and surrounding neurovasculature. Extradural exposure and preparation of this region, whether as initial preparation for a combined intra-extradural approach or as the main avenue of surgical exposure, can enlarge surgical corridors and minimize the need for brain retraction in this very confined space. We provide a detailed assessment of the entry corridors to the CS that are available within each approach, the surgical exposure and freedom provided by each of these corridors, and demonstrate how extradural and intradural preparation of these corridors can be used to widen the available working space and facilitate surgery.

METHODS

Pterional, frontotemporal-orbital, frontotemporal-orbitozygomatic, frontotemporal-zygomatic, perilabyrinthine transtentorial, and endoscopic transnasal transsphenoidal approaches were performed on cadaveric heads to access the perisellar and CS regions. Periclinoid maneuvers (extradural cutting of the meningo-orbital band, anterior clinoidectomy, unroofing of the optic canal, opening of the superior orbital fissure, displacement of the extra-annular structures, opening of the annulus of Zinn, and interdural dissection), pericavernous maneuvers (intradural cutting of the distal dural ring, mobilization of the supraclinoid internal carotid artery, opening of the oculomotor porus, and mobilization of cranial nerve (CN) III), peritrigeminal extensions (extradural mobilization of CN V2 [maxillary] and/or V3 [mandibular]), and other surgical maneuvers were performed and evaluated. The CS was divided into 8 anatomical compartments and 9 entry corridors were described, and exposure and freedom were assessed accordingly.

RESULTS

Intradurally, the standard unextended pterional, frontotemporal-orbital, and frontotemporal orbitozygomatic transsylvian approaches provided access solely to the parasellar entry corridor into the superior wall of the CS. Expanding these approaches with extradural periclinoid maneuvers allowed for subsequent application of the intradural pericavernous maneuvers and enlargement of the parasellar corridor and exposure of the carotid cave. Extradurally, the frontotemporal-orbital approach could be expanded via application of periclinoid maneuvers, which provided access to the anterior portions of the main lateral wall entry corridors. The frontotemporal-orbitozygomatic approach could also be expanded with periclinoid maneuvers to provide extradural access to all 6 lateral wall entry corridors. The extradural frontotemporal-zygomatic approach only provided exposure following interdural dissection, which allowed for access to the inferolateral entry corridors into the lateral wall. Extradural peritrigeminal extension in the frontotemporal-orbitozygomatic and frontotemporal-zygomatic approaches allows for enlargement of the supramaxillary and pre- and postmandibular corridors. The perilabyrinthine approach to the posterior wall was enlarged with opening of Dorello's canal and the endoscopic transnasal transsphenoidal approach was enlarged with opening of the optic canal.

CONCLUSIONS

Targeted extradural preparation optimizes exposure and significantly improves access to deep-seated targets by enhancing surgical maneuverability through the unlocking of neurovascular structures and widening of surgical corridors without the need for additional brain retraction.

Traumatic optic neuropathy: a review of current studies

Traumatic optic neuropathy (TON) is a serious complication of craniofacial trauma that directly or indirectly damages the optic nerve and can cause severe vision loss. The incidence of TON has been gradually increasing in recent years. Research on the protection and regeneration of the optic nerve after the onset of TON is still at the level of laboratory studies and which is insufficient to support clinical treatment of TON. And, due to without clear guidelines, there is much ambiguity regarding its diagnosis and management. Clinical interventions for TON include observation only, treatment with corticosteroids alone, or optic canal (OC) decompression (with or without steroids). There is controversy in clinical practice concerning which treatment is the best. A review of available studies shows that the visual acuity of patients with TON can be significantly improved after OC decompression surgery (especially endoscopic transnasal/transseptal optic canal decompression (ETOCD)) with or without the use of corticosteroids. And new findings of laboratory studies such as mitochondrial therapy, lipid change studies, and other studies in favor of TON therapy have also been identified. In this review, we discuss the evolving perspective of surgical treatment and experimental study.

Endoscopic Transorbital Approaches to Anterior and Middle Cranial Fossa: Exploring the Potentialities of a Modified Lateral Retrocanthal Approach

BACKGROUND

Among the new perspectives to revolutionize skull base surgery, there are the transorbital neuroendoscopic (TONES) approaches to reach the anterior and middle cranial fossa (ACF and MCF). We conceived to explore the potentialities of a modified superiorly and medially extended lateral retrocanthal (LRC) approach.

METHODS

Six head specimens were dissected. Applying the established conic model and the key surgical landmark of sphenofrontal suture, we tested the feasibility of a modified LRC to reach ACF and MCF; computed tomography (CT) scans were performed before and after dissection to obtain a morphometric analysis of the surgical corridors using a polygonal surfaces model.

RESULTS

Through our anatomical study, we were able to identify and explore 3 different surgical corridors to reach the ACF and MCF: the superomedial, the superolateral, and the inferolateral. The superomedial corridor appeared most suitable to reach the medial part of the ACF and the optic-carotid region, whereas through the superolateral and inferolateral corridors it was possible to reach and explore the lateral part of ACF and MCF. The mean volumes of the 3 surgical corridors calculated on post-dissection CT scans were: 12.72 ± 1.99, 5.69 ± 0.34, and 6.24 ± 0.47 cm³, respectively.

CONCLUSIONS

The development of TONES approaches has not replaced the traditional open or endoscopic approach; nonetheless, identification of surgical corridors and the possibility to combine them represent a major breakthrough. Clinical studies are necessary to demonstrate their validity and test the effectiveness, safety, and reproducibility of TONES approaches in managing lesions harboring in the ACF and MCF.

A Systematic Literature Review on Traumatic Optic Neuropathy

Traumatic optic neuropathy (TON) is an uncommon vision-threatening disorder that can be caused by ocular or head trauma and is categorized into direct and indirect TON. The overall incidence of TON is 0.7-2.5%, and indirect TON has a higher prevalence than direct TON. Detection of an afferent pupillary defect in the presence of an intact globe in a patient with ocular or head trauma with decreased visual acuity strongly suggests TON. However, afferent pupillary defects may be difficult to detect in patients who have received narcotics that cause pupillary constriction and in those with bilateral TON. Mechanical shearing of the optic nerve axons and contusion necrosis due to immediate ischemia from damage to the optic nerve microcirculation and apoptosis of neurons is a probable mechanism. The proper management of TON is controversial. High-dose corticosteroid therapy and decompression of the optic nerve provide no additional benefit over observation alone. Intravenous erythropoietin may be a safe and efficient treatment for patients with TON.

The extradural extended eyebrow approach: A cadaveric feasibility study

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Reconstruction of Complex Cranial and Orbit Fractures with Associated Hemorrhages: Case Report and Review of the Literature

We present our experience following a unique case of coincident intracranial hemorrhage and comminuted fractures of both the squamous temporal bone and zygomaticofrontal orbit. Surgical techniques and outcome for this presentation have yet to be sufficiently described. A 55-year-old male presented following trauma with Glasgow Coma Scale score of 7. Radiographic evaluation revealed comminuted fractures of the squamous temporal bone with extension into the lateral orbit, along with zygomatic process fracture extending 2.5 cm medially into the orbital roof. Zygomaticofrontal orbital roof fragments reached superiorly into the middle cranial fossa and inferiorly into the orbit. Surgical intervention was deemed necessary to address underlying epidural hematoma, subarachnoid hemorrhage, correction of cranial bone defects, and decompression of the optic nerve and other intraorbital nerves. A frontotemporal approach was employed. Repair of temporal and orbital fractures was accomplished using a combination of wire mesh screws and titanium miniplates. Postoperative imaging demonstrated bony approximation and successful evacuation of traumatic hemorrhage. The patient remains functionally and neurologically intact apart from a sluggishly responsive left eye presumed to result from a left optic nerve or ciliary ganglion lesion. Although rapid reconstruction of complex cranial-orbital trauma and hematoma evacuation can permit acceptable gross functional neurological outcome following massive trauma, orbital fracture and subsequent hemorrhagic processes may be the nidus of neurological sequelae in this complex traumatic constellation. Thus, alterations in surgical approach and reconstruction are appropriate in order to maximize neurological function while supporting restoration of cosmetic space.

How I do it: contralateral supraorbital approach for tuberculum sellae meningioma

BACKGROUND

The resection of tuberculum sellae meningiomas poses a challenge particularly when dealing with the medial aspect of the optic nerve. Dissection of the tumor off the optic nerve is usually carried out in the blind spot "behind" the optic nerve. We describe a contralateral approach for asymmetric tuberculum sellae meningiomas, allowing direct visualization of the medial optic nerve.

METHOD

Contralateral lateral supraorbital approach was performed, and complete tumor resection was achieved without any injury to the optic nerve.

CONCLUSION

The contralateral approach for asymmetric tuberculum sellae meningioma is an efficient technique allowing improved visualization of the medial optic nerve.

Optic Canal Decompression with a Lateral Approach for Optic Nerve Injury Associated with Traumatic Optic Canal Fracture

Optic canal fracture (OCF) is a traumatic injury that requires urgent intervention because it can induce optic nerve damage and visual impairment. Despite the severity of OCF, a standard treatment method has not been established. In this article, we report a case of OCF and traumatic optic nerve injury in which visual acuity was recovered by releasing the optic canal using an unconventional lateral approach. A 43-year-old man presented with right lateral ethmoid fracture, right orbit blowout fracture, and OCF. The visual acuity was “hand motion” before surgery. Decompression was performed 10 hours after injury by approaching the right optic canal laterally from a coronal incision in front of the right ear, cutting along the border of the sphenoid bone, and scraping away some of the sphenoid wing and zygomatic bone. Steroid pulse therapy was added. Eventually, the visual acuity improved to 0.2 and the intraocular pressure decreased to 16.0 mm Hg. Compared with conventional methods, this method associates with better safety because (1) it causes relatively little bleeding and cerebrospinal fluid leak; (2) once the sphenozygomatic suture is identified, the distance to the optic canal is relatively short; and (3) if the fracture point is on the outer optic canal, the fracture line can be observed directly. Steroid pulse therapy may also have contributed to the good visual outcome. This is the first report of a novel lateral approach to OCF that is safe, effective, and only requires plastic surgery skills.

On-Demand Intraoperative 3-Dimensional Printing of Custom Cranioplastic Prostheses

BACKGROUND

Currently, implantation of patient-specific cranial prostheses requires reoperation after a period for design and formulation by a third-party manufacturer. Recently, 3-dimensional (3D) printing via fused deposition modeling has demonstrated increased ease of use, rapid production time, and significantly reduced costs, enabling expanded potential for surgical application. Three-dimensional printing may allow neurosurgeons to remove bone, perform a rapid intraoperative scan of the opening, and 3D print custom cranioplastic prostheses during the remainder of the procedure.

OBJECTIVE

To evaluate the feasibility of using a commercially available 3D printer to develop and produce on-demand intraoperative patient-specific cranioplastic prostheses in real time and assess the associated costs, fabrication time, and technical difficulty.

METHODS

Five different craniectomies were each fashioned on 3 cadaveric specimens (6 sides) to sample regions with varying topography, size, thickness, curvature, and complexity. Computed tomography-based cranioplastic implants were designed, formulated, and implanted. Accuracy of development and fabrication, as well as implantation ability and fit, integration with exiting fixation devices, and incorporation of integrated seamless fixation plates were qualitatively evaluated.

RESULTS

All cranioprostheses were successfully designed and printed. Average time for design, from importation of scan data to initiation of printing, was 14.6 min and average print time for all cranioprostheses was 108.6 min.

CONCLUSION

On-demand 3D printing of cranial prostheses is a simple, feasible, inexpensive, and rapid solution that may help improve cosmetic outcomes; significantly reduce production time and cost-expanding availability; eliminate the need for reoperation in select cases, reducing morbidity; and has the potential to decrease perioperative complications including infection and resorption.

Refining Operative Strategies for Optic Nerve Decompression: A Morphometric Analysis of Transcranial and Endoscopic Endonasal Techniques Using Clinical Parameters

BACKGROUND

Various approaches can be considered for decompression of the intracanalicular optic nerve. Although clinical experience has been reported, no quantitative study has yet compared the extent of decompression achieved by an endoscopic endonasal versus transcranial approach.

OBJECTIVE

Toward this aim, our morphometric analysis compared both approaches by quantifying the circumferential degree of optic canal decompression that is possible before any meningeal violation, which would result in cerebrospinal fluid (CSF) leak.

METHODS

From 10 cadaver heads, 20 optic canals were sequentially decompressed using an endoscopic endonasal approach and pterional craniotomy with extradural clinoidectomy. Dissections ended before violation of the sphenoid sinus during the transcranial approach, and before intracranial transgression from the endonasal corridor. Based on our study criteria, decompressions were not maximal for either approach, but were maximal before violating the other compartment. Decompression achieved from each approach was quantified using CT scans for each stage.

RESULTS

Greater circumferential bony optic canal decompression was obtained from transcranial (245.2°) than endonasal (114.8°) routes (P < .001). By endonasal perspective, the anatomical point where the optic nerve traverses intracranially was approximated by the medial border of the anterior ascending cavernous internal carotid artery.

CONCLUSION

Our morphometric analysis comparing optic canal decompression for endonasal and transcranial corridors provides important guidance for this location. Ample visualization and wide exposure can be achieved via a transcranial approach with limited risk of CSF leak. A landmark, where the intracanalicular segment ends and optic nerve traverses intracranially, can mark the extent of decompression safely obtained before risking CSF leak.

Technical Description of Minimally Invasive Extradural Anterior Clinoidectomy and Optic Nerve Decompression. Study of Feasibility and Proof of Concept

BACKGROUND

Several diseases that involve the optic canal or its contained structures may cause visual impairment. Several techniques have been developed to decompress the optic nerve.

OBJECTIVE

To describe minimally invasive extradural anterior clinoidectomy (MiniEx) for optic nerve decompression, detail its surgical anatomy, present clinical cases, and established a proof of concept.

METHODS

Anatomic dissections were performed in cadaver heads to show the surgical anatomy and to show stepwise the MiniEx approach. In addition, these surgical concepts were applied to decompress the optic nerve in 6 clinical cases.

RESULTS

The MiniEx approach allowed the extradural anterior clinoidectomy and a nearly 270° optic nerve decompression using the no-drill technique. In the MiniEx approach, the skin incision, dissection of the temporal muscle, and craniotomy were smaller and provided the same extent of exposure of the optic nerve, anterior clinoid process, and superior orbital fissure as that usually provided by standard techniques. All patients who underwent operation with this technique had improved visual status.

CONCLUSIONS

The MiniEx approach is an excellent alternative to traditional approaches for extradural anterior clinoidectomy and optic nerve decompression. It may be used as a part of more complex surgery or as a single surgical procedure.

Extended Supraorbital Approach with Modified Eyebrow Incision: Technical Note

BACKGROUND

The extended supraorbital approach through a modified eyebrow incision is a minimally invasive variant of the frontotemporal or pterional approach that enriches a neurosurgeon's armamentarium for the treatment of pathologies lateral to the anterior clinoid process, by advancing laterally with frontal facial nerve branches monitoring. To demonstrate the steps of the approach, we studied 2 formalin-fixed and artery/vein silicone-injected adult cadaveric heads, and reviewed 1 of the 3 clinical cases operated on to illustrate the applicability of the approach.

CLINICAL PRESENTATION

A 56-year-old woman presented with a history of seizures and a complaint of headache that started 2 months ago. She underwent an examination with brain magnetic resonance imaging that showed a dural-based lesion at the medial third of the lesser wing of sphenoid (which is consistent with meningioma). The patient underwent craniotomy with an extended supraorbital approach through a modified eyebrow incision that allowed Simpson grade II removal to be performed and good aesthetic outcome to be achieved.

CONCLUSIONS

The extended supraorbital approach through a modified eyebrow incision is a minimally invasive approach that can add to a neurosurgeon's armamentarium and be used with microscopy, assisted by endoscope, or both to reach the anterior and middle cranial fossae.

The carotico-clinoid bar: A systematic review and meta-analysis of its prevalence and potential implications in cerebrovascular and skull base surgery

BACKGROUND

The caroticoclinoid bar (CCB) is implicated in both transcranial and endonasal surgery. Its morphology reflects differences in the microsurgical anatomy of the parasellar area while its manipulation during an anterior or middle clinoidectomy can result in ICA injury. Although safe surgical access to the paraclinoidal region is related to adjustment of surgical technique according to CCB anatomical variants, a review of the literature indicates the lack of a systematic assortment of published data regarding the prevalence of this variable structure. As such the topic needs further investigation.

OBJECTIVE

To systematically review and document the prevalence of the CCB and its anatomic variations.

METHODS

3 Databases were systematically reviewed according to the PRISMA statement through August of 2018 for the identification of relevant studies.

RESULTS

A total of 27 articles (7,521 subjects/specimens, 14,449 sides) were included in this meta-analysis. The overall pooled prevalence of the CCB was 32.6% (95% CI 26.6% - 38.8%) when measured over subjects/specimens and 23.6% (95% CI 19.7% - 27.6%) when measured over sides. Overall prevalence of the CCB reported from imaging studies was 23.1% (95% CI 8.9% - 41.4%) when measured over subjects/specimens and 18.7% (95% CI 12.6% - 25.7%) when measured over sides. Moreover, the CCB was slightly more prevalent (p = 0.050), on the right side.

CONCLUSION

Our results indicate considerable CCB prevalence rates and that imaging studies report lower prevalence rates. Although meticulous preoperative investigation is mandatory, surgeons carrying for patients with parasellar pathologies should always be vigilant about this structure.

Surgical Treatment for Traumatic Optic Neuropathy

Traumatic optic neuropathy (TON) is an important cause of severe visual loss after blunt or penetrating head and facial trauma. High-dose steroids and surgical interventions have been applied in the indirect TON. However, there is no convincing evidence that results of the treatment have any strong benefits in terms of improvement of visual acuity. Nevertheless, surgical decompression should be considered in the case of a direct bony compression to the optic nerve and a progressive visual loss in indirect TON. Neurosurgeon should be aware the surgical indication, optimal timing and relevant technique for the optic canal (OC) decompression. In this review article, we will focus on the surgical approaches to the OC and how to decompress it.

Contralateral supraorbital keyhole approach to medial optic nerve lesions: an anatomoclinical study

OBJECTIVE The authors describe the supraorbital keyhole approach to the contralateral medial optic nerve and tract, both in a series of cadaveric dissections and in 2 patients. They also discuss the indications and contraindications for this procedure. METHODS In 3 cadaver heads, bilateral supraorbital keyhole minicraniotomies were performed to expose the ipsilateral and contralateral optic nerves. The extent of exposure of the medial optic nerve was assessed. In 2 patients, a contralateral supraorbital keyhole approach was used to remove pathology of the contralateral medial optic nerve and tract. RESULTS The supraorbital keyhole craniotomy provided better exposure of the contralateral superomedial nerve than it did of the same portion of the ipsilateral nerve. In both patients gross-total resections of the pathology was achieved. CONCLUSIONS The authors demonstrate the suitability of the contralateral supraorbital keyhole approach for lesions involving the superomedial optic nerve.

The evolving role of the oculoplastic surgeon in skull base surgery

PURPOSE OF REVIEW

Classical orbital approaches in skull base surgery have involved large incisions with extensive bone removal resulting in prolonged recovery with associated morbidity and mortality. The purpose of this review is to explore recent advances in skull base surgery that are applicable to the orbital surgeon.

RECENT FINDINGS

Transnasal endoscopic surgery provides access to the medial 180 degrees of the orbit. Access to the lateral 180 degrees may be obtained using transmaxillary and transcranial techniques. Transorbital approaches and multiport techniques further expand the reach of the skull base surgeon. These minimally invasive techniques are supplanting the classical pterional, frontotemporal, frontotemporal orbitozygomatic, frontal, and subfrontal approaches.

SUMMARY

The role of the orbital surgeon in skull base surgery is changing. Transnasal and transcranial approaches to orbital disorders using minimally invasive techniques are becoming more common. In addition, transorbital access to the skull base, paranasal sinuses, and anterior and middle cranial fossa is offering new opportunities for the orbital surgeon.