No abstract

Since the introduction of the modern, smaller endoscopes in the 1960s, neuroendoscopy has become an expanding field of neurosurgery. Neuroendoscopy reflects the tendency of modern neurosurgery to aim towards minimalism; that is, access and visualization through the narrowest practical corridor and maximum effective action at the target point with minimal disruption of normal tissue. Transventricular neuroendoscopy allows the treatment of several pathologies inside the ventricular system, such as obstructive hydrocephalus and intra-/paraventricular tumors or cysts, often avoiding the implantation of extracranial shunts or more invasive craniotomic approaches. Endoscopic endonasal transphenoidal surgery allows the treatment of pathologies of the sellar and parasellar region, with the advantage of a wider vision of the surgical field, less traumatism of the nasal structures, greater facility in the treatment of possible recurrences and reduced complications. However, an endoscope may be used to assist microsurgery in virtually any kind of neurosurgical procedures (endoscope-assisted microsurgery), particularly in aneurysm and tumor surgery. Basic principles of optical imaging and the physics of optic fibers are discussed, focusing on the neuroendoscope. The three main chapters of neuroendoscopy (transventricular, endonasal transphenoidal and endoscope-assisted microsurgery) are reviewed, concerning operative instruments, surgical procedures, main indications and results.

Endodermal cysts of the central neuraxis are benign, non-neoplastic epithelium-lined cysts arising from endodermal tissue that have been displaced early in fetal life. Intracranial endodermal cysts are rare and usually located in the posterior fossa. The present study involves a 36-year-old man with a typical epithelial cyst in the posterior fossa. Microscopically, the cyst has a simple columnar epithelium with mucus-producing cells, containing an area composed of dysplastic epithelium with evidence of an intraepithelial carcinoma. The atypical cells have a high proliferative fraction demonstrated by Ki-67 immunostain. Based on these findings, the authors view this case as evidence of a malignant transformation of a classic endodermal cyst. The clinicopathologic features and a review of the literature are discussed.

In certain cases endoscopic-assisted microsurgery is an exceptional aid to the surgeon and must become part of the operating theatre equipment and kept on hand ready for use. The endoscope is, in our opinion, particularly useful in certain aneurysm localisations (internal carotid artery-anterior communicating artery [ICA-ACOMA]).

Adult idiopathic occlusion of the foramen of Monro (AIOFM) is a rare condition, with only few cases described in the modern literature. We propose that AIOFM may result from unilateral or bilateral occlusion of Monro foramina, as well as from progression of a monolateral hydrocephalus. Different surgical strategies may be required for effective treatment according to the type of occlusion. To date, only 12 cases of AIOFM have been reported in the literature. We report the cases of two patients, aged 20 and 47 years respectively, who presented with intracranial hypertension secondary to bilateral ventricular dilatation due to obstruction at the level of the foramen of Monro. Both patients were successfully treated with endoscopic fenestration of the primarily obstructed foramen of Monro and, in one patient, fenestration of the septum. We propose that septum pellucidum displacement could play a role in the occlusion of the second foramen of Monro. AIOFM can, therefore, result also from unilateral stenosis of Monro. The difference in AIOFM (i.e. unilateral vs bilateral) will be useful in guiding the most suitable surgical approach in this rare condition.