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Clival Chordomas

Preoperative Considerations Chordomas are locally aggressive neoplasms that arise from embryonic remnants of the notochord along the vertebral axis. They represent less than 1% of all intracranial neoplasms. They can be divided in three groups according to their location: Cranial (30–35%) Sacrococcygeal (50%) Vertebral (15%). Symptom presentation depends on the location of the tumor and its relationship to adjacent structures. Compression of cranial nerves in the…

Surgical Treatment of Craniopharyngiomas

Preoperative Considerations Craniopharyngiomas are tumors with solid-cystic components that originate from embryological remnants of the Rathke's pouch. They represent 1–3% of lifetime intracranial tumors and up to 5–10% occurring during childhood. They are commonly located in the suprasellar region, arising from the pituitary stalk and adjacent to the optic chiasm but they can be found anywhere in the sella and suprasellar space following the embryologic migration…

Pituitary Adenomas

Preoperative Considerations Pituitary adenomas are the most prevalent intrasellar lesions and the third most prevalent primary intracranial tumors. These lesions can lead to significant neurologic and/or endocrine-related morbidity secondary to compression of neurovascular structures and hormonal dysfunction. Pituitary adenomas may be either nonfunctioning tumors or hormone-secreting lesions (including ACTH, GH, prolactin, FSH, LH, TSH-secreting tumors). These tumors can be classified, according to size, as microadenomas (smaller…

Principles and Anatomy in Endoscopic Endonasal Surgery

There are many surgical variants of the endoscopic endonasal approach (EEA), which can be used for management of lesions at the ventral skull base. The main goal of this chapter is to provide the skull base surgeon with strong anatomic and surgical foundations for a safe and efficient endonasal dissection. Operating Room Setup for the EEA The patient positioning and the equipment used during an EEA…

The Far Lateral Approach

Preoperative Considerations The far lateral provides wide access to the dorsolateral compartment yet allowing exposure to the lateral aspect of the ventromedial compartment of the posterior fossa (270° visualization of the circumference around the medulla). Variants of the far lateral approach: Transcondylar Supracondylar Paracondylar CT angiography (CTA) or angio-MRI (MRA) may be useful to study the anatomy of the vertebral arteries (VA), posterior spinal and the…

Retrosigmoid Versus Extended Retrosigmoid Approach

Preoperative Considerations The standard retrosigmoid approach allows for expeditious access to the posterior fossa, specifically to the cerebellopontine angle (CPA). The extended retrosigmoid approach includes the skeletonization of the transverse–sigmoid sinus and an optional partial mastoidectomy to the standard retrosigmoid craniotomy. This provides a wider corridor in between the cerebellum and petrous bone in those patients with tight cerebellopontine and cerebellomedullary cisterns and allows more anterior…

Subfrontal and Extended Subfrontal Craniotomy/Transbasal Approach

There are a variety of different techniques that can be used to surgically manage anterior skull base lesions. In this chapter we demonstrate the value of the standard and extended subfrontal craniotomies. Indications The subfrontal approach allows access and excellent visualization to the majority of the anterior cranial fossa floor. This includes vital structures adjacent to the anterior midline and parasellar regions such as the tuberculum…

Supraorbital Osteotomy: Eyelid and Eyebrow Incisions

Introduction The supraorbital approach gives access to several areas of the anterior and middle cranial fossa, sellar and parasellar region. It is a minimally invasive alternative to larger approaches such as fronto-orbital, pterional and orbitozygomatic approaches. Two minimally invasive incisions, the eyelid and eyebrow incision, can be used to perform the supraorbital cranitomy with optimal cosmetic resuts. Preoperative Considerations The decision to use these techniques is…

Orbitozygomatic Craniotomy

Indications and Contraindications The addition of the orbitozygomatic (OZ) osteotomies to the fronto-temporosphenoidal craniotomy increases the surgeon's workspace and minimizes the brain retraction required to reach deep-seated pathology. The orbital osteotomy allows increased visualization above the anterior clinoids while the zygomatic osteotomy gives additional access to the middle fossa by permitting the temporal lobe to be mobilized laterally. Pathology of the anterior cranial fossa, suprasellar/parasellar region,…

Pterional Craniotomy

Indications The pterional craniotomy and the transsylvian approach are the most used techniques in contemporary neurosurgery. The pterional craniotomy allows exposure of the frontoparietal and temporal opercula together with the basal subarachnoid cisterns ( Figure 17.1 ). This approach allows opening of the entire sylvian fissure, which allows for exposure of the circle of Willis, sphenoid wing, sella turcica, upper clivus, cavernous sinus and parasellar regions.…

Endoscopic Approach to the Ventricles

Preoperative Considerations Microscopic transcortical or transcallosal approaches may be associated with brain injury and/or retraction that can result in seizures, focal neurologic deficits and cognitive impairment. Endoscopic approaches for the management of intraventricular lesions are intended to be minimally invasive with less brain retraction while providing direct visualization of the lesion. MRI is preferred over CT to assess ventricular caliber, tumor characteristics and vascular anatomy to…

Telovelar Approach

Indications Indicated for lesions located within the fourth ventricle or brainstem that extend higher than the pontomedullary junction. The alternative approach has traditionally been the transvermian approach, where the vermis is split. This approach takes advantage of natural corridors without the risk of consequent neural deficits attendant on other techniques. Contraindications Cervical pathology that opposes neck flexion. To access the foramen magnum region the neck needs…

Transcallosal Approach for Intraventricular Tumors

Preoperative Considerations The transcallosal approach allows midline exposure of the anterior two-thirds of the third ventricle. Preoperatively, in addition to standard MR imaging, venography is often helpful to assess the pattern of cortical venous drainage in order to help determine the side of the craniotomy. When venous drainage permits and when the pathology is appropriate, an approach on the non-dominant side is preferred. Preoperative neuropsychological evaluation…

Transcortical Approach to the Lateral Ventricles

Introduction Tumors of the lateral ventricle represent less than 1% of all intracranial tumors. The majority of these lesions are benign or low grade. The lateral ventricles are amongst the most challenging areas to operate in the brain and require special approaches to facilitate maneuverability. The principal approaches to the lateral and third ventricles include ( Figure 13.1 ): The transcortical approach: Anterior transcortical. Posterior transcortical.…

Posterior Fossa Meningiomas

Indications and Preoperative Considerations Posterior fossa meningiomas are uncommon lesions that can be found virtually anywhere in the infratentorial space. The management of these lesions will depend on their size, location, growth rate and clinical presentation. These tumors can be classified according to their location as suboccipital, petrosal or tentorial cerebellar surfaces, cerebellopontine angle (CPA), fourth ventricle or petroclival meningiomas ( Table 12.1 ). Each location…

Falcine and Falcotentorial Meningiomas

Indications and Preoperative Considerations Falcine meningiomas are extradural lesions that arise from the falx cerebri. They might be classified based on their relationship with the superior sagittal sinus (SSS) into anterior, middle or posterior lesions, each requiring different techniques for surgical resection. Meningiomas that arise both from the falx and tentorium are named falcotentorial meningiomas. These lesions may rise in any portion of the straight and…

Convexity and Parasagittal Meningiomas

Indications and Preoperative Considerations Meningiomas are one of the most common primary intracranial brain tumors. They represent 34% of all primary brain tumors and originate from the arachnoid cells in the brain and spine. The brain convexity is the most frequent site of these lesions (19–34%), followed by the parasagittal region (18–25%), sphenoid wing and middle cranial fossa (17–25%), anterior skull base (10%) and posterior fossa…

Intraoperative Assessment of Extent of Resection

Introduction Neuro-oncological surgery has rapidly emerged and developed as a new field in neurosurgery focused on the treatment of tumors affecting the brain, cord and the peripheral nerves. It has undoubtedly relied on a parallel advance with technology. With the introduction of computerized tomography (CT) and magnetic resonance imaging (MRI), neurosurgeons can plan the safest and most direct approach preoperatively. In addition, obtaining functional data through…

Supracerebellar Infratentorial Approach

Indications This approach is well suited for midline tumors in the pineal region: germinoma, teratoma, pineocytoma, pineoblastoma, astrocytoma, metastasis, ependymoma, epidermoid tumor, cavernoma ( Figure 8.1 ). Tumors in the midline tectal region. Midline pontomesencephalic lesions. Contraindications The approach is not optimally suited if the tumor infiltrates laterally or superiorly above the tentorium. Transcallosal interhemispheric or occipital transtentorial approaches are preferred under the following circumstances: Tumors…

Cervicomedullary Tumors

Indications In general, most focal cervicomedullary tumors are considered benign in pathology. Common tumors of the cervicomedullary region include low-grade astrocytomas, gangliogliomas and ependymomas. They are typically well-delineated and benign tumors, typically amen­able to gross total resection. Contraindications Anaplastic astrocytomas with a diffuse growth pattern may also be encountered and are challenging to resect (biopsy can be done to establish a diagnosis). Lesions that are stable…