Experimental Reconstruction of the Optic Nerve with a Sural Nerve Graft: An in Vivo Experimental Study.

BACKGROUND: Neurosurgical interventions and trauma are common causes of damage to the optic nerve. This determines the relevance of research for solutions aimed at restoration of the nerve's anatomical integrity, electrical conductivity, and subsequently - restoration of its function. Restore a damaged (cut) optic nerve using n. suralis autograft in vivo. METHODS: The experiment involved reconstruction of the optic nerve through injury modulation, graft placement and restored nerve harvest and evaluation. Injury modulation included removal of a fragment of the optic nerve. Autograft harvesting and placement involved resection of a fragment of the sural (sensory) nerve and its subsequent anastomosis in place of the removed fragment of the optic nerve. As an experimental model, a rabbit of the "Burgundy" breed was used. The animal was previously examined for the presence of infectious and other diseases to confirm its health. RESULTS: Four months post operatively when stimulating the operated right eye, low-amplitude components altered in shape are registered. Thus, signs of mild restoration of electrical conductivity on the treated optic nerve were seen. CONCLUSIONS: Our initial experience shows the technical feasibility of reconstructing the optic nerve using an autograft, the possibility of axonal growth through the graft and, in the future, using this method for direct optic nerve reconstruction, as well as a bypass method for damage to the optic nerve with various tumor diseases of the optic nerve, tumors of the chiasmatic-sellar localization, orbital injuries.

Expanded endoscopic transnasal odontoidectomy and posterior stabilization: a combined approach.

BACKGROUND: Lesions of the craniovertebral junction are difficult to access, which is due to the anatomical features and high concentration of vital structures in the area. The transoral access has been most used for anterior approach to treat craniovertebral junction pathology. This method has consistently shown a high complication rate and difficulties in-patient rehabilitation. In this study we analyzed the benefits of surgical treatment of the craniovertebral junction area pathology with the transnasal approach. METHODS: Four patients with C2 odontoid process invagination and brain stem compression were treated with the transnasal endoscopic resection of the pathological process combined with simultaneous occipital-cervical stabilization (OCS). Surgical procedure, anatomical findings, complications, and rehabilitation period were assessed. RESULTS: Transnasal treatment of C2 odontoid process lesions was applied successfully in all four cases. A modified extended transnasal approach was used. This approach is characterized by an increased operating time (238 minutes), lower complication rate, safer access (less traumatization of oropharyngeal tissue), better patient rehabilitation (no need for tracheostomy or feeding tube), better recovery and higher patient satisfaction (quick regression of the symptomatic patients). CONCLUSIONS: The extended transnasal access to the craniovertebral junction is a safer, more comfortable technique, which facilitates more radical treatment of lesions in this area. For brain stem compression due to C2 odontoid process invagination, a combination of transnasal resection and OCS shows excellent preliminary results. This method should be favorable over the transoral approach in certain cases, as it provides a better direct access to lesion of the craniovertebral junction and allows for more complex combined procedures.

Primary Sellar Abscesses: A Systematic Review and 2 Rare Observations.

BACKGROUND: Abscesses of the chiasmatic-sellar region are quite rare and are often a result of surgical intervention, trauma, or tumor growth. Primary abscesses are extremely rare and represent a group of abscesses the occur because of internal microbial seeding. Primary abscesses are rarely reported. We present 2 clinical cases featuring primary abscesses of the chiasmal-sellar region. To put into perspective the rarity of these findings, we performed a systematic review of existing clinical reports regarding this pathology. METHODS: A systematic review of literature was conducted to gather existing clinical reports on primary abscesses of the chiasmatic-sellar region. Two personal findings are added to the literature review, including a 13-year-old girl and a 58-year-old man who presented with chiasmal-sellar region primary abscesses. The diagnostic aspects, treatment strategy, and outcomes are discussed. RESULTS: Both patients included in the report had positive outcome. The pediatric patient developed a recurrence of the abscess and was treated accordingly. Overall, 41 cases of primary abscesses of this region have been reported in literature, of which 6 are in children under 18 years of age. The main nonspecific clinical manifestations include headaches, visual impairment, and endocrine pathology. Acute inflammatory responses are rarely seen, despite infectious genesis. Transnasal endoscopic surgical treatment offers diagnostic and treatment advantages. CONCLUSIONS: Proper diagnostic procedures can aid in correct treatment strategy and improve overall outcome.

Surgical Correction of a Clivus Cerebrospinal Fluid Fistula: A Technical Report.

BACKGROUND: Cerebrospinal fistulas of the clivus region often result from previous surgical intervention at the skull base. The localization and size of the fistula determine the appropriate treatment strategy. When flap closure is not possible, the microsuture technique with autograft placement provides a favorable outcome. METHODS: We present a technical report on the application of the microsuture technique for clivus region cerebrospinal fluid fistula closure in a patient with previous chordoma treatment and nonspecific coronavirus disease 2019 complications. RESULTS: The application of the microsuture technique resulted in stable remission of the fistula and complete regression of the clinical manifestations. CONCLUSIONS: The microsuture technique for clivus region fistula closure is a potentially valuable alternative to vascularized flap closure.

CyberKnife for the management of Cushing's disease: our institutional experience and review of literature.

INTRODUCTION: Surgery is the primary treatment for Cushing's disease(CD). In cases with no biochemical remission after surgical resection or when recurrence occurs after a period of remission stereotactic radiosurgery (SRS) is used as alternative/adjuvant treatment. The aim of this study is to demonstrate the effectiveness of SRS and FSRS(Fractionated stereotactic radiosurgery) for the treatment of CD in a long term follow up. METHODS: This is a retrospective study in which 41 patient (36 females and 5 males) who underwent surgery for CD from 2009 to 2019 were included. Out of 41 cases, 34 cases had microadenomas while 7 had macroadenomas. These patients had recurrence or persistence of hypercortisolism post-operatively. After multidisciplinary evaluation, these patients were treated by CyberKnife (SRS & FSRS). RESULTS: Remission rate in our study was 60.97% with a median follow up period of 79.03 months. The median time to biochemical remission was 14 months. Tumour growth control was achieved in 95.12%. Hypopituitarism of different axes was seen in 34.14% patients. Secondary hypothyroidism was the most common pituitary insufficiency (34%) followed by secondary hypogonadism in 17%. CONCLUSION: CyberKnife radiosurgery and hypofractionated radiosurgery can be used as an adjuvant treatment in patient with active disease and no biochemical remission after one or multiple surgical resections. Risk of radiation induced hypopituitarism and other complication is relatively low 34.14% and tumour growth control is significantly higher.

Internal Carotid Artery Injury in Transsphenoidal Surgery: Tenets for Its Avoidance and Refit-A Clinical Study.

One of the most serious/potentially fatal complications of transsphenoidal surgery (TSS) is internal carotid artery (ICA) injury. Of 6230 patients who underwent TSS, ICA injury occurred in 8 (0.12%). The etiology, possible treatment options, and avoidance of ICA injury were analyzed. ICA injury occurred at two different stages: (1) during the exposure of the sella floor and dural incision over the sella and cavernous sinus and (2) during the resection of the cavernous sinus extension of the tumor. The angiographic collateral blood supply was categorized as good, sufficient, and nonsufficient to help with the decision making for repairing the injury. ICA occlusion with a balloon was performed at the injury site in two cases, microcoils in two patients, microcoils plus a single barrel extra-intracranial high-flow bypass in one case, stent grafting in one case, and no intervention in two cases. The risk of ICA injury diminishes with better preoperative preparation, intraoperative navigation, and ultrasound dopplerography. Reconstructive surgery for closing the defect and restoring the blood flow to the artery should be assessed depending on the site of the injury and the anatomical features of the ICA.

Modern Methods of Stereotactic Radiosurgery and Radiotherapy for the Treatment of Cushing Disease.

Cushing's disease is caused by a pituitary tumor causing increased production of adrenocorticotropic hormone, which leads to chronic hypersecretion of cortisol through adrenal cortices. Endoscopic trans-sphenoidal adenomectomy is the first choice of treatment with greatest efficiency for the treatment of the disease. However, in the absence of remission or recurrence of hypercortisolism after neurosurgical resection (adenomectomy), as well as in cases when surgical intervention cannot be carried due to medical contraindications to surgical intervention, radiation treatment is used as an alternative or adjoining therapy. In this literature review the efficiency of different radiation techniques (the conventional and the modern techniques), as well as possible complications of modern methods of radiosurgery and radiotherapy have been looked for.

Anatomical Aspects of the Transnasal Endoscopic Access to the Craniovertebral Junction.

OBJECTIVE: Interest in endoscopic transnasal access has increased with continued technological advances in endoscopic technology. The goals of this study were to review the normal anatomy in transnasal endoscopic neurosurgery and outline the anatomical basis for an expanded surgical approach. Defining anatomical aspects of surgical endoscopy helps guide the surgeon by defining normal anatomy of the access vector. METHODS: This anatomic study was conducted on 15 adult male cadaver specimens using various microsurgical tools and endoscopic instruments and 1 intraoperative case. The vasculature was injected with colored silicone to aid visualization. Different transnasal approach techniques were used, with angles of endoscope access at 0°, 30°, 45°, and 70° accordingly for extensive anatomical mapping. RESULTS: The proximity of critical structures is different in each approach degree. A full understanding of the possible structures to be met during transnasal access is described. As a result of the study, anatomical aspects and important structures were outlined, and a surgical protocol was defined for minimal risk access in respect to normal anatomy of the area. CONCLUSIONS: Thorough knowledge of topographic anatomy of the craniovertebral junction is required for performing minimal-risk surgical intervention in this region. It is important to know all anatomical aspects of the transnasal approach in order to reduce the risk of damage to vital structures. Transnasal endoscopic surgery of the craniovertebral junction is a relatively new direction in neurosurgery; therefore, anatomical studies such as the one described in this article are extremely important for the development of this access method.

Endoscopic Transsphenoidal Approach in Treatment of Germinomas of the Chiasmosellar Region.

INTRODUCTION: Germinogenic central nervous system (CNS) tumors represent a heterogeneous group of tumors, constituting approximately 0.4% of all primary brain tumors. Removal of the tumor has no prognostic value. In "pure" primary germinomas of the CNS, the alpha-fetoprotein and human chorionic gonadotropin levels are within normal limits, and no specific biochemical tumor markers currently exist for this tumor type, making histological verification crucial for the choice of treatment tactics. When the tumor is located in the chiasmosellar region, one of the possible verification methods is endoscopic endonasal transsphenoidal biopsy. OBJECTIVE: The main objective of the study is to demonstrate the feasibility and safety of endoscopic transsphenoidal approach for histological verification of primary germinomas of the CNS with chiasmosellar localization. MATERIALS AND METHODS: The current study includes 13 patients with "pure" germinomas of the chiasmosellar region who underwent endoscopic endonasal surgical interventions with subsequent treatment according to the "Germinoma 2008" protocol. RESULTS: The extent of surgical intervention ranged from biopsy (4) to partial (5) and total (4) removal of the tumor. In all cases, histological verification of the diagnosis was achieved and none of the patients presented with cerebrospinal fluid leaks and/or meningitis in the postoperative period, allowing to evaluate endoscopic intervention in our patient series as safe and effective. Two out of 13 patients were lost to follow-up. CONCLUSION: The endoscopic endonasal approach for histological verification and removal of chiasmosellar region germinomas is safe, and in some cases, less traumatic for the patient than transcranial and transventricular approaches.

Endoscopic Endonasal Transclival Approach to Tumors of the Clivus and Anterior Region of the Posterior Cranial Fossa (Results of Surgical Treatment of 136 Patients).

INTRODUCTION: With the introduction into the neurosurgical practice of minimally invasive methods using endoscopic techniques, it became possible to effectively remove hard-to-reach tumors, including central tumors of the anterior region of the posterior cranial fossa. OBJECTIVE: To analyze the results of surgical treatment of patients with various centrally located tumors of the base of the skull that extend into the anterior region of the posterior cranial fossa using the endoscopic endonasal transclival approach. METHODS: The personal surgical experience of the first author is 136 patients with various tumors (e.g., chordomas, meningiomas, pituitary adenomas, and fibrous dysplasia). RESULTS: Radicality of tumor removal was total 61.03%; subtotal 25%; partial 13.23%; and insufficient removal 0.74%. Postoperative cerebrospinal fluid leaks occurred in 9 cases (6.62%) and meningitis in 13 cases (9.56%). In 2 cases, surgical treatment had a lethal outcome (1.47%). CONCLUSIONS: The endoscopic endonasal transclival approach can be used to obtain access to centrally located skull base tumors. This approach allows for a radical and low-risk removal of various skull base tumors of central localization that, until recently, were considered to be almost inoperable.

Endoscopic Endonasal Transclival Approach to Tumors of the Clivus and Anterior Region of the Posterior Cranial Fossa: An Anatomic Study.

OBJECTIVE: To present the basic topographic and anatomic features of the clivus and adjacent structures with an objective of possible improvements and optimization of the extended endoscopic endonasal posterior (transclival) approach when removing tumors of the clivus and anterior regions of the posterior cranial fossa. MATERIALS AND METHODS: A craniometric study was conducted on 125 human skulls. A topographic anatomic study was conducted on 25 cadaver head specimens with arterial and venous beds stained with colored silicone, according to the method developed by us, to visualize its features and individual variability. RESULTS: The most important anatomic features of the external and internal regions of the clivus and the adjacent neural and vascular structures were analyzed. An accessible zone for the most effective transclival approach to the posterior cranial fossa is also specified. CONCLUSION: The endoscopic endonasal transclival approach can be used to obtain access to centrally located tumors of the posterior cranial fossa. It is an alternative to transcranial approaches in the surgical treatment of tumors of the clivus.

Making Anatomic Preparations of the Human Brain Using Colored Silicone for Vascular Perfusion Staining (Technical Description).

BACKGROUND: A thorough understanding of the central nervous system anatomy is a fundamental part of a neurosurgeon's training. Development of novel neurosurgical approaches and optimization of existing ones directly depend on the comprehensive study of topographic anatomy of the head and neck using cadaveric specimens. Staining the vessels of the arterial and venous systems of a cadaveric specimen aids a detailed study of the vascularization of anatomic structures of the brain. Here we describe an alternative expedited method for creating anatomic preparations of the human brain using colored silicone for vascular perfusion staining. METHODS: A nonfixed, whole cadaver (with the head intact), without central nervous system pathology, no later than 48 hours after death, is used to prepare the human brain specimen through staining of arterial and venous vessels. RESULTS: Our proposed method provides a fast and inexpensive approach to making anatomic preparations of the human brain with staining of the vascular system. The preparations thus obtained can be used for educational purposes, aiding the study of normal and topographic anatomy of the brain, as well as the development of new microsurgical and/or endoscopic approaches. CONCLUSIONS: In experienced hands, our proposed method allows the creation of anatomic preparations relatively fast, at low cost, and with excellent quality.

Transoral Decompression and Stabilization of the Upper Cervical Segments of the Spine Using Custom-Made Implants in Various Pathologic Conditions of the Craniovertebral Junction.

BACKGROUND: Surgical treatment of patients with atlantoaxial instability caused by pathologic changes of the skull base and craniovertebral junction combined with anterior compression of the brain stem is still associated with substantial technical difficulties and remains a matter of debate. Currently, anterior stabilization of the atlantoaxial junction is a promising approach that allows for the resection of the pathologic lesion of the skull base and craniovertebral junction with subsequent stabilization of C1-C2 or C1-C3 in 1 stage. METHODS: In this article, we present 5 clinical cases in which transoral decompression and anterior stabilization of the C1-C2 (4 cases) and C1-C3 (1 case of anteroposterior stabilization) segments with custom-made fixation systems was used to treat various pathologic conditions of the craniovertebral junction. RESULTS: In all cases, complete removal of the pathologic lesion and decompression of the upper cervical spinal cord as well as reliable stabilization of the upper spinal segments were achieved. Some degree of movement in the cervical spine was preserved in all patients due to unfixed C0-C1 and C3-C7 segments in 4 cases and C0-C1 and C4-C7 in 1 case. Implant migration or instability was not observed in any of the cases. The follow-up period was from 1 to 4 years after surgery. CONCLUSIONS: The first experience of anterior fixation using individually manufactured C1-C2 and C1-C3 systems demonstrated their effectiveness. This approach can be safely used as an alternative or in combination with standard posterior stabilization methods. An innovative surgical technology developed and implemented in our surgical practice allows for optimization of the surgical technique, reduces the number of perioperative complications, eliminates movement restrictions in the cervical spine, improves motor activity, and makes earlier patient rehabilitation possible.

Transoral Removal of Ventrally Located Meningiomas of the Craniovertebral Junction.

BACKGROUND: Surgical treatment of ventral pathologic lesions of the craniovertebral junction and upper cervical spine is extremely difficult due to limited accessibility, as well as the difficulty of performing surgical manipulations in a deep, narrow wound in conditions of restricted surgical freedom and angle of attack. METHODS: In this article we present 2 clinical cases in which the transoral approach was used to treat ventral meningiomas of the craniovertebral junction. Endoscopic assistance and an original method of anterior atlantooccipital stabilization were used. RESULTS: Subtotal removal in the first case and complete removal of the tumor in the second case were achieved. In the first case, an unsuccessful attempt of anterior stabilization was made. In the second case, there were no indications for instrumentation (anterior or posterior) as local bone autograft fusion between the condyles and lateral masses of C1 was effectively carried out. CONCLUSIONS: Previously, the transoral approach garnered interest only from a historical point of view, but with technical progress it has acquired a "second life." Novel surgical techniques allow for a more radical resection of named tumors, as well as lower morbidity and invasiveness of the surgical procedures, which, in the long term, leads to lower complication rates.

Endoscopic endonasal transclival removal of tumors of the clivus and anterior region of the posterior cranial fossa (results of surgical treatment of 140 patients).

BACKGROUND: Until recently, tumors of the clivus and the anterior region of the posterior cranial fossa were considered extremely difficult to access and often inoperable using standard transcranial approaches. With the introduction into the neurosurgical practice of minimally invasive methods utilizing endoscopic techniques, it became possible to effectively remove hard-to-reach tumors, including central tumors of the anterior region of the posterior cranial fossa. METHODS: From 2008 to the present time, the inpatient institution has operated on 140 patients with various tumors of the base of the skull, localized to the clivus and anterior region of the posterior cranial fossa (65 men and 75 women). The age of patients ranged from 3 to 74 years. Tumor distribution according to the histopathological features was as follows: chordomas, 103 (73.57%); meningiomas, 12 (8.57%); pituitary adenomas, 9 (6.43%); fibrous dysplasia, 4 (2.86%); cholesteatoma, 3 (2.14%); craniopharyngiomas, 2 (1.43%); plasmacytomas, 2 (1.43%); and other tumors (giant cell tumor, neurohypophyseal glioma, osteoma, carcinoid, chondroma), 5 (3.57%). The tumors had the following size distribution: giant (more than 60 mm), 35 (25%); large (35-59 mm), 83 (59.3%); medium (21-35 mm), 21 (15%); and small (less than 20 mm), 1 (0.7%). In 11 cases, intraoperative monitoring of the cranial nerves was performed (21 cranial nerves were identified). RESULTS: Upper, middle, and lower transclival approaches provide access to the anterior surface of the upper, middle, and lower neurovascular complexes of the posterior cranial fossa. The chordoma cases were distributed as follows according to extent of removal: total removal, 68 (66.02%); subtotal removal, 25 (24.27%); and partial removal, 10 (9.71%). The adenomas of the pituitary gland were removed totally in 6 cases, subtotally in 1 case and partially in 2 cases. The meningiomas were removed totally in 1 case, subtotally in 5 cases, and partially in 5 cases, with less than 50% of the tumor removed in 1 case. Other tumors (cholesteatoma, craniopharyngioma, fibrous dysplasia, giant cell tumor, glioma of the neurohypophysis, osteoma, plasmacytoma, carcinoid, and chondroma) were removed totally in 9 cases and subtotally in 7 cases. Postoperative CSF leaks occurred in 9 cases (6.43%) and meningitis in 13 cases (9.29%). Oculomotor disorders developed in 19 patients (13.57%), 12 of which regressed during the period from 4 to 38 days after surgery, and 7 of which were permanent. In 2 cases, surgical treatment had a lethal outcome (1.43%). CONCLUSION: The endoscopic endonasal transclival approach can be used to obtain access to the centrally located tumors of the posterior cranial fossa. It is an alternative to transcranial approaches in the surgical treatment of tumors of the clivus. The results of using this approach are comparable with the results of transcranial and transfacial approaches and, in some cases, surpass them in effectiveness. The extended endoscopic endonasal posterior (transclival) approach, considering its minimally invasive nature, allows fora radical and low-risk (in terms of postoperative complications and lethality) removal of various skull base tumors of central localization with the involvement and without the involvement of the clivus, which, until recently, were considered to be almost inoperable.

Transoral Decompression and Anterior Stabilization of Atlantoaxial Joint in Patients with Basilar Impression and Chiari Malformation Type I: A Technical Report of 2 Clinical Cases.

OBJECTIVE: Presentation of clinical cases involving successful anterior stabilization of the C1-C2 segment in patients with invaginated C2 odontoid process and Chiari malformation type I. METHODS: Clinical case description. RESULTS: Two patients with C2 odontoid processes invagination and Chiari malformation type I were surgically treated using the transoral approach. In both cases, anterior decompression of the upper cervical region was performed, followed by anterior stabilization of the C1-C2 segment. In 1 of the cases, this procedure was performed after posterior decompression, which led to transient regression of neurologic symptoms. In both cases, custom-made cervical plates were used for anterior stabilization of the C1-C2 segment. During the follow-up period of more than 2 years, a persistent regression of both the neurologic symptoms and Chiari malformation was observed. CONCLUSIONS: Anterior decompression followed by anterior stabilization of the C1-C2 segment is a novel and promising approach to treating Chiari malformation type I in association with C2 odontoid process invagination.

Neurophysiological Identification of Cranial Nerves During Endoscopic Endonasal Surgery of Skull Base Tumors: Pilot Study Technical Report.

INTRODUCTION: Intraoperative identification of cranial nerves is crucial for safe surgery of skull base tumors. Currently, only a small number of published papers describe the technique of trigger electromyography (t-EMG) in endoscopic endonasal removal of such tumors. OBJECTIVE: To assess the effectiveness of t-EMG in preventing intraoperative cranial nerve damage in endoscopic endonasal surgery of skull base tumors. MATERIALS AND METHODS: Nine patients were operated on using the endoscopic endonasal approach within a 1-year period. The tumors included large skull base chordomas and trigeminal neurinomas localized in the cavernous sinus. During the surgical process, cranial nerve identification was carried out using monopolar and bipolar t-EMG methods. Assessment of cranial nerve functional activity was conducted both before and after tumor removal. RESULTS: We mapped 17 nerves in 9 patients. Third, fifth, and sixth cranial nerves were identified intraoperatively. There were no cases of postoperative functional impairment of the mapped cranial nerves. In one case we were unable to get an intraoperative response from the fourth cranial nerve and observed its postoperative transient plegia (the function was normal before surgery). CONCLUSION: t-EMG allows surgeons to control the safety of cranial nerves both during and after skull base tumor removal.

Surgical Treatment of Skull Base Tumors, Extending to Craniovertebral Junction.

OBJECTIVE: To conduct a comparative analysis of 2 groups of patients with skull base chordomas extending onto the craniovertebral junction, who underwent surgical treatment using extracranial approaches with and without craniocervical fusion. METHODS: The study group included 29 patients with skull base chordomas, extending to the craniovertebral junction, who were operated on from 2000 to 2015. The patients underwent the following surgical treatment: posterior craniocervical fusion followed by tumor removal using transoral and combined transoral and transnasal approaches. The reference group included 21 patients with the same disease, who underwent tumor removal surgery using the transoral approach without craniocervical fusion. RESULTS: In the study group, in 27.5% of all cases (8 patients), the tumors were removed radically; in 65.5% of all cases (19 patients), the tumors were removed subtotally; and in 7% of all cases (2 patients), the tumors were removed partially. In the reference group, the extent of surgical radicality was as follows: radical, 0%; subtotal, 19% (4 cases); partial, 81% (17 cases). CONCLUSIONS: Use of the proposed surgical technique in clinical practice may help increase the radicality of tumor excisions, decrease the number of postoperative complications, accelerate the rehabilitation process, and increase the quality of life in patients with skull base tumors extending to the craniovertebral junction.