Microsurgical anatomy and approaches to thalamic gliomas. Part 1: A cartography guide for navigating to the thalamus. Integrating 3D model rendering with anatomical dissections.

OBJECTIVE: The selection of appropriate microsurgical approaches to treat thalamic pathologies is currently largely subjective. The objective of this study was to provide a structured cartography map for surgical navigation to treat gliomas involving different surfaces of the thalamus. METHODS: Fifteen formalin-fixed, silicone-injected cadavers (30 sides) were dissected, and 10 adult brain specimens (20 sides) were used to illustrate thalamic microsurgical anatomy using the Klingler fiber dissection technique. Exposures and trajectories for the six most common microsurgical approaches were depicted using MR data from healthy subjects converted into surface-rendered 3D virtual brain models. Additionally, thalamic surfaces exposed with all six approaches were color mapped on the virtual 3D model and compared side-by-side in 360° views with previously reported microsurgical approaches. These 3D models were then used in conjunction with topographic data to guide cadaveric dissection steps. RESULTS: There are two general surgical routes to thalamic lesions: the subarachnoid transcisternal and transcortical routes. The transcisternal route consists of the following three approaches: 1) anterior interhemispheric transcallosal approach, which exposes the anterior and superior thalamus; 2) posterior interhemispheric transcallosal approach, which exposes the posterosuperior thalamus; and 3) supracerebellar infratentorial approach, which exposes the posteromedial cisternal thalamus and can be extended laterally to approach the posterolateral thalamus by cutting the tentorium. The three transcortical approaches are the 1) superior parietal lobule approach, which exposes the posterosuperior thalamus and is particularly advantageous in the setting of hydrocephalus; 2) transtemporal gyrus approach, which exposes the inferolateral thalamus; and 3) transsylvian transinsular approach, which exposes the lateral thalamus (slightly more superiorly and posteriorly) and is advantageous for pathologies extending laterally into the peduncle, lenticular nucleus, or insula. CONCLUSIONS: Microsurgical approaches to thalamic gliomas continue to be challenging. Nonetheless, safe and effective cisternal, ventricular, and cortical corridors can be developed with thoughtful planning, anatomical understanding, and knowledge of the advantages, risks, and limitations of each approach. In some cases, it is wise to combine these approaches with staged procedures, as the authors demonstrate in Part 2. In Part 1 of this two-part series, they discuss thalamic microsurgical anatomy and illustrate the trajectory and exposures of all six approaches to guide decision-making. Part 2 discusses their thalamic glioma microsurgical case series, which utilizes these microsurgical approaches.

Treatment Response to Acute Total Ophthalmoplegia in Primary Pituitary Lymphoma: A Case Report and Review of the Literature.

Primary pituitary lymphoma (PPL) is an extremely rare localized lymphoma without systemic involvement. The most common clinical presentations of PPL are hypopituitarism, headaches, and ophthalmoplegia. Diagnosing PPL without a biopsy is almost impossible. There is no study that has specifically investigated and reviewed treatment responses to the ophthalmological symptoms of PPL patients. Herein, we present a 66-year-old female patient who had acute-onset total ophthalmoplegia and headache as admission symptoms, which was diagnosed as PPL after subtotal resection. In the present study, we discussed the response of ophthalmological symptoms to treatment with a review of the literature. Only 18 reported cases had postoperative ophthalmological examination, and in 94.4% of these cases, ophthalmoplegia resolves after surgery and chemotherapy. The complete resection rate of the PPL in the literature was found to be as low as 12.3% in this region because of the hard and adhesive nature of the tumor. Our review unveiled that complete recovery of ophthalmoplegia can be achieved even in the late phase of the symptoms. In the present case, ophthalmoplegia resolved completely following subtotal resection and rituximab, high-dose methotrexate, and cytarabine treatment.

Calvarial Tumors: A Retrospective Analysis and Clinical Experience.

AIM: To elucidate the prognosis, frequency, and diverse nature of pathologies for calvarial tumors among different age groups. MATERIAL AND METHODS: Seventy-six patients who underwent surgery for calvarial lesions between January 2007 and March 2021 are included in this study. Clinical data obtained retrospectively from patients? electronic records. Radiological images and surgical notes are reviewed to determine extent of the tumor and resection. RESULTS: Among 76 patients, 33 (43.4%) were male and 43 (56.6%) were female. The mean age was 36.0 years (range: 1?81 years) at the time of initial operation. Children consisted 28.9% (n=22) of the patients. In children, 59.1% (n=13) had tumor-like pathologies, while 27.3% (n=6) had benign pathologies, and 13.6% (n=3) had malignant tumors. In the adult population, 42.6% (n=23) had malignant tumors, 31.5% (n=17) had benign tumors, 16.7% (n=9) had tumor-like pathologies, and 9.2% (n=5) had intermediate-grade tumors. F-fluorodeoxyglucose positron emission tomography (FDG-PET) scan was performed in 16 patients, 10 cases underwent whole-body bone scintigraphy (WBBS), and 4 cases underwent both. Among these examinations, 16 (80%) of the FDG-PET scans and 5 (35.7%) of the WBBS scans revealed an extracranial pathological lesion. A calvarial tumor was diagnosed in 13 of 18 cases of metastatic lesions (72.2%) before the primary tumor detection. CONCLUSION: Lesions of the calvarium include malignant tumors, intermediate grade tumors, tumor-like lesions, and benign tumors. These masses may be the first presentation in patients with underlying primary tumors. In our study, the malignant tumor rate in the calvaria was 34.2%, and 72.2% of the metastatic tumors were diagnosed with a calvarial resection before the primary tumor was found. Operating a calvarial lesion and making an early diagnosis are crucial for the treatment of the primary lesions.

Rare Cause of Acute Tetraplegia and Respiratory Arrest: Cervicomedullary Neuroenteric Cyst in a Child: Case Report.

BACKGROUND: Neuroenteric cysts (NCs) are benign, rare congenital lesions which are most commonly found in the lower cervical and upper thoracic segments. Even though these are benign lesions, it may present with fatal neurologic deterioration particularly in pediatric patients. CASE REPORT: We here report a 16-year-old boy who has unique manifestation with acute tetraplegia and respiratory arrest in emergency room. According to English literature, this is the first case of cervicomedullary intradural neuroenteric cyst which causes acute tetraplegia and respiratory arrest in a child. CONCLUSION: The NCs can be manifested with unpredictable, life threating clinical presentation. The exact pathophysiology of an acute neurological deterioration is still unclear, however prolonged latent period with minor symptom should be considered carefully in child population.

Management of occipitocervical junction and upper cervical trauma.

OBJECTIVE: The treatment modality of occipitocervical junction (OCJ) and upper cervical traumas carries great importance because of unique form of bone, complex ligamentous, and neurovascular structure. MATERIALS AND METHODS: Eighty-eight patients were admitted to Mersin University Department of Neurosurgery between January 2007 and January 2017 for injuries of the OCJ and upper cervical spine and evaluated retrospectively. In the group, there were 60 male, 28 female patients in the mean age of 42.9 (18-87) years. Among those, 2 occipital condyle fractures, 28 C1 fractures (26 isolated and 2 with transverse ligament injury), 9 combined C1/C2 fractures, 6 rotatory C1/C2 dislocations, and 43 C2 fractures (32 odontoid, 5 Hangman's, and 6 miscellaneous fractures) were diagnosed. In addition to clinical cases, ten cadavers were used to study the OCJ in a step-wise manner. RESULTS: Occipital condyle fractures, isolated C1 fractures, and rotatory C1/C2 dislocations were treated conservatively. Two patients with C1 fracture including transverse ligament injury were operated in one of the methods of C1-C2 fusion which is posterior sublaminar wiring. Five patients having Type II odontoid fracture were treated surgically. One instable Hangman's fracture patient was treated as anterior cervical discectomy and fusion. CONCLUSIONS: Cases with isolated C1 fracture with intact transverse ligament should be conservatively treated without surgical approach. Atlas fractures with transverse ligament rupture, odontoid Type II fractures with dislocation >6 mm, and unstable Hangman's fractures required surgical treatment. Vital neurovascular, ligamentous, and accompanying bone structures should be evaluated for diagnosis and treatment modality. In addition, patient's health status, patient's treatment preference, and surgical team experience are the affecting factors for the decision of surgery.

Clinical course of the untreated calcified big cerebellar liponeurocytoma.

Cerebellar liponeurocytoma (CLN) is a very rare tumor of central nervous system, classified as glioneuronal tumor by the latest classification of World Health Organization (WHO) in 2016. There are limited data in the literature about biologic behavior, growth pattern and radiological features of this tumor. In this case report, we operated a big calcified CLN patient who had denied any surgical procedures suggested by an another institute and had been followed for 4 years.

Occipital Artery and Its Segments in Vertebral Artery Revascularization Surgery: A Microsurgical Anatomic Study.

OBJECTIVE: To study the microsurgical anatomy of the occipital artery (OA) to determine the optimal segment for use as a conduit in revascularization bypass surgery. METHODS: Twelve sides of 6 cadaveric heads that had been injected with colored silicone were exposed using C-shaped postauricular incision. The OA was dissected from its point of origin to the proximal part of the distal segment. For each segment, the diameters and length were measured, and its branches and proximity to the recipient vessel (V3) were examined. RESULTS: The mean diameters were 2.6 mm at the digastric segment, 2.04 mm at the point where it exits the mastoid sulcus, 2.0 mm, at the point just before the last descending muscular branch, and 1.8 mm and 1.5 mm after the branch and attached to the superior nuchal line, respectively. The length of the OA from the point where it exits the mastoid sulcus to the point at which it revealed the last descending muscular branch was 53 mm, and the distance of this section to the V3 was 31 mm. CONCLUSIONS: In pathologies necessitating vertebral artery revascularization surgery, it is possible to easily mobilize the OA with a C-shaped postauricular incision in the lateral suboccipital region. To reach a more appropriate segment in terms of diameter, length, and easy anastomosis, V3 sulcal and OA suboccipital segments are more suitable. Thus, if bypass surgery is indicated in cases of vertebrobasilar ischemia, the suboccipital segment of the OA may be an ideal choice and considered as an artery that can be used in "SOS" conditions.

Comparison of the effects of different electrocautery applications to peripheral nerves: an experimental study.

BACKGROUND: This study was designed to investigate the effects of bipolar and mononopolar electrocauterization on peripheral nerve tissue. The comparison on the deleterious effects of the different cautery modalities and the importance of probe tip placement are evaluated using electrophysiological, electron microscopic and biochemical assessment parameters. METHODS: Ninety-eight male Wistar albino rats, each weighing 250-275 g, were randomly divided into 14 groups. Each group consisted of seven animals. Monopolar and bipolar electrocautery were performed at 15 watts. The application was performed either directly on the nerve or 1 mm lateral to the longitudinal axis of the nerve for 'near the nerve groups', respectively. RESULTS: The electrophysiological findings showed that the mean amplitudes were at the lowest value in the first day for all the groups. At the end of the 3rd week, we recognised that the electrophysiological recovery continued. Electron microscopic evaluation showed myelin disruption in all groups. Myelin disruption of healthy neurons was at the highest level in the 1st day of application in accordance with the electrophysiological findings. Biochemical evaluation revealed statistical significance between the control and the two of the 'near the nerve groups' (GIII and GV) for NO (nitrite and nitrate) serum level. CONCLUSION: The data of the present study might suggest that electrocautery, independent of the type and form of application, may result in significant damage in histological and electrophysological basis. Although the relative proportions cannot be ascertained, the time course of recovery suggests that both axon and myelin damage have occurred. The probable electrocautery damage may be of substantial importance for the situation that the nerves are displaced by tumor masses or atypical neural traces.