The cranio-orbital foramen, the groove on the lateral wall of the human orbit, and the orbital branch of the middle meningeal artery

Correlation Analysis on Anatomical Variants of Accessory Foramina in the Sphenoid Bone for Oncological Surgery

The sphenoid bone presents several anatomical variations, including accessory foramina, such as the foramen meningo-orbitale, the foramen of Vesalius, the canaliculus innominatus and the palatovaginal canal, which may be involved in tumor invasion or surgery of surrounding structures. Therefore, clinicians and surgeons have to consider these variants when planning surgical interventions of the cranial base. The prevalence of each variant is reported in the published literature, but very little information is available on the possible correlation among different variants. Here, 300 CT scans of patients (equally divided among males and females) were retrospectively assessed to investigate the presence of the foramen meningo-orbitale, the foramen of Vesalius, the canaliculus innominatus and the palatovaginal canal. Possible differences in the prevalence of each accessory foramen according to sex were assessed, as well as possible correlations among different variants through the Chi-square test (p < 0.01). Overall, the prevalence of the foramen meningo-orbitale, the foramen of Vesalius, the canaliculus innominatus and the palatovaginal canal was 30.7%, 67.7%, 14.0% and 35.3%, respectively, without any difference according to sex (p > 0.01). A significant positive correlation was found between the foramen of Vesalius and canaliculus innominatus, both in males and in females (p < 0.01). In detail, subjects with canaliculus innominatus in 85.7-100.0% of cases also showed the foramen of Vesalius, independently from sex and side. The present study provided novel data about the prevalence of four accessory foramina of the sphenoid bone in an Italian population, and a correlation between the foramen of Vesalius and the canaliculus innominatus was found for the first time. As these accessory foramina host neurovascular structures, the results of this study are thus useful for appropriate planning surgical procedures that are tailored to the anatomical configuration of the patient and for improving techniques to avoid accidental injuries in cranial base surgery. Knowledge of the topography, frequencies and the presence/absence of these additional foramina are pivotal for a successful procedure. Clinicians and surgeons may benefit from these novel data for appropriate recognition of the variants, decision-making, pre-operative and treatment planning, improvement of the procedures, screening of patients and prevention of misdiagnosis.

Human Palatine Tonsils Are Linked to Alzheimer’s Disease through Function of Reservoir of Amyloid Beta Protein Associated with Bacterial Infection

Amyloid-β (Aβ)-peptide production or deposition in the neuropathology of Alzheimer’s disease (AD) was shown to be caused by chronic inflammation that may be induced by infection, but the role of pathogenic-bacteria-related AD-associated Aβ is not yet clearly understood. In this study, we validated the hypothesis that there is a correlation between the Aβ-protein load and bacterial infection and that there are effects of bacteria, Staphylococcus aureus (S. aureus), on the Aβ load in the inflammatory environment of human tonsils. Here, we detected Aβ-peptide deposits in human tonsil tissue as well as tissue similar to tonsilloliths found in the olfactory cleft. Interestingly, we demonstrated for the first time the presence of Staphylococcus aureus (S. aureus) clustered around or embedded in the Aβ deposits. Notably, we showed that treatment with S. aureus upregulated the Aβ-protein load in cultures of human tonsil organoids and brain organoids, showing the new role of S. aureus in Aβ-protein aggregation. These findings suggest that a reservoir of Aβ and pathogenic bacteria may be a possible therapeutic target in human tonsils, supporting the treatment of antibiotics to prevent the deposition of Aβ peptides via the removal of pathogens in the intervention of AD pathogenesis.

Cribra orbitalia is correlated with the meningo-orbital foramen and is vascular and developmental in nature

Cribra orbitalia is a phenomenon with interdisciplinary interest. However, the etiology of cribra orbitalia remains unclear. Recently, the appearance of cribra orbitalia was identified as vascular in nature. This study assessed the relationship between anatomical variation of vasculature, as determined by the presence of meningo-orbital foramina, and the presence of cribra orbitalia in 178 orbits. Cribra orbitalia was identified in 27.5% (49:178) of orbits (22.7%, 35:154 adult orbits and 58.3%, 14:24 subadult orbits) and meningo-orbital foramina were identified in 65.8% (100:152) of orbits. Among the 150 total intact adult orbits (i.e., orbital roof and posterior orbits both intact), cribra orbitalia was found in 35 (23.3%). Of these 35 occurrences of cribra orbitalia, 32 (91.4%) had the concurrent finding of a meningo-orbital foramen. However, in the absence of the meningo-orbital foramen, cribra orbitalia was only found in three sides out of the total sample of intact orbits (3:150; 2.0%). Fisher's exact test revealed that the presence of cribra orbitalia and the meningo-orbital foramen were statistically dependent variables (p = .0002). Visual evidence corroborated statistical findings-vascular impressions joined cribra orbitalia to meningo-orbital foramina. This study identifies that individuals who possess a meningo-orbital foramen are anatomically predisposed to developing cribra orbitalia. Conversely, cribra orbitalia is unlikely to occur in an individual who does not possess a meningo-orbital foramen. Thus, the antecedent of cribra orbitalia is both vascular and developmental in nature. This report represents an important advancement in the understanding of cribra orbitalia-there is an anatomical predisposition to the development of cribra orbitalia.

Sphenoidal artery: review of the literature and analysis of a dissected arterially injected fetal orbit

PURPOSE

The sphenoidal artery is considered a component of the complex and dangerous arterial anastomoses of the human orbitocranial region, particularly with the advent of interventional neuroimaging. The objective of this publication was to analyze the various descriptions of the sphenoidal artery in the literature as related to relevant photographs of a dissected arterially injected fetal middle cranial fossa and orbit.

METHODS

Publications dealing with middle meningeal-ophthalmic arterial anastomoses, focusing on the sphenoidal artery, were reviewed. A relevant dissection of a fetal specimen was analyzed.

RESULTS

The literature dealing with the sphenoidal artery is at times not in agreement. The nomenclature and anatomy of its passage through the superior orbital fissure or Hyrtl canal have variable descriptions. Photographs of the skull base of a dissected arterially injected fetal specimen show bilateral prominent orbital branches of the middle meningeal arteries. These branches entered both orbits in a course similar to the diagrammatic representations of the sphenoidal artery, and give rise to several major intraorbital arteries. This study provides the only photographic image in the literature of this variation in a human fetal anatomic dissection.

CONCLUSIONS

Review of the literature dealing with the sphenoidal artery shows inconsistent nomenclature and conflicting descriptions of its anastomotic connections, and varying evolutionary and embryologic theories. Analysis of the dissected fetal skull base indicates that the sphenoidal artery is not a distinct artery but just a middle meningeal orbital arterial branch, an important component of the complex and dangerous arterial anastomoses of the human orbitocranial region.

Endoscopic transorbital superior eyelid approach: anatomical study from a neurosurgical perspective

OBJECTIVERecent studies have proposed the superior eyelid endoscopic transorbital approach as a new minimally invasive route to access orbital lesions, mostly in otolaryngology and maxillofacial surgeries. The authors undertook this anatomical study in order to contribute a neurosurgical perspective, exploring the anterior and middle cranial fossa areas through this purely endoscopic transorbital trajectory.METHODSAnatomical dissections were performed in 10 human cadaveric heads (20 sides) using 0° and 30° endoscopes. A step-by-step description of the superior eyelid transorbital endoscopic route and surgically oriented classification are provided.RESULTSThe authors' cadaveric prosection of this approach defined 3 modular routes that could be combined. Two corridors using bone removal lateral to the superior and inferior orbital fissures exposed the middle and anterior cranial fossa (lateral orbital corridors to the anterior and middle cranial base) to unveil the temporal pole region, lateral wall of the cavernous sinus, middle cranial fossa floor, and frontobasal area (i.e., orbital and recti gyri of the frontal lobe). Combined, these 2 corridors exposed the lateral aspect of the lesser sphenoid wing with the Sylvian region (combined lateral orbital corridor to the anterior and middle cranial fossa, with lesser sphenoid wing removal). The medial corridor, with extension of bone removal medially to the superior and inferior orbital fissure, afforded exposure of the opticocarotid area (medial orbital corridor to the opticocarotid area).CONCLUSIONSAlong with its minimally invasive nature, the superior eyelid transorbital approach allows good visualization and manipulation of anatomical structures mainly located in the anterior and middle cranial fossae (i.e., lateral to the superior and inferior orbital fissures). The visualization and management of the opticocarotid region medial to the superior orbital fissure are more complex. Further studies are needed to prove clinical applications of this relatively novel surgical pathway.

Incidence of anomalous canals in the base of the skull: a retrospective radio-anatomical study using cone-beam computed tomography

PURPOSE

Several skull-base foramina including foramen meningo-orbitale, craniopharyngeal canals, canaliculus innominatus, foramen vesalius, palatovaginal canals, and canalis basalis medianus are visible on cone-beam computed tomographs. A good understanding of the anatomical variants of these foramina is important to accurately diagnose fractures, understand the paths that infections may take, and identify associated anomalies. We used cone-beam computed tomography to measure the incidences of skull-base foramen variants in a normal population.

METHODS

A total of 350 subjects (200 females, 150 males, 6-30 years of age) were included. The prevalences of foramen meningo-orbitale, craniopharyngeal canals, canaliculus innominatus, foramina vesalius, palatovaginal canals, and canalis basalis medianus were evaluated by age and gender.

RESULTS

Subject age ranged from 6 to 30 years (mean age ± SD = 15.1 ± 4.08). Foramen meningo-orbitale, craniopharyngeal canals, canaliculus innominatus, foramen vesalius, palatovaginal canal, and canalis basalis medianus were observed in 51 (14.6%), 19 (5.4%), 60 (17.1%), 145 (41.1%), 34 (9.7%), and 15 (4.3%) patients, respectively.

CONCLUSIONS

Skull-base foramina are important clinically and radiologically. Imaging of such variants via cone-beam computed tomography is valuable for both physicians and patients. Few studies of skull-base foramina have used cone-beam computed tomography. Additional research is required for a fuller understanding of this phenomenon.

Morphology and Navigational Landmarks of the Cranio-orbital Foramen in a Portuguese Population

PURPOSE

The cranio-orbital and accessory foramina are located in the lateral wall of the orbit and adjacent to the superior orbital fissure. In the literature, there is a lack of consistency concerning the location and morphology of these foramina in different populations. Therefore, considering its clinical importance during orbital surgeries, it was the authors' aim to determine the incidence, location, and number of cranio-orbital and accessory foramina in a Portuguese population and compare the findings with data from other studies.

METHODS

A total of 310 orbits from 155 dry skulls from the collection of the Museum of Anatomy of the Faculty of Medicine of Porto were studied. The characterization of both cranio-orbital and accessory cranio-orbital foramina was performed.

RESULTS

The cranio-orbital foramen was present in at least 1 orbit per skull in 58.17% with a median diameter of 0.60 ± 0.33 mm. No relation was found between the presence of this foramen and the gender of the individuals or a tendency for laterality. However, it was found that the presence of 1 or more accessory foramina was related to higher diameters of the cranio-orbital foramen.

CONCLUSIONS

There might be a relationship between the localization, diameter, and communication of foramina with the cranial fossae. Foramina located on the greater wing of the sphenoid bone presented a larger diameter and communicated with the middle cranial fossa. High diameters of the main vessel in the cranio-orbital foramen may imply more developed branches and collateral irrigation of the orbital structures using 1 or more accessory foramina. Surgeons should be aware of the location of the cranio-orbital foramen to reduce potential sources of hemorrhage during orbital dissections.

Endoscopic transorbital route to the cavernous sinus through the meningo-orbital band: a descriptive anatomical study

OBJECTIVE Exposure of the cavernous sinus is technically challenging. The most common surgical approaches use well-known variations of the standard frontotemporal craniotomy. In this paper the authors describe a novel ventral route that enters the lateral wall of the cavernous sinus through an interdural corridor that includes the removal of the greater sphenoid wing via a purely endoscopic transorbital pathway. METHODS Five human cadaveric heads (10 sides) were dissected at the Laboratory of Surgical NeuroAnatomy of the University of Barcelona. To expose the lateral wall of the cavernous sinus, a superior eyelid endoscopic transorbital approach was performed and the anterior portion of the greater sphenoid wing was removed. The meningo-orbital band was exposed as the key starting point for revealing the cavernous sinus and its contents in a minimally invasive interdural fashion. RESULTS This endoscopic transorbital approach, with partial removal of the greater sphenoid wing followed by a "natural" ventral interdural dissection of the meningo-orbital band, allowed exposure of the entire lateral wall of the cavernous sinus up to the plexiform portion of the trigeminal root and the petrous bone posteriorly and the foramen spinosum, with the middle meningeal artery, laterally. CONCLUSIONS The purely endoscopic transorbital approach through the meningo-orbital band provides a direct view of the cavernous sinus through a simple and rapid means of access. Indeed, this interdural pathway lies in the same sagittal plane as the lateral wall of the cavernous sinus. Advantages include a favorable angle of attack, minimal brain retraction, and the possibility for dissection through the interdural space without entering the neurovascular compartment of the cavernous sinus. Surgical series are needed to demonstrate any clinical advantages and disadvantages of this novel route.

Anatomy of the Ophthalmic Artery: Embryological Consideration

There are considerable variations in the anatomy of the human ophthalmic artery (OphA), such as anomalous origins of the OphA and anastomoses between the OphA and the adjacent arteries. These anatomical variations seem to attribute to complex embryology of the OphA. In human embryos and fetuses, primitive dorsal and ventral ophthalmic arteries (PDOphA and PVOphA) form the ocular branches, and the supraorbital division of the stapedial artery forms the orbital branches of the OphA, and then numerous anastomoses between the internal carotid artery (ICA) and the external carotid artery (ECA) systems emerge in connection with the OphA. These developmental processes can produce anatomical variations of the OphA, and we should notice these variations for neurosurgical and neurointerventional procedures.

Trigeminocardiac reflex caused by selective angiography of the middle meningeal artery

We describe an interesting case of trigeminocardiac reflex (TCR) caused by selective angiography of the middle meningeal artery (MMA). A 28-year-old woman presented with a symptomatic meningioma. Preoperative tumour embolisation was performed. In the procedure, when selective MMA angiography was done with Omnipaque 300 mg I/mL for 3 mL by manual injection, the patient complained of flashing lights in her eye followed by vomiting and bradycardia down to 40 bpm without increased intracranial pressure signs. On selective MMA angiography, the choroidal crescent and arteries of the periorbital region were opacified by anastomosis from the MMA via the meningo-ophthalmic artery. We diagnosed that her symptoms were caused by selective MMA angiography leading to high pressure stimulation towards the ophthalmic nerve innervation around the orbit as a TCR. We suggest that the operator should be prepared to manage TCR during treatment with expected selective MMA angiography, and gentle low pressure contrast injection should be attempted.

Trigeminocardiac reflex caused by selective angiography of the middle meningeal artery

We describe an interesting case of trigeminocardiac reflex (TCR) caused by selective angiography of the middle meningeal artery (MMA). A 28-year-old woman presented with a symptomatic meningioma. Preoperative tumour embolisation was performed. In the procedure, when selective MMA angiography was done with Omnipaque 300 mg I/mL for 3 mL by manual injection, the patient complained of flashing lights in her eye followed by vomiting and bradycardia down to 40 bpm without increased intracranial pressure signs. On selective MMA angiography, the choroidal crescent and arteries of the periorbital region were opacified by anastomosis from the MMA via the meningo-ophthalmic artery. We diagnosed that her symptoms were caused by selective MMA angiography leading to high pressure stimulation towards the ophthalmic nerve innervation around the orbit as a TCR. We suggest that the operator should be prepared to manage TCR during treatment with expected selective MMA angiography, and gentle low pressure contrast injection should be attempted.

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.

The small foramina of the orbit and periorbital region: assessment with multi detector computed tomography

BACKGROUND

Familiarity with the variants of the foramina of the orbit and periorbital region is important in planning anesthesiological blocks and during orbital and maxillofacial surgery to avoid damage to nerves and vessels.

PURPOSE

To assess the visibility and the incidence of variants of the small foramina of the orbit by multidetector computed tomography (MDCT).

MATERIAL AND METHODS

The MDCT scans of 400 orbits from 200 patients were evaluated retrospectively. Slice thickness of the reconstructed images were in the range of 0.5-1.0 mm. The visibility and the variants of the foramen supraorbitale, the foramen infraorbitale, the foramen zygomaticofaciale, the foramen ethmoidale anterius et posterius, and the foramen cranio-orbitale were assessed using three-dimensional reconstruction tools.

RESULTS

The foramen infraorbitale (100%; n = 400), foramen supraorbitale (99.5%, n = 398), foramen zygomaticofaciale (76.5%; n = 307), and foramen zygomatico-orbitale (74.5%; n = 298) were most reliably detected by MDCT, while the foramen ethmoidale anterius (58.7%; n = 235) et posterius (56.7%; n = 225) were depicted less frequently. The foramen cranio-orbitale could not be identified in any case. Doubling was found for the foramen supraorbitale in 3.25% (n = 13), the foramen infraorbitale in 1.75% (n = 7), the foramen zygomaticofaciale in 16% (n = 64), and the foramen zygomatico-orbitale 14% (n = 56). Three foramina zygomatico-orbitale and foramina infraorbitale were found in 1.5% (n = 6) and in 0.5% (n = 2) of orbits, respectively.

CONCLUSION

The foramina supraorbitale, infraorbitale, zygomatico-orbitale, and zygomaticiofaciale and their variants are well visible on MDCT. Knowledge of the exact number of these small foramina is relevant for preoperative evaluation.

Ophthalmic systems completely supplied from dural arteries indicate the utility of endovascular treatment of cerebral aneurysms

We report a 67-year-old man who harboured an unruptured left basilar-superior cerebellar artery aneurysm. Cerebral angiography and cone beam computed tomography with diluted contrast medium showed that the bilateral ophthalmic arteries were not supplied from internal carotid arteries but, rather, were supplied from the middle meningeal and accessory meningeal arteries. This meant that the ophthalmic system was predominantly supplied from the dural arteries and, therefore, pterional craniotomy might cause a compromise in blood supply to the retinal artery. To avoid this complication, coil embolization was selected instead of neck clipping, and this endovascular therapy succeeded without neurological deficit. This case report shows the importance of cerebral angiography (including cone beam computed tomography) and consideration of the patterns of ophthalmic artery perfusion when selecting operative procedures for management of aneurysms that require manipulation around the sphenoid ridge.

Clinical anatomy of the orbitomeningeal foramina: variational anatomy of the canals connecting the orbit with the cranial cavity

PURPOSE

In addition to the optic canal and the superior orbital fissure, orbits are connected with the cranial cavity via inconstant canals including the orbitomeningeal foramen. This study has been carried out in order to define many anatomical and radiological details of the orbitomeningeal foramen that are relevant in the clinical practice.

METHODS

Almost 1000 skulls and 50 computerized tomographies were examined to determine incidence, number, length, and caliber of the orbitomeningeal foramen as well as the topography of their orbital and cranial openings. A retrospective study of angiographies carried out on more than 100 children was performed to look for arteries candidate to run through the orbitomeningeal foramen.

RESULTS

Orbitomeningeal foramina were detected in 59.46% of skulls and in 54% of individuals by computerized tomography. Orbits with two to five foramina were found. Canals were classified as M-subtype or A-subtype depending on their cranial opening. Large foramina, with the caliber ranging between 1 and 3 mm, were found in 12.17% of orbitomeningeal foramen-bearing orbits. By computed tomography the average caliber measured 1.2 ± 0.3 and 1.5 ± 0.5 mm (p < 0.005) at the orbital and cranial openings, respectively (p < 0.005). Angiographies showed meningo-lacrimal and meningo-ophthalmic arteries, meningeal branches of the lacrimal and supraorbital arteries, and some unidentified arteries that could pass through the orbitomeningeal foramina.

CONCLUSIONS

Orbitomeningeal foramina are a common occurrence. When large they may house important arteries that can be the source of severe bleedings during deep dissection of the lateral wall of the orbit. Orbital surgeons should be aware of their existence.

Morphology and morphometry of the meningo-orbital foramen as a result of plastic responses to the ambient temperature and its clinical relevance

The meningo-orbital foramen (FMO) is an osteal opening, containing vessels providing an accessory blood supply to the orbit, situated close to the superior orbital fissure. Recent studies show FMO to be ubiquitous, with localization and occurrence varying, depending on a population, what may be due to environmental conditions (ie, temperature). It is often located near the operating area in surgeries in the orbital cavity, and its accurate localization allows avoiding unexpected bleeding during intervention. Because there is a lack of clarity in the literature concerning the morphology and the morphometry of the FMO, this study aimed to clarify the issue with clinical relevance. We studied dry adult human skulls (50 men and 33 women). The morphology and minimal distances between the FMO and standard anthropologic landmarks (nasion, frontomalare orbitale, supraorbital foramen, and zygomaticomaxillary suture) were measured, using MicroScribe G2L, a three-dimensional contact scanner. We compared the result with results of previous studies on populations from various climate zones. The FMO was present in 69.88% of the skulls (56.02% of orbits): in 60.34% of the skulls, the FMO was bilateral; and in 39.66%, unilateral. We observed 74 single, 10 double, and 2 triple foramina. The FMO was present mostly on the sphenoid and the frontal bone. There was no difference in minimal distances between the FMO and the anthropologic landmarks, depending on sex, except the distance to the nasion (shorter in women). The occurrence of the FMO in the population differed from that of other populations. The results show that it is possible that the morphology and the morphometry of the FMO depend on the climate zone or ambient temperature during growth, which should be considered before performing surgery in the orbital cavity.

Different ophthalmic artery origins: Embryology and clinical significance

This retrospective study gives a summary of ophthalmic artery (OA) variations to serve as guidelines for surgical interventionists and trainees. Pubmed and Medline searches were conducted. The OA usually arises intradurally (superomedial, anteromedial, or rarely superolateral) from the internal carotid artery (ICA). Rare extradural origin (primitive dorsal OA) (PDOA) remnant and extremely rare interdural origin (primitive ventral OA) (PVOA) remnant are of significance when sectioning the dural ring. Rarely, a persistent PDOA with ICA origin, or a PDOA remnant with inferolateral trunk origin, enters the orbit via the superior orbital fissure (SOF) for sole or partial orbital supply. Extremely rare, the PDOA and PVOA persist and form double OAs that arise from the ICA and run via the SOF and optic foramen. Occasionally, the OA arises from the middle meningeal artery (MMA), when both the PDOA and VDOA regress and enter the orbit via the SOF. Sole orbital supply via the external carotid artery (ECA), i.e. meningo-ophthalmic artery and/or MMA branches, or dual OAs (ECA and ICA origins) may occur. Other rare OA origins include anterior or posterior communicating artery; anterior or middle cerebral artery; basilar artery; posterior inferior cerebellar artery; and the carotid bifurcation. Primitive arteries (persistent or remnant), and/or abnormal anastomoses play pivotal roles in manifestations of OA variations. Of clinical importance are orbital collateral routes and dangerous extracranial-intracranial anastomoses. Awareness of OA origins and collateral routes is imperative for transarterial embolizations or infusion chemotherapy in the ECA territory to prevent visual complications.

Navigational area of the cranio-orbital foramen and its significance in orbital surgery

The cranio-orbital foramen (COF) is located on the lateral wall of the orbit. It is a potential source of hemorrhage during deep lateral orbital dissection, since it functions as an anastomosis between the lacrimal artery and the middle meningeal artery. The aim of this study was to guide and facilitate the surgical procedures in the orbit, so as to determine a navigational area and the precise location of the COF and to standardize certain anatomical marks. The navigational area of the COF and topographical features were studied in 75 craniums with presented COF. 33 bilateral main COFs, 41 (18 on the right, 23 on the left) unilateral main COFs at the main cranium and 19 accessory COFs were studied for their navigational features on the orbit. The distances between the COF and the fronto-zygomatic suture, supraorbital notch, lateral angle of the superior orbital fissure (SOF) and Whitnall's tubercle were measured. The mean distance of the COF from the fronto-zygomatic suture, supraorbital notch, lateral angle of the SOF and Whitnall's tubercle was 26.3, 37.3, 92 and 27.1 mm, respectively. For the navigational area signs of the COF, areas of the orbit that form the transversal and vertical lines are generated on the reference points. Whilst the upper outer area of the orbit contains a potential bleeding risk, the bottom section of the outer column is identified as safe for the surgical operations of the lateral orbital wall. The fronto-zygomatic suture and Whitnall's tubercle are recommended as the most reliable navigational landmarks for identifying the COF. Hence, the transversal and vertical orientation of the COF should be mastered by the surgeons reconstructing the anterior base of the skull and the orbit.

The meningo-orbital foramen in a Scottish population

The meningo-orbital foramen is a small opening in the orbit lateral to the lateral end of the superior orbital fissure. It is widely reported to contain an orbital branch of the middle meningeal artery. The foramen may be single or multiple and may occur in the posterosuperior part of the lateral orbital wall or in the posterolateral part of the orbital roof. There is a lack of clarity in the literature as to whether foramina occurring in the orbital roof are the same entity as those occurring in the lateral wall. The disposition of the lesser wing of the sphenoid at the anterior limit of the middle cranial fossa makes it difficult to see how a foramen communicating with the anterior cranial fossa could transmit a branch of the middle meningeal artery. Our study contained 16 meningo-orbital foramina in the orbital roof that would transmit a fine probe. Fourteen of these passed into canals that tracked posteriorly in the bone to open into the middle cranial fossa close to the lateral extremity of the superior orbital fissure. The other two of these foramina communicated with the anterior cranial fossa and both were associated with a more posterior foramen that communicated with the middle cranial fossa. We hope this study clarifies an issue with relevance to surgery in the anterior cranial fossa.

Impact of anomalous origin of the ophthalmic artery from the middle meningeal artery on selection of surgical approach to skull base meningioma

BACKGROUND

Ectopic sites of origin of the ophthalmic artery from the MMA are associated with visual complications of surgery directed along the sphenoidal wing or embolization of the MMA.

CASE DESCRIPTION

Three cases of skull base meningioma in which retinal blood supply originated from the MMA are presented. In one case, the patient experienced transient blindness during selective angiography of the external carotid artery. Because surgical obliteration of the MMA might have caused visual impairment due to sacrifice of the collateral branches from the MMA to the retina during a skull base approach, we selected an approach not involving the MMA.

CONCLUSIONS

In a case in which retinal blush is observed from the MMA on selective angiography of the ECA, we should select an appropriate surgical approach to avoid visual complications in cranial base surgery, taking into account a retinal blood supply.