**6. Challenges and complications**

ETV is considered a safe and direct procedure by a huge group of neurosurgeons, and on the contrary due to the low incidence of mortality due to vascular injury, a fatal risk in comparison to VP shunt implantation is considered by another group of neurosurgeons [33]. Insertion of a foreign hardware to the human's body is always associated with increased risk of infection and/or hardware malfunction, which favors the trial of the ETV as a primary management modality especially in adult patients with obstructive hydrocephalus [15]. On the contrary, late failure or reclosure is considered as a potential risk that can be fatal after ETV [40].

has been shown to be less effective in patients with myelomeningocele and intraventricular hemorrhage, while having a similar success rate to adults in cases of aqueductal stenosis [60].

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Choroid plexus coagulation is the surgical ablation of the choroid plexus either endoscopic or microscopic [61]. It has recently become popular as a method of management of hydrocepha-

Since 2005, the combination of CPC and ETV became more popular but ever since remained a debatable issue [66]. Warf and colleagues published their results of ETV + CPC in 2005; the majority of patients were infants. The long-term outcome and neurocognitive results were reported in later studies and showed that ETV + CPC increased the success rate from 20 to 47% to 63 to 76%. In North American experience, multicentric studies proved the safety of

In 2004, Morota described the technique of CPC through a parietal burr hole using a flexible endoscope and monopolar cautery [70]. Warf described the combined ETV/CPC procedure using the flexible endoscope, through a frontal burr hole. Bilateral CPC adds 15–30 minutes to the procedure; adequate coagulation is realized by the blanching of all visible parts of the choroid plexus and the associated blood vessels [61, 66, 67]. The overall mortality (within 30 days of the surgery) was 1.3%. There was no increase in mortality compared to those with

Patients with postinfectious and posthemorrhagic hydrocephalus have not been included in ETV studies in significant numbers. Instead, such patients are considered by many authors to

Posthemorrhagic hydrocephalus of prematurity (PHHP) is one of the most common causes of infant hydrocephalus in developed countries; this is mainly due to the high standards of care

PHHP occurs when blood in the CSF-filled spaces, together with the initial inflammatory reaction in the ependyma, would lead to obstruction of CSF outflow and hinder absorption, usually by the mechanism of posterior fossa arachnoiditis and aqueductal obstruction. In addition, a diffuse inflammatory reaction in the basal cisterns could coexist, which supports

On the contrary, putting these in consideration, with the fact that the use of VP shunts in these too young patients carries a high risk of failure, makes trial for an ETV a possible choice for

A large multicentric retrospective study showed that patients with obstructive hydrocephalus and history of hemorrhage or infection may be candidates for ETV. In this group ETV is reasonably safe, with a success rate that is comparable to the general series. ETV is highly

be prone to failure of ventriculostomy, thus contraindicating ETV [48, 71, 72].

the theory that predict the ETV failure in these cases [73, 74].

treating this group of patients, and decreasing shunt dependency [73].

**6.1. Choroid plexus coagulation**

lus not caused by the overproduction of CSF [62–65].

ETV alone and those with ETV + CPC [61, 66].

**6.2. Communicating hydrocephalus**

for prematurely born babies [73].

combined ETV/CPC procedure with technical improvement [67–69].

The success of the secondary ETV after ventricular shunt insertion is still debatable, where some studies identified the previous shunting procedure as a weakening factor against the ETV success [19, 41]. Other studies mentioned the success of the secondary ETV in hindering the shunt dependency [42, 43]. In our opinion, ETV is considered a competent treatment option in cases with obstructive hydrocephalus with repeated VP shunt failure. It can be easily tried and may lead to shunt independency.

Seven to ten percent of patients with Chiari type I present with hydrocephalus [44–46]. ETV has proven to be highly effective in the treatment of obstructive hydrocephalus, thus explaining its increasing use in cases of Chiari I-associated hydrocephalus [27, 47–50] with some limitations. The literature shows that most of patients may benefit from ETV. Syringomyelia shows better improvement than CIM. This is most probably due to the obvious role of hydrocephalus and increased pressure in the development of syrinx.

The large incidence of ETV failure in children leads to increased rate of shunt dependency in pediatric age groups, even in obstructive hydrocephalus [24]. The drop of the number of children where ETV is successful is thought due to the rapid formation of the arachnoid and scar membranes in children which closed the ventriculostoma rapidly [51]. On the contrary some authors support the ETV as effective management of obstructive hydrocephalus even in young children [52]. Other authors report the clear impact of age on the success rate of ETV when talking about infants, where the success rate increases gradually during the first months of life. Many studies were performed to determine the cause of failure in young children thus poor absorption of CSF and closure of the ventriculostoma or formation of new arachnoid membranes in the basal cisterns [51, 53]. In addition, reduced absorption of CSF as a cause of failure of ETV was recognized by many authors [54, 55] to be related to poor absorption from the arachnoid villi in young children and to the high compliance of the newborn skull in relation to older children leading to less CSF pressure gradient across the arachnoid villi, added to the previously mentioned probable failure due to arachnoid scarring (**Figure 3**) [56]. This was the initiative to relaunch the choroid plexus coagulation (CPC) technique to decrease the CSF production: thus, it would increase the success of ETV when performed together.

Due to repeated reports about failure in patients below 2 years old [57–59], a consideration of not doing this procedure in this age group has been implemented; however, it is now widely accepted that the etiology of the hydrocephalus rather than the age of the patient is more important in determining the efficacy of ETV even in patients less than 2 years old [60]. ETV has been shown to be less effective in patients with myelomeningocele and intraventricular hemorrhage, while having a similar success rate to adults in cases of aqueductal stenosis [60].

#### **6.1. Choroid plexus coagulation**

**6. Challenges and complications**

100 Hydrocephalus: Water on the Brain

ily tried and may lead to shunt independency.

cephalus and increased pressure in the development of syrinx.

ETV is considered a safe and direct procedure by a huge group of neurosurgeons, and on the contrary due to the low incidence of mortality due to vascular injury, a fatal risk in comparison to VP shunt implantation is considered by another group of neurosurgeons [33]. Insertion of a foreign hardware to the human's body is always associated with increased risk of infection and/or hardware malfunction, which favors the trial of the ETV as a primary management modality especially in adult patients with obstructive hydrocephalus [15]. On the contrary, late failure or reclosure is considered as a potential risk that can be fatal after ETV [40].

The success of the secondary ETV after ventricular shunt insertion is still debatable, where some studies identified the previous shunting procedure as a weakening factor against the ETV success [19, 41]. Other studies mentioned the success of the secondary ETV in hindering the shunt dependency [42, 43]. In our opinion, ETV is considered a competent treatment option in cases with obstructive hydrocephalus with repeated VP shunt failure. It can be eas-

Seven to ten percent of patients with Chiari type I present with hydrocephalus [44–46]. ETV has proven to be highly effective in the treatment of obstructive hydrocephalus, thus explaining its increasing use in cases of Chiari I-associated hydrocephalus [27, 47–50] with some limitations. The literature shows that most of patients may benefit from ETV. Syringomyelia shows better improvement than CIM. This is most probably due to the obvious role of hydro-

The large incidence of ETV failure in children leads to increased rate of shunt dependency in pediatric age groups, even in obstructive hydrocephalus [24]. The drop of the number of children where ETV is successful is thought due to the rapid formation of the arachnoid and scar membranes in children which closed the ventriculostoma rapidly [51]. On the contrary some authors support the ETV as effective management of obstructive hydrocephalus even in young children [52]. Other authors report the clear impact of age on the success rate of ETV when talking about infants, where the success rate increases gradually during the first months of life. Many studies were performed to determine the cause of failure in young children thus poor absorption of CSF and closure of the ventriculostoma or formation of new arachnoid membranes in the basal cisterns [51, 53]. In addition, reduced absorption of CSF as a cause of failure of ETV was recognized by many authors [54, 55] to be related to poor absorption from the arachnoid villi in young children and to the high compliance of the newborn skull in relation to older children leading to less CSF pressure gradient across the arachnoid villi, added to the previously mentioned probable failure due to arachnoid scarring (**Figure 3**) [56]. This was the initiative to relaunch the choroid plexus coagulation (CPC) technique to decrease the

CSF production: thus, it would increase the success of ETV when performed together.

Due to repeated reports about failure in patients below 2 years old [57–59], a consideration of not doing this procedure in this age group has been implemented; however, it is now widely accepted that the etiology of the hydrocephalus rather than the age of the patient is more important in determining the efficacy of ETV even in patients less than 2 years old [60]. ETV Choroid plexus coagulation is the surgical ablation of the choroid plexus either endoscopic or microscopic [61]. It has recently become popular as a method of management of hydrocephalus not caused by the overproduction of CSF [62–65].

Since 2005, the combination of CPC and ETV became more popular but ever since remained a debatable issue [66]. Warf and colleagues published their results of ETV + CPC in 2005; the majority of patients were infants. The long-term outcome and neurocognitive results were reported in later studies and showed that ETV + CPC increased the success rate from 20 to 47% to 63 to 76%. In North American experience, multicentric studies proved the safety of combined ETV/CPC procedure with technical improvement [67–69].

In 2004, Morota described the technique of CPC through a parietal burr hole using a flexible endoscope and monopolar cautery [70]. Warf described the combined ETV/CPC procedure using the flexible endoscope, through a frontal burr hole. Bilateral CPC adds 15–30 minutes to the procedure; adequate coagulation is realized by the blanching of all visible parts of the choroid plexus and the associated blood vessels [61, 66, 67]. The overall mortality (within 30 days of the surgery) was 1.3%. There was no increase in mortality compared to those with ETV alone and those with ETV + CPC [61, 66].

#### **6.2. Communicating hydrocephalus**

Patients with postinfectious and posthemorrhagic hydrocephalus have not been included in ETV studies in significant numbers. Instead, such patients are considered by many authors to be prone to failure of ventriculostomy, thus contraindicating ETV [48, 71, 72].

Posthemorrhagic hydrocephalus of prematurity (PHHP) is one of the most common causes of infant hydrocephalus in developed countries; this is mainly due to the high standards of care for prematurely born babies [73].

PHHP occurs when blood in the CSF-filled spaces, together with the initial inflammatory reaction in the ependyma, would lead to obstruction of CSF outflow and hinder absorption, usually by the mechanism of posterior fossa arachnoiditis and aqueductal obstruction. In addition, a diffuse inflammatory reaction in the basal cisterns could coexist, which supports the theory that predict the ETV failure in these cases [73, 74].

On the contrary, putting these in consideration, with the fact that the use of VP shunts in these too young patients carries a high risk of failure, makes trial for an ETV a possible choice for treating this group of patients, and decreasing shunt dependency [73].

A large multicentric retrospective study showed that patients with obstructive hydrocephalus and history of hemorrhage or infection may be candidates for ETV. In this group ETV is reasonably safe, with a success rate that is comparable to the general series. ETV is highly successful when performed in patients with intraventricular hemorrhage (IVH) and previous shunting; it is also highly successful in patients with primary aqueductal stenosis, while patients with history of both hemorrhage and infection are poor candidates for ETV [72, 73].

**7. Complications**

warranted.

**Author details**

**References**

In a previous literature review, the overall complication rate was 8.5%; among the individual series, the rate ranged from 0 to 31.2%. Complications reported in the immediate postoperative period were mainly hemorrhagic, infectious, subdural collections and CSF leak [84]. These complications represent actually the same complications that can be encountered with the ventricular shunting in exclusion of the hardware-related complications with variable

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In conclusion, although ETV is considered a reliable resort to control the hydrocephalus without implanting a shunt, the debate on its success rate is still not finalized especially in young children and communicating hydrocephalus. So that more studies covering those types are

incidence rates that can differ according to the variable age groups.

Ehab Ahmed El Refaee1,2\* and Ahmed A Abdullah1

Neurosurgery. 1999;**25**:21-60

Neurochirurgie. 1998;**59**(2):121-128

491 discussion 491-2

American Medical Association. 1923;**81**(26):2166

\*Address all correspondence to: e.elrefaee@googlemail.com

2 Department of Neurosurgery, University Medicine Greifswald, Germany

hydrocephalus. Annals of Surgery. 1918 Dec;**68**(6):569-579

[1] American Urological Association. Meeting. Philip Bozzini's Lichtleiter. 1971. 2 p

[2] Fries G, Perneczky A. Intracranial endoscopy. Advances and Technical Standards in

[3] Dandy WE. Extirpation of the choroid plexus of the lateral ventricles in communicating

[4] Duffner F, Freudenstein D, Wacker A, Straub-Duffner S, Grote EH. 75 years after Dandy, fay and Mixter--Looking back on the history of neuroendoscopy. Zentralblatt für

[5] Mixter WJ. Importance of complete examination of the cerebrospinal fluid. Journal of the

[6] McNickle HF. The surgical treatment of hydrocephalus. A simple method of performing

[7] Schroeder HWS.A new multipurpose ventriculoscope. Neurosurgery. 2008 Feb;**62**(2):489-

third ventriculostomy. The British Journal of Surgery. 1947;**34**(135):302-307

1 Department of Neurosurgery, Cairo University, Egypt

Some authors recommended the use of temporary CSF diversion, such as Ommaya reservoir in the acute stage of IVH, and performed the ETV when evidence of ventricular dilatation is obvious [75]. Moreover, in adult patients with IVH, studies showed that endoscopic third ventriculostomy may be an option in cases of acute intracranial hemorrhage with intraventricular extension in which there is clearly established CSF outflow obstruction, with special concern paid toward the surgeon experience [76].

#### **6.3. Redo success rate**

The question of in which cases a reclosure of the ETV opening occurs is still not answered. The recent data indicate that failure of ETV may occur immediately after the primary procedure, where the main cause is poor indication of remaining membranes or even years after where it is due to scarring [77, 78]. A redo ETV is supported before deciding to do other CSF diversion procedures whenever a failure was encountered, at which the ETVSS predicts the chance of successful redo ETV. Failure of the ETV and thus redo ETV can be also predicted by the presence of excessive prepontine arachnoid membranes in addition the use of external ventricular drain EVD [78, 79].

#### **6.4. Dandy-Walker malformation**

In such cases, hydrocephalus is caused by a large posterior fossa cyst in cases of Dandy-Walker malformation. ETV alone, with aqueductal stent, or with fenestration of the cyst can be sufficient in some cases to control hydrocephalus [80, 81].

Cystoventricular stent placement with endoscopic third ventriculostomy is a promising alternative in patients with Dandy-Walker malformation with aqueductal obstruction [26].

#### **6.5. Normal pressure hydrocephalus**

ETV has been recently introduced as a treatment option for normal pressure hydrocephalus. Gangemi et al. mentioned an overall success rate of 72%, in a series of 25 patients [31]. In a larger multicentric study, the clinical improvement reached 69.1%, where the improvement was correlated to the short clinical history, better neurological score before the operation, and the intraoperative appearance of normal cerebral pulsations [82]. Hailong et al. reported an 82.35% success rate and claimed that the preoperative Kiefer score and the patient's age are significant prognostic factors for ETV dysfunction [30]. However, the criteria of patients' selection and the small sample size in most previous literature would justify the actual deficiency of solid evidence that supports ETV as a treatment option in normal pressure hydrocephalus. Large-scale clinical studies are needed to reach better evidence and define the role of ETV in the management of INPH [83].
