Ophthalmic artery originating from the anterior cerebral artery: anatomo-radiological study, histological analysis, and literature review.

The ophthalmic artery has an anomalous origin in 2-3 % of cases and rarely arises from the anterior cerebral artery. Herein, we provide the first anatomical, radiological, and histological description of such an anomalous origin, together with a literature review. During the anatomical dissection of an 81-year-old Caucasian male, the absence of the right ophthalmic artery in its usual location was evident from an endonasal transsphenoidal perspective. The specimen was then studied in detail, through multiple dissections, corrosion casting, high-resolution CT, and histological analysis. The English literature on anomalous origins of the ophthalmic artery was reviewed, together with reported associated pathologies. Anatomo-radiological analysis documented that the right ophthalmic artery arose from the inferior surface of A1 tract of the anterior cerebral artery (A1) and passed over the optic nerve in its subarachnoid tract. A meningo-ophthalmic artery was evident on the same side and reached the orbit through the superior orbital fissure. Histological examination of both internal carotid artery (ICA) walls documented a significantly decreased thickness of the tunica media and adventitia on the side of the anomalous ophthalmic artery, with a significantly different content of collagen types I and III. The literature review documented an association of aneurysms and anomalous ophthalmic arteries. To the best of our knowledge, this is the first anatomical report that includes a radiological and arterial wall analysis of a persistent ventral ophthalmic artery. The latter provides histological data that support the clinical evidence of a higher association of aneurysms with anomalous origins of the ophthalmic artery.

Multiple anatomical variations of the renal vessels associated with malrotated and unrotated kidneys: a case report.

Variations in the number of renal vessels represent the most common anatomical variations in renal vasculature. Here, a rare case of multiple anatomical variations of renal vessels was found in a 70-year-old female cadaveric dissection. Three renal arteries and two renal veins were observed to supply the right kidney, which was malrotated and ectopic; on the left side, the kidney was unrotated and presented two renal arteries and normal renal vein. In particular, we paid attention to the pattern of the three renal arteries that originated from the lateral side of the aorta and passed anteriorly to the inferior vena cava. A rare case of ovarian vein that drained into the right renal vein was also reported. The descriptions of these multiple anatomical variations should be considered by clinicians for performing correct surgical and radiological procedures.

Skull base embryology: a multidisciplinary review.

INTRODUCTION: The skull base represents a central and complex bone structure of the skull and forms the floor of the cranial cavity on which the brain lies. Anatomical knowledge of this particular region is important for understanding several pathologic conditions as well as for planning surgical procedures. Embryology of the cranial base is of great interest due to its pronounced impact on the development of adjacent regions including the brain, neck, and craniofacial skeleton. MATERIALS AND METHODS: Information from human and comparative anatomy, anthropology, embryology, surgery, and computed modelling was integrated to provide a perspective to interpret skull base formation and variability within the cranial functional and structural system. RESULTS AND CONCLUSIONS: The skull base undergoes an elaborate sequence of development stages and represents a key player in skull, face and brain development. Furthering our holistic understanding of the embryology of the skull base promises to expand our knowledge and enhance our ability to treat associated anomalies.

Identification of the internal carotid artery at the superior part of the cavernous sinus during endoscopic endonasal cavernous sinus tumor surgery.

BACKGROUND: Identification of the internal carotid artery (ICA) is essential for successful endoscopic endonasal cavernous sinus tumor surgery. This study aimed to develop a method for identifying the ICA in cavernous sinus tumors at the superior part of the cavernous sinus. METHODS: Ten fresh cadavers were studied with a 4-mm 0° and 30° endoscope to identify surgical landmarks of the ICA in the cavernous sinus. Clinical cases of cavernous sinus tumors were surgically treated using an endoscopic transpterygoid approach. RESULTS: Anatomical study indicated the ICA at the superior part of the cavernous sinus can be identified using three steps: 1) exposure of the optic nerve sheath by drilling the optic canal; 2) identification of the proximal orifice of the optic nerve sheath at the transition of the optic nerve sheath and dura mater of the tuberculum sellae; and 3) identification of the clinoid segment of the ICA at the distal dural ring just below the proximal orifice of the optic nerve sheath. Although the ICA was encased and transposed by tumors in preliminary surgical cases, the clinoid segment of the ICA was safely exposed at the superior part of the cavernous sinus using this method. CONCLUSIONS: Dural structures around the cavernous sinus are key to identifying the ICA at the superior part of the cavernous sinus. This method is expected to reduce the risk of ICA injury during endoscopic endonasal surgery for cavernous sinus tumors.

Three-dimensional susceptibility-weighted imaging at 7 T using fractal-based quantitative analysis to grade gliomas.

INTRODUCTION: Susceptibility-weighted imaging (SWI) with high- and ultra-high-field magnetic resonance is a very helpful tool for evaluating brain gliomas and intratumoral structures, including microvasculature. Here, we test whether objective quantification of intratumoral SWI patterns by applying fractal analysis can offer reliable indexes capable of differentiating glial tumor grades. METHODS: Thirty-six patients affected by brain gliomas (grades II-IV, according to the WHO classification system) underwent MRI at 7 T using a SWI protocol. All images were collected and analyzed by applying a computer-aided fractal image analysis, which applies the fractal dimension as a measure of geometrical complexity of intratumoral SWI patterns. The results were subsequently statistically correlated to the histopathological tumor grade. RESULTS: The mean value of the fractal dimension of the intratumoral SWI patterns was 2.086 ± 0.413. We found a trend of higher fractal dimension values in groups of higher histologic grade. The values ranged from a mean value of 1.682 ± 0.278 for grade II gliomas to 2.247 ± 0.358 for grade IV gliomas (p = 0.013); there was an overall statistically significant difference between histopathological groups. CONCLUSION: The present study confirms that SWI at 7 T is a useful method for detecting intratumoral vascular architecture of brain gliomas and that SWI pattern quantification by means of fractal dimension offers a potential objective morphometric image biomarker of tumor grade.

Cranial sutures: a multidisciplinary review.

INTRODUCTION: Progress in cranial suture research is shaping our current understanding of the topic; however, emphasis has been placed on individual contributing components rather than the cranial sutural system as a whole. Improving our holistic view helps further guide clinicians who treat cranial sutural abnormalities as well as researchers who study them. MATERIALS AND METHODS: Information from anatomy, anthropology, surgery, and computed modeling was integrated to provide a perspective to interpret suture formation and variability within the cranial functional and structural system. RESULTS: Evidence from experimental settings, simulations, and evolution suggest a multifactorial morphogenetic process associated with functions and morphology of the sutures. Despite molecular influences, the biomechanical cranial environment has a main role in both the ontogenetic and phylogenetic suture dynamics. CONCLUSIONS: Furthering our holistic understanding of the intricate cranial sutural system promises to expand our knowledge and enhance our ability to treat associated anomalies.

Endoscopic far-lateral approach to the posterolateral craniovertebral junction: an anatomical study.

Minimally invasive surgery to the posterolateral craniovertebral junction (CVJ) has not been sufficiently described. The aims of this study were to evaluate the feasibility of an endoscopic far-lateral approach to the posterolateral craniocervical junction and to better understand the related anatomy under distorted endoscopic view. Ten fresh cadavers were studied with 4-mm 0° and 30° endoscopes to develop the surgical approach and to identify surgical landmarks. After making a 3-cm straight incision behind the mastoid process, the superior oblique and rectus capitis posterior major muscles were partially exposed. An endoscope was then introduced and the two muscles were followed inferiorly until the posterior arch of the atlas appeared. The two muscles were removed to create ample working space without violating the posterior atlanto-occipital membrane. The vertebral artery was identified by the landmark of the posterior arch of the atlas, and the atlanto-occipital joint and foramen magnum were exposed. In addition to suboccipital craniectomy, transcondylar, supracondylar, and paracondylar extension by drilling were applicable through the narrow corridor under superb visualization. The intradural neurovascular structures from the acousticofacial bundle to the dorsal root of C2, anterolateral space of the foramen magnum, cerebellomedullary fissure, and fourth ventricle were clearly demonstrated. This endoscopic far-lateral approach offers excellent exposure of surgical landmarks around the posterolateral CVJ with minimal invasiveness. Endoscopic soft tissue dissection is key to creating the surgical corridor. This approach could offer an alternative to the conventional far-lateral approach in selected cases.

The temporo-parietal fascial flap in extended transnasal endoscopic procedures: cadaver dissection and personal clinical experience.

Due to progressively expanded indications of endoscopic transnasal surgery, having different reconstructive options in the armamentarium becomes of paramount importance. We herein report our experience with the use of the temporo-parietal fascial flap after extended endoscopic procedures for malignancies of the clival and nasopharyngeal regions. We focus our report on the surgical anatomy of this flap and the technique for its intranasal transposition through an infratemporal corridor. The main steps of the procedure and anatomic landmarks were highlighted, thanks to previous cadaver dissection. Five patients underwent an extended endoscopic resection for malignant tumors: one with persistent clival chordoma, three with recurrent nasopharyngeal carcinomas, and 1 recurrent nasopharyngeal adenoid cystic carcinoma. In all patients a temporo-parietal fascial flap was harvested to protect critical structures or irradiated denuded bone. The Mean harvesting and hospitalization time were 120 min and 5 days, respectively. No major or minor complications were observed. Whenever local flaps are not available for oncologic reasons or previous surgery, the temporo-parietal fascial flap is a safe and relatively easy option to protect the residual skull base and critical structures such as the internal carotid artery and dura of the posterior cranial fossa, after extended endoscopic resections.

Anatomical landmarks for transoral robotic tongue base surgery: comparison between endoscopic, external and radiological perspectives.

PURPOSE: To describe the transoral viewpoint of the tongue base anatomy, focusing on a superior to inferior perspective, which is less familiar to the head and neck surgeon but, at the same time, worthy to be known given the expanding interest and diffusion of the transoral robotic technique. METHODS: Seven heads were dissected, two with the Da Vinci(®) robotic system, three by means of a transoral endoscopic approach and another two by means of a lateral "traditional" external approach. Ten normal patients, with normal oral cavity and oropharynx, were studied as control samples by means of a 3-T MRI scanner. RESULTS: Major neurovascular elements are placed laterally and deeply within the tongue base. Dissection within intrinsic and genioglossus muscles is safe because the main trunk of the lingual artery lies on the lateral surface of genioglossus muscle, covered by the hyoglossus muscle. The hypoglossal nerve, with its comitant vein, is more lateral, lying on the external surface of the hyoglossus muscle. Radiological evaluation can visualize important details of this complex anatomy. The position of the vessels can be directly identified, whereas major nerves are more difficult to be visualized unless they are surrounded by fibro-fatty tissue. CONCLUSIONS: A medial to lateral dissection of the tongue base can be considered safe. A strict collaboration with the radiologist is helpful in approaching these cases by means of a robotic technique and in improving a true 3D understanding of this complex anatomy.

Endoscopic telovelar approach to the fourth ventricle: anatomic study.

The telovelar approach allows reliable access to the fourth ventricle and avoids the splitting of the vermis and its associated "posterior vermal split syndrome." Our objective was to describe the endoscopic topographical anatomy of the telovelum approach to the fourth ventricle as accessed by the cerebellomedullary corridor. A series of 20 fresh and fixed injected anatomical specimens were used. The endoscopic equipment consisted of rigid endoscopes with different lens angles, while the extradural step required the use of the microscope and/or the exoscope. All the anatomical landmarks and relationships within the fourth ventricle and the cerebellomedullary fissure were identified by means of the endoscopic microscope/exoscope-assisted telovelar approach. In conclusion, we showed that the endoscope is a valid tool to gain an anatomic understanding of the fourth ventricle reached by means of the telovelar approach.

The subdiaphragmatic cistern: historic and radioanatomic findings.

BACKGROUND: In the past, sporadic demonstrations of the existence of a subarachnoid subdiaphragmatic cistern have been published. The aim of this study was to evaluate the anatomical characteristics of the subdiaphragmatic cistern of the pituitary gland. METHODS: After a complete review of the literature published on the topic, we report anatomical observations of the subdiaphragmatic cistern and its relationship to the pituitary gland and to the chiasmatic cistern. Ten cadaveric heads were studied using different techniques and surgical methods (plastination, plastic casts of the subarachnoid spaces, microscopic and transsphenoidal endoscopic approaches). Moreover, 3-T magnetic resonance images of ten healthy volunteers were analyzed to investigate the presence and anatomical variability of the subdiaphragmatic cistern. RESULTS: By means of our qualitative radioanatomic study, we found that the roof of the subdiaphragmatic cistern is formed by the diaphragma sellae, the floor by the superior face of the pituitary gland, the lateral walls by the arachnoidea extending laterally through the medial walls of the cavernous sinus, and the medial walls by the infundibular stem. The subdiaphragmatic cistern communicates by means of the ostium of the diaphragm with the chiasmatic cistern. CONCLUSION: We confirmed the existence of the subdiaphragmatic cistern. The overused term "suprasellar cistern" refers more to a complex of cisterns, formed by the subdiaphragmatic cistern, below the diaphragma sella, and by the chiasmatic cistern, above it, in direct communication with the lamina terminalis and carotid cisterns.

The veins of the nucleus dentatus: anatomical and radiological findings.

The veins of the dentate nucleus are composed of several channels draining the external surface and one single vein draining the internal surface. We analyzed specimens of the human cerebellum and described the central vein of the nucleus dentatus as the main venous outflow of the nucleus. The central vein of the nucleus dentatus is formed by a network of smaller vessels draining the sinuosities of the gray matter; it emerges from the hilum of the nucleus and runs along the superior cerebellar peduncle, opening in the anterior vermian vein. We looked for this structure and for the surrounding veins on ultra-high-field (7 Tesla) MR, using susceptibility-weighted imaging. An anatomical and radiological description of the veins of the dentate nucleus is provided, with some remarks on the future clinical applications that these findings could provide.

Angioarchitectural heterogeneity in human glioblastoma multiforme: a fractal-based histopathological assessment.

There is currently no standard technique to objectively quantify the microvascularization of brain tumors. Fractal analysis has been proposed as a useful descriptor of tumor microvascularity. Standardization of the fractal analysis methodology could offer a new tool for this type of characterization. In this study, we applied fractal analysis to the characterization of the different angioarchitectures found in specimens of glioblastoma multiforme (GBM), the most common and most malignant type of human brain tumor. A retrospective series of 114 primary GBM specimens was carried out. To quantify neoplastic microvascularity, the level of two-dimensional geometrical complexity of the microvascular patterns was assessed using the box-counting algorithm, which estimates the microvascular fractal dimension (mvFD). mvFD makes information on the non-Euclidean space filled by vessels embedded in the tumor microenvironment available because it depends on vessel number, shape, magnitude and distribution pattern. A mean mvFD value of 1.44 ± 0.17 (range: 1.06-1.87) was found. The coefficient of variation was 44%. The high geometric variability, found objectively, in these samples reflects the angioarchitectural heterogeneity underlying GBM. The present study shows that angioarchitectural subtypes can be identified by mvFD, making this parameter a potential tool for quantifying different neoplastic microvascular patterns.

Anterior interosseous nerve compression syndrome: is there a role for endoscopy?

BACKGROUND: Anterior interosseous nerve syndrome is characterized by paralysis of the flexor digitorum profundus, the flexor pollicis longus and the pronator quadratus muscles without sensory loss. Extended exploration of the anterior interosseous nerve is the surgical treatment of choice. The present study evaluates the feasibility of an endoscopic approach for nerve decompression. METHODS: Preparation of the anterior interosseous nerve was performed in ten human cadaver arms. Subsequently, one female patient suffering from anterior interosseous nerve syndrome was endoscopically operated on. FINDINGS: A skin incision of 3-4 cm in the proximal direction was made at the forearm, and the median nerve was visualized between the pronator teres muscle and the flexor digitorum superficialis. Subsequently, the anterior interosseus nerve branch was identified, followed distally and decompressed under endoscopic view. The procedure could be accomplished in all cases under endoscopic view. Due to the very steep surgical angle, a branch of the anterior interosseus nerve was injured in one cadaver case. In all other cases, no adverse effects were observed. In the clinical case, the anterior interosseus nerve was endoscopically identified and decompressed, but a skin incision of 5 cm was required. CONCLUSIONS: The results demonstrate that an endoscopic decompression of the anterior interosseus nerve is possible. Several difficulties occurred: Due to the depth of the surgical approach, especially in case of bulky muscles and very small skin incisions, the view is limited, harboring a higher risk of nerve injury. With more experience and specially designed endoscopes, application of this technique in anterior interosseus nerve compression syndrome might become more feasible.

Endoscopic transsphenoidal optic nerve decompression: an anatomical study.

PURPOSE: The endoscopic transnasal, transsphenoidal approach is considered by many a valid option to reach the sellar region and, in selected cases, to decompress the optic nerve. However, few data are available in literature about the real effectiveness of the procedure and the extent of nerve decompression needed to obtain a clinical result. The aim of this anatomical study was to describe the most important landmarks of the endoscopic transsphenoidal approach to the optic nerve. METHODS: Six silicone-injected cadaver heads were dissected via the endoscopic transnasal approach, performing a bilateral optic nerve decompression. The lateral optocarotid recess (OCR) and optic canal were identified in each case. Moreover, the relationship between the ophthalmic artery at its origin and the optic nerve was examined. RESULTS: Twelve decompressions of the optic nerve were performed, obtaining the following measurements: intercarotid distance 12 mm ± 1.5, median length of OCR 5 mm ± 1 and average length of optic nerve decompression 15 mm ± 2. The ophthalmic artery was observed emerging from the internal carotid artery (ICA) medially in six cases, ventrally in four cases and laterally in two cases. CONCLUSION: A wide optic nerve decompression may be obtained with transsphenoidal approach. However, the risk of ophthalmic artery injury seems to be more relevant than with supratentorial approaches, due to the intimate relationship between artery and nerve on its inferior surface. Knowledge of anatomical landmarks, such as lateral OCR and the position of the ophthalmic artery, is useful to prevent this injury.

Correlation of microvascular fractal dimension with positron emission tomography [(11)C]-methionine uptake in glioblastoma multiforme: preliminary findings.

Neuroradiological and metabolic imaging is a fundamental diagnostic procedure in the assessment of patients with primary and metastatic brain tumors. The correlation between objective parameters capable of quantifying the neoplastic angioarchitecture and imaging data may improve our understanding of the underlying physiopathology and make it possible to evaluate treatment efficacy in brain tumors. Only a few studies have so far correlated the quantitative parameters measuring the neovascularity of brain tumors with the metabolic profiles measured by means of amino acid uptake in positron emission tomography (PET) scans. Fractal geometry offers new mathematical tools for the description and quantification of complex anatomical systems, including microvascularity. In this study, we evaluated the microvascular network complexity of six cases of human glioblastoma multiforme quantifying the surface fractal dimension on CD34 immunostained specimens. The microvascular fractal dimension was estimated by applying the box-counting algorithm. As the fractal dimension depends on the density, size and shape of the vessels, and their distribution pattern, we defined it as an index of the whole complexity of microvascular architecture and compared it with the uptake of (11)C-methionine (MET) assessed by PET. The different fractal dimension values observed showed that the same histological category of brain tumor had different microvascular network architectures. Fractal dimension ranged between 1.19 and 1.77 (mean: 1.415+/-0.225), and the uptake of (11)C-methionine ranged between 1.30 and 5.30. A statistically significant direct correlation between the microvascular fractal dimension and the uptake of (11)C-methionine (p=0.02) was found. Our preliminary findings indicate that that vascularity (estimated on the histologic specimens by means of the fractal dimension) and (11)C-methionine uptake (assessed by PET) closely correlate in glioblastoma multiforme and that microvascular fractal dimension can be a useful parameter to objectively describe and quantify the geometrical complexity of the microangioarchitecture in glioblastoma multiforme.

Influence of medial parapatellar nail insertion on alignment in proximal tibia fractures--special consideration of the fracture level.

INTRODUCTION: Although a lateral starting point for tibial nailing is recommended to avoid valgus misalignment, higher rates of intra-articular damage were described compared with a medial parapatellar approach. The aim of this anatomic study was to evaluate the fracture level allowing for a safe medial nail entry point without misalignment or dislocation of fragments. MATERIALS AND METHODS: Thirty-two fresh-frozen cadaver lower extremities were used to create 1-cm osteotomies at four different levels (n = 8) from 2 cm to 8 cm below the tibial tuberosity. Nine-millimeter unreamed solid titanium tibial nails (Connex, I.T.S. Spectromed, Lassnitzhohe, Austria) were inserted from a medial parapatellar incision. Misalignment (degree) and dislocation of the distal fragment were measured in the frontal and sagittal plane. RESULTS: A medial parapatellar approach for tibial nail insertion mainly caused valgus and anterior bow misalignment and ventral and medial fragment displacement. Mean misalignment and fragment displacement did not exceed 0.5 degree if the osteotomy was performed 8 cm to 9 cm below the tibial tuberosity. DISCUSSION: According to the results of this study, a medial parapatellar approach can be performed without misalignment and fragment dislocation in proximal tibia fractures extending 8 cm or more below the tibial tuberosity.

Magnetic resonance elastography: a general overview of its current and future applications in brain imaging.

Magnetic resonance elastography (MRE) has been developed over the last few years as a non-invasive means of evaluating the elasticity of biological tissues. The presence of the skull has always prevented semeiotic palpation of the brain, but MRE now offers the possibility of "palpating by imaging" in order to detect brain consistency under physiological and pathological conditions. The aim of this article is to review the current state-of-the-art of MRE imaging and discuss its possible future diagnostic applications in neuroscience.

Temporalis myofascial flap in maxillary reconstruction: anatomical study and clinical application.

The authors describe indications and advantages of temporalis myofascial flap in the reconstruction of surgical defects after partial maxillectomies. This flap is thin and reliable and can be used as an alternative to free flap tissue transfer in the reconstruction of partial defects of the upper maxilla. The surgical steps to raise the flap are simple, but the dissection must be careful to avoid damages to the fronto-temporal branches of the facial nerve on the outer surface, and to the feeding vessels on the inner surface of the temporal muscle. In the present series no major surgical complications were observed. No injuries to the facial nerve branches were reported. Neither total nor partial flap losses were experienced. Post-operative aesthetic and functional results were satisfying. Temporalis muscle flap can be considered as a first-line reconstructive option for limited resection of the upper maxilla with sparing of the orbital floor and of the anterior alveolar crest.

Management of severely bleeding ethmoidal arteries.

OBJECTIVES: Ethmoidal arteries (EAs) can be responsible for severe bleeding. Clinical features of EA bleeding are rather extensive because it can occur within the nasal cavity or in orbital spaces. Furthermore, surgical management of EA bleeding is challenging. STUDY DESIGN: Retrospective evaluation. METHOD OF STUDY: Five clinical patients with severe bleeding from EAs and/or epistaxis refractory to sphenopalatine artery closure were included in this work. Careful anatomic dissection of the orbitoethmoidal region was performed in 3 fresh injected heads. RESULTS: Ethmoidal artery management is not uniform because it depends on the rapidity and severity of the bleeding and the chambers within which it happens. Trauma-related bleeding usually requires a lateral canthotomy, whereas in intraoperative bleeding, efforts should be made to directly coagulate the bleeding vessel, even within the orbital fat. Spontaneous epistaxis refractory to sphenopalatine artery closure is to be addressed externally, preferably under endoscopic vision. CONCLUSIONS: Ethmoidal artery management differs according to the clinical situation. Elective surgery is advisable for spontaneous epistaxis, whereas emergency treatment, ranging from intraorbital coagulation of the bleeding vessel to lateral canthotomy (when the patient is in a sight-threatening condition), is necessary when the bleeding occurs within orbital spaces. A treatment management algorithm is useful in cases of severe and refractory EA bleeding.