Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_4368_Библиотеки_им_академика_М_И_Перельмана

The evolution of minimally invasive techniques has led to a concomitant evolution of minimally invasive approaches to the skull base. The goal of minimally invasive skull base approaches is to minimize surgical morbidity using anatomically-directed corridors. This reduces the need for brain retraction and unnecessary tissue exposure. The endoscopic endonasal approach (EEA) to the skull base provides safe access to the medial anterior, middle, and posterior cranial fossa along both sagittal (median) and coronal (paramedian) planes from an anteromedial trajectory. This median corridor provides the most direct access to the entire ventral skull base, including CNs. The anteromedial approaches to the anterior, middle, and posterior fossa can be grouped into median and paramedian approaches. The median approaches will be limited laterally by critical neurovascular structures, while the paramedian approaches may be limited both medially and laterally. A combination of median and paramedian approaches to the skull base allows access to CNs I–XII.

In the following sections, we describe the common anteromedial corridors to address ventral pathology affecting each of the CNs. We also identify the extradural sinonasal corridor used to access each region. Given that the endoscope requires physical space in the nares, we generally suggest a “cavity and a half” sinonasal corridor. We have previously described this concept, which provides one-half nasal cavity for visualization and manipulation of the endoscope and the remaining one-half nasal cavity and full contralateral nasal cavity (“cavity and a half”) for bimanual dissection.

The olfactory nerve and bulb (CN I) can be accessed via an anteromedial transcribriform approach. scribriform approach is typically combined with the

The tran-

The optic nerve (CN II) to the optic chiasm can be accessed via the median endonasal transsellar and expanded endonasal transplanum/transtuberculum approaches. The general technique for bilateral expo­sure using the binasal approach is utilized to gain ac­cess to the sphenoid sinus.3 Bilateral sphenoidotomies are completed and widened laterally to the carotid canal, superiorly to the posterior ethmoid sinus, and posteriorly along the floor of the sphenoid to the cli-

Extension of the transsellar approach rostrally allows access to the suprasellar cistern and anterior cranial fos­sa floor via a transplanum/transtuberculum approach without going through the sellae turcica. provides access to the optic canals and optic chiasm. Fol­lowing a general bilateral transsphenoidal approach, the rostral extension begins with wide bilateral posterior ethmoidectomies, extending superiorly to the anterior cranial fossa floor and laterally to the lamina papyracea, which is the medial wall of the orbit. The anterior mar­gin of the exposure is the posterior ethmoidal arteries, which travel in the posterior ethmoidal canals (Fig. 32.2). The posterior ethmoidal canal courses from the lamina papyracea laterally to the fovea ethmoidalis medially. The dissection is limited to the posterior ethmoidal arteries as the anterior margin to avoid injuring the olfactory fil­aments and creating anosmia. The planum sphenoidale is removed in a caudal to rostral direction with a V-shaped lateral osteotomy to avoid injuring the optic canal (Fig. 32.3). The rostral portion of the sellar floor can be opened to the SIS, and the SIS mobilized to allow access to the suprasellar parachiasmatic cisterns (Fig. 32.4). This approach provides a cranial base opening that extends posteriorly from the junction of the cribriform plate and planum sphenoidale to the clival recess, and to the lamina papyracea bilaterally (Fig. 32.5). The dura mater is opened and the paraclinoid ICA identified as it enters the dura at the level of the mOCR. The ICA can be followed superiorly to identify the optic nerve, which can be followed to the optic chiasm and the contralateral optic nerve. The optic canals at the orbital apex represent the lateral limit of the transplanum/transtuberculum approach.

Following the bilateral sphenoeth-

To gain access to the intradural/intracisternal seg­ments of the ventral CN III, CN IV, V1, V2, V3, and CN VI,

As the cavernous ICA is the lateral boundary of a medi­an approach, the CNs coursing lateral to the ICA can be accessed via a paramedian EEA. CN III, CN IV, V1, V2, and CN VI in the cavernous sinus can be accessed via the para­median transpterygoid inferior cavernous sinus/quad­rangular space approach and superior cavernous sinus approach, while CN III, CN IV, V1, and CN VI in the su­perior orbital fissure can be accessed via the paramedian temporal/infratemporal approach.