Important Anatomical Variant Research Articles

Anatomy and Pathology of the Skull Base: Malignant and Nonmalignant Lesions.

The skull base (SB) is the osseous foundation of the cranial vault. It contains many openings that allow communication between the extracranial and intracranial structures. This communication is crucial in normal physiologic processes yet may also arrow spread of disease. This article provides a comprehensive review of SB anatomy including important landmarks and anatomic variants relevant to SB surgery. We also illustrate the diverse pathologies affecting the SB.

Normal and Variant Sinonasal Anatomy.

The anatomy of the paranasal sinuses is complex with multiple anatomic variants that can predispose patients to disease. Knowledge of this complex anatomy is important not only for successful treatment but to also avoid complications at the time of surgery. This article will review the anatomy with emphasis on a variety of clinically important anatomic variants.

Fenestration of the vertebrobasilar junction detected with multidetector computed tomography angiography.

The complex embryonic origin of the vertebrobasilar system may result in a wide range of anatomical variations. It has been hypothesized that the formation of fenestrations are likely to occur due to the failure of regression of the bridging arteries that connect the longitudinal neural arteries during embryogenesis. Fenestration of the vertebrobasilar system is a rare anatomical variation that involves a luminal division of the artery, that has a single origin into two separate and parallel channels which are rejoined distally. Fenestrations are important anatomical variants in patients undergoing endovascular and invasive intracranial interventions. Vascular fenestration has been associated with aneurysms, arteriovenous malformations, neuralgia, and vertebrobasilar ischaemia. We report on 3 cases of fenestration at the vertebrobasilar junction in 1 female and 2 male patients, respectively, using multidetector computed tomography angiography. The length of the fenestrated segment of the artery measured 4.41 mm, 3.90 mm, and 5.90 mm, respectively in the patients. Our report is clinically important as the presence of this anatomical variation may influence the management of cervical and intracranial pathologies. Increased awareness of the prevalence of anatomic variations contributes to the advancement of noninvasive imaging capabilities.

Do Something or Do Nothing? Anatomical Variants and Incidental Findings on Cone Beam CT. Part 2: Beyond the Dento-alveolar Complex and Neighbouring Structures

Cone beam computed tomography (CBCT) is a popular and often indispensable imaging modality used for the dento-alveolar tissues and immediate surrounding structures. It can be used across several dental disciplines including endodontics, implant planning, oral surgery and orthodontics. Furthermore, it is commonly used in the medical specialties of oral and maxillofacial surgery (OMFS) and ear, nose and throat (ENT) surgery. In part 1 of this series, we described some of the common incidental findings found in the dento-alveolar complex and immediate neighbouring structures. Part 2 looks further afield and depicts some common and important incidental findings and anatomical variants that can be found on larger fields of view. CPD/Clinical Relevance: Many incidental findings are innocuous, yet their recognition and documentation are essential because some will warrant medical or surgical intervention.

An artificial intelligence algorithm that identifies middle turbinate pneumatisation (concha bullosa) on sinus computed tomography scans.

Convolutional neural networks are a subclass of deep learning or artificial intelligence that are predominantly used for image analysis and classification. This proof-of-concept study attempts to train a convolutional neural network algorithm that can reliably determine if the middle turbinate is pneumatised (concha bullosa) on coronal sinus computed tomography images. Consecutive high-resolution computed tomography scans of the paranasal sinuses were retrospectively collected between January 2016 and December 2018 at a tertiary rhinology hospital in Australia. The classification layer of Inception-V3 was retrained in Python using a transfer learning method to interpret the computed tomography images. Segmentation analysis was also performed in an attempt to increase diagnostic accuracy. The trained convolutional neural network was found to have diagnostic accuracy of 81 per cent (95 per cent confidence interval: 73.0-89.0 per cent) with an area under the curve of 0.93. A trained convolutional neural network algorithm appears to successfully identify pneumatisation of the middle turbinate with high accuracy. Further studies can be pursued to test its ability in other clinically important anatomical variants in otolaryngology and rhinology.

Relation between volume of sphenoid sinuses and protrusion of Vidian nerve: possible applications to Vidian neurectomy.

Vidian neurectomy is a surgical procedure applied to different pathological conditions, including chronic rhinitis and sphenopalatine neuralgia. The choice of the correct surgical approach depends upon the possible protrusion of Vidian nerve into the sphenoid sinuses. The present study analyzes the possible relationship between protrusion of Vidian nerve and volume of sphenoid sinuses. In total, 320 maxillofacial CT-scans were retrospectively assessed. Subjects equally divided among males and females (age range 18-94years) were divided into three groups according to the profile of Vidian nerve protrusion: type 1: Vidian nerve inside the sphenoid corpus; type 2: partially protruding into the sphenoid sinus; and type 3: entirely protruding into the sphenoid sinus through a stalk. Volume of sphenoid sinuses was extracted through the ITK-SNAP-free software and automatically calculated. Possible statistically significant differences in prevalence of the three types between males and females were assessed through Chi-squared test (p < 0.05). Differences in volume of sphenoid sinuses in subjects included within the three types were assessed through one-way ANOVA test (p < 0.05), separately for males and females. Type 2 was the most prevalent (46.5%), followed by type 1 (38.8%) and type 3 (14.7%), without significant differences according to sex (p > 0.05). Volume significantly increased passing from type 1 to type 3 both in males (p < 0.01) and in females (p < 0.01). The results prove the existence of a strict relationship between sphenoid sinuses pneumatization and protrusion of the Vidian canal and give a contribution to the knowledge of this important anatomical variant in endoscopic surgery.

Avoiding Misdiagnosis in Patients With Posterior Circulation Ischemia: A Narrative Review.

Posterior circulation strokes represent 20% of all acute ischemic strokes. Posterior circulation stroke patients are misdiagnosed twice as often compared to those with anterior events. Misdiagnosed patients likely have worse outcomes than correctly diagnosed patients because they are at risk for complications of the initial stroke as well as recurrent events due to lack of secondary stroke prevention and failure to treat the underlying vascular pathology. Understanding important anatomic variants, the clinical presentations, relevant physical examination findings, and the limitations of acute brain imaging may help reduce misdiagnosis. We present a symptom-based review of posterior circulation ischemia focusing on the subtler presentations with a brief discussion of basilar stroke, both of which can be missed by the emergency physician. Strategies to avoid misdiagnosis include establishing an abrupt onset of symptoms, awareness of the nonspecific presentations, consideration of basilar stroke in altered patients and using a modern approach to diagnosis of the acutely dizzy patient.

Buckled Thyroid Cartilage: An Anatomic Variant

Anatomic abnormalities in the larynx can cause significant and bothersome symptoms. Identified here is an anatomical variant of the thyroid cartilage. This study is a retrospective case series of 11 subjects diagnosed with an anatomic variant of the thyroid cartilage. Patients with an anatomic inward buckling of the thyroid cartilage, termed here as buckled thyroid cartilage, were identified through a 20-year retrospective chart review of a tertiary care laryngology practice. We describe 11 patients with fullness or asymmetry in the area of the false vocal fold and an associated inward buckling of the thyroid cartilage on computed tomography scan. All patients presented with a bothersome voice-related complaint. The most common presenting complaints were hoarseness (54%), globus sensation (45%), or vocal fatigue (27%). One patient was found to have a history of known laryngeal trauma. Surgical correction through an external approach on one patient was successfully performed with subsequent resolution of symptoms. We postulate that deformity and protrusion of the false vocal fold can result in a dampening effect on the vibratory capacity of the vocal fold that can lead to symptomatic hoarseness and vocal fatigue. Buckled thyroid cartilage is, therefore, an important anatomical variant to be aware of and be able to recognize.

Prevalence of the aberrant right subclavian artery reported in a published systematic review of cadaveric studies: The impact of an outlier.

The aberrant or anomalous right subclavian artery (ARSA), which arises directly from the aortic arch and crosses to the right side usually behind the esophagus, is a rare but clinically important anatomical variant. A published systematic review (SR) of 15 cadaveric studies on ARSA reported that prevalence ranged from 0.2% to 13.3% of the general population; the total unweighted prevalence of ARSA was 325 cases in 13,208 bodies or 2.46%. The present review, however, found that the 13.3% figure was for 133 cases from a larger case series without a denominator. Three other studies either had an imprecise denominator or were limited to congenital conditions associated with ARSA. After exclusions and modifications, ARSA prevalence for the remaining 11 studies in the SR ranged from 0.19%, with a 95% confidence interval (CI) of 0.00-1.08%, to 2.52% (CI= 0.69-6.32%). The unweighted prevalence for all 11 studies combined was 1.23%, and the pooled prevalence estimate from a meta-analysis was 1.30% (CI = 0.86-1.82%). In conclusion, overall findings from SRs on the prevalence of rare anatomical variants such as ARSA may be affected by outliers. Clin. Anat. 30:1024-1028, 2017. © 2017 Wiley Periodicals, Inc.

Radiologic Assessment of Native Renal Vasculature: A Multimodality Review.

A wide range of clinically important anatomic variants and pathologic conditions may affect the renal vasculature, and radiologists have a pivotal role in the diagnosis and management of these processes. Because many of these entities may not be suspected clinically, renal artery and vein assessment is an essential application of all imaging modalities. An understanding of the normal vascular anatomy is essential for recognizing clinically important anatomic variants. An understanding of the protocols used to optimize imaging modalities also is necessary. Renal artery stenosis is the most common cause of secondary hypertension and is diagnosed by using both direct ultrasonographic (US) findings at the site of stenosis and indirect US findings distal to the stenosis. Fibromuscular dysplasia, while not as common as atherosclerosis, remains an important cause of renal artery hypertension, especially among young female individuals. Fibromuscular dysplasia also predisposes individuals to renal artery aneurysms and dissection. Although most renal artery dissections are extensions of aortic dissections, on rare occasion they occur in isolation. Renal artery aneurysms often are not suspected clinically before imaging, but they can lead to catastrophic outcomes if they are overlooked. Unlike true aneurysms, pseudoaneurysms are typically iatrogenic or posttraumatic. However, multiple small pseudoaneurysms may be seen with underlying vasculitis. Arteriovenous fistulas also are commonly iatrogenic, whereas arteriovenous malformations are developmental (ie, congenital). Both of these conditions involve a prominent feeding artery and draining vein; however, arteriovenous malformations contain a nidus of tangled vessels. Nutcracker syndrome should be suspected when there is distention of the left renal vein with abrupt narrowing as it passes posterior to the superior mesenteric artery. Filling defects in a renal vein can be due to a bland or tumor thrombus. A tumor thrombus is most commonly an extension of renal cell carcinoma. When an enhancing mass is located predominantly within a renal vein, leiomyosarcoma of the renal vein should be suspected. ©RSNA, 2017.

The Preoperative Sinus CT: Avoiding a "CLOSE" Call with Surgical Complications.

Although functional endoscopic sinus surgery is an effective means of treating patients with recurrent and refractory sinusitis, the procedure is not without risk of serious surgical complications. Preoperative computed tomography (CT) affords radiologists the opportunity to prospectively identify anatomic variants that predispose patients to major surgical complications; however, these critical variants are not consistently evaluated or documented on preoperative imaging reports. The purpose of this review is to illustrate important anatomic variants and landmarks on the preoperative sinus CT with a focus on those that predispose patients to surgical complications. These critical variants and landmarks can be quickly recalled and incorporated into the preoperative imaging report through the use of the mnemonic "CLOSE": Cribriform plate, Lamina papyracea, Onodi cell, Sphenoid sinus pneumatization, and (anterior) Ethmoidal artery. This approach will greatly enhance the value of the preoperative imaging report for referring otolaryngologists and help reduce the risk of surgical complications. (©) RSNA, 2016 Online supplemental material is available for this article.

A Left Nonrecurrent Inferior Laryngeal Nerve in a Patient with Vascular and Atlantoaxial Abnormalities: A Case Report.

We present a case of a fifty-eight-year-old woman with chronic occipital headaches and neck pain who underwent C2-C3 anterior and posterior fusion for cervical instability. Perioperative discovery of multiple cervical anomalies, including a left nonrecurrent inferior laryngeal nerve, greatly complicated the approach. A left nonrecurrent inferior laryngeal nerve is a rare anatomical anomaly that may co-occur with other cervical abnormalities. It is an important anatomical variant to consider during an anterior approach to the cervical spine, especially when preoperative images of the cervical region show vascular and cervical spine anatomical anomalies.

Flow-Through Flap for Salvage of Fibula Osseocutaneous Vascular Variations: A Surgical Approach and Proposed Modification of Its Classification

The osseocutaneous fibula free flap is commonly used in mandibular reconstruction. Clinically important anatomic variants of the donor vessels have been reported. The authors describe a rare variant encountered while raising an osseocutaneous fibula flap. The fibula was supplied by the peroneal vessels and the overlying skin paddle was supplied by musculocutaneous perforators arising from the posterior tibial vessels. By raising 2 separate free flaps and configuring them in microvascular series with the fibula acting as a flow-through flap, the reconstruction was successful. Although the anatomic variant has been described, the authors' approach to it has not. The benefits of this method over other options include preservation of a skin paddle for monitoring and watertight oral closure and a long pedicle to the skin paddle permitting a wide arc of movement. The authors suggest a modification to the existing classification of perforators to the lateral leg skin to guide intraoperative decision making.

The salivary ducts of Wharton and Stenson: Analysis of normal variant sialographic morphometry and a historical review

Submandibular and parotid salivary glands acquire lengthy ducts as they migrate during development. No conclusive reports exist on clinically important anatomical normal variants and morphometry of the submandibular duct of Wharton and the parotid duct of Stenson. We retrospectively analyzed 67 normal digital subtraction sialograms on patients ranging from 16 to 85 years of age (M:F=15:52). In 43 sialograms, the mean parotid duct length was 50 mm. The mean width of the proximal, mid, and distal segments of the parotid duct were 1.8 mm, 1.1 mm, and 1.6 mm, respectively. An accessory parotid gland was present in 68% of patients, with a mean angle of confluence of its tributary duct with the parotid duct of 53°. In 24 sialograms the mean length of the submandibular duct was 58 mm. The mean width of the proximal, mid, and distal segments of the submandibular duct were 2.0 mm, 2.7 mm, and 2.1 mm, respectively. The submandibular duct genu had a mean angle of 115°. The effect of independent variables (age, gender, and side) was statistically tested on the dependent variables (length, mean calibre, and angle) using regression analysis. None of the independent variables affected variations in length, size and angulation. These reported comprehensive and detailed morphometrics are useful for therapeutic planning of luminal procedures on the salivary ducts, including sialography, sialoendoscopy, interventional therapies, and lithotripsy.

Nonrecurrent Laryngeal Nerve: A Case Report and a Review of an Important Anatomical Variant

ABSTRACTAn important anatomical structure commonly encountered during major head and neck surgery is the recurrent inferior laryngeal nerve. Nonrecurrent inferior laryngeal nerve variants are rarely encountered. Although much less common, these variants represent a significant risk for intraoperative nerve injury and patient morbidity. We present a case of a right nonrecurrent inferior laryngeal nerve variant along with a retrospective analysis and systematic review investigating the overall incidence of these variants.How to cite this articleSukharamwala P, Korbin S, Ghani A, Smith J. Nonrecurrent Laryngeal Nerve: A Case Report and a Review of an Important Anatomical Variant. World J Endoc Surg 2012;4(3):112-114.

Posterior Lumbar Vein Off the Retrohepatic Inferior Vena Cava: A Novel Anatomical Variant With Surgical Implications

Resection of tumors involving the inferior vena cava requires vascular control of posteriorly draining lumbar veins to ensure a bloodless field. Surgical texts and atlases assert that lumbar veins do not insert into the inferior vena cava superior to the renal hilum. However, at our institution we have encountered patients undergoing inferior vena cava tumor thrombectomy who have a posterior lumbar vein cephalad to the renal veins. Since this represents an unrecognized source of hemorrhage, we investigated the frequency of a superior lumbar vein in cadaveric dissection. Retroperitoneal cadaveric dissection of the inferior vena cava was done to assess the frequency of a lumbar vein draining into the inferior vena cava cephalad to the renal veins. Of the 49 cadaveric dissections performed 19 (38.8%) showed a single posterior lumbar vein between the diaphragm and the renal hilum. Of these 19 cadavers 15 (78.9%) were male. This vein was located an average ± SD of 7.4 ± 0.6 cm cephalad to the right renal vein and it was 3.7 ± 1.6 cm in diameter. In all cadavers this vein inserted within 30 degrees to the left or right of the posterior (also termed dorsal) aspect of the inferior vena cava. The identification of a lumbar vein between the renal hilum and the diaphragm represents an important anatomical variant that occurs in a significant percent of individuals. Surgeons will benefit from the knowledge of this variant of inferior vena cava vasculature and should anticipate the presence of this vein to prevent unnecessary morbidity and mortality secondary to unexpected hemorrhage, particularly in male patients.

The Onodi Cell

The Onodi cell is the posterior-most ethmoid air cell and an important anatomical variant because of the intimate spatial relationship with the optic nerve, internal carotid artery, and sellar floor during sphenoid sinus surgery. The authors evaluated the incidence of Onodi cells, their clinical importance, and the association between preoperative radiological findings and surgical findings. Case series with chart review. Tertiary care medical center. The authors retrospectively reviewed the medical records of 162 cases, including preoperative paranasal sinus computed tomography (PNS CT) findings and the findings with the endoscopic endonasal transsphenoidal approach (EETSA). They evaluated the prevalence of Onodi cells and the clinical manifestations in the patients with these cells. They also examined the clinical significance of these cells during EETSA. Onodi cells were identified in the preoperative PNS CT of 53 patients, whereas Onodi cells were observed in 54 (33.3%) of the 162 patients at EETSA. The Onodi cells were bilateral in 23 patients and unilateral in 31. In all cases, the Onodi cells limited the exposure of the sellar floor. Only after removing these cells was the entire sellar floor exposed so that the tumors could be removed completely. Onodi cells were observed more frequently than in previous studies, and 98.1% of them were identified on preoperative PNS CT. When reviewing PNS CT images preoperatively, one needs to identify the presence of Onodi cells. The Onodi cells must be removed to completely resect tumors located in the sellar region during EETSA.

1766 POSTERIOR LUMBAR VEIN OFF THE RETROHEPATIC INFERIOR VENA CAVA: A NOVEL ANATOMICAL VARIANT WITH SURGICAL IMPLICATIONS

You have accessJournal of UrologyKidney Cancer: Advanced1 Apr 20111766 POSTERIOR LUMBAR VEIN OFF THE RETROHEPATIC INFERIOR VENA CAVA: A NOVEL ANATOMICAL VARIANT WITH SURGICAL IMPLICATIONS Ammara Abbasi, Timothy Johnson, Renee Kleris, Kai Ying, Michael Bonner, Shishir Maithel, David Kooby, and Viraj Master Ammara AbbasiAmmara Abbasi Atlanta, GA More articles by this author , Timothy JohnsonTimothy Johnson Atlanta, GA More articles by this author , Renee KlerisRenee Kleris Atlanta, GA More articles by this author , Kai YingKai Ying Atlanta, GA More articles by this author , Michael BonnerMichael Bonner Atlanta, GA More articles by this author , Shishir MaithelShishir Maithel Atlanta, GA More articles by this author , David KoobyDavid Kooby Atlanta, GA More articles by this author , and Viraj MasterViraj Master Atlanta, GA More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2011.02.2094AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Resection of renal tumors involving the inferior vena cava (IVC) requires vascular control of posteriorly draining lumbar veins to ensure a bloodless field. Surgical texts and atlases assert that lumbar veins do not insert into the IVC superior to the renal hilum. However, we have encountered patients undergoing IVC tumor thrombectomy at our institution who exhibited a posterior lumbar vein cephalad to the renal veins. As this represents an unrecognized source of hemorrhage, we sought to investigate the frequency of a superior lumbar vein in cadaveric dissections. METHODS Retroperitoneal cadaveric dissections of the IVC were performed to assess the frequency of a lumbar vein draining into the IVC cephalad to the renal veins. RESULTS 49 cadaveric dissections were performed. 19 (38.8%) exhibited a single posterior lumbar vein between the diaphragm and renal hilum. Of these 19 cadavers, 15 (78.9%) were male. This vein was located on average 7.4 cm (SD 0.6) cephalad to the right renal vein and was 3.7 mm (SD 1.6) in diameter. In all cadavers, this vein inserted within 30° to the left or right of the posterior, also termed dorsal, aspect of the IVC. CONCLUSIONS The identification of a lumbar vein between the renal hilum and diaphragm constitutes an important anatomical variant that occurs in a significant percentage of individuals. Surgeons will benefit from knowledge of this variant of the IVC vasculature, and should anticipate the presence of this vein to prevent unnecessary morbidity and mortality secondary to unexpected hemorrhage, particularly in male patients. Table 1. Raw data Gender Posterior Vessel Above the Renal Veins? Distance form the Midpoint of Right Renal Vein (cm) Diameter of the vein (mm) Radial location (o'clock) M Y 8 4 – M Y 8.5 4.5 – M Y 8 5 7 M Y 7.5 4 7 M Y 8.4 3 6 M Y 7 2.5 6.5 F Y 6.3 5.5 5 F Y 7.5 3 7 M Y 7.1 3.5 6 M Y 7.3 7 6.5 M Y 7.2 4.5 – M Y 7.2 4 6 M Y 6.4 2.5 7 F Y 6.7 1.2 6 M Y 6.8 7 7 M Y 7.4 3.5 8 M Y 7.6 1.8 6 M Y 7.4 1.9 7 F Y 8.3 2.2 6 F N F N F N F N F N F N F N M N M N M N M N M N F N F N F N F N F N F N M N M N M N M N M N F N M N F N M N M N F N F N © 2011 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 185Issue 4SApril 2011Page: e708-e709 Advertisement Copyright & Permissions© 2011 by American Urological Association Education and Research, Inc.MetricsAuthor Information Ammara Abbasi Atlanta, GA More articles by this author Timothy Johnson Atlanta, GA More articles by this author Renee Kleris Atlanta, GA More articles by this author Kai Ying Atlanta, GA More articles by this author Michael Bonner Atlanta, GA More articles by this author Shishir Maithel Atlanta, GA More articles by this author David Kooby Atlanta, GA More articles by this author Viraj Master Atlanta, GA More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Radix entomolaris dificultad y reto endodóntico

The most important anatomical variant which presents the first molar is third distolingual additional root called radix entomolaris paramolaris call or oral. In root canal treatment is important to have complete information on variations of the root canals to the extent that this ensures the result substantially. For endodontic treatment to succeed, it is necessary to locate all the canals, clean them thoroughly and completely sealed with an inert material. The endodontist must know the internal morphology of permanent teeth and possible variations that they can have as is the case of an additional root located on the tongue (the radix entomolaris) or buccally (the radix paramolaris). The root canal anatomy is very complex and unpredictable and understanding of the presence of an additional root is important because it determines the success of endodontic treatment.

CT Angiography of the Mesenteric Circulation

Significant advancements in computed tomography (CT) scanner technology along with the development of powerful and affordable 3-dimensional (3D) software have resulted in new applications for CT imaging. The mesenteric vasculature was traditionally imaged with conventional angiography, but can now easily be imaged rapidly and safely using multidetector-row CT (MDCT) scanners and 3D imaging software. CT can now be used to visualize the normal mesenteric vasculature, both arteries and veins, identify important anatomic variants, and evaluate a wide range of pathology. This article examines the technique of MDCT and its role in imaging the mesenteric circulation.