Endoscopic approaches to the posterior wall of the third ventricle: An anatomical comparison.

INTRODUCTION: Surgery of lesions in the posterior wall of the third ventricle requires great expertise due to its deep location and important surrounding structures. This region has been traditionally reached through a supracerebellar infratentorial approach, but new options have emerged, especially with the development of neuroendoscopy. METHODS: One formalin-fixed cadaver human head was dissected. Five different endoscopic approaches were performed: interhemispheric transcallosal transchoroidal, frontal transforaminal transchoroidal, supraorbital subfrontal translamina terminalis, expanded endonasal, and supracerebellar infratentorial. An anatomical description of the different approaches was conducted and quantitative measurements (craniocaudal and latero-lateral distances) were taken using the StealthStation ® workstation after performing a CT scan of the specimen. RESULTS: The interhemispheric transcallosal transchoroidal, frontal transforaminal transchoroidal, and supraorbital subfrontal translamina terminalis approaches provided great view of all the structures of the posterior wall of the third ventricle. Maximum craniocaudal distance was obtained through the supraorbital subfrontal translamina terminalis approach (10.6 mm), with great difference from the expanded endonasal approach (5.2 mm). The widest latero-lateral distance from inside the third ventricle was achieved through the interhemispheric transcallosal transchoroidal approach (4.6 mm), similar to the expanded endonasal (4.1 mm), and differing from the supraorbital subfrontal translamina terminalis (2.4 mm). CONCLUSIONS: The endoscopic approaches provided an adequate alternative to more traditional microsurgical approaches to the posterior wall of the third ventricle, with a great view of all its structures. The selection of the approach must be taken under consideration in each case.

Optic Foraminotomy for Clipping of Superior Carotid-Ophthalmic Aneurysms.

Background: Carotid-ophthalmic aneurysms usually cause visual problems. Its surgical treatment is challenging because of its anatomically close relations to the optic nerve, carotid artery, ophthalmic artery, anterior clinoid process, and cavernous sinus, which hinder direct access. Despite recent technical advancements enabling risk reduction of this complication, postoperative deterioration of visual function remains a significant problem. Therefore, the goal of preserving and/or improving the visual outcome persists as a paramount concern. Objective: We propose optic foraminotomy as an alternative microsurgical technique for dorsal carotid-ophthalmic aneurysms clipping. As a secondary objective, the step by step of that technique and its benefits are compared to the current approach of anterior clinoidectomy. Methods: We present as an example two patients with superior carotid-ophthalmic aneurysms in which the standard pterional craniotomy, transsylvian approach, and optic foraminotomy were performed. Surgical techniques are presented and discussed in detail with the use of skull base dissections, microsurgical images, and original drawings. Results: Extensive opening of the optic canal and optic nerve sheath was successfully achieved in all patients allowing a working angle with the carotid artery for correct visualization of the aneurysm and further clipping. Significant visual acuity improvement occurred in both patients because of decompression of the optic nerve. Conclusion: Optic foraminotomy is an easy and recommended technique for exposing and treating superior carotid-ophthalmic aneurysms and allowing optic nerve decompression during the first stages of the procedure. It shows several advantages over the current anterior clinoidectomy technique regarding surgical exposure and facilitating visual improvement.

Use of Neuroanatomic Knowledge and Neuronavigation System for a Safe Anterior Petrosectomy.

INTRODUCTION: The petroclival region is among the most challenging anatomical areas to deal with in skull base surgery. Drilling of the anterior part of the petrous bone during the anterior transpetrosal approach involves the risk of injury of the cochlea, superior semicircular canal, internal carotid artery, and internal auditory canal. A thorough understanding of the microneurosurgical anatomy of this region is mandatory to execute the transpetrosal approaches, decreasing the risk of complications. The aim of this study is to describe the anatomical structures of the petroclival region, highlighting the importance of neuronavigation for safe performance of the anterior transpetrosal approach. METHODS: Three adult cadaveric human heads were formalin-fixed and injected with colored silicone. They underwent an axial 1 mm slab CT scan, which was used for neuronavigation during the surgical approaches. The anterior petrosectomy was performed with the aid of neuronavigation during the drilling of the petrous bone. The surgical management of a patient harboring a petroclival meningioma, operated on using an anterior transpetrosal approach, was reported as an illustrative case. RESULTS: The anterior petrosectomy was completed accurately with wide exposure of the surgical target without injuring the cochlea and other structures in all three cadaveric specimens. In the surgical case, no approach-related complications occurred, and a gross total resection of the tumor was achieved. CONCLUSIONS: Deep knowledge of the location and relationships of the vital elements located within the temporal bone, along with the use of neuronavigation, are the key aspects to perform the anterior transpetrosal approach safely, reducing the risk of complications.

White Matter Topographic Anatomy Applied to Temporal Lobe Surgery.

BACKGROUND: The temporal lobe is an important and complex anatomic region of the brain. Accurate knowledge of anatomic relationships becomes extremely relevant when deciding surgical strategy, such as epilepsy or oncologic surgery, involving this lobe. To our knowledge, there is no strong literature highlighting the relationship between white matter tracts and craniometric landmarks applied to temporal lobe surgery. We aim to describe the topographic relationship between the craniometric points and white matter tracts of the temporal lobe through dissection of cadaveric specimens and describe the potential preoperative usefulness of diffusion tensor imaging in relation to the anatomic features found during the dissections. METHODS: Fifteen formalin-fixed whole cadaveric heads were dissected by the Klingler technique in a stepwise manner across the temporal and sphenoid bone windows. The white matter pathways were identified in their different planes and their position was described in relation to craniometric landmarks. Diffusion tensor studies were performed in 2 healthy volunteers to analyze the temporal fasciculi in vivo. RESULTS: We identified the topographic relationships between craniometric points and relevant association tracts that lie within the cranial corridors (superior and inferior frontal, parietal, occipital, sphenoidal, and temporal). Important landmarks were defined in correspondence to these different fasciculi. CONCLUSIONS: Through this kind of microsurgical anatomic study, a better understanding of the different anatomic layers of the temporal region might be achieved. This factor is essential in planning adequate surgery and strategies to operate in the temporal lobe, improving surgical results and minimizing functional deficits.

Intrathecal baclofen as a treatment for spasticity: Review of the cases treated in our hospital. / Baclofeno intratecal para el tratamiento de la espasticidad: revisión de los casos presentes tratados en nuestro servicio.

INTRODUCTION: Spasticity represents a medical problem whose incidence is increasing during the last years due to pathologies such as cerebral palsy, stroke, multiple sclerosis, trauma or encephalopathy, affecting both adults and children. The treatments include rehabilitation, pharmacotherapy and surgery, among which we highlight intrathecal baclofen infusion devices. MATERIAL AND METHODS: Intrathecal baclofen devices implanted patients in Clinical Hospital of Santiago de Compostela from 2005 to 2018 were selected for retrospective analysis using assessment of spasticity scales, such as Ashworth scale. Complications are described. RESULTS: Surgery was performed in 17 patients for baclofen pump implant, achieving an improvement of 2 points on the Ashworth Scale in 88,2% of the patients and of 1 point on the Penn Scale in 94%. Complications were seen in 3 patients. CONCLUSIONS: Intrathecal baclofen is a simple technique with good results for improving the quality of life of patients with spasticity.

Solitary fibrous tumour/haemangiopericytoma of the spinal cord. / Tumor fibroso solitario/hemangiopericitoma de la médula espinal.

Solitary fibrous tumours/haemangiopericytomas (SFT/HPC) are fibroblastic mesenchymal neoplasms that harbour a genetic fusion of NAB2/STAT6. There are few reported cases in the central nervous system (CNS), of which spinal tumours are minority. We present a case of a 63-year-old woman with progressive paraparesis and a sensory level of T6. On the MRI we detected an intradural extramedullary lesion on T9-T10. We performed a laminectomy with an intraoperative ultrasound study in which we observed a heterogeneous lesion with an infiltrating pattern affecting the medulla at several points, and resection of the lesion. Immunohistological findings revealed positivity for vimentin, CD34 and STAT6; Ki-67 was 2%. A final diagnosis of SFT/HPC with SFT phenotype was made. SFT/HPC of the CNS is a rare neoplasm that should be taken into account in the differential diagnosis of these kinds of lesions, as clinical and MRI findings often lead to errors in diagnostic approach. The support of intraoperative ultrasound can assist in surgical decision-making.