Endoscopic third ventriculostomy for shunt malfunction in children: A review

Journal of Clinical Neuroscience xxx (2018) xxx–xxx

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Review article

Endoscopic third ventriculostomy for shunt malfunction in children: A review Mueez Waqar a,⇑, Jonathan R. Ellenbogen b,c, Conor Mallucci b,c a

Department of Neurosurgery, Salford Royal NHS Foundation Trust, Manchester M6 8HD, UK Department of Neurosurgery, The Walton Centre NHS Foundation Trust, Liverpool L9 7LJ, UK c Department of Paediatric Neurosurgery, Alder Hey Children’s Hospital, Liverpool L12 2AP, UK b

a r t i c l e

i n f o

Article history: Received 24 July 2017 Accepted 4 February 2018 Available online xxxx Keywords: Endoscopic third ventriculostomy Shunt Shunt malfunction Hydrocephalus

a b s t r a c t Endoscopic third ventriculostomy (ETV) is increasingly used in place of shunt revision for shunt malfunction (secondary ETV). This review provides a comprehensive overview of preoperative, operative and postoperative considerations for patients undergoing a secondary ETV. Preoperatively, patient selection is vital and there is evidence that secondary ETV is more effective than primary ETV in certain hydrocephalic aetiologies. Operative considerations include use of neuronavigation and consideration of surgeon technical experience due to anatomical differences that are likely to accompany chronic shunting, management of existing shunt hardware and the use of temporary external ventricular drains or short/long-term ventricular access devices. Postoperatively, there are varying institutional practices with regards to ICP monitoring and length of follow-up after discharge. Finally, this review examines the slit ventricle syndrome as a special case requiring a different approach. Ó 2018 Elsevier Ltd. All rights reserved.

1. Introduction Endoscopic third ventriculostomy (ETV) is commonly used to manage patients with obstructive hydrocephalus, either as a firstline procedure (primary ETV), or in the setting of shunt malfunction (secondary ETV). Although ventriculostomy for shunt malfunction has been described since the 1960s, surgeons were largely reluctant to use the technique until the advent of refined neuroendoscopic techniques in the late 1990s, when its use became more widespread [1–4]. There are several important factors that surgeons performing a secondary ETV should consider. These can be broadly divided based on clinical course into preoperative, operative and postoperative factors. Preoperatively, the choice of CSF diversion procedure is most important. Scoring systems have been developed to aid clinician decision making, particularly with regards to the likelihood of ETV success [5]. Aetiology of hydrocephalus is a particularly important prognostic indicator. Operative factors include: surgeon technical experience - distorted ventricular anatomy can arise from chronic shunting; management of existing shunt hardware - whether to leave it in, ligate it or remove it entirely; and whether to anticipate ⇑ Corresponding author at: Department of Neurosurgery, Salford Royal NHS Foundation Trust, Stott Lane, Manchester M6 8HD, UK. E-mail addresses: [email protected], [email protected] (M. Waqar), [email protected] (J.R. Ellenbogen), conor.mallucci@ alderhey.nhs.uk (C. Mallucci).

ETV failure, most likely in the early postoperative period, by employing an external ventricular drain or ventricular access device. Postoperative factors include the decision to use ICP monitoring and follow-up after hospital discharge. In this study, we review the literature to provide a comprehensive understanding of secondary ETV. 2. Methods MEDLINE (PubMed interface) was queried using combinations of the following terms: endoscopic third ventriculostomy, ventriculostomy, ETV, shunt malfunction, shunt failure. Articles were limited to the English language. The search was performed until December 2016. For analysis of secondary ETV outcome, articles meeting the following criteria were included: (1) presentation of clinical outcomes with secondary ETV; (2) inclusion of only paediatric (<18) patients or a predominantly paediatric age group; (3) adequate sample size (n > 10). 3. Preoperative factors 3.1. Efficacy Studies reporting outcomes with secondary ETV in children are shown in Table 1. Outcomes were available for 519 patients included in 15 observational studies, with a mean age of 9.8 years

https://doi.org/10.1016/j.jocn.2018.02.012 0967-5868/Ó 2018 Elsevier Ltd. All rights reserved.

Please cite this article in press as: Waqar M et al. Endoscopic third ventriculostomy for shunt malfunction in children: A review. J Clin Neurosci (2018), https://doi.org/10.1016/j.jocn.2018.02.012

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M. Waqar et al. / Journal of Clinical Neuroscience xxx (2018) xxx–xxx Table 1 Outcomes after secondary ETV [4,6–19]. Results from our institution were presented in the study by Stovell et al. (highlighted in grey). NR = not reported; AS = aqueductal stenosis; IVH = intraventricular haemorrhage; C-SB: chiari/spina-bifida; mo = months. Sample size, n

Secondary cause

Study

Mean Age, years (range)

Mean followup, months (range)

Shuntfree, n (%)

Complications

Total

AS

Tumour

Meningitis

IVH

C-SB

Malfunction

Jones 1990 Sydney, Australia 1979-1988

14

7

2

1

0

3

NR

NR

12 (9mo-17)

42 (2-120)

8 (57.1%)

0 (0.0%)

Jones 1996 Sydney, Australia 1979-1988

14

0

0

0

0

14

12

2

NR

NR

13 (92.9%)

NR

Teo 1996 Arkansas, USA 1978-1995

55

0

0

0

0

55

NR

NR

11 (1w - 32)

32 (NR)

46 (83.6%)

NR

Cinalli 1998 Paris, France 1974-1995

30

10

7

5

4

0

17

13

8.7 (NR)

104 (6-186)

23 (76.7%)

4 (13.3%)

Beems 2002 Nijmegen, Netherlands Up to 2001

13

2

NR

NR

4

2

NR

NR

5 (3d-18)

50 (6-119)

8 (61.5%)

0 (0.0%)

Siomin 2002 Multi-centre 1993-2000

29

0

0

16

13

0

NR

NR

6.9 (0-65)

22 (7-120)

24 (82.8%)

NR

Buxton 2003 Nottingham, UK 1994-2001

88

27

4

6

12

13

88

0

14 (2mo-76)

36 (1-72)

46 (52.3%)

14 (15.9%)

O’Brien 2005 Multi-centre 1998-2005

63

19

6

4

7

20

49

14

20 (9mo-69)

49 (7-64)

44 (70.0%)

5 (7.9%)

Bilginer 2009 Ankara, Turkey 2002-2007

45

21

6

9

4

3

38

7

12.2 (1-30)

30 (12-60)

36 (80.0%)

0 (0.0%)

Marton 2010 Treviso, Italy 1995-2008

22

4

3

3

7

0

20

2

6.7 (4mo-14)

64 (12-122)

14 (63.6%)

0 (0.0%)

Neils 2013 Illinois, USA 2004-2009

20

6

1

0

3

7

20

0

11.5 (7mo-29)

NR

14 (70.0%)

0 (0.0%)

Brichtova 2013 Brno, Czech Republic 2001-2011

42

15

0

7

15

5

NR

NR

9.5 (NR)

NR

29 (69.0%)

2 (4.8%)

Tamburrini 2013 Rome, Italy 2001-2007

14

0

0

0

0

14

14

0

2.7 (NR)

79 (65-94)

9 (64.0%)

NR

Zhao 2016 Shanghai, China 2005-2014

37

14

9

8

3

0

27

10

1.8 (8mo-3)

3 (NR)

22 (59.5%)

0 (0.0%)

Stovell 2016 Liverpool, UK 1998-2006

33

10

1

2

10

10

25

8

6.9 (7d-15.5)

53 (1-190)

18 (55%)

0 (0.0%)

(95% CI 7.9–11.8 years). The overall pooled efficacy of secondary ETV was 68.2% over a mean follow-up period of 37 months (range 1–190 months) [4,6–19]. The reported efficacy varies between studies due to differences in patient baseline characteristics. ETV is effective in patients presenting with shunt malfunction, as demonstrated by its success in patients with up to 22 prior shunt revisions [4,6,11].

Infection

rate than primary ETV in patients with hydrocephalus due to haemorrhage or infection (OR = 5.79, 95% CI 2.46–13.61; p < 0.001) and chiari malformation (OR = 5.57, 95% CI 2.81–11.00; p < 0.001). These findings are perhaps expected as long-term CSF diversion can induce a state of acquired aqueductal stenosis, for which the efficacy of ETV is similar to the obstructive setting. 3.3. Complication rate

3.2. Aetiology of hydrocephalus Table 2 shows the impact of aetiology of hydrocephalus on the efficacy of primary and secondary ETV. For aqueductal stenosis and tumours, there was no significant difference in success rate between primary and secondary ETV (OR = 1.19, 95% CI 0.46– 3.11; p = 0.74). Secondary ETV had a significantly higher success

The pooled complication rate of secondary ETV was low at 6.1% across all studies. Reported complications were homologous to primary ETV, including haemorrhage, infection, transient cranial nerve palsies and closure of the stoma site. The complication rates of primary and secondary ETV are similar [12,20], though there are isolated reports of a higher complication rate with the latter [21].

Please cite this article in press as: Waqar M et al. Endoscopic third ventriculostomy for shunt malfunction in children: A review. J Clin Neurosci (2018), https://doi.org/10.1016/j.jocn.2018.02.012

M. Waqar et al. / Journal of Clinical Neuroscience xxx (2018) xxx–xxx Table 2 Primary versus secondary ETV for various indications in paediatric patients [4,6–19]. % patients remaining shunt-free

Primary ETV Secondary ETV

Aqueductal stenosis and tumours

Infection and haemorrhage

Chiari and spina bifida

70.6% 74.1%

37.7% 77.8%

36.5% 76.2%

Table 3 Anatomical variations that may be encountered in patients undergoing secondary ETV [29–36]. Area Skull vault

Skull base

3.4. Determining outcome The ETV success score was devised from pooled data from 618 children undergoing ETV from 5 centres in the UK, Canada and Israel. Multivariate analysis showed that age, aetiology and previous shunt were the most important factors influencing ETV outcome [5]. The score favours shunt-naive patients, who receive an additional 10 points compared to those with a prior shunt. However, factors such as age and aetiology can influence the score to a greater degree.

Intracranial cavity

Intraventricular space

3.5. Imaging Patients with suspected shunt malfunction should undergo a CT scan or rapid sequence MRI (‘‘quick-brain” MRI) to check for ventricular dilatation. MRI is gaining favour as shunt patients typically undergo an average of 2 CT scans per year, which provides enough radiation for 1 in 230 to develop an excess fatal cancer [22]. The sensitivity and specificity of these imaging methods are also similar, between 60 and 90% and 95%, respectively [23,24]. It is important to note that imaging can be normal in up to 20% of patients and operative intervention should be considered if shunt malfunction is strongly suspected. Shunt series - serial radiographs of extraventricular shunts (‘‘shunt series”), are inherently unreliable, with a sensitivity of 20–30%, and should be avoided [25,26]. Following diagnosis of shunt malfunction, an MRI scan should be obtained to delineate intracranial anatomy [27,28]. A Constructive Interference in Steady-state Sequence (CISS) or Fast Imaging Employing Steady-state Acquisition (FIESTA) scan is particularly useful to define structures within CSF spaces and at CSF interfaces, such as the third ventricle floor [27]. This is particularly important given the anatomical differences that can be encountered in these patients (see below). Some select patients for secondary ETV based on the presence of triventricular hydrocephalus [4,9]. This pattern of ventriculomegaly usually accompanies aqueductal stenosis and given the efficacy of ETV for this pathology, this seems a logical choice. However, outcomes based on ventricular morphology are rarely reported in the literature and in fact, in one study, the presence of triventricular hydrocephalus did not significantly affect outcome [8]. Other studies are lacking. 4. Operative factors 4.1. Anatomical considerations Long-term shunt use can cause several anatomical changes (Table 3) [29–36]. Neuroendoscopy is also more technically challenging than shunt revision, such that surgeon technical experience is particularly important when deciding management of patients with shunt malfunction, especially out of hours. An ETV is technically possible if the following criteria are met:  Presence of at least one route from one lateral ventricle to the third ventricle floor that is large enough for the endoscope and manoeuvring.

3

Subarachnoid space

Anatomical variations  Chronic brain deflation reduces the outward expansion force on the skull; the inner table can then expand and increase skull thickness  Reduced force separating the sutures can lead to premature suture fusion and scaphocephaly  Shape may be more curved  Sella may be superiorly displaced and smaller if hydrocephalus is poorly controlled  Clivus may be displaced more posteriorly and be more closely related to the basilar artery  Chronic intracranial hypotension causes reduced stretch tension on the dura and dural thickening  Reduced cerebral perfusion pressures lead to increased meningeal vascular proliferation to compensate  Brain deflation can widen the sulci, which are then filled by a dense network of blood vessels  Recurrent surgery can lead to ventricular wall thickening and gliosis  Intraventricular septae can reduce ventricular dimensions and make navigation and identification of structures more difficult  There may be very little choroid plexus remaining due to previous episodes of ventriculitis or intraventricular haemorrhage  The interventricular foramen may be distorted or even completely occluded by gliosis  The mammillary bodies may be joined by adhesions and difficult to identify as the overlying vascular hue is blocked by adhesional membranes  The floor of the third ventricle can be unusually thick, in contrast to the lamina terminalis, making them difficult to differentiate  Gliosis reduces the size of the cisterns and makes it difficult to identify vital structures (e.g. basilar artery, cranial nerves III and VI)  Gliosis can also thicken Liliequist’s membrane, an arachnoid membrane that connects the diaphragm sellae to the mammillary bodies

 Absence of major anatomical abnormalities of the third ventricle.  Adequate space between the dorsum sella and basilar artery, to avoid injury to the vessel. 4.2. Equipment Most studies have reported experience with a rigid neuroendoscope for secondary ETV [4,13,16]. However, a flexible multichannel scope can also be used. The size of the scope depends on patient age but an external diameter of 3–6 mm is adequate, with 3 mm being employed in younger children. Neuronavigation using electromagnetic (EM) guidance systems is important due to anatomical differences, as outlined above. Other important equipment will vary according to surgeon preference, but generally includes: neuroendoscopic monopolar cautery, laser, a variety of neuroendoscopic forceps to assist in fenestration of the 3rd ventricle floor and sizes 2–4 French Forgarty balloon catheters or light touch double balloon (Integra) for dilation of the ventriculostomy site. 4.3. Management of shunt hardware There are three options  Complete removal: advised where possible. A partially functioning extraventricular shunt can reduce flow through the ventriculostomy site, promoting its closure. Retained shunt hardware can also result in chronic infection and even organ perforation [11,13,14,37,38]. However, shunts can be difficult to remove,

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M. Waqar et al. / Journal of Clinical Neuroscience xxx (2018) xxx–xxx

particularly after years of placement. In one study for example, 22 patients had attempted shunt removal prior to secondary ETV and complete removal was possible in 18 cases, with the remaining 4 being ligated [14]. In another study, only 24 of 35 shunt could be removed completely prior to secondary ETV [21].  Ligation: usually performed if the shunt is difficult to remove. The main advantage is a lower risk of haemorrhage compared to complete shunt removal, particularly if the ventricular catheter is close to choroid plexus. Brichtova et al. described a variation of this approach where they ligated the shunt and connected the ventricular catheter to an Ommaya reservoir. The reservoir could be tapped in an emergency in the case of ETV failure [15].  Leave in situ: although the least preferred, there are theoretical advantages to leaving the shunt in place. These include a lower risk of intracranial haemorrhage and trauma. A Czech study reported experience with this method. Neils et al. removed the shunt or left it in situ in 10 and 8 patients, of which 6 and 7 remained shunt-free at follow-up, respectively. Although sample size was limited, absolute ETV failure rate was higher in the group in whom the shunt was left in situ [16]. In another study, three patients with retained shunt hardware had dismal outcomes. Two developed shunt infection, whilst the third experienced wound dehiscence. After shunt removal however, all remained shunt-free after 24 months mean follow-up [38]. 4.4. ETV procedure In principle, the procedure is the same as primary ETV, though special consideration should be given to potential anatomical differences. Briefly, the neuroendoscope is navigated to the third ventricle floor and a stoma is created about halfway between the mammillary bodies and infundibulum. Fenestration can be achieved with the tip of a Fogarty balloon catheter, hydrodissection or a variety of surgical aids/forceps as described above. Direct use of the neuroendoscope tip should be avoided to maintain orientation and control at all times. After its creation, the stoma should be enlarged progressively with Fogarty balloon catheters. These can also be used to divide subarachnoid membranes, especially Liliequist’s membrane. Failure to divide the latter can result in ETV failure [33]. 4.5. Post-procedure EVD Use of an EVD is a particularly contentious area and there are advantages and disadvantages of a temporary postoperative external ventricular drain (EVD). The drain is usually left closed and removed after 72 h if no complications occur. Advantages:  Immediate ventricular drainage in the setting of ETV failure – commonest in the initial postoperative period.  Temporary management of intraventricular haemorrhage – the commonest complication of ETV.  CSF drainage and administration of intrathecal antibiotics in the setting of CNS infection – another common complication of ETV. Disadvantages:  The belief that postoperative ICP is higher in patients after secondary versus primary ETV, was a key argument in favour of routine postoperative EVD use. However, studies have shown that there is no significant difference in postoperative ICP measurements between patients undergoing primary versus

secondary ETV. Furthermore, ICP measurement does not influence outcome (see below) [39].  Another route for CNS infection in a high risk patient group.  CSF diversion can in theory reduce flow through the ventriculostomy site, increasing the risk of stoma closure. Institutional practice varies with regards to use of postoperative EVDs. Given the paucity of evidence to guide this decision, a patient-centred approach is necessary until data can support either approach. Situations in which a postoperative EVD would be recommended include a critically unwell preoperative course and intraoperative haemorrhage [40]. 4.6. Post-procedure access device Access devices are rarely employed after ETV. Their advantages and disadvantages are similar to those described for EVDs, though they allow for long-term ventricular tapping. Specific complications include CSF and subdural collections. Some units routinely implant these devices with all ETVs, given reports of fatalities after long-term ETV failure [41]. Access devices may be suited to patients in remote areas, with a history of multiple shunt revisions and rapid decompensation, in whom emergency ventricular tapping can be life saving. Evidence for use of access devices in the setting of secondary ETV is sparse. Brichtova et al. connected the original shunt ventricular shunt catheter to Ommaya reservoirs. Most (>50%) of their patients had post-meningitic or post-haemorrhagic hydrocephalus. Postoperatively, 69% remained shunt-free, with a complication rate of <5% [15]. Another study reported use of Ommaya reservoirs in combination with EVDs in four patients, two with postmeningitic hydrocephalus and two with post-haemorrhagic hydrocephalus, of whom three in total remained shunt-free [14]. 5. Postoperative factors 5.1. Postoperative care The highest risk of ETV failure is in the immediate postoperative period, when there is an adaptation period. Postoperative care may therefore be required to take place in a neurointensive care or HDU setting, and a CSF-flow MRI should be performed within the first few weeks to determine ETV patency. 5.2. ICP monitoring Some centres employ ICP monitoring in all patients after ETV, especially in the case of secondary ETV, though this is not our usual practice. Cinalli et al. studied postoperative ICP in 64 children undergoing primary (n = 44) or secondary (n = 20) ETV [39]. There were several important findings of their study:  There was no significant difference in ETV failure rate between patients with raised versus normal ICP.  Raised ICP was usually transient and lasted on average for 4.5 postoperative days (range 2–9 days).  There was no significant difference in average ICP between the primary and secondary ETV groups.  Two patterns of ICP trace (‘‘progressive rise” and ‘‘secondary increase”), were associated with ETV failure, as could have been predicted. On the basis of these findings, the authors concluded that routine ICP monitoring was not required, but they still recommended its

Please cite this article in press as: Waqar M et al. Endoscopic third ventriculostomy for shunt malfunction in children: A review. J Clin Neurosci (2018), https://doi.org/10.1016/j.jocn.2018.02.012

M. Waqar et al. / Journal of Clinical Neuroscience xxx (2018) xxx–xxx

consideration in the setting of secondary ETV. However, their results actually showed that the only ICP pattern associated with ETV failure was a progressive rise or abrupt, secondary rise, which could arguably be picked up also on clinical grounds. Other studies are lacking in this area, such that it is difficult to make universal recommendations. ICP monitoring may be considered for those patients in whom a clinical assessment is particularly difficult or unreliable. 5.3. Follow-up Studies have shown that patients with ETV can have late malfunction, after several years of follow-up [17,42,43]. A study from our centre describing long-term outcomes of ETV in children, found 3 cases of ETV malfunction after 5 years, all of whom were secondary ETV cases [17]. Although for many patients, malfunction can be detected and treated appropriately, it can even be fatal. There are reports of sudden death after ETV, which reinforce the idea that CSF re-diversion with ETV is not infallible or curative [44]. The above evidence would suggest it is actually dangerous to ever discharge patients with ETV. This is currently debated with varying institutional practices. At our institute, patients are discharged after 3 days and seen in clinic within 2 weeks, followed by 2-monthly outpatient appointments for the first year and then yearly throughout childhood. We perform a CSF-flow MRI at the 2 month appointment and then based on clinical need. Advantages of indefinite follow-up for children include opportunity for continued education of parents and children to recognise treatment failure and symptoms of recurrent hydrocephalus, ready access to specialist advice should there be any concern of ETV malfunction and opportunity to discuss new symptomatology should concerns arise. Disadvantages are mainly cost based. It could also be argued that parents may delay presentation to fixed appointments, though this can be avoided through appropriate education. 5.4. Secondary ETV failure Secondary ETV patients presenting with ETV failure present a particular challenge and there is little evidence to guide management. The choice is between a repeat (‘‘redo”) ETV procedure or a different CSF diversion procedure. It is advisable to perform a CSF-flow MRI in the first instance, to check for patency of the stoma site. This may reveal an indication for a redo ETV procedure, such as occlusion of the stoma by secondary membranes. However, imaging can be unhelpful and endoscopy for diagnostic +/ treatment purposes may be required. Existing studies also suggest that redo ETV is more technically challenging in patients with failed secondary ETV. In one study, a repeat ETV was technically possible in only 11 out of 42 patients (26%) with secondary ETV failure [11]. In another study including both primary and secondary ETV failures, 215/316 (68%) patients had successful reopening of the stoma site, though 72 (23%) had anatomical distortion that did not permit a redo procedure [45]. At neuroendoscopy, the stoma site may be found to be of normal size, narrowed or occluded. In the latter two cases, it should be enlarged or reopened. A second stoma at a different site on the third ventricle floor is almost never required [45]. If the stoma site is visibly patent, the cisternal space should be carefully inspected for the presence of secondary membranes, which can also obstruct CSF flow. If no obstructive membranes are found however, then a different CSF diversion procedure can be performed in the same operation [45,46]. 6. CSF overdrainage: the slit ventricle syndrome (SVS) Chronic CSF over-drainage at an early age can result in narrow, slit-like ventricles due to ventricular wall collapse followed by the

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development of non-compliance in the ventricular system. This presentation requires special consideration. Management options include active surveillance without CSF diversion in the first instance, shunt revision with upgrade of valve plus antisiphon/gravitational device or ETV. ETV is gaining popularity as a first line treatment for SVS. In this setting ETV can be technically very difficult due to the small ventricular size limiting vision and maneuverability within the ventricular system. Baskin et al. developed an algorithm for patients presenting with SVS. They admitted patients for 72 h and externalised and occluded their shunts to create iatrogenic shunt malfunction. Patients were subsequently ICP monitored and reviewed regularly. Those who remained asymptomatic with normal ICP underwent complete shunt removal. Patients with evidence of raised ICP or symptomatic hydrocephalus underwent an ETV with accompanying EVD using the proximal shunt catheter. 16 patients underwent an ETV, with 10 remaining shunt-free during follow-up. The added usefulness of the first part of their algorithm includes the fact that 5 patients with SVS were weaned off shunts, with no requirement for ETV [47]. Other studies have also reported favourable results with the method of controlled ventricular dilation and ETV, though not all have included a trial of ICP monitoring or EVDs [48]. 7. Conclusion Secondary ETV is a commonly used procedure. It is more efficacious than primary ETV in several aetiologies of hydrocephalus, such as infection, haemorrhage and chiari/spina bifida malformations. These findings reaffirm the conventional view of ETV as a treatment primarily for patients with aqueductal stenosis, which can be acquired after chronic shunting. Secondary ETV is more technically challenging given the numerous anatomical differences between shunt-naive and shunt dependent patients, and routine neuronavigation is advised. Complications are usually rare, however and the overall rate is about 6%. It is recommended that the shunt be removed in its entirety where possible. The decision to employ a temporary EVD or ventricular access device should be patient dependent in the absence of robust evidence. Postoperatively, patients may be managed on neurointensive care/HDU, though ICP monitoring is not usually required, unless clinical assessment is particularly difficult. Importantly, patients are not actually cured after ETV and life long follow-up is advised, given the numerous reports of long-term treatment failure and sudden death. Further studies are awaited before more definitive guidance can be provided for many of the above points. Disclosures The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper. Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at https://doi.org/10.1016/j.jocn.2018.02.012. References [1] Volkel JS, Voris HC. Third ventriculostomy in obstructive hydrocephalus. Longterm arrest of hydrocephalus in 4 cases. J Neurosurg 1966;24:568–9. [2] Jones RF, Stening WA, Kwok BC, Sands TM. Third ventriculostomy for shunt infections in children. Neurosurgery 1993;32:855–9. [3] Yamamoto M, Oka K, Ikeda K, Tomonaga M. Percutaneous flexible neuroendoscopic ventriculostomy in patients with shunt malfunction as an alternative procedure to shunt revision. Surg Neurol 1994;42:218–23.

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Please cite this article in press as: Waqar M et al. Endoscopic third ventriculostomy for shunt malfunction in children: A review. J Clin Neurosci (2018), https://doi.org/10.1016/j.jocn.2018.02.012