**4. Simplifications of complex hydrocephalus and intracranial cysts**

#### **4.1 Multiloculated hydrocephalus**

Multiloculated hydrocephalus is a condition in which there is isolated CSF compartments within the ventricular system that tend to enlarge even if the patient has a functioning V-P shunt. Multiloculation usually develops as a complication of meningitis, intraventricular hemorrhage, post shunt infection, head injury, ependymal trauma during shunt insertion and other inflammatory processes [26].

Following neonatal meningitis in infants, more than 30% of the survivors will develop hydrocephalus, most of these neonates have a risk of having multiloculated hydrocephalus [27]. The compartments are separated by septa that prevent accumulated CSF from being absorbed by either the ventricular catheter or normal sites of CSF absorption [28]. Even with multiple shunts, all compartments may not be drained properly. As a consequence, shunts are associated with high failure rates. There is also the risk of subsequent infections.

Endoscopy offers a simple means of communicating isolated CSF spaces and ventricles by membrane fenestration. A good analysis of the preoperative MRI scans will help to achieve a good outcome in these cases. Entry points are to be determined in a way, so that through the least number of burr holes, maximum number of cysts can be fenestrated and communication among them can be established [29]. Same burr hole as that for the placement of a ventricular catheter can also be taken into account for the fenestration procedure. Fenestration of the septum pellucidum to connect the two lateral ventricles in patients with loculated ventricles will preclude the need for two shunts in the majority of patients [20].

Spennato et al., explained high incidence of shunt obstruction in multiloculation by the chronic inflammation of the ependyma and appearance of new septa. They considered multiloculated hydrocephalus as progressive disease [30]. Akbari et al., found that 38.5% of patients with multiloculated hydrocephalus required additional endoscopic fenestrations after the initial surgery, while El-Ghandour found that in 33% of patients endoscopic fenestration was repeated during the follow-up period [31, 32].

Aqueductoplasty can be used for the treatment of trapped fourth ventricle syndrome. There is a high closure rate, which can be prevented by stenting. In these cases, endoscopic third ventriculostomy should also be done. Applied neuroendoscopic techniques have been extended to foraminoplasty of the foramens of Monro and Magendie, as well as endoscopic fourth ventriculostomy [1, 2, 11].

#### **4.2 Intracranial cysts**

The ventricular system may lodge many types of cysts like arachnoid cysts (AC), choroid plexus cysts, neoplastic cysts and infected cysts (e.g. hydatid and cysticercotic cysts). ACs, although typically extra-axial, may occur within the ventricles.

#### *Endoscopy in Neurosurgery DOI: http://dx.doi.org/10.5772/intechopen.100252*

ACs can be treated with either endoscopic resection or fenestration to achieve a successful outcome in many patients [33].

Intracranial ACs comprise about 1% of all intracranial space-occupying lesions [34]. In the recent years with increased availability of computed tomography (CT) and magnetic resonance imaging (MRI), the incidence has seem to be increased as more are detected [35, 36]. Different surgical techniques are recommended. Because of the development of neuroendoscopy, pure endoscopic AC fenestration has become increasingly popular, where a communication can also be established with either ventricles or cisterns, and is actually preferred by many neurosurgeons [36, 37], especially in cases of cysts located in the suprasellar or quadrigeminal as well as in the posterior fossa [38–40].

Walker et al. reported in their preliminary series that 9 of 14 children (64%) with arachnoid cysts were successfully treated by endoscopic fenestration through a burr hole, thereby avoiding the need for craniotomy and brain manipulation [41]. Even cysts confined to the pituitary fossa are ideally suited to endoscopic transsphenoidal surgery. Ventriculo-cysto-cisternostomy offers long-term decompression of suprasellar arachnoid cysts without the need for shunting. Most patients with intraventricular cyst or tumors have concomitant hydrocephalus. These cases are better managed by endoscopic surgery rather than open, as procedures can be performed for both CSF diversion and tumor management simultaneously [42, 43]. Teo et al. had successful outcome in fenestrating ACs, cysts of the cavum velum interpositum, neuroepithelial cysts of the ventricle, colloid cysts and large pineal region cysts. While operating in smaller ventricles, frameless stereotactic guidance has been useful in planning the site(s) of the burr hole(s) and to plan the trajectory to these cysts. The current advancement of neuronavigation with electromagnetic guidance helps the endoscopic surgery more precise and well directed. The goal of surgery for arachnoid cysts is symptomatic improvement. This is particularly pertinent with endoscopic fenestration, as the appearance of the cyst on postoperative imaging may be only slightly diminished, despite marked clinical improvement [6].
