Neuroendoscopy

Neuroendoscopic surgical procedures are routinely used in the ventricular system and the skull base. Tumors in the ventricular system often lead to a blockage of cerebrospinal fluid (CSF) drainage, resulting in the enlargement of the brain ventricles. This enlargement creates a more favorable working environment for the surgeon *. Particularly, the lateral ventricles and the third ventricle are well accessible for neuroendoscopic surgical intervention.

In most cases, treatment of hydrocephalus consists of artificial CSF drainage via a ventriculoperitoneal shunt.

However, individual forms of hydrocephalus allow the CSF circulation to be restored alternatively via a full-endoscopic procedure, thus avoiding the implantation of a drainage system. This can be considered, for example, in cases of hydrocephalus occlusus, which can be caused by aqueductal stenosis, cysts, or tumors. A refined solution in such cases is the endoscopic third ventriculocisternostomy (ETV), in which the floor of the 3rd ventricle is opened endoscopically, thus allowing CSF drainage to the external CSF spaces.

A much rarer form of hydrocephalus may be isolated congested temporal horns of the lateral ventricle, which may occur, for example, secondarily as a complication after tumor surgery. Unfortunately, there is no standard therapy for this rare condition, but an endoscopic approach is a treatment option in some cases *.

Arachnoid cysts are benign cystic changes of the middle meninges arachnoid, which are primarily asymptomatic and rarely require surgical treatment. Symptomatic cysts or cysts that become larger may require what is known as cyst fenestration. Depending on the localization and radiological findings, this can be performed purely endoscopically and minimally invasively. Suprasellar arachnoid cysts are particularly suitable for this procedure if they lead to a hydrocephalus. The dilated ventricles allow good access and the possibility of large fenestration of the cyst, which significantly reduces the risk of recurrence. Study data showed that repeated fenestration of suprasellar cysts is necessary only in the rarest of cases *.

However, the neuroendoscopic surgical procedure is not limited to suprasellar arachnoid cysts but can also be used for cysts in the middle and posterior fossa if sufficient access is available *.

Endoscopic biopsy

Brain tumors are usually operated on microsurgically. An exception are intraventricular or paraventricular tumors, i.e., tumors that grow in the brain ventricles or in close proximity to them. These do not always need to be surgically removed; some of these tumor types respond well to other forms of treatment. However, a fine tissue examination of the tumor is usually necessary to diagnose and determine further therapy. If the tumor is located at an easily accessible site, an endoscopic biopsy is possible. In contrast to conventional biopsy, the endoscopic approach offers a distinct advantage due to the visual view of the tumor. Thus, the surgeon can visually see the exact biopsy site – a fact that leads to an increased diagnosis rate. Likewise, minor bleeding caused by the biopsy can be stopped directly. Because tumors in the ventricular system can obstruct CSF outflow, the neuroendoscopic approach provides the opportunity to directly perform an endoscopic third ventriculostomy or septostomy.

Full endoscopic tumor resection

In some instances, a fully endoscopic removal of an intraventricular tumor is possible. Tumors with a moderate blood vessel supply, a soft consistency, and a size of < 2–3 cm are particularly suitable for this *. However, if the tumor shows adhesions to structures such as the fornix or the thalamostriate vein, a complete resection is often not possible in order to avoid injury to these structures *. The disadvantage of neuroendoscopic tumor surgery for the surgeon primarily lies in the restricted maneuverability afforded by the endoscope and the absence of bimanual dexterity, as is possible in an open surgery.