**3. Surgical technique**

**2.8. Obstruction due to giant aneurysm**

136 Hydrocephalus: Water on the Brain

be performed in the usual way [49].

**2.9. Further indications for ETV**

the cisterns through the ventriculostoma.

An obstructive hydrocephalus through giant aneurysm is rare, but it has been already reported in some cases [49–52]. Commonly, these cases are treated via shunt placement, although an aneurysm growing after shunt implantation has been already reported. The theory is that the decreased intracranial pressure after shunt placement reduces the tamponade effect, leading

In certain cases, an endoscopic ventriculostomy might be performed [49, 50]. Even though the anatomy is commonly changed as a consequence of the aneurysm (e.g., the third ventricle or aqueduct may be compressed and the anatomical structures as the floor of ventricle and mammillary bodies may be displaced), the landmarks can be identified and the surgery can

Every surgical revision after shunt implantation is considered as shunt failure. Many studies established that endoscopic third ventriculostomy in shunt failures might be an effective treatment option (**Figure 8**). The presence of shunt failure does not exercise influence on the failure rate of ETV. However, the success seems to be diverse in certain etiology groups [14]. It was observed that hydrocephalus patients less than 65 years of age with idiopathic normal pressure, where the dominant symptom was gait disturbances and only minimal cognitive

**Figure 8.** Hydrocephalus with shunt malfunction (a and b) preoperative MRI scan, (c) scarred thick floor of the third ventricle, (d) perforation of adhesions in the prepontine cistern with forceps, (e) with bipolar diathermy, and (f) view on

to aneurysm expansion and an increase in the risk for rupture [51].

deficits could be observed, had a good success rate [14].

#### **3.1. Neuroendoscopic equipment**

For endoscopic ventricular surgery, either rigid or flexible endoscope can be used. Rigid endoscopes have a higher image quality and allow an easier insertion and handling of instruments. In contrast, the flexible one allows a flexible mobility of the scope, even though producing a lower image quality [53]. Endoscopic equipment for ETV includes various rigid rod lens Hopkins optics and instruments (scissors, hooks, puncture needles, forceps for tumor biopsy and grasping, bright cold Xenon light source, HD video camera system, irrigation device, and Fogarty balloon catheter) [7].

#### **3.2. Surgical technique**

The operation is performed under general anesthesia. The patient is placed in supine position, the head in 3-pin fixation and tilted slightly forward. The hair is shaved and the approach is marked. The standard placement of the burr hole is anterior to the coronal suture and 2 cm lateral to the midline. After skin disinfection and sterile draping of the operating field, the scalp is incised in a straight line, about 2–3 cm long. After placement of the burr hole (about 1 cm) and opening the dura, the operating sheath is introduced into the lateral ventricle and the trocar is inserted at about 5 cm depth of dura. The endoscope is fixed and the trocar is removed. The rigid 0° diagnostic optic is inserted for inspection and identification of the main landmarks. In the lateral ventricle, the fornix, the foramen of Monro, and the choroid plexus are identified (**Figures 9** and **10**). Under direct visual control, the endoscope is advanced through the foramen of Monro into the third ventricle. In the third ventricle, the main landmarks are the mammillary bodies and the infundibular recess. The diagnostic inspection is extended with

**Figure 9.** Steps of endoscopic third ventriculostomy. (A) View of foramen of Monro, plexus choroideus, anterior septal vein in lateral ventricle, (B) view of mammillary bodies, infundibular recess in the third ventricle, (C) ventriculostomy with bipolar diathermy, (D) ventriculostoma, (E) enlarging with perforation forceps, (F) dilatation with Fogarty balloon catheter, (G) expanded ventriculostoma, and (H) view of basilar artery.

the fiberscope inserted. After forwarding the fiberscope through the aqueduct, the patency of outlets of the fourth ventricle can be inspected. The fiberscope is withdrawn and a 0° diagnostic optic inserted to check for contusion or bleeding during the withdrawal of the work sheath [19].

Presentation of the Success Rate of ETV in Distinct Indication Cases of Hydrocephalus

http://dx.doi.org/10.5772/intechopen.72889

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In case of a successful third ventriculostomy, the symptoms mostly improve soon after surgery. Most of the patients, who suffered from deterioration of consciousness because of obstructive hydrocephalus, show a rapid improvement after the surgery [6]. Of course, it requires an adequate indication and it depends considerably on the underlying pathology

Postoperative CT scan is routinely performed; however, the radiological findings alone do not count as an indicator of ETV success. It must be assessed in all cases with the clinical findings [6, 10, 58, 59]. After ETV, the intraventricular pressure does not decrease immediately in certain cases [10]. The ventricle size can increase, decrease, and remain unchanged after ventriculostomy [6]. In most cases, the ventricle size might correlate with the clinical outcome as early as 1 month after the surgery. In successful cases, a significant decrease can be seen, while it is not observable or not significant in ETV failures [58, 60]. Especially, decreasing of the third ventricle size is

Aqueduct stenosis 67–93.5 Vulcu et al. [6], Grunert et al. [9], Hellwig et al. [10], Hopf

Cysts 56–95 Vulcu et al. [6], Oertel et al. [7], Hopf et al. [11], Moorthy

Hemorrhage 43–73 Vulcu et al. [6], Oertel et al. [39], Grunert et al. [9], Siomin

Congenital malformations 21–80 Wu et al. [25], Mohanty et al. [26], Rei et al. [46], Warf et al. [47]

Infection 60–64 Mugamba et al. [13], Siomin et al. [40], Oertel et al. [63]

Far distal obstruction 72–76 Oertel et al. [31], Mohanty et al. [26], Warf et al. [47] Tumors 56–81 Vulcu et al. [6], Oertel et al. [7], Grunert et al. [9], Hellwig

Cerebellar infarction 86 Oertel et al. [7], Baldauf et al. [37]

Tuberculous meningitis 60–83 Singh et al. [74], Bhagwati et al. [43]

et al. [65]

et al. [10], Hopf et al. [11]

et al. [40], Roux et al. [73]

65–72 Hellwig et al. [10], Moorthy et al. [14], Gangemi et al. [75]

et al. [11], Moorthy et al. [14], Oertel et al. [63], Gangemi

et al. [14], Ray et al. [27], MacArthur et al. [69]

**4. Success rate of distinct indications**

**Indication Success rate (%) References**

Giant aneurysm No adequate data

**Table 1.** Success rate of ETV in distinct indication cases.

Further (e.g.,

noncommunicating HC)

[6, 7, 12] (**Table 1**).

**Figure 10.** (Left) Landmarks on the MRI scan TRUFI sequence, (L) lateral ventricle, (III.) third ventricle. Infundibular recess (grey arrow), mammillary body (wavy arrow), and interpeduncular and prepontine cistern (dotted arrow). (Right) Entry point.

30°, 45°, and/or 70° optics to view the anterior and posterior parts of the ventricles if applicable. It can be useful in case of obstruction of the aqueduct or tumor. In the midline between the mammillary bodies and the infundibular recess, the perforation is performed. For fenestration, there are several possibilities. The perforation can be performed by sharp perforation with semisharp probe [54], by blunt perforation with the endoscope itself, the balloon catheter itself [8], by coagulation with monopolar or bipolar diathermy [7, 8, 54], and by laser perforation [54, 55], waterjet dissection [55], ventriculostomy forceps [7], or ultrasonic probe [56]. It is recommended to use a blunt perforation to avoid vascular injury [8, 55]. In case of thick ventricle floor, it is recommended to use cauterization with bipolar diathermy at low energy [7, 8], sharp perforation with semisharp catheter [54], or waterjet dissection [55]. However, laser perforation and monopolar diathermy should be avoided [8]. After the perforation by a rigid instrument, enlarging ventriculostomy is initially performed by a perforation forceps and subsequently by inflation of a Fogarty balloon catheter (4–7 mm). After ventriculostomy, an inspection is performed with the 0° diagnostic optic to identify the dorsum sellae and the tip of the basilar artery to ensure free CSF flow. If a Liliequist membrane or subarachnoid adhesions are present, they also should be perforated (**Figure 8**). While withdrawing the operating sheath, an active bleeding at the foramen of Monro or at the corticotomy should be ruled out. After removal of instruments, a gelatin sponge is inserted in the burr hole and the galea is tightly closed to avoid a subgaleal CSF accumulation and leakage. The skin is sutured with clamp or thread. As standard, no EVD is inserted (**Figure 1**) [7, 9].

In case of infants up to 2 years of age, the procedure is performed in the same way; the only exception is that the head is fixed with bandages running over the forehead [57].

In addition, a flexible endoscope can be used for transaqueductal inspection. Following ETV, the work sheath should be moved posteriorly to achieve a straight approach to the Sylvian aqueduct. If the size of diameter of the aqueduct allows it, the working optic can be withdrawn and the fiberscope inserted. After forwarding the fiberscope through the aqueduct, the patency of outlets of the fourth ventricle can be inspected. The fiberscope is withdrawn and a 0° diagnostic optic inserted to check for contusion or bleeding during the withdrawal of the work sheath [19].
