[Clinical observation of highly selective vidian neurectomy guided by the palatovaginal canal].

Objective:Summarize the safety and feasibility of highly selective vidian neurectomy guided by the palatovaginal canal. Methods:Hypothermal plasma surgery was performed on 53 patients with perennial allergic rhinitis （PAR）. Remove the soft tissue covering the anterior wall of the sphenoid process of palatine bone using the Coblation system. Find the palatovaginal canal and cut off the neurovascular bundle in the palatovaginal canal. Expose the anterior orifice of the vidian canal and cut off the vidian nerve. Results:53 PAR patients have conducted the novel vidian neurectomy without sphenopalatine artery trunk damage. No secondary hemorrhage and hard palate numbness happened. The symptoms of nasal obstruction, sneeze, nasal discharge, and rhinocnesmus were relieved significantly. Conclusion:The simple and safe approach of highly selective vidian neurectomy guided by the palatovaginal canal provides an alternative surgical option for clinicians.

[A vidian neurectomy approach with the sphenoid process of the palatine bone as a landmark].

Objective:To explore a safe and effective surgical approach to locate and cut the vidian nerves with the sphenoid process of the palatine bone as a landmark. Methods: The landmarks of locating the external opening of the vidian canal were confirmed by the dissection of the cadaveric heads, and the feasibility of locating the vidian nerves with the determined landmarks was verified during operation. Results:The anatomical landmarks, which are the anterior opening of palatovaginal canal, the posterior opening of palatovaginal canal, palatovaginal canal and the nasal pharyngeal crest of the root of the pterygoid process can be used as the important landmarks of locating vidian nerve. In the cases of 10 patients with refractory allergic rhinitis and vasomotor rhinitis, the vidian nerves were successfully located and sectioned, and one patient was complicated with short-term unilateral palatal numbness after surgery. Conclusion:The anterior opening of palatovaginal canal, the posterior opening of palatovaginal canal, palatovaginal canal and the nasal pharyngeal crest of the root of the pterygoid process can be used as surgical markers for vidian neurectomy with the sphenoid process of the palatine bone as landmarks.

Effect of clival bone growth on the localization of the abducens nerve at the petroclival region: a postmortem anatomical study.

PURPOSE: To investigate the effect of the clival bone pattern on the abducens nerve (AN) localization in the petroclival region between the Pediatric and Adult Groups. METHODS: This study used 12 pediatric and 17 adult heads obtained from the autopsy. The length and width of the clivus and the length of the petrosphenoidal ligaments (PSLs) were measured. The ratio of the length and width of the clivus was accepted as the clival index (CI). The localization of the AN at the petroclival region below the PSL, classified as lateral and medial, were recorded. RESULTS: The average length of the clivus was 26.92 ± 2.88 mm in the Pediatric Group, and 40.66 ± 4.17 mm in the Adult Group (p < 0.001). The average width of the clivus was 22.35 ± 2.88 mm in the Pediatric Group, and 29.96 ± 3.86 mm in the Adult Group (p < 0.001). The average value of the CI was 1.20 in the Pediatric Group and 1.36 in the Adult Group (p = 0.003). The length of the PSL was 7.0 ± 1.47 mm in the Pediatric Group and 11.05 ± 2.95 mm in the Adult Group (p < 0.001). The nerve was located below the medial side of the PSL in the Pediatric Group and below the lateral side in the Adult Group (p = 0.002). CONCLUSIONS: The petrous apex localization of the AN in adults compared with pediatric subjects could be related to the increased growth in the length of the clivus than its width.

Intra- and extradural anterior clinoidectomy: anatomy review and surgical technique step by step.

PURPOSE: The complex relations of the paraclinoid area make the surgical management of the pathology of this region a challenge. The anterior clinoid process (ACP) is an anatomical landmark that hinders the visualization and manipulation of the surrounding neurovascular structures, hence in certain surgical interventions might be necessary to remove it. We reviewed the anatomical relationships that involve the paraclinoid area and detailed the step-by-step techniques of intra and extradural clinoidectomy in cadaveric specimens. MATERIALS AND METHODS: A literature review was done describing the most relevant anatomic relationships regarding the anterior clinoid process. Extradural and intradural clinoidectomy techniques were performed in six dry bone heads and in ten previously injected cadaverous specimens with colored latex (Sanan et al. in Neurosurgery 45:1267-1274, 1999) and each step of the procedure was recorded using photographic material. Finally, an analysis of the anatomical exposure achieved in each of the techniques used was performed. RESULTS: The main advantage of the intradural clinoidectomy technique is the direct visualization of the neurovascular structures adjacent to the ACP when drilling, at the same time, opening the Sylvian fissure will allow the direct visualization of the ACP variants. The main advantage offered by the extradural technique is that the dura protects adjacent eloquent structures while drilling. Among the disadvantages, it is noted that the same dura that would protect the underlying structures also prevents the direct visualization of these neurovascular structures adjacent to the ACP. CONCLUSION: We reviewed the anatomy of the paraclinoid area and made a step-by-step description of the technique of the anterior clinoidectomy in its intra- and extradural variants in cadaveric preparations for a better understanding.

Vidian canal and sphenoid sinus: an MDCT and cadaveric study of useful landmarks in skull base surgery.

PURPOSE: To present the anatomical variations of vidian canal (VC) and sphenoid sinus (SS), relative to other anatomical landmarks of skull base area, which may be helpful for safer surgical approach to this area. MATERIALS: MDCT scans (128-row MDCT system) of 90 patients (mean age 62 years) and six cadaveric heads were studied, and the following parameters were evaluated: mean length and types of VC, distance between VC and foramen rotundum (FR) and optic canal (OC), position of the VC regarding the lateral pterygoid plate (MPTG) and petrous ICA, pneumatization of SS, position of intrasinus septum regarding ICA and OC, bone dehiscence and protrusion of ICA and OC into SS. Six cadaveric heads underwent MDCT and endoscopic dissection, and the type and length of VC were evaluated. The statistical significance was assessed using Chi-square (χ2) test. Significance level was set at p < 0.05. RESULTS: A statistical analysis was performed between the measurements at both sides, as well as between measurements in MDCT and dissection of the six cadaveric heads. Statistically significant difference was found between right and left sides in the horizontal and vertical distances between FR and VC, as well as between VC and OC. Also, there was a statistically positive correlation between type II of VC and lateral pneumatization on the right side. There was not statistically significant difference concerning VC type and length between MDCT and dissection measurements. CONCLUSION: Surgeons addressing skull base surgery must be familiar with the anatomical and positional variations of VC and SS in the preoperative CT images so as to avoid serious complications during surgery.

The pterygospinous and pterygoalar ligaments and their relationship to the mandibular nerve: Application to a better understanding of various forms of trigeminal neuralgia.

INTRODUCTION: Ossification of the pterygospinous and pterygoalar ligaments has been well documented forming pterygospinous and pterygoalar bars. However, the actual ligaments have been rarely shown in the existing literature. Therefore, this study aimed to reveal the anatomy of the pterygoalar ligament/bar and pterygospinous ligament/bar, and its relationship with the branches of the mandibular nerve. METHODS: Thirty sides from fifteen Caucasian fresh frozen cadaveric heads were used in this study. The branches of the mandibular nerve and any ligaments or bony bridges between the lateral plate of the pterygoid process and spine of the sphenoid were observed. RESULTS: A pterygospinous ligament/bar and pterygoalar ligament/bar were defined based on the relationship with the branches of the mandibular nerve. The pterygoalar ligament/bar was further classified into two types. Twenty-seven sides (90%) had at least one pterygoalar ligament/bar or pterygospinous ligament/bar. A pterygospinous ligament/bar was found on 15 sides (50.0%). A pterygoalar ligament/bar was found on 16 sides (53.3%), and a type I on 11 sides and type II on 5 sides. CONCLUSIONS: This finding and classification are simple to understand and easy to apply for future studies, and have important implications regarding the clinical anatomy of trigeminal neuralgia and facial pain.

Endoscopic prelacrimal approach to lateral recess of sphenoid sinus: feasibility study.

BACKGROUND: Various pathologies, including cerebrospinal fluid leaks and meningoencephaloceles, may arise in the lateral recess of the sphenoid sinus (LRSS), which may be accessed via an endonasal transpterygoid approach. The objective of this study was to evaluate the feasibility of accessing the LRSS via an endoscopic prelacrimal approach. Furthermore, we hypothesized that this approach may protect the pterygopalatine ganglion and vidian nerve. METHODS: Five cadaveric heads (9 sides) with a well-pneumatized LRSS were identified and an endonasal prelacrimal approach was performed. The infraorbital nerve, at the orbital floor, served as a critical landmark. After identification of the foramen rotundum at the pterygoid base, the vascular compartment of the pterygopalatine fossa and the pterygopalatine ganglion were displaced inferomedially and superomedially, respectively. Drilling of the bone inferomedial to the foramen rotundum allowed entry into the LRSS. RESULTS: The average distances from the prelacrimal window to the pterygoid base and the posterior wall of the LRSS were 6.22 ± 0.39 cm and 7.16 ± 0.50 cm, respectively. The average areas of the bony prelacrimal window and pterygoid base window were 4.33 ± 0.32 cm2 and 0.73 ± 0.10 cm2 , respectively. The LRSS could be accessed using a 0-degree endoscope, and pterygopalatine neurovascular structures, including the pterygopalatine ganglion and vidian nerve, could be preserved on all 9 sides. CONCLUSION: Our findings suggest that an endonasal prelacrimal approach provides a reasonable alternative to access the LRSS while preserving the vidian nerve and pterygopalatine ganglion.

Visualization of the vidian canal and nerve using magnetic resonance imaging.

BACKGROUND AND PURPOSE: Few studies have investigated the vidian nerve (VN) and vidian canal (VC) with the use of magnetic resonance imaging (MRI). The present study aimed to characterize the VC and VN using MRI. MATERIALS AND METHODS: A total of 91 patients underwent thin-sliced, contrast MRI. The course of the VC and VN and the relationships with relevant structures were analyzed. RESULTS: The VC was identified in 95% of axial images on the right side and in 93% on the left. The course of the VC was delineated in 99% of serial coronal images on both sides. The VN location in the VC was highly variable. The course of the VC and transmitting VN was delineated in 95% of sagittal images on the right side and in 91% on the left. The mean length of the VC was 19.8 mm on the right side and 19.3 mm on the left. Topographical relationships between the anterior genu of the petrous internal carotid artery and the posterior end of the vidian canal could be classified into three types. Of these, the type terminating at the level of the petrous carotid was the most predominant, comprising 76% of 182 sides. The course of the VC and transmitting VN could be classified into four types. The straight type was the most predominant and was found in 41%. CONCLUSIONS: The VC and transmitting VN are structures with variable morphologies. Contrast MRI is useful for delineating the VC and VN.

The "polymorphous" history of a polymorphous skull bone: the sphenoid.

For a long time, because of its location at the skull base level, the sphenoid bone was rather mysterious as it was too difficult for anatomists to reach and to elucidate its true configuration. The configuration of the sphenoid bone led to confusion regarding its sutures with the other skull bones, its shape, its detailed anatomy, and the vascular and nervous structures that cross it. This article takes the reader on a journey through time and space, charting the evolution of anatomists' comprehension of sphenoid bone morphology from antiquity to its conception as a bone structure in the eighteenth century, and ranging from ancient Greece to modern Italy and France. The journey illustrates that many anatomists have attempted to name and to best describe the structural elements of this polymorphous bone.

Attempted validation of a method to locate entry and exit foramens of the branches of the trigeminal nerve; benefits for an original cephalometric analysis technique.

INTRODUCTION: Trigeminal analysis focuses on the skeletal entrance and exit orifices of the sensitive fibers of the trigeminal nerve. The aim of this study was to validate the techniques used to locate these landmarks as described by the creator of trigeminal analysis of the face. MATERIALS AND METHOD: This descriptive study was performed on a dry human skull. Two tin balls forming markers R1 and R2 were fixed at random on the skull in a median sagittal position. Two headfilms of the skull were made. The first showed tin balls fixed at the entrance and exit foramens of the sensitive fibers of the trigeminal nerve. The second showed the foramens without the tin balls. The position of the reference point corresponding to the entrance and exit points of the trigeminal fibers was entered on a tracing made from the headfilm (without the balls on the foramens) by 16 operators using an ad hoc guide supplied by Crocquet. A comparison was made between the points as positioned by these operators and the true points as revealed by the X-rays of the balls on the first image (Gold Standard) by calculating the difference between their coordinates on an axis connecting R1 et R2 (X-axis) and the line perpendicular to it passing through R2 (Y-axis). Trigeminal cephalometric analysis was then performed on each of the tracings. The angles and linear values were compared. The validity of the positioning of the points and of the values provided by the analysis was demonstrated by the existence of a difference of less than 2units (mm or degrees). RESULTS: No difference in the means between the trigeminal points found by the operators and the Gold Standard points represented by the X-rays of the balls placed on the foramens exceeded 2mm in absolute value on the Y-axis. On the X-axis, the differences greater than 2mm in absolute value related to: the supra-orbital notch (ESO) and the foramen ovale (FO) (2.12 and 8.19mm, respectively). The angles (ESO-TGR-TO) and (TGR-ESO-TSO) were the only ones to display differences exceeding 2° in absolute value between the two images. CONCLUSION: The detection method advanced by Crocquet for the positioning of the eight points of reference used for analyzing the entrance and exit foramens of the trigeminal nerve is valid apart from the TO and ESO points. Consequently, the validity of the angle measurements involving these points is affected. Further research is required to confirm these findings. If necessary, new recommendations should be devised in order to improve the localization of the TO and ESO cephalometric points.

Looking for landmarks in medial orbital trauma surgery.

Knowledge of the precise location of anatomical landmarks such as the anterior (AEC) and posterior ethmoid (PEC) canals facilitates medial orbital wall surgery and is of major importance for the protection of the orbital nerve. The aim of this study was to identify these anatomical structures in 100 consecutive CT scans and measure the distance between them. The authors investigated whether a predictable symmetry existed between the left and right side. The AEC was not identified unilaterally in one patient, the PEC was not identified unilaterally in six patients and not bilaterally in one patient. An additional PEC was found unilaterally in 12 and bilaterally in five patients. If an anatomical structure was found bilaterally, the authors obtained a strong Pearson's correlation between the sides (r=0.798-0.903, p<0.001). An anatomical variation was found in nearly every fourth patient. The authors think that these data call into question the use of the PEC and AEC as reliable surgical landmarks in medial orbital surgery.

Applied anatomy of the pterygomandibular space: improving the success of inferior alveolar nerve blocks.

A thorough knowledge of the anatomy of the pterygomandibular space is essential for the successful administration of the inferior alveolar nerve block. In addition to the inferior alveolar and lingual nerves, other structures in this space are of particular significance for local anaesthesia, including the inferior alveolar vessels, the sphenomandibular ligament and the interpterygoid fascia. These structures can all potentially have an impact on the effectiveness of local anaesthesia in this area. Greater understanding of the nature and extent of variation in intraoral landmarks and underlying structures should lead to improved success rates, and provide safer and more effective anaesthesia. The direct technique for the inferior alveolar nerve block is used frequently by most clinicians in Australia and this review evaluates its anatomical rationale and provides possible explanations for anaesthetic failures.

5-HT(1D) receptor immunoreactivity in the sphenopalatine ganglion: implications for the efficacy of triptans in the treatment of autonomic signs associated with cluster headache.

OBJECTIVE: To determine if 5-HT(1D) receptors are located in the sphenopalatine ganglion. BACKGROUND: While the 5-HT(1D) receptor has been described in sensory and sympathetic ganglia in the head, it was not known whether they were also located in parasympathetic ganglia. METHODS: We used retrograde labeling combined with immunohistochemistry to examine 5-HT(1D) receptor immunoreactivity in rat sphenopalatine ganglion neurons that project to the lacrimal gland, nasal mucosa, cerebral vasculature, and trigeminal ganglion. RESULTS: We found 5-HT(1D) receptor immunoreactivity in nerve terminals around postganglionic cell bodies within the sphenopalatine ganglion. All 5-HT(1D) -immunoreactive terminals were also immunoreactive for calcitonin gene-related peptide but not vesicular acetylcholine transporter, suggesting that they were sensory and not preganglionic parasympathetic fibers. Our retrograde labeling studies showed that approximately 30% of sphenopalatine ganglion neurons innervating the lacrimal gland, 23% innervating the nasal mucosa, and 39% innervating the trigeminal ganglion were in apparent contact with 5-HT(1D) receptor containing nerve terminals. CONCLUSION: These data suggest that 5-HT(1D) receptors within primary afferent neurons that innervate the sphenopalatine ganglion are in a position to modulate the excitability of postganglionic parasympathetic neurons that innervate the lacrimal gland and nasal mucosa, as well as the trigeminal ganglion. This has implications for triptan (5-HT(1D) receptor agonist) actions on parasympathetic symptoms in cluster headache.

Contribución al estudio de la anatomía funcional del hueso esfenoides / Contribution to the study of the functional anatomy of the sphenoid bone

Los libros de Anatomía Clásica Descriptiva y Topográfica realizan una detallada y completa descripción de los accidentes anatómicos (orificios, conductos, hendiduras o fisuras, espinas, apófisis, tubérculos, fosas, fositas, crestas, división en sectores,configuración interna e inserciones musculares y ligamentosas del hueso esfenoides, necesaria para comprender nuestra propuesta.También describen sus relaciones con otros huesos del cráneo y cara, con la hipófisis y con los elementos neurovasculares que entran o salen de la cavidad craneal.En este trabajo se pretende presentar y jerarquizar la visión de un hueso esfenoides clave en la base de cráneo y proponemos una división en sectores acorde a las funciones que cumple cada uno de ellos. Por lo tanto consideramos que el hueso esfenoides esun centro de crecimiento de la base de cráneo, centro de pasaje de elementos neurovasculares, centro de resistencia de la base de cráneo junto al cuerpo del hueso occipital, centro de inserciones musculares y continente de los senos esfenoidales, el seno cavernoso y la glándula hipófisis.Es finalmente un hueso multiarticulado y multicavitario, ya que forma cavidades del cráneo, de la cara y comunes a ambos sectores anatómicos. Forma parte de una vía transnasal para el abordaje de la silla turca (fosa hipofisaria) y su contenido, lahipófisis. Permite la salida del cráneo de las tres ramas del nervio trigémino (V par craneal ), de indudable valor odontológico.

The books on Classic Descriptive and Topographic Anatomy carry out a complete and detailed description of the anatomicalaccidents (orifices, conducts, fissures, spines, apophysis, tubercules, cavities and pits, crests, sector divisions, internalconfiguration and mucular and ligamental insertions of the sphenoid bone, necessary to understand our proposal.They also describe their relations with other bones in skull and face, with the hypophysis and with the neurovascular elements that enter or exit from the cranial cavity.In this paper we expect to present and arrange in order of hierarchy the overview of a bone that is key at the cranial base and we propose a division in sectors in accordance to the functions that each one of them plays. We therefore consider that the sphenoidbone is a growth centre of the cranial base, passageway point of neurovascular elements, resistance center together with the occipital bone, center of muscle insertions and continent of the sphenoid sinuses, cavernous sinus and hypophyis gland.Finally, it is a multiarticulated bone and multicavernous, given that it forms cavities in the cranium, in the facies and common to both anatomical sectors.It conforms part of a transnasal tract for the approaching of the Sella Turcica and its contents, the hypophysis.It allows the exit from the cranium of the three branches of the Trigeminal Nerve (V cranial pair), of undoubtable value indentistry

Microsurgical and endoscopic anatomy of the vidian canal.

OBJECTIVE: The vidian canal, the conduit through the sphenoid bone for the vidian nerve and artery, has become an important landmark in surgical approaches to the cranial base. The objective of this study was to examine the anatomic features of the vidian canal, nerve, and artery, as well as the clinical implications of our findings. METHODS: Ten adult cadaveric specimens and 10 dried skulls provided 40 vidian canals for examination with x 3 to x 20 magnification and the endoscope. RESULTS: The paired vidian canals are located in the skull base along the line of fusion of the pterygoid process and body of the sphenoid bone. The canal opens anteriorly into the medial part of the pterygopalatine fossa and posteriorly at the upper part of the anterolateral edge of the foramen lacerum. The vidian nerve, when followed posteriorly, reaches the lateral surface of the anterior genu of the petrous carotid and the anteromedial part of the cavernous sinus where the nerve is continuous with the greater petrosal nerve. The bone surrounding the upper part of 12 of 20 vidian canals protruded into the floor of the sphenoid sinus and one canal had a bony dehiscence that exposed its contents under the sinus mucosa. Nine petrous carotid arteries (45%) gave rise to a vidian artery, all of which anastomosed with the vidian branch of the maxillary artery in the vidian canal or pterygopalatine fossa. The vidian canal can be exposed by opening the floor of the sphenoid sinus, the posterior wall of the maxillary, the posterior part of the lateral wall of the nasal cavity, and the medial part of the floor of the middle fossa. CONCLUSION: The vidian canal and nerve are important landmarks in accessing the anterior genu of the petrous carotid, anteromedial part of the cavernous sinus, and petrous apex.

Endoscopic study for the pterygopalatine fossa anatomy: via the middle nasal meatus-sphenopalatine foramen approach.

OBJECTIVE: The purposes of this study were to locate the constant anatomic landmarks, which are very important and helpful for endoscopic surgery and not well described for the pterygopalatine fossa (PPF) surgery via the middle nasal meatus-sphenopalatine foramen approach to establish a safe surgical mode. METHODS: Eight cases of adult skull specimens were selected for the simulated surgery. The Messerklinger surgical approach was used under the endoscope. The uncinate process was removed successively, and the anterior ethmoid sinus and posterior ethmoid sinus were opened. The opening of the maxillary sinus was identified and was expanded forward and backward. The ethmoidal crest was found and was used as an anatomic landmark to find the sphenopalatine foramen. The sphenopalatine artery was protected and was used as a guide to enter the PPF region. The sphenopalatine artery was followed conversely to anatomize the blood vessels and nerves in the PPF. RESULTS: It was found that our surgical procedure provides a clear view of the constant anatomic landmark including ethmoidal crest and sphenopalatine foramen. By retrograde dissection, following the sphenopalatine artery, which runs out of the sphenopalatine foramen behind the ethmoidal crest, the internal maxillary artery (IMA) and the branches of the IMA in the PPF were exposed. Posterior to the sphenopalatine artery, the typical Y-shaped structure with the pterygopalatine ganglion as the center was visible when the IMA and its branches were moved downward and outward. The Y structure, which is consisted of the pterygopalatine ganglion, branches of the internal maxillary nerve, vidian nerve, and descending palatine nerve, served as the other anatomic landmark. By following the Y structure, it was easy to locate the pterygoid canal, foramen rotundum, and the infraorbital nerve, and the integrity of the nerve structure could be protected. CONCLUSION: Endoscopic PPF surgery via the middle nasal meatus-sphenopalatine foramen approach is safe, and the ethmoidal crest, sphenopalatine foramen, and Y structure with the pterygopalatine ganglion in the center are important anatomic landmarks that can be referred to during the surgery.

Endoscopic anatomy of the pterygopalatine fossa and the transpterygoid approach: development of a surgical instruction model.

INTRODUCTION: The pterygopalatine fossa (PPF) is a narrow space located between the posterior wall of the antrum and the pterygoid plates. Surgical access to the PPF is difficult because of its protected position and its complex neurovascular anatomy. Endonasal approaches using rod lens endoscopes, however, provide better visualization of this area and are associated with less morbidity than external approaches. Our aim was to develop a simple anatomical model using cadaveric specimens injected with intravascular colored silicone to demonstrate the endoscopic anatomy of the PPF. This model could be used for surgical instruction of the transpterygoid approach. METHODS: We dissected six PPF in three cadaveric specimens prepared with intravascular injection of colored material using two different injection techniques. An endoscopic endonasal approach, including a wide nasoantral window and removal of the posterior antrum wall, provided access to the PPF. RESULTS: We produced our best anatomical model injecting colored silicone via the common carotid artery. We found that, using an endoscopic approach, a retrograde dissection of the sphenopalatine artery helped to identify the internal maxillary artery (IMA) and its branches. Neural structures were identified deeper to the vascular elements. Notable anatomical landmarks for the endoscopic surgeon are the vidian nerve and its canal that leads to the petrous portion of the internal carotid artery (ICA), and the foramen rotundum, and V2 that leads to Meckel's cave in the middle cranial fossa. These two nerves, vidian and V2, are separated by a pyramidal shaped bone and its apex marks the ICA. CONCLUSION: Our anatomical model provides the means to learn the endoscopic anatomy of the PPF and may be used for the simulation of surgical techniques. An endoscopic endonasal approach provides adequate exposure to all anatomical structures within the PPF. These structures may be used as landmarks to identify and control deeper neurovascular structures. The significance is that an anatomical model facilitates learning the surgical anatomy and the acquisition of surgical skills. A dissection superficial to the vascular structures preserves the neural elements. These nerves and their bony foramina, such as the vidian nerve and V2, are critical anatomical landmarks to identify and control the ICA at the skull base.

The pterygopalatine fossa: an anatomic report.

The pterygopalatine fossa (PPF) is a small anatomic region of particular interest in cranial base surgery. Infectious diseases and malignancy may spread through the PPF to contiguous areas as a result of the low resistance offered by the numerous foramina and fissures that surrounds the fossa. We present an anatomic report on the PPF. Twelve sides of six fixed cadaveric heads were dissected through a LeFort I maxillary osteotomy with transantral exposure of the neurovascular content of the PPF. Arterial vascular patterns of the maxillary artery were observed. The pterygopalatine fossa is a deeply located small anatomic region with a rich neurovascular content. The third portion of the maxillary artery in the PPF may demonstrate a variable vascular morphology. A correct understanding and knowledge of the anatomic structures lodged into the PPF, as well as their relationships and functions, remain crucial to minimizing postsurgical morbidity and intraoperative complications.

Surgical consideration to optic nerve protrusion according to sinus computed tomography.

OBJECTIVES: This study aimed to investigate the prevalence of optic nerve protrusion (ONP) and its clinical indicators by using sinus computed tomography (CT) scan. STUDY DESIGN: Sinus CT scans of 260 consecutive patients with chronic inflammatory sinus disease were reviewed. RESULTS: The prevalence of ONP in our study population was 28%. Nineteen percent of the optic nerves protruded into the sphenoid sinuses including indentation of the sinus wall (12%) and coursing through the sphenoid sinus (8%). In the presence of contralateral ONP and/or ipsilateral anterior clinoid process pneumatization, the chance of ONP occurrence was significantly higher (both P < 0.01). They were reliable indicators of ONP (R(2) = 0.47, P < 0.01). CONCLUSIONS: ONP is a common anatomic variation observed in patients with chronic inflammatory sinus disease. To reduce optic nerve damage in surgeries, the presence of ONP according to sinus CT scans and the intraoperative findings should be carefully evaluated. EBM RATING: C-4.

Anatomy of greater palatine foramen and canal and pterygopalatine fossa in Thais: considerations for maxillary nerve block.

This study aims to investigate the anatomy of the greater palatine foramen (GPF), greater palatine canal (GPC) and pterygopalatine fossa (PPF) with special reference to the blockage of the maxillary nerve. A correlation between the length of GPC and PPF and the heights of the orbit and the maxilla was also studied using simple linear regression analysis. The morphology of the GPF, GPC and PPF as well as heights of the orbit and the maxilla were assessed in 105 Thai skulls. The thickness of the mucosa over the GPF was also measured from the dissection of 55 cadavers. The results showed that most GPF appeared as an oval foramen located at the palatal aspect of the upper third molar. The GPF was 16.2+/-1.3 mm lateral to the median sagittal plane of the hard palate, 2.1+/-1.3 mm anterior to the posterior border of the hard palate and 5.1+/-1.3 mm from the greatest concavity of the distolateral margin of the hard palate. The mean length of GPC and PPF was 29.7+/-4.2 mm. The mean angles of the GPC in relation to the hard palate and the vertical plane were 57.9+/-5.8 degrees and 6.7+/-5.2 degrees , respectively. In attempting to insert a needle to reach the foramen rotundum through the GPF, 31.7% passed into the orbit while 8.7% passed into the brain. The mean thickness of the mucosa over GPF was 6.7+/-2.3 mm. Two models for estimating the depth of needle injection in maxillary nerve block have been developed as follows: Length of GPC and PPF=19.038+0.314 (orbital height) and length of GPC and PPF=21.204+0.187 (maxillary height). The calculated length combined with the mucosal thickness was the estimated depth of needle injection. In conclusion, our results concerning the GPF, GPC and PPF will provide the useful reference for clinicians to anesthetize the maxillary nerve with a greater degree of success.