Software-enabled computed tomography analysis of the carotid artery and sphenoid sinus pneumatization patterns

BACKGROUND: The critical relationship of the carotid artery with the sphenoid sinus has been long established. Sophisticated imaging software in conjunction with three-dimensional high-resolution computed tomography (CT) imaging now facilitates detailed analysis of these anatomic relationships. METHODS: Siemens VolumeZoom CT scanner was used to obtain high-resolution computed tomography data that was subsequently transferred to the CBYON Suite Doctor Station version 2.6 for analysis. Various surgical planning tools were used for evaluating the CT scans. The relationship of the carotid artery with the sphenoid sinus was delineated. RESULTS: One-hundred twenty-eight sides in 64 cadaveric specimens were reviewed. Pneumatization of the sphenoid sinus was classified into four categories: conchal, presellar, sellar, and postsellar. The incidence of these four types was 4.7, 4.7, 25, and 65%, respectively. Carotid artery exposure was categorized as follows: no exposure, <90 degrees, >90 to <180 degrees, and >180 degrees. The incidence of the carotid exposure was 12.5, 32.8, 50, and 4.7%, respectively. Septal insertions onto the carotid artery were noted in 37.5% and dehiscences in 19.5% of the specimens. CONCLUSION: Computer-aided CT analysis allows for a detailed study of the critical relationship of sphenoid pneumatization and carotid artery position. Such technology can be invaluable in surgical planning and navigation during endoscopic sinus surgery. In lieu of these findings, sinus surgeons must exercise extreme caution when operating in this region to prevent unintentional injury to the carotid artery.     

蝶窦的解剖及其在鞍区手术中的意义

目的　回顾近年来有关蝶窦的解剖研究，总结其在鞍区手术中的意义。方法　分析近年来有关的文献23篇。结果　蝶窦于10岁时基本气化完全，其大小、形态、气化程度和分隔均变异极大。蝶窦内中隔很少居中，视神经和颈内动脉常不同程度地凸向窦腔。后筛窦亦可伸入蝶窦，形成蝶上筛房。自蝶窦口至鞍底中心的距离大约为1.5cm。结论　经蝶入路手术中，保持与鼻底成32°夹角入路和以两侧窦口下缘连线为横轴打开窦壁，可使手术准确导向鞍内，必要时可打开蝶上筛房。蝶骨前嵴和犁骨是指引窦内中线操作的可靠标志，入窦腔后应注意识别和保护侧壁上的隆起结构。若见窦腔浅,看不到鞍底下凸，即可能存在额状位间隔、蝶窦气化不良或鞍底本身不下凸。     

蝶窦外侧壁相关结构的CT和MRI对比研究

目的 :对正常人蝶窦外侧壁相关结构的CT和MRI进行对比研究 ,为该区域疾病诊断和鉴别诊断提供理论依据。方法 :对 2 5例正常人行冠状和水平位高分辨率CT扫描。对 2 0例正常人行MRI冠状、水平位SET1 WI和FSET2 WI扫描。结果 :①蝶窦气化分为蝶骨体气化类型和蝶骨体突起气化类型。前者分 3型 :甲介型 (2 % ) ,鞍前型 (2 0 % ) ,鞍型 (78% )。后者分 4型 :蝶骨小翼气化型 (38% ) ,蝶骨大翼气化型 (40 % ) ,翼突气化型(34% ) ,鞍背气化型 (6 % )。②蝶骨外侧骨壁最薄 (<1mm)处位于视神经管内壁 (96 % )、蝶筛隐窝层面骨壁(86 % )、颈内动脉管层面骨壁 (6 6 % )。③过度气化的蝶窦可使圆孔 (6 4 % )和翼管 (44 % )突入蝶窦腔内。结论 :临床应对视神经管周围不同气化类型给予充分重视     

经鼻内镜蝶鞍区手术蝶窦壁的应用解剖

目的研究蝶窦壁相关解剖结构的分区及空间定位，为经鼻内镜蝶鞍区手术提供立体解剖学依据。方法10具去脑颅底骨按九分区法划分蝶窦壁区域，测量蝶窦各壁之间相关的角度和距离参数；在1具新鲜完整尸头上模拟内镜下手术观察。结果视交叉平面-球形鞍底隆起角度为（121±8．52）°，海绵窦平面一鞍底平面角度为（129±9．35）°，斜坡凹陷平面-鞍底平面角度（124±7．54）°，颈内动脉视神经隐窝至鞍底移行处距离为（5．54±1．86）mm，至斜坡后缘的距离为（22．43±1．96）mm，至颈内动脉海绵窦段后曲部的距离为（15．86±2.13）mm；根据测量结果可建立起蝶窦壁九分区法的立体模型。结论蝶窦壁九分区法的立体模型，丰富了鼻内镜下蝶窦壁九分区法的内容，使其更加方便应用于手术。     

Asociación entre fístula de líquido cefalorraquídeo y persistencia del canal de Sternberg: ¿coincidencia o causa?

Endoscopic surgical techniques allow treating various pathological diseases of the cranial base, including cerebrospinal fluid leaks (CSF). These approaches have a high success rate and reduce surgical time and morbidity. However, when they are located in the lateral wall of the sphenoid, the surgery is more complex. In our case, the CSF appeared to be related with a Sternberg's canal. Predisposing factors were also associated with an extensive unilateral pneumatization of the sinus and benign intracranial hypertension. The closure of the leak was achieved using an endoscopic transethmoidal transpterygoid approach for proper exposition of the lateral wall of the sphenoid. After five years of monitoring, the patient has had no more episodes of rhinoliquorrhea.     

Anatomic variations of the sphenoid sinus on computed tomography

Anatomic variations of the vital structures adjacent to the sphenoid sinus can be jeopardized during functional endoscopic sinus surgery (FESS). The knowledge of the size and extent of pneumatization of the sphenoid sinus (SS) is an important condition for adequate surgical treatment of its disease. The bony anatomic variations of SS as well as its relationship with adjacent vital structures were reviewed in this paper. The study was performed on 267 patients with a complaint of chronic or recurrent sinusitis. Computed tomographic (CT) scans were obtained upon completion of therapy. The evaluations of the sphenoid sinuses were regarded separately, so as 534 sides were examined. Especially bony anatomic variations as well as mucosal abnormalities of the sphenoid sinuses were examined. Pneumatization of the pterygoid process and anterior clinoid process were found in 39.7% and 17.2% of the patients respectively. Vidian canal protrusion was found in a total of 158 sides of which 60 were bilateral. These entities were encountered usually when pneumatization of the pterygoid process occurred. Carotid canal and optic canal protrusions were found in 5.2% and 4.1% of the patients respectively. Mucosal thickening, and polyps or cysts of sphenoid sinuses were detected in 20.6% and 4.5% of the patients respectively. There was a statistically significant correlation between pterygoid pneumatization and vidian canal protrusion (p < 0.001), and vs. foramen rotundum protusion (p = 0.004). While the optic canal protrusion was found significantly associated with the anterior clinoid pneumatization (p < 0.001), there was no statistically significant correlation between a carotid canal protrusion and anterior clinoid pneumatization (p = 0.250). Sphenoid sinus surgery is very risky, because of changing variations of the cavity. We are in the opinion that detailed data from CT scans of SS will enable the surgeon to interpret any anatomic variations and pathological conditions before initiation of the surgical therapy.     

Co-existence of the Onodi cell with the variation of perisphenoidal structures

The presence of the Onodi cell (OC) may be accompanied by morphological variations of the neighboring anatomic structures. Such variations carry significant surgical implications and challenges. Pneumatization of the sphenoid sinus induces anterior clinoid pneumatization (ACP), affects the type of the Vidian nerve (VN) canal or alters the courses of the internal carotid artery (ICA), and the optic nerves (ONs) are strongly depending on it. Onodi cell pneumatization may reach and surround the optic nerve in various extension. Our aim in the study was to investigate the effect of Onodi cell’s potential co-existence on these structures. This study was planned as a retrospective and cross-sectional study. This study performed in a tertiary referral center. Coronal computerized tomography images of 999 patients were examined. Using an 64 slices tomography machine, images taken at 3-mm sections were reconstructed using a bone algorithm and evaluated. OCs were present at 212 of the total 320 sides in 160 patients. Type-2 was found to be the most prevalent type of VN canal configuration (Type-2: VN canal partially protrudes into the sphenoid sinus or into the floor of the sphenoid) among all patients (66.5 %) and among those with OCs (71.2 %). The presence or absence of the OC did not cause a statistically significant alteration of the intrasphenoidal course of the VN. The presence of OCs was found to be significant (p < 0.01) in accompanying pneumatization of the anterior clinoid process (34.4 %, 73/212), protrusion (80.1 %, 170/212) and dehiscence (36.3 %, 77/212) of the optic nerve, and protrusion (59 %, 125/212) and dehiscence (20.8 %, 44/212) of the ICA. In 108/320 sides where OCs were absent, no significant correlations existed. This study shows that in the co-existence of an OC, ACP, protrusion and dehiscence of the optic nerve and ICA are encountered at significantly higher rates, while the course of the VN is not necessarily altered.     

Surgical measurement to sphenoid sinus for the Chinese in Asia based on CT using sagittal reconstruction images

The objective this study was to measure the changes of sphenoid sinusin the Chinese in AsiausingCT sagittal thin-slice reconstruction images, and to clarify the three-dimensional anatomical features of sphenoid sinus with its surrounding structures, relevant to the performing of the endoscopic sphenoidotomy. The sagittal reconstruction images were obtained from 178 CT images of 89 cases of normal adult participants (54 males and 35 females) with sphenoid sinus. We took the high-resolution axial CT images, from all the subjects, of the thickness by 0.625 mm, and reconstructed 1-mm-thick gapless sagittal CT images to measure the distance of all the sellar and pre-sellar types on the three-dimensional reconstructable sagittal plane under the bone window (4,000 at its width, and 400 at its level) in the CT images. The length of mean vertical line from the center of sphenoid ostium to the roof of sphenoid sinus of Non Onodi cell type is 10.6 ± 1.5 mm, and of Onodi cell type is 3.3 ± 1.5 mm. The length of vertical line from the center of sphenoid ostium to the lowest level of the bottom of sphenoid sinus is 12 mm ± 3.7 mm. The length of mean horizontal line from the sphenoid ostium to the posterior wall of sphenoid sinus is 18 ± 1.5 mm or 28 ± 2.5 mm. The mean horizontal line from the lowest point of the sella to the anterior wall of sphenoid sinus is 17.5 ± 1.3 mm in length. The mean horizontal distance from anterior wall to posterior wall of sphenoid sinus of Non Onodi cell type lining skull base is 10.1 ± 1.0 mm, and of Onodi cell type, is 5.2 ± 4.3 mm. The longest horizontal distance from the anterior wall to the posterior wall of sphenoid sinus is 22.0 ± 7.7 mm. The present study provides atomical information about sphenoid sinus of the Chinese in Asia with some surgical distance measured between the sphenoid ostium and the surrounding structures, which is essential to avoid the complications during surgery.     

Anatomic variations of the lateral nasal wall in the computed tomography scans of patients with chronic rhinosinusitis.

The development of computed tomography (CT) technique results in the advance in visualization of the anatomic structures of the lateral nasal wall. It allows the anatomic variations of this region to be identified precisely, which is important in surgical treatment of chronic rhinosinusitis. The aim of this study was to determine the incidence of anatomic variations of the lateral nasal wall in a group of patients with chronic rhinosinusitis. The preoperative, frontal plane CT scans of the study group were evaluated using the method of the four-zone interpretation. The incidence of the anatomic variations of the lateral nasal wall was consistent with the results reported by other authors.     

Ultrasonography in the diagnosis of nasal bone fractures: a comparison with conventional radiography and computed tomography

The purpose of this study was to evaluate and compare the diagnostic efficacy of ultrasonography (US) with radiography and multi-detector computed tomography (CT) for the detection of nasal bone fractures. Forty-one patients with a nasal bone fracture who underwent prospective US examinations were included. Plain radiographs and CT images were obtained on the day of trauma. For US examinations, radiologist used a linear array transducer (L17-5 MHz) in 24 patients and hockey-stick probe (L15-7 MHz) in 17. The bony component of the nose was divided into three parts (right and left lateral nasal walls, and midline of nasal bone). Fracture detection by three modalities was subjected to analysis. Furthermore, findings made by each modality were compared with intraoperative findings. Nasal bone fractures were located in the right lateral wall (n = 28), midline of nasal bone (n = 31), or left lateral wall (n = 31). For right and left lateral nasal walls, CT had greater sensitivity and specificity than US or radiography, and better agreed with intraoperative findings. However, for midline fractures of nasal bone, US had higher specificity, positive predictive value, and negative predictive value than CT. Although two US evaluations showed good agreements at all three sites, US findings obtained by the hockey-stick probe showed closer agreement with intraoperative findings for both lateral nasal wall and midline of nasal bone. Although CT showed higher sensitivity and specificity than US or radiography, US found to be helpful for evaluating the midline of nasal bone. Furthermore, for US examinations of the nasal bone, a smaller probe and higher frequency may be required.     

经鼻小柱-鼻中隔-蝶窦入路切除132例大型和巨型垂体腺瘤分析

目的介绍经鼻小柱-鼻中隔-蝶窦入路切除大型和巨型垂体腺瘤132例的临床经验,探讨治疗大型和巨型垂体腺瘤的有效方法。方法鼻小柱切开是采用(左)鼻内中隔切口为基础,鼻小柱切开,增加侧斜切口或两侧鼻前庭小柱切开上翻法,后经鼻中隔-蝶窦,打开蝶窦,开窗近圆形直径1~1.5 cm,中线处凿开鞍底,探查并切除鞍内肿瘤。结果132例中行包膜内全切除42例(31.8%),其余行次全切除或大部分切除。术后症状改善者118例(89.4%);术后部分病例出现暂时性尿崩症、鼻腔渗血、脑脊液鼻漏和垂体功能低下等,经对症治疗而好转。结论对于大型和巨型垂体腺瘤,绝大多数病人因蝶窦气化条件良好,同时垂体瘤大多质地为稀软性,便于吸除而可采用经蝶窦手术治疗获得良好效果。而此切口具有径路短、出血少、不需要填塞纱条等优点。     

鼻内镜下经鼻中隔后蝶窦入路切除累及鞍外的鞍区肿瘤

目的总结内镜下经鼻蝶扩大手术入路切除侵犯鞍外的鞍区肿瘤的临床经验,并对术后疗效及并发症进行评估。方法选择侵犯鞍外的鞍区肿瘤13例,在鼻内镜下经鼻腔切除鼻中隔后端,进入蝶窦,再磨去鞍底及周围骨质,进入鞍区及鞍外,行肿瘤切除术。结果术后病理检查结果显示,13例患者中垂体腺瘤8例,颅咽管瘤4例,脑膜瘤1例;8例肿瘤完全切除（61.5%）,4例部分切除（30.7%）,1例死亡。术后发生的主要并发症有尿崩症、脑脊液鼻漏、脑膜炎、下丘脑衰竭等。结论侵犯鞍外的鞍区肿瘤可以经鼻内镜下手术切除,但具有一定风险,需要谨慎选择。     

Endoscopic surgery for inverted papilloma originating from the sphenoid sinus and related clinical characteristics

Conclusions. Bony changes on CT imaging of inverted papilloma (IP) are useful for predicting tumor origin and recurrence sites. Because the lateral wall and floor of the sphenoid sinus are the most common origin and recurrence sites, the anterior wall of the sphenoid sinus should be opened as wide as the lateral wall and inferiorly to the level of the floor, especially in deeply pneumatized sphenoid sinuses. Objectives. The incidence of isolated sphenoid IP is exceedingly low. So far, there have not been studies on the usual origin and recurrence sites of the sphenoid sinus. We sought to identify the sites of origin and recurrence and describe clinical characteristics, radiological features, and proper endoscopic management. Patients and methods. We retrospectively reviewed medical records of patients with IP of the sphenoid sinus. Data collection included clinical presentations, origin and recurrent sites, radiological features, and surgical methods. Results. Seven patients were identified. The most common symptoms were headache and nasal obstruction. Radiological findings showed that most tumors extended into the nasal cavity or ethmoid sinus combined frequently with erosion of the lateral wall or intersinus septum. We noted simultaneous attachment to multiple walls in five subjects, including both lateral wall and floor attachment in three subjects.     

Anatomical relationship of pterygoid process pneumatization and vidian canal

IntroductionThe vidian canal acts as landmark for the identification of the petrous carotid artery, especially during extended endoscopic endonasal approaches in cranial base surgeries. In order to localize the canal and to understand the relationship of pneumatization of pterygoid process to the type of vidian canal, this study was designed.ObjectivesThe objective was to describe the anatomical relationship of pneumatization of the pterygoid process with types of vidian canal. The length of vidian canal, relationship to medial plate of pterygoid process and relationship to the petrous part of internal carotid artery were evaluated.MethodsHead computer tomography scans of 52 individuals for suspected paranasal pathology were studied. The degree of sphenoid sinus pneumatization, pterygoid process pneumatization and types of vidian canal (type 1, 2 and 3) were noted. The length of vidian canal, distance from the plane of medial pterygoid plate and relation of vidian canal to the junction of petrous and Gasserian (ascending) part of internal carotid artery was noted.Results46 (92%) sphenoid sinuses were of the sellar variety. Out of 104 sides that were studied, 57 sides demonstrated a pneumatised pterygoid process and 47 were not pneumatised. In 49 sides (47.1%) the vidian canal was on the same plane as that of the medial pterygoid plate in the coronal section. The vidian canal partially protruded into the sphenoid sinus (type 2) was the most common type (50.9%), found both on right and left sides. There is a statistically significant association between the pterygoid process pneumatization and occurrence of type 2 and type 3 vidian canal configuration. The average length of the vidian canal was 16.16 ± 1.8 mm. In 96 sides, the anterior end of vidian canal was inferolateral to petrous part of internal carotid artery in the coronal plane.ConclusionPneumatization of the pterygoid process indicates either type 2 or type 3 vidian canal configuration.     

Endoscopic transnasal transpterygopalatine fossa approach to the lateral recess of the sphenoid sinus

OBJECTIVES: Lesions affecting the lateral recess of the sphenoid sinus are rarely discussed in the literature as a separate entity. This region is difficult to visualize and manipulate through the transnasal routes, especially when extensive pneumatization is present. External approaches to this area involve extensive surgery and are associated with significant morbidity. The objectives of this study are to present our experience with the endoscopic transpterygopalatine fossa approach as a method for exposing and manipulating lesions of the lateral recess of the sphenoid and to illustrate the detailed surgical steps of the procedure. STUDY DESIGN: Retrospective review. METHODS: Clinical charts of patients who had lesions originating from or extending into the lateral recess of the sphenoid sinus and who were treated at our institutions from September 1995 to June 2002 were retrospectively reviewed. All these patients were managed by the endoscopic transpterygopalatine fossa approach. RESULTS: Twelve patients (7 males and 5 females) were included in the study. Lesions included seven cerebrospinal fluid (CSF) leaks and five tumors. One patient with squamous cell carcinoma (SCC) of the sphenoid died of his disease. All CSF leaks were successfully repaired, and benign tumors were removed with good local control through the follow-up period. CONCLUSION: The endoscopic transpterygopalatine fossa approach is an excellent approach for dealing with lesions of the sphenoid lateral recess.     

Shortcomings of lateral sinus radiograph in the preoperative determination of the extent of endonasal endoscopic sinus surgery

Lateral sinus radiograph is helpful in determining the distances between certain anatomic landmarks in preparation for endonasal endoscopic sinus surgery. However, some misleading factors limit the usefulness of this radiograph. In this study these distances were measured in 49 patients and compared with measurements obtained from another imaging modality, magnetic resonance imaging, which provides more accurate measurements. Results show a discrepancy in the measurements of distances between some of these landmarks that cannot be explained by the factor of magnification alone on the sinus radiographs. Statistical analysis of the results for women revealed a significant discrepancy between the distances from the nasal spine to the midfovea ethmoidalis, the sphenoethmoid junction, and the posterior sphenoid wall as measured on MR images and those as measured on lateral sinus radiographs (P<.05). For men the same was true for the distances from the nasal spine to the midfovea ethmoidalis and the posterior sphenoid wall (P<.05). It is concluded that there should be reservations in the surgical application of data provided by the lateral sinus radiograph before endoscopic sinus surgery.     

Interpretation of Anatomic Variations of Computed Tomography Scans of the Sinuses: A Surgeon's Perspective

Four hundred computed tomography (CT) scans of patients undergoing endoscopic sinus surgery were studied with particular attention to anatomic variations. Six specific variations were identified that may predispose the surgeon to inadvertent penetration of the orbit or anterior cranial cavity. These anatomic variants are: 1. lamina papyracea lies medial to the maxillary sinus ostium; 2. maxillary sinus hypoplasia; 3. fovea ethmoidalis abnormalities, such as low or sloping fovea and encephaloceles; 4. lamina papyracea dehiscence resulting in herniation of orbital content into the ethmoids; 5. sphenoid sinus wall variations such as septa attached to the carotid covering, and penetration of the sphenoid by the internal carotid artery or optic nerve; 6. sphenoethmoid cells (Onodi cells), the most posterior ethmoid cells pneumatizing lateral and superior to the sphenoid and intimately associated with the optic nerve.     

Correlation between temporal bone pneumatization, location of lateral sinus and length of the mastoid process.

The relationship between temporal bone pneumatization and the location of the lateral sinus and length of the mastoid process was investigated in 60 fresh frozen adult temporal bones, by plain X-rays, computed tomography and surgical dissection including otomicroscopic findings. Temporal bone pneumatization was classified as small, moderate and large. After drilling, the shortest distances between the middle fossa dura and mastoid tip representing the mastoid length and between the sigmoid sinus and posterior border of external auditory canal were measured and compared to the degree of pneumatization. The distances in the specimens with pathological eardrum and adhesions in the middle ear were compared to the ones without gross pathology. The length of mastoid process was significantly shorter in specimens with small pneumatization than those with large (Mann Whitney P less than 0.001). The specimens with a pathological eardrum and middle ear adhesions had a significantly shorter mastoid length than those without gross pathology. There was no significant difference between degree of pneumatization and the shortest distance between sigmoid sinus and external auditory canal (Mann Whitney P greater than 0.05). It is demonstrated that the 'under-developed' mastoid process can be a consequence of hampered pneumatization.     

Pneumatization of the sphenoid sinus in children evaluated by magnetic resonance imaging

Previous studies concerned with the normal development of the sphenoid sinus have reported that the onset of initial pneumatization varies from 6 months to 4 years of life, and that the pneumatization is completed by 12 to 14 years of age. This study was designed to evaluate the age-related development of the sphenoid sinus pneumatization in children using magnetic resonance (MR) imaging technique. MR images of the sphenoid sinus in 152 children, ages 2 months to 163 months, were retrospectively reviewed. The degree of pneumatization was classified into four grades as 0, 1, 2, and 3 in axial images, and into five grades as 0, 1, 2, 3, and 4 in sagittal images. The numbers of grades were age-matched in the studied children. The pneumatized sphenoid sinus was identifiable as early as 2 months of age on axial image, and 4 months on sagittal image. Pneumatized sphenoid sinuses were identified in 100% of the subjects studied at the age of 3 years on axial image, and 6 years on sagittal image. All the children over 9 years old showed pneumatization of grade 2 or more both on axial and sagittal images. The results of this study may indicate that the sphenoid sinus begins and completes pneumatization earlier than previously described.     

Analysis of sphenoid sinus in the operative plane of endoscopic transsphenoidal surgery using computed tomography

Recently, the endoscopic transsphenoidal approach for sphenoid sinus or intracranial lesion has gained more popularity and the study of the surgical anatomy and relationships of the sphenoid sinus has gained increased significance. The aim of this study was to clarify the anatomical features of the sphenoid sinus including surrounding structures as seen in the operative view of endoscopic transsphenoidal surgery. The various distances in the sphenoid sinus as well as the relationships between the sphenoid sinus ostium (SO) and important structures such as the optic canal (OC) and carotid artery (CA) according to the presence of Onodi cell (sphenoethmoidal cell; Onodi group vs. non-Onodi group) were assessed using multiplanar and three-dimensional model of CT scans in 100 patients. The SO was more inferior in Onodi group and located superior to the lowest point of the sella. The horizontal distance from the SO to sella was approximately 13 or 14 mm depending on the existence of Onodi cells. Regardless of Onodi cell, the whole course of the OC in the sinus ran superolaterally to inferomedially in the endoscopic view. However, Onodi cell made the angles from the SO to OC larger. In Onodi group, the CA was located from the SO in a superolateral direction, but in non-Onodi group, the CA was located from the SO in the inferolateral direction. This study provides anatomical information about the sphenoid sinus, with important surgical distances between the SO and surrounding structures measured, which is essential to avoid complications during transsphenoidal surgery.