Neuroendoscopy

Hydrocephalus is usually treated with a shunt that drains cerebrospinal fluid (CSF). In hydrocephalus occlusus, also known as occlusive or obstructive hydrocephalus, the drainage of cerebrospinal fluid is impeded by a blockage or narrowing of the ventricles or the cerebrospinal fluid pathways. In this case, endoscopic surgery can help restore the natural flow of cerebrospinal fluid and thus avoid the need for a shunt. In a procedure known as endoscopic third ventriculocystostomy (ETV), the floor of the third ventricle is opened so that cerebrospinal fluid can flow out again.

It is rare for only the temporal horns of the cerebral ventricles to be congested, which may occur, for example, secondarily as a complication after tumor surgery. In some cases, endoscopic surgery may also be a treatment option *.

Arachnoid cysts are benign cystic changes of the middle meninges arachnoid, which are primarily asymptomatic and rarely require surgical treatment. 

However, if cysts cause symptoms or grow larger, a procedure known as cyst fenestration may be necessary. This involves opening the cyst so that the fluid can drain out. Depending on the location and findings, this procedure can be performed using a minimally invasive, purely endoscopic approach.

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 show 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 (biopsy) is almost always necessary for diagnosis and planning further treatment. If the tumor is located in an easily accessible area,an endoscopic biopsy is possible. This gives the surgeon the advantage of being able to select the biopsy site precisely thanks to a direct view of the tumor. This increases the accuracy of the examination and also makes it possible to stop minor bleeding immediately.

Since tumors in the brain ventricles can impede the flow of cerebrospinal fluid, a decompression procedure such as an endoscopic third ventriculocisternostomy or septostomy can be performed at the same time as an endoscopic biopsy, if necessary.

Fully 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.