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The authors report on and discuss the historical evolution of the 3 intellectual and scientific domains essential for the current understanding of the function of the human thalamus: 1) the identification of the thalamus as a distinct anatomical and functional entity, 2) the subdivision of thalamic gray matter into functionally homogeneous units (the thalamic nuclei) and relative disputes about nuclei nomenclature, and 3) experimental physiology and its limitations.Galen was allegedly the first to identify the thalamus. The etymology of the term remains unknown although it is hypothesized that Galen may have wanted to recall the thalamus of Odysseus. Burdach was the first to clearly and systematically define the thalamus and its macroscopic anatomy, which paved the way to understanding its internal microarchitecture. This structure in turn was studied in both nonhuman primates (Friedemann) and humans (Vogt and Vogt), leading to several discrepancies in the findings because of interspecies differences. As a consequence, two main nomenclatures developed, generating sometimes inconsistent (or nonreproducible) anatomo-functional correlations. Recently, considerable effort has been aimed at producing a unified nomenclature, based mainly on functional data, which is indispensable for future developments. The development of knowledge about macro- and microscopic anatomy has allowed a shift from the first galenic speculations about thalamic function (the "thalamus opticorum nervorum") to more detailed insights into the sensory and motor function of the thalamus in the 19th and 20th centuries. This progress is mostly the result of lesion and tracing studies. Direct evidence of the in vivo function of the human thalamus, however, originates from awake stereotactic procedures only.Our current knowledge about the function of the human thalamus is the result of a long process that occurred over several centuries and has been inextricably intermingled with the increasing accumulation of data about thalamic macro- and microscopic anatomy. Although the thalamic anatomy can currently be considered well understood, further studies are still needed to gain a deeper insight into the function of the human thalamus in vivo.

Chordoma is a rare, slow-growing tumor thought to arise from remnants of embryonic notochord associated with an aggressive outcome. Cancer stem-like cells (CSCs) are related to tumorigenesis, recurrence, and resistance in cancers. Therefore, chordoma CSCs are possible targets for chordoma treatment. In this study, dysregulated miRNAs were determined in chordoma CSCs and identified their role in chordoma. Dysregulated miRNAs were determined via miRNA microarray and validated through qPCR. miRNAs were transiently transfected to the chordoma cell lines and their roles in proliferation, apoptosis, migration and invasion capacities and stem-like properties were identified. Finally, a relationship between clinicopathological features and dysregulated miRNAs has been evaluated among 21 chordoma patients. CD133 + CD15 + cells exhibited CSC phenotype with increased CSC- and Epithelial-Mesenchymal Transition (EMT)-related gene expression, invasion, migration, tumorosphere- and colony-forming abilities. In addition, WNT5A, TGF-α, BTG2 and MYCBP genes involved in CSC-related pathways, were targets of miR-140-3p, miR-148a-3p, miR-210-5p and miR-574-5p, respectively. Transfection of CSC-related miRNAs also increased migration and invasion along with stem cell phenotype. Finally, we determined that miR-140-3p and miR-148a-3p expressions correlated with Ki67 while miR-140-3p and TGF-α expressions were correlated with p53. Moreover, MYCBP expression was positively correlated with tumor volume, and metastasis was associated with the expression of miR-210-5p and TGF-α in our patient cohort. Through these findings, we conclude that chordoma CSCs have distinctive miRNA profile, which can regulate stem-like properties of chordoma CSCs., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Intramedullary tumors of the spinal cord are rare and account for 2% to 8.5% of all central nervous system tumors. In adults, ependymomas are the most common intramedullary tumors. The primary choice of treatment should be radical surgical removal, as this is curative for most tumors. Adequate tumor exposure is crucial and mostly achieved through standard laminectomy followed by midline myelotomy. However, extensive removal of posterior spinal elements may lead to worsening kyphotic deformities.  After obtaining patient consent, this 3-dimensional video publication was prepared to present microneurosurgical removal of a C3-C6 cervical intramedullary tumor using right-sided hemilaminoplasty. C3-C6 hemilaminae were lifted en bloc. After dural and arachnoid incision, midline myelotomy was performed. Using microneurosurgical technique, the tumor was removed totally. After the dural closure, C3-C6 hemilaminae were placed into the previous position and reconstructed with mini-plates and screws. Preserving contralateral paraspinal muscles, spinous processes, midline spinal ligaments and bilateral facet joints helped maintaining the alignment of the spinal column.  Comparing to laminectomy, hemilaminoplasty, decreases the postoperative pain and the total blood loss as only one side muscle dissection is enough.  In the presented case, postoperative MRI showed total removal of the tumor. The final histopathology report indicated an ependymoma (WHO-Grade 2). Successful bone healing was demonstrated by postoperative cervical radiographs and CT scans. The patient has no postoperative neurological deficit.  In conclusion, hemilaminoplasty is an effective and a less-invasive method in removal of intradural-intramedullary tumors with its advantages such as preventing the instability and reduction of blood loss and postoperative pain., (Copyright © 2018 by the Congress of Neurological Surgeons.)

This video demonstrates resection of a left pontine cavernous malformation that is abutting the floor of the fourth ventricle (f4V). Even though accessing the lesion through the f4V seems to be reasonable, we used a lateral supracerebellar approach through the middle cerebellar peduncle to preserve especially the abducens and facial nuclei. After total resection the patient was neurologically intact at the 3-month follow-up. Postoperative MRI revealed 3.5-mm pontine tissue between the cavity and f4V that appeared to be absent in preoperative MRI. Approaching pontine lesions through the f4V is not the first choice. In our opinion, the philosophy of safe entry zones is a concept to be reassessed. The video can be found here: https://youtu.be/1Jh6giZc-48., Competing Interests: Disclosures The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this article., (© 2019, Abdullah Keleş, Mehmet Volkan Harput, and Uğur Türe.)

OBJECTIVE The semisitting position of a patient confers numerous advantages in various neurosurgical procedures, but venous air embolism is one of the associated complications of this position. To date, no prospective studies of the relationship between the degree of head elevation and the rate and severity of venous air embolism for patients undergoing a procedure in this position have been performed. In this study, the authors compared changes in the severity of venous air embolism according to the degree of head elevation (30° or 45°) in patients undergoing an elective cranial neurosurgical procedure in the semisitting position. METHODS One hundred patients undergoing an elective infratentorial craniotomy in the semisitting position were included, and each patient was assigned to 1 of 2 groups. In Group 1, each patient's head was elevated 30° during surgery, and in Group 2, each patient's head elevation was 45°. Patients were assigned to their group according to the location of their lesion. During surgery, the standard anesthetic protocol was used with total intravenous anesthesia, and transesophageal echocardiography was used to detect air in the blood circulation. Any air embolism seen on the echocardiography screen was classified as Grade 0 to 4. If multiple events occurred, the worst graded attack was used for statistical analysis. During hemodynamic changes caused by emboli, fluid and vasopressor requirements were recorded. Surgical and anesthetic complications were recorded also. All results were compared statistically, and a p value of < 0.05 was considered statistically significant. RESULTS There was a statistically significant difference between groups for the total rates of venous air emboli detected on transesophageal echocardiography (22.0% [n = 11] in Group 1 and 62.5% [n = 30] in Group 2; p < 0.0001). The rate and severity of air embolism were significantly lower in Group 1 than in Group 2 (p < 0.001). The rates of clinically important venous air embolism (Grade 2, 3, or 4, venous air embolism with decreased end-tidal carbon dioxide levels and/or hemodynamic changes) were 8.0% (n = 4) in Group 1 and 50.0% (n = 24) in Group 2 (p < 0.0001). There was no association between the rate and severity of venous air embolism with patient demographics (p > 0.05). An association was found, however, between the rate of venous air embolism and the type of surgical pathology (p < 0.001); venous embolism occurred more frequently in patients with a meningioma. There were no major surgical or anesthetic complications related to patient position during the postoperative period. CONCLUSIONS For patients in the semisitting position, an increase in the degree of head elevation is related directly to a higher rate of venous air embolism. With a 30° head elevation and our standardized technique of positioning, the semisitting position can be used safely in neurosurgical practice.

Accurate digital representation of major white matter bundles in the brain is an important goal in neuroscience image computing since the representations can be used for surgical planning, intra-patient longitudinal analysis and inter-subject population connectivity studies. Reconstructing desired fiber bundles generally involves manual selection of regions of interest by an expert, which is subject to user bias and fatigue, hence an automation is desirable. To that end, we first present a novel anatomical representation based on Neighborhood Resolved Fiber Orientation Distributions (NRFOD) along the fibers. The resolved fiber orientations are obtained by generalized q-sampling imaging (GQI) and a subsequent diffusion decomposition method. A fiber-to-fiber distance measure between the proposed fiber representations is then used in a density-based clustering framework to select the clusters corresponding to the major pathways of interest. In addition, neuroanatomical priors are utilized to constrain the set of candidate fibers before density-based clustering. The proposed fiber clustering approach is exemplified on automation of the reconstruction of the major fiber pathways in the brainstem: corticospinal tract (CST); medial lemniscus (ML); middle cerebellar peduncle (MCP); inferior cerebellar peduncle (ICP); superior cerebellar peduncle (SCP). Experimental results on Human Connectome Project (HCP)'s publicly available "WU-Minn 500 Subjects + MEG2 dataset" and expert evaluations demonstrate the potential of the proposed fiber clustering method in brainstem white matter structure analysis., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Giuseppe Campani (1635-1715) was a polymath in Rome, Italy, during the Scientific Revolution in the XVIIth century. In particular, he forged the screw barrel microscope and was manufacturing his own lenses for microscopes and telescopes. He mastered the art of lens grinding. Those lenses have been analyzed with modern methods and turned out to be of extremely good quality, shining light on the fact that Giuseppe Campani mastered the theories of optics. Moreover, in a letter that Giuseppe Campani sent to Pope Innocent XI, he clearly described the use of a microscope for the examination of wounds of legs. This letter dates back to 15 August 1686 and is the first evidence of the use of microscopes to analyze wounds, sores, and anatomic specimens in medical and surgical settings. MG Yasargil previously showed the lithography accompanying this letter and was the first to recognize its great importance. We accessed this original letter in the Vatican Library, and for the first time we have translated it from Latin to English in order to unveil its significance in the context of the Scientific Revolution and the history of medicine and surgery., (Copyright © 2017 by the Congress of Neurological Surgeons.)

This is the case of a 14-year-old female who presented with headache and seizures. Cranial magnetic resonance imaging revealed an arteriovenous malformation (AVM) located at the posterior portion of the right-sided fusiform gyrus. Cerebral angiography showed that the AVM was fed mainly by branches from the inferior temporal trunk of the posterior cerebral artery. The main venous drainage was to the right transverse sinus through the tentorial vein. The AVM was totally excised through the paramedian supracerebellar-transtentorial approach with the patient in a semisitting position. Postoperative MRI and cerebral angiography confirmed the total resection. The patient was discharged on the 5th postoperative day without neurological deficit. The video can be found here: https://youtu.be/QPrUl8AP7G8 .

Background: Surgical access to the temporal horn is necessary to treat tumors and vascular lesions, but is used mainly in patients with mediobasal temporal epilepsy. The surgical approaches to this cavity fall into 3 primary categories: lateral, inferior, and transsylvian. The current neurosurgical literature has underestimated the interruption of involved fiber bundles and the correlated clinical manifestations., Objective: To delineate the interruption of fiber bundles during the different approaches to the temporal horn., Methods: We simulated the lateral (trans-middle temporal gyrus), inferior (transparahippocampal gyrus), and transsylvian approaches in 20 previously frozen, formalin-fixed human brains (40 hemispheres). Fiber dissection was then done along the lateral and inferior aspects under the operating microscope. Each stage of dissection and its respective fiber tract interruption were defined., Results: The lateral (trans-middle temporal gyrus) approach interrupted "U" fibers, the superior longitudinal fasciculus (inferior arm), occipitofrontal fasciculus (ventral segment), uncinate fasciculus (dorsolateral segment), anterior commissure (posterior segment), temporopontine, inferior thalamic peduncle (posterior fibers), posterior thalamic peduncle (anterior portion), and tapetum fibers. The inferior (transparahippocampal gyrus) approach interrupted "U" fibers, the cingulum (inferior arm), and fimbria, and transected the hippocampal formation. The transsylvian approach interrupted "U" fibers (anterobasal region of the extreme capsule), the uncinate fasciculus (ventromedial segment), and anterior commissure (anterior segment), and transected the anterosuperior aspect of the amygdala., Conclusion: White matter dissection improves our knowledge of the complex anatomy surrounding the temporal horn. Identifying the fiber bundles at risk during each surgical approach adds important information for choosing the appropriate surgical strategy., (Copyright © 2016 by the Congress of Neurological Surgeons)

Cell lines established from tumors are the most commonly used models in cancer research, and their use in recent years has enabled a greater understanding of the biology of cancer and the means to develop effective treatment strategies. Astroblastomas are uncommon neuroepithelial tumors of glial origin, predominantly affecting young people, mainly teenagers and children, predominantly females. To date, only a single study has reported that astroblastomas contain a large number of neural stem-like cells, which had only a partial proliferation capacity and differentiation. Our objective was to establish an astroblastoma cell line to investigate the presence of astroblastic cells and cancer stem-like cells. The migratory and invasion abilities of the cells were quantified with invasion and migration assays and compared to a glioblastoma cell line. The presence of stem cells was detected with surface-marker analysis by using flow cytometry, and measuring the differentiation ability with a differentiation assay and the self-renewal capacity with a sphere-forming assay. These characteristics may determine whether this novel cell line is a model for astroblastomas that may have stem-cell characteristics. With this novel cell line, scientists can investigate the molecular pathways underlying astroblastomas and develop new therapeutic strategies for patients with these tumors., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Objective: The dense and complex distribution of neural structures in the brainstem makes it challenging to understand their real configuration. We used the fiber microdissection technique to show the course of the medial and lateral lemnisci within the brainstem. Although these structures seem anatomically alike, they are functionally distinct., Methods: Fifteen human brainstems and 8 brain hemispheres (formalin-fixed and previously frozen) were dissected and studied under the operating microscope by applying the fiber microdissection technique., Results: We delineated and described the medial and lateral lemnisci, noting their gross elaborate arrangement. These structures are intimately compact and closely related to one another in their common trajectory through the tegmenta of the pons and midbrain. However, we were not able to identify the exact origin and termination of their fibers or the accurate delimitation between the medial lemniscus, spinothalamic tract, and lateral lemniscus along their course in the brainstem., Conclusions: Using the fiber microdissection technique, we were able to define a general perspective of the topography and architecture of the medial and lateral lemnisci in the brainstem. This perspective should be incorporated into interpretations of magnetic resonance imaging techniques, recognizing both their benefits and limitations. It should also be applied to surgical planning and strategies to achieve a safer and more precise microsurgical procedure., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Objective: To describe the topographic anatomy of surgically accessible surfaces of the human thalamus as a guide to surgical exploration of this sensitive area., Methods: Using the operating microscope, we applied the fiber microdissection technique to study 10 brain specimens. Step-by-step dissections in superior-inferior, medial-lateral, and posterior-anterior directions were conducted to expose the surfaces and nuclei of the thalamus and to investigate the relevant anatomic relationships and visible connections., Results: There were 4 distinct free surfaces of the thalamus identified: lateral ventricle surface, velar surface, cisternal surface, and third ventricle surface. Each is described with reference to recognizable anatomic landmarks and to the underlying thalamic nuclei. The neural structures most commonly encountered during the surgical approach to each individual surface are highlighted and described., Conclusions: Observations from this study supplement current knowledge, advancing the capabilities to define the exact topographic location of thalamic lesions. This improved understanding of anatomy is valuable when designing the most appropriate and least traumatic surgical approach to thalamic lesions. These proposed surface divisions, based on recognizable anatomic landmarks, can provide more reliable surgical orientation., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Objective We planned a cross-sectional analysis to determine the frequency and severity of metabolic acidosis in patients taking topiramate while awaiting craniotomy. Methods Eighty patients (18 - 65 years) taking topiramate to control seizures while awaiting elective craniotomy were enrolled. Any signs of metabolic acidosis or topiramate-related side effects were investigated. Blood chemistry levels and arterial blood gases, including lactate, were obtained. The severity of metabolic acidosis was defined according to base excess levels as mild or moderate. Results Blood gas analysis showed that 71% ( n = 57) of patients had metabolic acidosis. The frequency of moderate metabolic acidosis was 56% ( n = 45), while that of mild metabolic acidosis was 15% ( n = 12). A high respiratory rate was reported in only 10% of moderately acidotic patients. Conclusions In patients receiving topiramate, baseline blood gas analysis should be performed preoperatively to determine the presence and severity of metabolic acidosis.

OBJECT Brainstem surgery remains a challenge for the neurosurgeon despite recent improvements in neuroimaging, microsurgical techniques, and electrophysiological monitoring. A detailed knowledge of the microsurgical anatomy of the brainstem surface and its internal architecture is mandatory to plan appropriate approaches to the brainstem, to choose the safest point of entry, and to avoid potential surgical complications. METHODS An extensive review of the literature was performed regarding the brainstem surgical approaches, and their correlations with the pertinent anatomy were studied and illustrated through dissection of human brainstems properly fixed with 10% formalin. The specimens were dissected using the fiber dissection technique, under ×6 to ×40 magnification. 3D stereoscopic photographs were obtained (anaglyphic 3D) for better illustration of this study. RESULTS The main surgical landmarks and their relationship with the cerebellum and vascular structures were identified on the surface of the brainstem. The arrangements of the white matter (ascending and descending pathways as well as the cerebellar peduncles) were demonstrated on each part of the brainstem (midbrain, pons, and medulla oblongata), with emphasis on their relationships with the surface. The gray matter, constituted mainly by nuclei of the cranial nerves, was also studied and illustrated. CONCLUSIONS The objective of this article is to review the microsurgical anatomy and the surgical approaches pertinent to the brainstem, providing a framework of its external and internal architecture to guide the neurosurgeon during its related surgical procedures.

Object: The goal in this study was to explore and further refine comprehension of the anatomical features of the temporal loop, known as Meyer's loop., Methods: The lateral and inferior aspects of 20 previously frozen, formalin-fixed human brains were dissected under the operating microscope by using fiber microdissection., Results: A loop of the fibers in the anterior temporal region was clearly demonstrated in all dissections. This temporal loop, or Meyer's loop, is commonly known as the anterior portion of the optic radiation. Fiber microdissection in this study, however, revealed that various projection fibers that emerge from the sublentiform portion of the internal capsule (IC-SL), which are the temporopontine fibers, occipitopontine fibers, and the posterior thalamic peduncle (which includes the optic radiation), participate in this temporal loop and become a part of the sagittal stratum. No individual optic radiation fibers could be differentiated in the temporal loop. The dissections also disclosed that the anterior extension and angulation of the temporal loop vary significantly., Conclusions: The fiber microdissection technique provides clear evidence that a loop in the anterior temporal region exists, but that this temporal loop is not formed exclusively by the optic radiation. Various projection fibers of the IC-SL, of which the optic radiation is only one of the several components, display this common course. The inherent limitations of the fiber dissection technique preclude accurate differentiation among individual fibers of the temporal loop, such as the optic radiation fibers.

Objective: A challenging step of the paramedian supracerebellar-transtentorial approach is to expose the anterior portion of the mediobasal-temporal region (MTR), a step that seems most affected by the steepness of the tentorium. The objective of this study was to define magnetic resonance imaging measurements that can predict the level of challenge in exposing the anterior portion of the MTR., Methods: Cranial magnetic resonance imaging studies of 100 healthy individuals were examined. The tentorial and occipital angles were measured, and the amount of brain tissue that remained hidden on the microscopic view in front of the petrous apex was indirectly estimated. These measurements were statistically compared with the cephalic index of each person., Results: The mean values for the tentorial and occipital angles were 42° (range 25°-53°) and 98° (range 69°-122°), respectively. The results proved that the higher the tentorial angle, the higher the occipital angle and the greater the amount of hidden brain tissue. Of 100 persons, 3 (3%) were found to be dolichocephalic, 23 (23%) were mesocephalic, and 74 (74%) were brachycephalic. Statistical analysis proved that individuals with a dolichocephalic cranial shape have lower tentorial and occipital angles., Conclusions: The results provide strong evidence proving that the lesser the tentorial and occipital angles, the easier the exposure of the anterior portion of the MTR during the paramedian supracerebellar-transtentorial approach. The tendency of the cranial shape toward dolichocephaly seems to have the same practical value in choosing the approach. It is easier to expose the anterior portion of the MTR in these individuals., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Objective: One significant drawback during a cranial reoperation is the presence of meningocerebral adhesions. The appearance of connective tissue bridges between the inner surface of the dura and the pia-arachnoid is mostly related to dural closure and the condition in which the surgical field was left in the previous surgery. This study was done to determine the benefit of placing a thin-layer gelatin sponge of polypeptides subdurally to prevent meningocerebral adhesions., Methods: From September 2005 through May 2012, 902 craniotomies were performed for various lesions by the senior author (U.T.). Beginning in February 2009, we began placing a gelatin sponge under the dural flap to isolate the dural healing process from the cortical surface. To compare the degree of meningocerebral adhesions statistically, reoperation cases between February 2009 and May 2012 were divided into 2 groups as group G (gelatin) and group C (Control) in which the dural closure was made with and without subdural application of the gelatin sponge, respectively., Results: In all patients of group G (n = 15), a neomembrane was found when the dura was opened. This layer was easily dissected and showed no or minimal attachment to the underlying cerebral cortex. However, in group C (n = 14), meningocerebral adhesions in various degrees were detected. Adhesion scores were significantly greater in group C than in group G (P < 0.001)., Conclusion: This study proves that, during the dural closure, placing a thin layer of gelatin sponge in the subdural space is a safe and effective method for preventing meningocerebral adhesions., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Background: During surgery for intrinsic brain lesions, it is important to distinguish the pathological gyrus from the surrounding normal sulci and gyri. This task is usually tedious because of the pia-arachnoid membranes with their arterial and venous complexes that obscure the underlying anatomy. Moreover, most tumors grow in the white matter without initially distorting the cortical anatomy, making their direct visualization more difficult., Objective: To create and evaluate a simple and free surgical planning tool to simulate the anatomy of the surgical field with and without vessels., Methods: We used free computer software (OsiriX Medical Imaging Software) that allowed us to create 3-dimensional reconstructions of the cerebral surface with and without cortical vessels. These reconstructions made use of magnetic resonance images from 51 patients with neocortical supratentorial lesions operated on over a period of 21 months (June 2011 to February 2013). The 3-dimensional (3-D) anatomic images were compared with the true surgical view to evaluate their accuracy. In all patients, the landmarks determined by 3-D reconstruction were cross-checked during surgery with high-resolution ultrasonography; in select cases, they were also checked with indocyanine green videoangiography., Results: The reconstructed neurovascular structures were confirmed intraoperatively in all patients. We found this technique to be extremely useful in achieving pure lesionectomy, as it defines tumor's borders precisely., Conclusion: A 3-D reconstruction of the cortical surface can be easily created with free OsiriX software. This technique helps the surgeon perfect the mentally created 3-D picture of the tumor location to carry out cleaner, safer surgeries.

Fixed atlantoaxial dislocations are difficult to treat and there is no consensus in the treatment protocol. Unilateral enlargement of the atlas-axis facet complex in fixed atlantoaxial dislocations is a very rare condition. These pathologies are usually quite unstable and surgical treatment is necessary in unreductable cases. A 52-year-old woman with a diagnosis of irreducible-fixed rotatory atlantoaxial dislocation presented with acute onset of dizziness, loss of balance, and tetraparesis. She was under 8 years of conservative follow-up. Review of radiology revealed unilateral C2 superior facet hypertrophy compressing the medulla and obstructing the vertebral artery. To treat this condition, we have used a posterior midline approach and removed the lateral portions of the posterior rim of the foramen magnum and the assimilated posterior arch of C1. The V3 segments of the vertebral arteries were exposed bilaterally. The atlantoaxial joint complex on the left was hypertrophied compressing V3. We have removed hypertrophied lateral mass of the atlas and the hypertrophic superior articular facet of C2 for decompression. Patency of both vertebral arteries were checked intraoperatively by Doppler and indocyanine green angiography. We have fixated craniocervical junction on the same session. Patient was neurologically intact and she had confirmed fusion on the surgical site after three years of follow-up. This is a rare case of unilateral hypertrophy of the C2 superior articular facet in a fixed atlantoaxial rotatory dislocation. Progressive compression of medulla and the left vertebral artery leaded to clinical worsening of neurology in this case after 8 years of follow-up. Surgical treatment was necessary for neurological decompression and to establish stability.

Achille Louis Foville's atlas of brain anatomy (1844) is one of the most artistic and detailed works on neuroanatomy in the medical literature. The outstanding drawings by the 2 artists, Emile Beau and Frédéric-Michel Bion, highlight all the philosophy, ability, and sensibility of A.L. Foville in carefully dissecting the superficial and deep structures of the brain and spinal cord. Several plates show true brain fiber dissections of high artistic and academic value. As a result of an early misrecognition in the medical literature, "inferior Foville syndrome" has been wrongly attributed to Achille Louis Foville rather than his son, Achille Louis François Foville (1832-1887), also called Defoville. Therefore, we suggest that Defoville, who actually described the pontine syndrome for the first time in the neurological literature, deserves to be credited for this syndrome and that the syndrome should be called the Defoville syndrome. Through analyzing the political and scientific events in France in the 19th century, we highlight the invaluable contributions of A.L. Foville and his son to the history of neuroanatomy and neurology.

Object: Chordomas are locally aggressive bone tumors known to arise from the remnants of the notochord. Because chordomas are rare, molecular studies aimed at developing new therapies are scarce and new approaches are needed. Chordoma cells and cancer stem-like cells share similar characteristics, including self-renewal, differentiation, and resistance to chemotherapy. Therefore, it seems possible that chordomas might contain a subpopulation of cancer stem-like cells. The aim of this study is to determine whether cancer stem-like cells might be present in chordomas., Methods: In this study, the authors used gene expression analysis for common cancer stem-like cellmarkers, including c-myc, SSEA-1, oct4, klf4, sox2, nanog, and brachyury, and compared chordoma cells and tissues with nucleus pulposus tissues (disc degenerated nontumorigenic tissues). Differentiation through agents such as all-trans retinoic acid and osteogenic differentiation medium was induced to the chordoma cells. Additionally, U-CH1 cells were sorted via magnetic cell sorting for stem cell markers CD133 and CD15. After separation, positive and negative cells for these markers were grown in a nonadherent environment, soft agar, to determine whether the presence of these cancer stem-like cells might be responsible for initiating chordoma. The results were compared with those of untreated cells in terms of migration, proliferation, and gene expression by using reverse transcriptase polymerase chain reaction., Results: The results indicate that chordoma cells might be differentiating and committing into an osteogenic lineage when induced with the osteogenic differentiation agent. Chordoma cells that are induced with retinoic acid showed slower migration and proliferation rates when compared with the untreated cells. Chordoma cells that were found to be enriched by cancer stem-like cell markers, namely CD133 and CD15, were able to live in a nonadherent soft agar medium, demonstrating a self-renewal capability. To the authors' knowledge, this is the first time that cancer stem-like cell markers were also found to be expressed in chordoma cells and tissues., Conclusions: Cancer stem-like cell detection might be an important step in determining the recurrent and metastatic characteristics of chordoma. This finding may lead to the development of new approaches toward treatments of chordomas.

Object: The exploration of lesions in the mediobasal temporal region (MTR) has challenged generations of neurosurgeons to achieve an appropriate approach. To address this challenge, the extensive use of the paramedian supracerebellar-transtentorial (PST) approach to expose the entire length of the MTR, as well as the fusiform gyrus, was investigated., Methods: The authors studied the microsurgical aspects of the PST approach in 20 cadaver brains and 5 cadaver heads under the operating microscope. They evaluated the features, advantages, difficulties, and limitations of the PST approach and refined the surgical technique. They then used the PST approach in 15 patients with large intrinsic MTR tumors (6 patients), tumor in the posterior fusiform gyrus with mediobasal temporal epilepsy (MTE) (1 patient), cavernous malformations in the posterior MTR including the fusiform gyrus (2 patients), or intractable MTE with hippocampal sclerosis (6 patients) from December 2007 to May 2010. Patients ranged in age from 11 to 63 years (mean 35.2 years), and in 9 patients (60%) the lesion was located on the left side., Results: In all patients with neuroepithelial tumors or cavernous malformations, the lesions were completely and safely resected. In all patients with intractable MTE with hippocampal sclerosis, the anterior two-thirds of the parahippocampal gyrus and hippocampus, as well as the amygdala, were removed selectively through the PST approach. There was no surgical morbidity or mortality in this series. Three patients (20%) with high-grade neuroepithelial tumors underwent postoperative radiotherapy and chemotherapy but needed a second surgery for recurrence during the follow-up period. In all patients with MTE, antiepileptic medication could be decreased to a single drug at lower doses, and no seizure activity has occurred until this point., Conclusions: The PST approach provides the surgeon precise anatomical orientation when exposing the entire length of the MTR, as well as the fusiform gyrus, for removing any lesion. This is a novel technique especially for removing tumors involving the entire MTR in a single session without damaging neighboring neural or vascular structures. This approach can also be a viable alternative for selective removal of the parahippocampal gyrus, hippocampus, and amygdala in patients with MTE due to hippocampal sclerosis.

Background: Gabapentin is an anticonvulsant drug that has analgesic properties for acute postoperative pain. However, the analgesic effect of gabapentin as an antiepileptic prophylactic drug on patients undergoing craniotomy is unclear. In this study, we evaluated the postoperative effectiveness of gabapentin on acute postoperative pain when it is used for antiepileptic prophylaxis in patients undergoing craniotomy for supratentorial tumor resection., Methods: Eighty patients undergoing craniotomy for supratentorial tumor resection were randomly assigned into two groups. Patients in Group G (n = 40) received oral gabapentin (3 x 400 mg), and patients in Group P (n = 40) received oral phenytoin (3 x 100 mg) for 7 days before the operation and postoperatively. An identical anesthesia protocol was performed for both the groups. Anesthesia was maintained with propofol and remifentanil infusion. Patient-controlled analgesia with morphine was used, and pain levels were measured. The antiepileptic-related side effects, anesthetic consumption, duration of anesthesia and surgery, tracheal extubation time, postoperative pain scores, morphine consumption, and sedation scores were recorded., Results: Thirty-seven patients in Group G and 38 patients in Group P completed the study. During the preoperative period in Group G, one patient had severe fatigue, one had severe dizziness, and one patient's surgical procedure was changed. The median plasma levels of gabapentin were 34 micromol/mL (range, 23-51 micromol/mL) in 34 patients. In Group P, one patient withdrew from the study preoperatively and one developed transient neurological symptoms postoperatively. The demographic data and mean duration of anesthesia and surgery were similar in both the groups. The total propofol and remifentanil consumption in Group G (1847 +/- 548 mg/3034 +/- 1334 microg) was significantly less than that of Group P (2293 +/- 580 mg/4287 +/- 1282 microg) (P = 0.01). However, tracheal extubation could be done earlier in Group P (4.5 +/- 2 min) than in Group G (16.6 +/- 22 min) (P < 0.001). Pain scores were significantly higher in Group P at 15 min, 30 min, and 1 h (P < 0.001). The total morphine consumption was also significantly higher in Group P (33 +/- 17 mg vs 24 +/- 19 mg) (P = 0.01). The postoperative sedation scores were significantly higher in Group G at 15 min, 30 min, 1 h, and 2 h (P < 0.001)., Conclusions: The administration of gabapentin to patients undergoing craniotomy for supratentorial tumor resection was effective for acute postoperative pain. It also decreased analgesic consumption after surgery. However, it may lead to side effects such as delayed tracheal extubation and increased sedation postoperatively.

Background: In this study, we investigated the effects of propofol infusion on hepatic and pancreatic enzymes and acid-base status compared with baseline values in children undergoing craniotomy who were receiving phenytoin for antiepileptic prophylaxis., Methods: In this prospective clinical study, we measured the serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyl transpeptidase (GGT), alkaline phosphatase (ALP), pancreatic amylase, lipase, and triglyceride levels of 30 children ranging from 4 to 12 yr. All children received propofol anesthesia and were taking phenytoin for antiepileptic prophylaxis. Patients already receiving phenytoin were continued on their medication. Peroral 5 mg x kg(-1) x d(-1) phenytoin was started in patients who were not receiving phenytoin. Serum AST, ALT, GGT, ALP, bilirubin, pancreatic amylase, lipase, and triglyceride levels were studied on admission to the hospital, 1 day before surgery, and on postoperative Days 1, 3, 5, and 7. Arterial blood gas samplings were taken after tracheal intubation, during the operation (2nd and 4th h), just after extubation, and 1, 2, 6, and 12 h after extubation., Results: Serum AST, ALT, GGT, ALP, pancreatic amylase, lipase, and triglyceride levels were increased significantly in the postoperative period compared with baseline with a peak value on postoperative Day 1 and returned to normal values within a week. Base excess levels after extubation were significantly decreased compared with baseline. They were in the normal range, however, and returned to baseline values by 6 h after surgery. There were no clinical signs of hepatitis or pancreatitis. Bilirubin levels were normal. None of the children developed complications related to the liver or pancreas during the 4-6 mo after surgery., Conclusions: Despite the slightly increased pancreatic and hepatic enzyme levels during the postoperative period, anesthesia maintenance with propofol in children undergoing craniotomy had no significant clinical effect on the acid-base status or pancreas or liver enzymes.

High cervical disc herniations (C2-C3) are extremely rare, and various approaches have been used to treat C2-C3. In this report, we recommend the anterolateral extradural approach as an alternative to treat C2-C3 disc herniation. A 72-year-old woman was referred to us with severe pain in the left side of her neck and occipital region. She had been taking high doses of analgesics but had no myelopathic symptoms. Magnetic resonance imaging of the cervical spine revealed that left paramedian, extruded C2-C3 disc material was compressing the spinal cord and the left C3 nerve root. A left-sided anterolateral extradural approach was done to remove the extruded disc material at the C2-C3 level. After resection of the transverse processes of C1 and C2, the V3 segment of the vertebral artery was mobilized posteromedially. The extruded disc material was carefully removed, and the vertebral artery was freed and repositioned. The anterolateral extradural approach to a C2-C3 disc herniation is a good alternative, especially in patients with thick or short necks.

Objective: We investigated the membranous architecture of the abducens nerve at the petroclival region and describe the characteristics of this area in cadaveric specimen and two children with hydrocephalus and sixth nerve palsy using magnetic resonance imaging (MRI)., Materials and Methods: Five adult cadaver heads were used to investigate the petroclival part of the abducens nerve. The heads were injected with colored latex for microsurgical dissection, and the length of the dural sleeve of the abducens nerve and its width at the apex were measured. In one cadaver head, the area between the petroclival entrance porus of the abducens nerve and the cavernous sinus was histologically studied under light microscopy. In two patients with hydrocephalus and abducens nerve palsy, the petroclival area was screened by using the MRI fat suppression technique., Results: In the cadavers, the arachnoid membrane on the clivus extended within the dural sleeve as far as the petrous apex, as an extension of the subarachnoid space. The average length of the dural sleeve was 9.5 mm and the average width was 1.5 mm at the apex, where the nerve entered the cavernous sinus. MRI scans showed that the cerebrospinal fluid distance of the petroclival region was 5 mm in the first patient and 7 mm in the second., Conclusion: The subarachnoid space inside the dural sleeve of the abducens nerve can be defined by using thin-slice MRI scans. Enlargement of the dural sleeve at the petroclival region may coexist with the abducens nerve palsy. It has been documented in this study that the arachnoid membrane forms a membraneous barrier between the subarachnoid and subdural spaces within Dorello's canal.

The injection of cadaver brains is invaluable for anatomic study, but cadavers that have been properly handled are not easy to obtain. A large number of cadavers pass through forensic departments around the world, and these cadavers could provide hundreds of research specimens, though they remain in the forensic unit for only a short time. The injection of a silicone mixture that quickly solidifies during autopsy would provide greater numbers of fresh specimens for study. The authors describe a technique for injecting a self-curing silicone mixture that can be used on autopsy specimens in a forensic unit. This technique does not interfere with routine autopsy findings. We describe the preparation of the mixture and autopsy specimens, the injection process, and the method for removing injected brains from cadavers. The solidifying process took a 1-h duration in this injection method and was in accord with autopsy procedure. The arterial bed was satisfactorily filled, and even small perforating branches and pial anastomoses were well demonstrated. Injecting autopsy specimens with the quick-solidifying silicone mixture allows anatomical studies of specimens even from cadavers admitted to forensic departments for only a short time. This method can provide neurosurgery laboratories with sufficient numbers of specimens appropriate for various studies.

The popularisation of cavernous sinus approaches and subsequent experience has shaped our treatment paradigms for cavernous sinus meningiomas. However, pathologies in this region are diverse and each one requires individual consideration. The purpose of this study was first to analyse, define and summarise the individual characteristics of different non-meningeal tumours of the cavernous sinus and, secondly, to stress that their surgery can be accomplished with acceptable morbidity and rewarding results when those characteristics are considered. A retrospective analysis of 42 cases of benign non-meningeal tumours of the cavernous sinus operated on at Marmara University between April 1992 and April 2003 is presented. The patients were 15 males and 27 females aged 24-72 years. The study cohort consisted of 13 pituitary adenomas, 11 trigeminal schwannomas, seven chordomas, three chondrosarcomas, two juvenile angiofibromas, two epidermoid tumours, one plasmacytoma, one cavernous haemangioma and one internal carotid plexus schwannoma. The 42 patients underwent 46 operations aimed at radical surgical excision. Total resection was achieved in 50% and subtotal resection in 50% of cases. The majority of incompletely resected tumours were pituitary adenomas and chordomas, and 95% required further treatment. Twenty-nine percent of patients developed complications, namely cerebrospinal fluid fistula, haematoma, hydrocephalus, diabetes insipidus, cerebral infarction and cranial nerve palsies. Recurrence was seen in 7.1% of patients. At final follow up at an average of 48.2 months after surgery, the mean Karnofsky performance scale had risen from 83.4 to 87.4. Non-meningeal tumours of the cavernous sinus can be surgically resected with acceptable morbidity and mortality. In selected tumours the results are better than those for cavernous sinus meningiomas. The best surgical results are achieved with interdural tumours of the lateral sinus wall and the worst surgical results are seen in invasive tumours such as chordomas and pituitary adenomas. Individual tumour characteristics are presented in the text.

Object: In this paper the authors correlate the surgical aspects of deep median and paramedian supratentorial lesions with the connective fiber systems of the white matter of the brain., Methods: The cerebral hemispheres of 10 cadaveric brains were dissected in a mediolateral direction by using the fiber dissection technique, corresponding to the surgical approach., Conclusions: This study illuminates the delicacy of the intertwined and stratified fiber laminae of the white matter, and establishes that these structures can be preserved at surgical exploration in patients.

A review of the history of ancient medicine reveals that most of the knowledge is concentrated in the studies of a few scientists. The best-known names include Hippocrates, Rufus of Ephesus, Celsus, and Galen. The survival of their works throughout the ages has been the most important factor contributing to their popularity. However, there are other scientists who made great contributions to science, but whose writings have been lost or destroyed over the course of time. As a result, their names are not as well known as those of others and the value of their contributions is not appreciated. With the improvement of communication technology in the past 50 years, links between the studies of ancient science can be made more effectively and scientists who have remained hidden under the shade of time have begun, after thousands of years, to receive the appreciation they deserve. In the field of neuroscience, the historical record focuses on Galen of Pergamon. But, when his marvelous works are carefully studied, it is interesting to note two names he frequently referenced: Herophilus (335-280 BC) and Erasistratus (310-250 BC). These two scientists were the first to place scientific value on the dissection of the human body. Herophilus is considered the father of scientific anatomy, and Erasistratus was the first experimental physiologist. Attracted by the prospect of material advancement and eminent students, both migrated from their homes in Asia Minor to Alexandria. The works of Herophilus and Erasistratus have been lost entirely, but some details of their teachings may be recovered from the writings of Galen. In this study, we focus on Herophilus, a master of ancient medicine, whose important discoveries about the human body formed the basis for positive science and the foundation for neuroscience.

We reviewed many of the essential Greek myths to identify the methods used at that time to relieve the pain of both illness and surgery, and we discovered many pioneering methods. Both gods and demigods implemented these methods to ease pain, to conduct surgery, and, on occasion, to kill mythological beings. The myths describe the three most common components of anesthesia: hypnosis, amnesia, and (an)algesia. Drugs and music-aided hypnosis were two of the most common methods use to treat emotional and surgical pain. This article identifies highlights in the development of concepts to treat pain in Greek mythology. The examples found in the Greek myths remind us of the historical significance of pain treatment.

Despite the introduction of skull base approaches, there is still controversy in the optimum surgical management of foramen magnum meningiomas. Between January 1990 and January 2003, 22 patients underwent 23 surgical procedures with a diagnosis of foramen magnum meningioma at Marmara University, Department of Neurosurgery. The suboccipital approach was used for 2 posteriorly located tumors with radiological total removal. The paramedian suboccipital approach was replaced by the far-lateral modification in the treatment of ventral meningiomas. 1 of the 20 ventral tumors was operated twice. The classical suboccipital approach was followed by the far-lateral modification. A gross-total removal was achieved in 21 patients. The overall morbidity was 32%. No specific and clinically significant complications attributable to the far-lateral modification were observed. The far-lateral approach has improved the success of surgery in ventrally located lesions. The posterior suboccipital approach is still indicated in the removal of lesions placed posterior to the dentate ligament.

Removal of lesions involving the jugular foramen region requires detailed knowledge of the anatomy and anatomical landmarks of the related area, especially the lower cranial nerves. The glossopharyngeal nerve courses along the uppermost part of the jugular foramen and is well hidden in the deep layers of the neck, making this nerve is the most difficult one to identify during surgery. It may be involved in various pathological entities along its course. The glossopharyngeal nerve can also be compromised iatrogenically during the surgical treatment of such lesions. The authors define landmarks that can help identify this nerve during surgery and discuss the types of lesions that may involve each portion of the glossopharyngeal nerve.

Rosai-Dorfman disease is a rare, non-neoplastic disease characterized by an unusual proliferation of histiocytic cells. It rarely manifests intracranially, and only 50 cases of intracranial lesions have been reported. We describe an unusual case of a huge, solid mass in the paranasal sinuses, orbits, cavernous sinuses, and suprasellar cisterns. A 29-year-old patient was admitted to our hospital with nasal obstruction and proptosis and visual loss in the right eye. A biopsy was done at another institution and the diagnosis was "pseudotumor of orbit". A right-sided cranio-orbitozygomatic craniotomy combined with a right-sided lateral rhinotomy was used to excise the tumor with right orbital exenteration. The histopathological diagnosis was consistent with Rosai-Dorfman disease. The patient underwent postoperative chemotherapy. Involvement of the central nervous system in Rosai-Dorfman disease is rare, but the disease's ability to mimic other pathologies underlines its importance.

The first reference to spinal cord injury is recorded in the Edwin Smith papyrus. Little was known of the function of the cord before Galen's experiments conducted in the second century AD. Galen described the protective coverings of the spinal cord: the bone, posterior longitudinal ligament, dura mater, and pia mater. He gave a detailed account of the gross anatomy of the spinal cord. During the medieval period (AD 700-1500) almost nothing of note was added to Galen's account of spinal cord structure. The first significant work on the spinal cord was that of Blasius in 1666. He was the first to differentiate the gray and white matter of the cord and demonstrated for the first time the origin of the anterior and posterior spinal nerve roots. The elucidation of the various tracts in the spinal cord actually began with demonstrations of pyramidal decussation by Mistichelli (1709) and Pourfoir du Petit (1710). Huber (1739) recorded the first detailed account of spinal roots and the denticulate ligaments. In 1809, Rolando described the substantia gelatinosa. The microtome, invented in 1824 by Stilling, proved to be one of the fundamental tools for the study of spinal cord anatomy. Stilling's technique involved slicing frozen or alcohol-hardened spinal cord into very thin sections and examining them unstained by using the naked eye or a microscope. With improvements in histological and experimental techniques, modern studies of spinal cord anatomy and function were initiated by Brown-Sequard. In 1846, he gave the first demonstration of the decussation of the sensory tracts. The location and direction of fiber tracts were uncovered by the experimental studies of Burdach (1826), Turck (1849), Clarke (1851), Lissauer (1855), Goll (1860), Flechsig (1876), and Gowers (1880). Bastian (1890) demonstrated that in complete transverse lesions of the spinal cord, reflexes below the level of the lesion are lost and muscle tone is abolished. Flatau (1894) observed the laminar nature of spinal pathways. The 20th century ushered in a new era in the evaluation of spinal cord function and localization; however, the total understanding of this remarkable organ remains elusive. Perhaps the next century will provide the answers to today's questions about spinal cord localization.

In this study, we examined the anatomical variations of the subependymal veins in the region of the foramen of Monro and the third ventricle by MR time of flight (TOF) venography. Fifty healthy subjects, ten patients with third-ventricle tumors, and four patients with lateral-ventricle tumors were included in the study. The courses of the anterior septal vein (ASV), thalamostriate vein (TSV), and internal cerebral vein (ICV) were studied. The proximity of the venous angle, the false venous angle, and the ASV-ICV junction to the posterior margin of the foramen of Monro was measured. In 69 (53.9%) sides, the ASV-ICV junction was located at the venous angle and at the posterior margin of the foramen of Monro. In 59 (46.1%) sides, the ASV-ICV junction was located beyond the foramen of Monro. Our study shows the high incidence of posteriorly located ASV-ICV junctions, which can be crucial in the planning of a better surgical approach. We strongly recommend that MR venography, which is a short radiological examination, be used before one operates on third-ventricle and lateral-ventricle tumors.

Objective: Compared with other lower cranial nerves, the glossopharyngeal nerve (GPhN) is well hidden within the jugular foramen, at the infratemporal fossa, and in the deep layers of the neck. This study aims to disclose the course of the GPhN and point out landmarks to aid in its exposure., Methods: The GPhN was studied in 10 cadaveric heads (20 sides) injected with colored latex for microsurgical dissection. The specimens were dissected under the surgical microscope., Results: The GPhN can be divided into three portions: cisternal, jugular foramen, and extracranial. The rootlets of the GPhN emerge from the postolivary sulcus and course ventral to the flocculus and choroid plexus of the lateral recess of the fourth ventricle. The nerve then enters the jugular foramen through the uppermost porus (pars nervosa) and is separated from the vagus and accessory nerves by a fibrous crest. The cochlear aqueduct opens to the roof of this porus. On four sides in the cadaver specimens (20%), the GPhN traversed a separate bony canal within the jugular foramen; no separate canal was found in the other cadavers. In all specimens, the Jacobson's (tympanic) nerve emerged from the inferior ganglion of the GPhN, and the Arnold's (auricular branch of the vagus) nerve also consisted of branches from the GPhN. The GPhN exits from the jugular foramen posteromedial to the styloid process and the styloid muscles. The last four cranial nerves and the internal jugular vein pass through a narrow space between the transverse process of the atlas (C1) and the styloid process. The styloid muscles are a pyramid shape, the tip of which is formed by the attachment of the styloid muscles to the styloid process. The GPhN crosses to the anterior side of the stylopharyngeus muscle at the junction of the stylopharyngeus, middle constrictor, and hyoglossal muscles, which are at the base of the pyramid. The middle constrictor muscle forms a wall between the GPhN and the hypoglossal nerve in this region. Then, the GPhN gives off a lingual branch and deepens to innervate the pharyngeal mucosa., Conclusion: Two landmarks help to identify the GPhN in the subarachnoid space: the choroid plexus of the lateral recess of the fourth ventricle and the dural entrance porus of the jugular foramen. The opening of the cochlear aqueduct, the mastoid canaliculus, and the inferior tympanic canaliculus are three landmarks of the GPhN within the jugular foramen. Finally, the base of the styloid process, the base of the styloid pyramid, and the transverse process of the atlas serve as three landmarks of the GPhN at the extracranial region in the infratemporal fossa.

Objective and Importance: The C3 level is the transition zone between the upper and lower cervical spine. Because of its high position and anatomic relationships to significant structures, exposing C3 is challenging, and the surgical approach is controversial., Clinical Presentation: A 16-year-old girl was admitted to our institution with a 3-year history of neck pain and progressive quadriparesis. Neuroradiological examination revealed severe spinal cord compression from kyphosis at the C3 level., Technique: We used the lateral approach to resect the C3 corpus and realign the cervical spine. Resecting the transverse processes of C2-C4 and mobilizing the V2 segment of the vertebral artery adequately exposed C3 for resection. Bilateral occipitocervical fusion was performed in a second procedure, and no postoperative complications occurred. The patient's neurological status improved drastically after surgery, and she has had no craniocervical instability during the follow-up period., Conclusion: The lateral approach to the C3 corpus offers the greatest degree of cord decompression and easy access to the lesion in a wide and sterile operative field. We describe the surgical technique of this approach as an alternative to the anterior transmucosal or anterolateral retropharyngeal approach.

Objective and Importance: Schwannomas of the central nervous system usually originate from the vestibular nerve and occasionally originate from the trigeminal nerve. Sympathetic plexus schwannomas are extremely rare and have never been noted within the cavernous sinus., Clinical Presentation: A 23-year-old man experienced occasional double vision for a period of 6 months. Magnetic resonance imaging studies revealed an isointense lesion, with enhancement after gadolinium administration, located inferomedial to the internal carotid artery within the left cavernous sinus., Intervention: We explored the cavernous sinus via a left-sided extradural-pterional approach and found the tumor inferomedial to the cavernous segment of the internal carotid artery. Microsurgical gross total resection of the tumor was performed. The IIIrd (oculomotor) to VIth (abducens) cranial nerves within the cavernous sinus were not related to the tumor and were preserved. The operative findings and the anatomic location of the tumor demonstrated that it originated from the internal carotid plexus within the cavernous sinus. The patient's postoperative course was uneventful, and he exhibited no cranial nerve deficits. However, incomplete Horner's syndrome was present on the treated side., Conclusion: We present the first reported case of an internal carotid plexus schwannoma, and we describe in detail its anatomic and neuroradiological characteristics. The microneurosurgical resection of this unusual tumor within the cavernous sinus was successful and without morbidity.

Introduction: Thalamic tumors comprise 1-5% of all brain tumors. Recent improvements in therapeutic approaches and surgical techniques have allowed a more accurate approach to these lesions and a reduction in morbidity and mortality., Discussion: In this article, the various surgical approaches for the resection of thalamic tumors are described. Each of these approaches has its own indications and risk of complications.

Object: Various approaches have been described for resection of the dens of the axis, each of which has potential advantages and disadvantages. Anterior approaches such as the transoral route or its modifications are the most commonly used for resection of this structure. The transcondylar approach, however, which allows the surgeon to view the craniovertebral junction (CVJ) from a lateral perspective, has been introduced by Al-Mefty, et al., as an alternative approach. In this report, the authors describe the surgical technique of the extreme lateral-transatlas approach and their clinical experiences., Methods: The authors first examined the surgical approach to the dens from a lateral perspective in five cadaveric heads. They found that removal of the lateral mass of the atlas provided adequate exposure for resection of the dens. Following this cadaveric study, the extreme lateral-transatlas approach was successfully performed at the authors' institution over a 1-year period (September 1998-August 1999) in five patients with basilar invagination due to congenital anomaly of the CVJ and rheumatoid arthritis. Furthermore, during the same procedure, unilateral occipitocervical fusion was performed following resection of the dens. In all cases complete resection of the dens was achieved using the extreme-lateral transatlas approach. This procedure provides a sterile operative field and the ability to perform occipitocervical fusion immediately following the resection. No postoperative complications or craniocervical instability were observed. The mean follow-up period was 17.2 months (range 13-24 months)., Conclusions: The extreme lateral-transatlas approach for resection of the dens was found to be safe and effective. Knowledge of the anatomy of this region, especially of the V3 segment of the vertebral artery, is essential for the success of this procedure.