The myloglossus in a human cadaver study: common or uncommon anatomical structure?

BACKGROUND: Additional extrinsic muscles of the tongue are reported in literature and one of them is the myloglossus muscle (MGM). Since MGM is nowadays considered as anatomical variant, the aim of this study is to clarify some open questions by evaluating and describing the myloglossal anatomy (including both MGM and its ligamentous counterpart) during human cadaver dissections. MATERIALS AND METHODS: Twenty-one regions (including masticator space, sublingual space and adjacent areas) were dissected and the presence and appearance of myloglossus were considered, together with its proximal and distal insertions, vascularisation and innervation. RESULTS: The myloglossus was present in 61.9% of cases with muscular, ligamentous or mixed appearance and either bony or muscular insertion. Facial artery provided myloglossal vascularisation in the 84.62% and lingual artery in the 15.38%; innervation was granted by the trigeminal system (buccal nerve and mylohyoid nerve), sometimes (46.15%) with hypoglossal component. CONCLUSIONS: These data suggest us to not consider myloglossus as a rare anatomical variant.

Symmetrical anatomical variant of the anterior belly of the digastric muscle: clinical implicat.

The digastric muscle is an important surgical landmark. Several anatomical variants of the digastric muscle are reported in literature and, in particular, the presence of accessory anterior bellies of the muscle is not uncommon. Here, an unreported symmetrical variant of the digastric muscle was found during a dissection of the suprahyoid region. The dissection showed digastric muscles with an accessory anterior belly, which originated from the anterior belly of muscles in proximity and anteriorly to the intermediate tendon. The accessory bellies were fused together on the midline and were attached with a unique tendon to the inner surface of the mental symphysis. These muscles completely filled the submental triangle. This unreported anatomical variant could be considered an additional contribution to description of the anatomical variants of the digastric muscle, with several implications in head and neck pathology, diagnosis and surgery.

Combined transnasal transcervical robotic dissection of posterior skull base: feasibility in a cadaveric model.

The current surgical trend is to expand the variety of minimally invasive approaches and, in particular, the possible application of robotic surgery in head and neck surgery. For this purpose, we explored the feasibility of a combined transcervical-transnasal approach to the posterior skull base, using the da Vinci Surgical System in 3 cadaver heads. Superb visualization of the sellar, suprasellar and clival regions was possible in all three specimens. The trocars` placement through a transcervical port made a more cephalad visualization possible, eliminating the need to split the palate. The advantages of robotic surgery applied to the posterior cranial fossa are similar to the ones already clinically experienced in other districts (oropharynx, tongue base), in terms of tremor-free, bimanual, precise dissection. The implementation of instruments for bony work will definitely increase the applicability of such a system in the forthcoming years.

The natural evolution of endoscopic approaches in skull base surgery: robotic-assisted surgery?

The current surgical trend is to expand the variety of minimally invasive approaches and, in particular, the possible applications of robotic systems in head and neck surgery. This is particularly intriguing in skull base regions. In this paper, we review the current literature and propose personal considerations on the role of robotic techniques in this field. A brief description of our personal preclinical experience on skull base robotic dissection represents the basis for further considerations. We are convinced that the advantages of robotic surgery applied to the posterior cranial fossa are similar to those already clinically experienced in other areas (oropharynx, tongue base), in terms of tremor-free, bimanual, precise dissection: the implementation of instruments for bony work and resolving current drawbacks will definitely increase the applicability of such a system in forthcoming years.

Endoscopic anatomy of persistent trigeminal artery: a cadaveric study.

BACKGROUND: Persistent trigeminal artery (PTA) is one of the carotid-basilar anastomoses and occasionally complicates vascular or neoplastic pathology. The aim of this study was to become more familiar with the anatomy associated with PTA using an endoscopic view. MATERIAL AND METHODS: PTA was incidentally encountered in a fresh cadaver. Purely endoscopic approaches via supraorbital (extradural and intradural routes), endonasal, and retrosigmoid routes were performed with 4-mm, 0- and 30-degree rigid endoscopes. RESULTS: The PTA belonged to Salas's lateral type and Saltzman's type 1. The supraorbital extradural approach allowed good visualization of the origin and the cavernous portion of the PTA through the infratrochlear triangle. Using the endonasal route, the cisternal portion of the PTA and its confluence to the basilar artery were demonstrated after opening the clival dura; however, the origin of the PTA and the cavernous portion of the PTA were not sufficiently exposed even using a direct approach to the cavernous sinus. The retrosigmoid approach revealed the anatomical relationship among the PTA, trigeminal nerve, and abducent nerve in the petroclival region. CONCLUSION: These 3 endoscopic approaches provided a superb image of the PTA and contribute to the anatomical comprehension of PTA. Additionally, these approaches make us more familiar with an endoscopic view of PTA.

Transnasal approach to the medial intraconal space: anatomic study and clinical considerations.

BACKGROUND: The aim of this study was to illustrate the anatomy of the medial compartment of the orbit by comparing the endoscopic transnasal perspective with the external ones. METHODS: 8 orbits from 5 double-injected heads were carefully dissected. An endoscopic anterior transconjunctival dissection was performed in one orbit while an endoscopic transnasal intraconal dissection was conducted in 3 orbits. External dissections (from medial, superior and anterior perspective) were also performed. RESULTS: The role of the medial rectus muscle is emphasised. It represents the first important landmark encountered, covering all the other structures during transnasal approaches. By displacing it, the medial intraconal space with its contents becomes visible: the ophthalmic artery and related branches, the superior ophthalmic vein, the nasociliary nerve and, in the deepest part of the medial compartment, the optic nerve. CONCLUSION: The medial compartment of the orbit can be addressed transnasally. By displacing the medial rectus muscle, it is possible to gain adequate space for the instruments and to control all of the medial compartment, including the medial aspect of the optic nerve.

Intraosseous anastomosis in the maxillary sinus.

AIM: During sinus-lift surgery, certain intra-osseous vessels may be accidentally cut and this cause bleeding complications in approximately 20% of osteotomies. Therefore, understanding vascular details of the maxilla is very important for the surgeon. Here, we have given an anatomical overview of maxillary sinus vascularization through anatomical dissection. We have analyzed the distribution, localization and distance from the alveolar ridge of intraosseous branches of the maxillary artery found during sinus lift surgery. METHODS: Fifty-six maxillary bone doors were made bilaterally in twenty-eight unfixed cadavers; the doors were made between the first molar and the second molar (24 doors) or between the first and the second premolar (32 doors). RESULTS: Intraosseous arteries were found in 37 maxillary bones (66%). The average height of the artery from the alveolar crest was 13+/-3.2 mm in the distal doors and 18 +/- 6.1 mm in the mesial doors. Generally, the intraosseous maxillary branches ran caudo-rostrally; but in five maxillae, we found two parallel arteries, while in three cases the maxillary artery ran vertically. No differences were found between the left and right side. CONCLUSION: The risk of vascular damage in sinus floor elevation surgery is a real problem for the oral surgeon. Detailed anatomical knowledge about sinus vascularization is very important to reduce the risk of vascular damage and bleeding. In addition the visualization of sinus anastomosis by radiology and less invasive surgery, such as piezo-surgery, could be helpful.

Endoscopic transnasal anatomy of the infratemporal fossa and upper parapharyngeal regions: correlations with traditional perspectives and surgical implications.

BACKGROUND: The aim of this study was to illustrate the endoscopic surgical anatomy of the infratemporal fossa (ITF) and upper parapharyngeal space and to provide useful landmarks by comparing transnasal perspectives with external ones. MATERIALS AND METHODS: 6 fresh double injected heads were dissected. External lateral dissection was performed through a pre-auricular skin incision while external anterior dissection started with a modified Weber-Ferguson incision. External medial to lateral dissection was performed starting from the rhinopharyngeal and pterygoid regions, after cutting the specimen in 2 halves passing through the nose. Endoscopic dissection was performed through an endonasal approach (0° and 45° scopes). RESULTS: Among all the structures identified during the dissection, the most useful landmark when dissecting the ITF in a lateral to medial direction is the lateral pterygoid muscle. In anterior approaches (mostly endoscopic) the role of the lateral pterygoid muscle is less important and the Eustachian tube (ET) represents the most important landmark to point out the upper portion of the parapharyngeal internal carotid artery (ICA). The role of the ET, in lateral dissection is, on the contrary, by far less important given the fact that it is very deep in the surgical field and that the ICA is encountered earlier during surgical approaches. Another crucial landmark during anterior endoscopic surgery is the vidian nerve because it points to the anterior genu of the internal carotid artery. CONCLUSION: The complex 3-dimensionality of the ITF and the upper parapharyngeal space needs a sound knowledge of the surgical anatomy. The role of the same landmarks changed in different approaches. The ability to orientate oneself in this complex area is related to an accurate knowledge of its anatomy through comparison of endoscopic and external perspectives.

The microvascular network of the pituitary gland: a model for the application of fractal geometry to the analysis of angioarchitecture and angiogenesis of brain tumors.

In geometrical terms, tumor vascularity is an exemplary anatomical system that irregularly fills a three-dimensional Euclidean space. This physical characteristic, together with the highly variable vessel shapes and surfaces, leads to considerable spatial and temporal heterogeneity in the delivery of oxygen, nutrients and drugs, and the removal of metabolites. Although these biological features have now been well established, quantitative analyses of neovascularity in two-dimensional histological sections still fail to view tumor architecture in non-Euclidean terms, and this leads to errors in visually interpreting the same tumor, and discordant results from different laboratories. A review of the literature concerning the application of microvessel density (MVD) estimates, an Euclidean-based approach used to quantify vascularity in normal and neoplastic pituitary tissues, revealed some disagreements in the results and led us to discuss the limitations of the Euclidean quantification of vascularity. Consequently, we introduced fractal geometry as a better means of quantifying the microvasculature of normal pituitary glands and pituitary adenomas, and found that the use of the surface fractal dimension is more appropriate than MVD for analysing the vascular network of both. We propose extending the application of this model to the analysis of the angiogenesis and angioarchitecture of brain tumors.

Microsurgical endoscopic-assisted retrosigmoid intradural suprameatal approach: anatomical considerations.

AIM: The aim of this study was to evaluate the feasibility of microscopic endoscopic assisted suprameatal tubercle drilling with a retrosigmoid approach and it focuses on the anatomic structures identified with the endoscope. The advantages of the 30 degrees optic view are also described. METHODS: Fifty dry temporal bones were studied in order to estimate the variability of the prominence of the suprameatal tubercle. Eight fresh cadaveric specimens were prepared for a retrosigmoid approach to allow for microscopic endoscopic assisted suprameatal tubercle drilling. The increase in trigeminal exposure and neurovascular structures visualization with the endoscope, using 0 degrees and 30 degrees optics were then evaluated. RESULTS: Three major types of the suprameatal tubercle were found: 1) a large size tubercle (> 6 mm, 9/50 cases); 2) a medium size tubercle (3-6 mm, 37/50 cases); and 3) an almost absent suprameatal tubercle (< 3 mm, 4/50 cases). Microscopic endoscopic assisted suprameatal tubercle drilling with opening of the Meckel's Cave was found to be technically feasible in all cases. The increase in trigeminal nerve exposition was of 9 mm on average. Endoscopic exploration with 0 degrees and 30 degrees optics made possible the identification of all neurovascular structures in the area. CONCLUSION: Microscopic endoscopic assisted suprameatal tubercle drilling is a feasible procedure that allows the identification of all neurovascular structures in the cerebellopontine angle and petrous apex region. The opening of Meckel's Cave may be particularly useful for lesions located in the cerebellopontine angle having a minor component that extends anteriorly and laterally in the middle cranial fossa.

Lumbar arachnoiditis and thecaloscopy: brief review and proposed treatment algorithm.

The term arachnoiditis describes the inflammation of the meninges and subarachnoid spaces. Lumbar arachnoiditis is characterized by obliterated nerve root sleeves and the adherence of nerve roots to each other in the proximity of the cauda equina, and may be secondary to infectious diseases or tumors, iatrogenic (subsequent to spinal surgery) or idiopathic. It is not very clearly defined epidemiologically or clinically, and various theories regarding its pathophysiology have been proposed; furthermore, its treatment is difficult because there is a lack of evidence-based diagnostic and therapeutic gold standards. Thecaloscopy has been recently described as a novel technique for retrograde transcutaneous neuroendoscopic inspection of the subarachnoid structures of the lumbar thecal sac; it has also been suggested for the treatment of lumbar arachnoiditis. We here review the most modern techniques for the treatment of this disease such as thecaloscopy and neurostimulation.

Endoscopic anatomy for transnasal transsphenoidal pituitary surgery in the presence of a persistent trigeminal artery.

OBJECTIVE: Endoscopic procedures are becoming increasingly important for transnasal transsphenoidal approaches to the skull base and particularly for pituitary surgery. A persistent trigeminal artery (PTA) is rare. Its presence, if it goes unnoticed or if the surgeon is not aware of such a variant, may endanger the success of surgery. METHOD: During an endoscopic inspection using a supraorbital approach in a fresh cadaveric specimen in which the arteries had been injected with latex glue, the presence of an anomalous intracranial artery, suggestive for PTA, was disclosed. The specimen was then fixed and a CT scan with 3D reconstruction of the circle of Willis was done to evaluate the imaging of such an anatomical variation. Thereafter an endoscopic transsphenoidal approach to the pituitary fossa was performed, to verify the endoscopic anatomy. RESULTS: The performed CT scan allowed visualization of the entire course of the anomalous vessel, confirming a PTA. During the endoscopic transsphenoidal approach, the presence of the vascular anomaly, altering the bony bulging of the internal carotid artery on the lateral side of the sphenoidal roof, was disclosed. The parasellar course of the PTA could be exposed by drilling the overhanging bone. The presence of the anatomical variant did not interfere with surgical manoeuvres and the procedure, simulating a transsphenoidal approach to the pituitary, could be safely completed. CONCLUSION: Variants such as PTA are rare and routine preoperative imaging for pituitary procedures does not always include studies to detect this vascular anomaly. The occasional intraoperative detection of a PTA during an endoscopic transsphenoidal procedure can be managed; almost any surgical manipulation is possible and pituitary surgery can be successfully completed, provided the surgeon is aware of the possible existence of this variant and its irregular anatomical course. However, the presence of a PTA may have dramatic consequences if surgery is directed to the lateral parasellar region, as for intracavernous lesions; in these cases a complete neuroradiological study including MRI-angiography and possibly CT-angiography is advised.

Endoscopic endonasal management of petroclival cerebrospinal fluid leaks: anatomical study and preliminary clinical experience.

BACKGROUND: Endonasal management of most anterior cranial fossa cerebrospinal fluid leaks is a well established procedure, and even some middle cranial fossa cerebrospinal fluid leaks can be managed safely endonasally. Endonasal endoscopic management of leakages of the posterior cranial fossa represents an unique challenge. OBJECTIVE: The aim of this study was to assess the feasibility of an endoscopic endonasal approach for treating well-selected cerebrospinal fluid leaks of the petroclival region. METHODS: Clinical charts of patients with leakages of the petroclival region treated at our institution were retrospectively reviewed. Careful dissection of the petroclival region was performed, both endonasally and externally, in three fresh injected heads. RESULTS: Two patients presented a leakage of the petroclival region. Both the patients presented multiple skull base defects. The two patients underwent a supratubaric trans-spheno-petroclival approach; in one of these, it was performed in combination with a middle cranial fossa approach. Multilayer reconstruction was performed in both patients. No cerebrospinal fluid leak recurrences were observed during follow-up (17 and 19 months, respectively). CONCLUSIONS: Endonasal endoscopic management of well-selected petroclival cerebrospinal fluid leaks is feasible.

Anatomical structures to provide passive motility of peripheral nerve trunks and fascicles.

It is well known that tendons have to be able to move if the muscle contracts. It is still not generally known that any structure in the body has to be able to move passively against other structures. This is especially important for the movement of limbs. In a monoaxial joint like the humero-ulnar joint only structures in the plane of the joint axis remain fixed. Structures in a certain distance to the flexion or to the extension side have to be able to move against other structures in different levels. The amount of passive motion is dependent on the distance to the plane of the joint axis. Tissues which provide a frictionless passive motion are discussed.

Percutaneous approach for thecaloscopy of the lumbar subarachnoidal space.

INTRODUCTION: Endoscopy of the lumbar subarachnoidal space is named thecaloscopy, which has been used for diagnostic and therapeutic purposes. However, the insertion of the endoscope required microsurgical assistance from the skin into thecal sac in the lumbar region. The current study was applied to explore the possibility of a percutaneous approach for lumbar thecaloscopy insertion, transferring from the previous microsurgical procedure. METHOD: A 2.8-mm fiberoptic endoscope (Storz and Co., Tuttlingen, Germany) was used in the study. In two fresh human cadavers, a thecaloscope was first inserted through a transsacral approach and the tip was advanced inside the thecal sac to the lumbar region for observation. A percutaneous endoscopic approach was performed with the Seldinger technique under fluoroscopic control into the lumbar subarachnoid space. After completing the endoscopic procedure, the lumbar subarachnoid space was exposed microsurgically for morphological investigation of rootlets and surrounding structures. RESULTS: By the observation through a live video in the thecal sac, the percutaneous insertion of a 2.8-mm endoscope into the lumbar subarachnoidal space is feasible without any neural structural damage seen. CONCLUSION: The percutaneous approach for flexible endoscopes into the lumbar subarachnoidal space is a practical option for the future of thecaloscopy.

The extended endoscopic endonasal approach to the clivus and cranio-vertebral junction: anatomical study.

OBJECT: Lesions located in the retroclival area and at the level of the cranio-vertebral junction are typically approached through a variety of anterior, antero-lateral and postero-lateral skull-based approach, either alone or in combination. The aim of this anatomical study was to demonstrate the possibility of an endoscopic endonasal approach to the clivus and cranio-vertebral junction. MATERIALS AND METHODS: Five fresh cadaver heads injected with colored latex were used. A modified endonasal endoscopic approach was made through two nostrils in all cases. Endoscopic dissections were performed using rigid endoscopes, 4 mm in diameter, 18 cm in length, with 0 degrees lenses. RESULTS: Access to the clivus was possible using a lower trajectory when compared to that necessary for the sellar region. The sphenoid sinus is entered, and its inferior wall is completely removed, permitting the union of the sphenoidal and rhinopharyngeal parts of the clivus. The entire clivus can be removed, and the cranio-vertebral junction is opened, removing the anterior arch of atlas and the odontoid process. After the opening of the dura, the anterior surface of the pons and upper spinal cord with corresponding nerves and vasculature are visible. CONCLUSION: The endoscopic endonasal approach to the clivus and cranio-vertebral junction could be a valid alternative for surgical treatment of anterior lesions of these regions. Adequate endoscopic skill, lab training on cadavers and dedicated tools are required for clinical applications of the approach.

Intraoperative imaging of the brachial plexus by high-resolution ultrasound.

The authors attempted to perform direct high resolution ultrasound imaging of the intraneural ultrastructure of the brachial plexus for intraoperative image guidance in brachial plexus surgery. The brachial plexuses of four fresh-frozen cadaver specimens were surgically exposed in a standard approach used in routine brachial plexus surgery to undergo direct ultrasound examination using a 15 MHz SonoCT scanhead. By placing the scanhead directly onto the epineurium, all components of the brachial plexus were directly visualized in an axial plane and compared with histologic findings. The internal neural structure at different levels could be visualized in high resolution, showing the specific fascicular pattern. The histologic processing revealed good correlation with the intraneural topography demonstrated on ultrasound. In the study, high resolution ultrasound examination of the brachial plexus showed substantial details of the ultrastructure of neural tissue, which may play a role in intraoperative image guidance in the surgical treatment of patients with brachial plexopathy.

Surgical anatomy of the puboprostatic complex with special reference to radical perineal prostatectomy.

OBJECTIVE: To investigate the retropubic space and attachments of the prostate and urethra, with special reference to radical perineal prostatectomy. MATERIALS AND METHODS: Anatomical relationships were assessed intraoperatively in 60 patients, and in five cadavers after preparing the dorsal vein complex with coloured latex. Cross-sections of the area of interest were evaluated by microscopy. RESULTS: The puboprostatic (pubovesical) ligaments could be clearly distinguished from the median part of the puboprostatic complex continuous with the urethral suspensory mechanism. The dorsal vein complex is integrated into this fibromuscular attachment of the prostate and male urethra. During the perineal approach, dissection in this region follows the so-called avascular plane. CONCLUSION: With this new insight into the anatomical relationships the nomenclature derived from radical retropubic prostatectomy could be mirrored. In radical perineal prostatectomy, both the urethral suspensory mechanism and the dorsal vein complex can be preserved.

Thecaloscopy part III: first clinical application.

PURPOSE: We have already dealt with the technical and anatomical basics for thecaloscopy. The first results of clinical application are presented and the indications for its diagnostic and therapeutic use are described. The aetiology of aseptic arachnitis and the term "Wide spinal canal syndrome" are discussed. PATIENTS AND METHODS: Twelve patients who fulfilled the criteria for entry to the study were selected and the criteria were chosen according to German medical and legal rules. All patients underwent an endoscopic inspection and, if necessary, therapeutic manipulation under general anaesthesia. RESULTS: In all cases the procedure was safely and successfully performed. The pathomorphology of the arachnoid was detected and endoscopically treated in almost all cases. Arachnoid cysts were successfully fenestrated and an intraspinal meningocoele treated with endoscopic assistance. CONCLUSION: Thecaloscopy is a safe procedure if skilfully performed. It provides an opening for a wide range of new diagnostic and therapeutic options.

Microsurgical anterior cervical foraminotomy (uncoforaminotomy) for unilateral radiculopathy: clinical results of a new technique.

BACKGROUND: The authors report the clinical application of a new microsurgical technique. The cervical anterior foraminotomy (uncoforaminotomy), which is used for the surgical treatment of unilateral cervical radiculopathy secondary to posterolateral disc herniations or spondylotic foraminal stenoses. METHOD: Between June 2000 and May 2001, 34 patients (16 men and 18 women with a mean age of 43.8 years, range 29 to 80 years) underwent anterior cervical foraminotomy (uncoforaminotomy) for the treatment of cervical radiculopathy at one or two adjacent levels in the Neurosurgical Department of the University of Vienna. This surgical technique was devised to accomplish direct anterior decompression of the affected nerve root by removing an offending posterolateral sponylotic spur or disc fragment. The nerve root is decompressed from its origin in the spinal cord to the point were it passes behind the vertebral artery laterally. The intervertebral disc of the affected level is maintained in its form and function. Thus, the functioning motion segment is preserved and fusion related sequelae, including graft related complications, graft site complications and the adjacent level disease, are avoided. Prior to its clinical application, anatomical features of the anterior cervical spine were reviewed, and an anatomical morphometric analysis and work-up of the technique was performed in 4 cervical specimens. FINDINGS: The follow-up period varied from two to 17 months with a mean of 8.2 months. The large majority (97%) of patients were pleased with the results of their operation. The relief of neck pain and redicular pain in the affected dermatome was immediate in all patients. Motor-weakness and sensory deficit improved dramatically immediately postoperatively, and improved to normalisation in the majority of patients within 3 to 6 months. Two of the patients sustained an incomplete transient recurrent laryngeal nerve palsy, which fully resolved within two to 4 weeks. One of the patients had a repeat herniation on the second postoperative day, but recovered completely after re-operation and continued to do well at the 6-month follow-up. No permanent surgery related morbidity or associated complications were encountered. INTERPRETATION: The results indicate that this new microsurgical technique is an attractive treatment option for adequate anterior decompression of the cervical nerve root via a minimized approach. It was associated with excellent clinical outcome and a less painful postoperative course, allowing patients an almost immediate return to unrestricted full activity.