Role of choroid plexus cauterization in augmenting the success rate of endoscopic third ventriculostomy in Chiari II-associated hydrocephalus

Abstract

Objective

This study evaluates the efficacy and outcomes of endoscopic third ventriculostomy combined with choroid plexus cauterization (ETV + CPC) as a primary treatment for hydrocephalus associated with Chiari II malformation in infants.

Methods

This retrospective study analyzed 53 infants, all under 12 months of age and post-myelomeningocele repair, who presented with hydrocephalus (Evans’ Index > 0.3 or Frontal occipital horn ratio (FOHR) > 0.4). All patients underwent Endoscopic third ventriculostomy (ETV) and bilateral choroid plexus cauterization (CPC) using a rigid endoscope. Success was defined as shunt-free survival with clinical and radiological improvement over a 12-month follow-up period.

Results

The cohort of 53 infants (28 males, 25 females) had a mean age of 3.4 months, with 36% consanguinity. Patients were stratified into three age groups: < 3 months (n = 13), 3–6 months (n = 19), and 6–12 months (n = 21). The ETV + CPC success rate showed a positive correlation with age: 54% in the youngest group, 63% in the middle group, and 67% in the oldest group. Of the 20 failures, 14 required ventriculoperitoneal shunts (VPS), and 6 were managed with re-endoscopy for stoma closure. Meningitis was the most common complication (15%), with all affected patients eventually requiring a VP shunt.

Conclusion

ETV + CPC offers an effective, safe, and durable alternative to traditional VPS for infants with Chiari II-associated hydrocephalus. It significantly reduces shunt dependency and its associated long-term complications. Success rates improve with advancing age, making it a viable first-line surgical option in pediatric neurosurgery, particularly in resource-limited settings.

Introduction

Hydrocephalus in the context of Chiari II malformation presents a challenge in pediatric neurosurgery. Pathophysiology is multifactorial, involving aqueductal stenosis, hindbrain herniation, and impaired CSF reabsorption [26, 30, 31]. Hydrocephalus in myelomeningocele (MMC) is mainly caused by Chiari II malformation, which obstructs CSF flow at the foramen magnum and cervicomedullary junction. A small posterior fossa and cerebellar prolapse further increase venous resistance and impair absorption. Additionally, structural anomalies, such as abnormal glycosaminoglycan distribution in subependymal regions, may contribute to a communicating type. Patients often present with diverse intraventricular and paraventricular anatomical variations [6, 8].

Traditionally, VPS have served as the cornerstone of treatment [26]. However, shunted patients require lifelong follow-up and are liable to multiple complications including obstruction, infection, and migration; therefore, the term “shunt revision rate” has become known, indicating limited success of shunt systems [9, 46].

ETV is a minimally invasive approach designed to create a bypass for CSF flow at the floor of the third ventricle [4, 42]. Nevertheless, its success in infants has historically been limited due to immature subarachnoid absorption pathways [18, 20]. Another factor that may hinder the effectiveness of ETV in infants is the altered ventricular and paraventricular anatomy, particularly in those with MMC [25]. To compensate for the low success rate in endoscopic procedures, the addition of choroid plexus cauterization (CPC) aims to reduce CSF production, offering a dual mechanism to control hydrocephalus [12, 13, 20, 42]. This study evaluates the role of ETV + CPC in improving outcomes in infants with Chiari II-associated hydrocephalus at our center.

Patients and methods

This retrospective study was conducted at the Pediatric Neurosurgery Department of Mansoura University Hospitals between January 2020 and January 2024. Fifty-three patients diagnosed with hydrocephalus secondary to Chiari II malformation were included. All patients were under 12 months of age at the time of surgery and had previously undergone surgical repair of MMC. The interval between MMC closure and ETV + CPC ranged from 2 to 8 weeks and the majority of patients proceeded to surgery at 4 to 6 weeks post-repair.

The diagnosis of hydrocephalus was confirmed through clinical signs (bulging anterior fontanelle, increased head circumference, sunsetting sign) and neuroimaging including cranial ultrasound and MRI.

Inclusion criteria included: (1) age ≤ 12 months, (2) Chiari II malformation with ventriculomegaly (Evans’ Index > 0.3 or FOHR > 0.4), (3) no prior CSF diversion procedure, and (4) consent from parents or legal guardians. Exclusion criteria were CSF infection, multiloculated hydrocephalus, and prior shunt insertion.

Preoperative assessment included full clinical examination, head circumference monitoring, ultrasonography, and MRI. Hydrocephalus was assessed sonographically using anterior horn width, third ventricular width, and thalamo-occipital distance, with ventricular enlargement defined as a frontal horn ratio exceeding age-adjusted norms.

MRI used to assess hydrocephalus through measuring Evans’ Index; ratio of maximum frontal horn width to maximum skull diameter, threshold > 0.30) [31] and FOHR; average of frontal and occipital horn widths divided by twice the biparietal diameter, threshold > 0.40. MRI provided high-resolution characterisation of ventricular anatomy, posterior fossa morphology, degree of cerebellar herniation through the foramen magnum, aqueductal patency, and the anatomy of the third ventricular floor including the infundibular recess and mammillary bodies as landmarks for safe ETV fenestration.

Preoperative CSF analysis was performed in all 53 patients via fontanelle tap or lumbar puncture as clinically appropriate. CSF was normal in all patients who proceeded to surgery, with white cell count, protein, glucose, and Gram stain all within acceptable ranges, confirming the absence of active CSF infection at the time of the procedure. Any patient with abnormal CSF was excluded per protocol. Surgical procedures were performed using a rigid 0-degree endoscope (Karl Storz) under general anesthesia. A right frontal burr hole was made at Kocher’s point. The third ventricular floor was fenestrated anterior to the mammillary bodies and posterior to the infundibular recess, followed by dilation with a Fogarty balloon as in Fig. 1. Bilateral CPC was performed using a Bugby wire to coagulate the choroid plexus from the foramen of Monro to the temporal horn as visualized in Fig. 2. Septostomy was performed when access to the contralateral ventricle was limited and most of the cases had a fenestrated septum.

Fig. 1.

Performing ETV with a puncture in tuber cinereum anterior to mamillary bodies

Fig. 2.

Performing CPC using endoscopic monopolar cautery

Postoperatively, patients were monitored in the neurosurgical ICU. A structured three-tier radiological protocol was followed. Cranial ultrasound was the primary surveillance modality, performed at all follow-up visits (2 weeks, 3 months, 6 months, and 12 months). It was the preferred tool given its safety, absence of radiation, bedside availability, and the open anterior fontanelle present in this infant cohort. CT was performed on postoperative day 1 exclusively to exclude acute intracranial haemorrhage; this was a single targeted scan and was not used as a routine surveillance tool. When CT was obtained, hydrocephalus severity was assessed using EI and FOHR. FIESTA MRI was reserved for cases of suspected failure, to assess stoma patency and CSF flow dynamics without radiation exposure.

On MRI, EI and FOHR were calculated on coronal T2 sequences; stoma patency was confirmed by CSF signal continuity between the third ventricle and the prepontine cistern on thin-slice FIESTA sequences; and the subarachnoid spaces and posterior fossa anatomy were assessed on sagittal T2 sequences. Clinical and radiological follow-up was conducted at 2 weeks, 3 months, 6 months, and 12 months postoperatively. Clinical improvement was assessed by normalization of head growth, resolution of bulging fontanelle, and absence of symptoms. Radiological success was defined as stable or decreased ventricular size. Success was defined as shunt-free survival with clinical and radiological improvement over a 12-month follow-up period.

Failure was defined by symptomatic deterioration and the need for VPS or revision endoscopy. In case of procedure failure, the patients were fully investigated for the cause of failure. CSF flowmetry and FIESTA MRI were used to detect patency of the stoma. In case of a closed stoma as in Fig. 3, re-endoscopy was used to manage rise of ICP. In case of a patent stoma as in Fig. 4, VPS was used. If meningitis was the cause of failure, properly prescribed antibiotics and external ventricular drain (EVD) were used until CSF was clear, then VPS.

Fig. 3.

Post operative FIESTA MRI showing an arrow point to the site of closed stoma

Fig. 4.

Post operative FIESTA MRI showing an arrow point to the site of patent stoma

Statistical analysis

Data analysis was performed using SPSS version 28. Continuous variables such as age were summarized as mean ± standard deviation (SD), and categorical variables such as presence of complications and shunt requirement were reported as counts and percentages. Chi-square or Fisher’s exact test was used for categorical comparisons. Statistical significance was defined as a p-value less than 0.05.

Results

A total of 53 infants were included (28 males, 25 females) with a mean age of 3.4 months (range 13–195 days). Consanguinity was present in 19 patients (36%). All patients had previously undergone myelomeningocele repair; 9 presented with ruptured sacs, while 44 had intact repairs.

We categorized our patients into three groups according to the age at which they underwent ETV-CPC, and they were all followed up for one year. Group A included patients below the age of three months and consisted of 13 patients. Group B included patients from the age of 3 to 6 months and consisted of 19 patients. Group C included patients from the age of 6 to 12 months and consisted of 21 patients.

In group A, 13 patients were managed with ETV + CPC. Seven patients improved, representing a success rate of 54%. However, six patients had a persistent rise of intracranial pressure, representing a failure rate of 46%. Of those six patients, two patients underwent re-endoscopy for a closed stoma detected on CSF flowmetry and FIESTA MRI, while four patients had a persistent stoma with a rise of ICP and were managed with a VP shunt.

In group B, we had 19 patients managed with ETV + CPC whose ages ranged from 3 to 6 months. Twelve patients improved with a success rate of 63%, while seven patients experienced failure with the procedure. This failure was managed with re-endoscopy in one patient, and six patients received VP shunt.

In group C, we had 21 patients managed with ETV and CPC between the ages of 6 and 12 months. Fourteen patients improved with a success rate of 67%, while seven patients had persistent rise of ICP. Three patients underwent re-endoscopy, while four patients underwent ventriculoperitoneal shunt. All this data are illustrated in Table 1.

Table 1.

Patient categorization according to age and their management

Age	Number of patients	Outcome	Management
>3 months	13 managed with ETV+CPC	1. Improved symptoms: 7 (54%) 2. Persistent rise of ICP: 6 (46%)	a) 2 patients underwent re-endoscopy b) 4 patients underwent VPS
3–6 months	19 managed with ETV+CPC	1. Improved symptoms: 12 (63%) 2. Persistent rise of ICP: 7 (37%)	a) 1 patient underwent re-endoscopy b) 6 patients underwent VPS
6–12 months	21 managed with ETV+CPC	1. Improved symptoms: 14 (67%) 2. Persistent rise of ICP: 7 (33%)	a) 3 patients underwent re-endoscopy b) 4 patients underwent VPS

Preoperative CSF analysis was performed in all 53 patients. CSF results were within normal limits in all patients, including white cell count, protein, glucose, and Gram stain, all within acceptable ranges. Intraoperatively, CSF appearance was assessed at the time of burr hole entry and ventricular cannulation; cloudy or xanthochromic CSF intraoperatively would have prompted abandonment of the procedure, and all cases included had clear CSF at the time of the procedure.

Regarding complications, meningitis was the most common, occurring in 8 patients (15%) following the procedures. All 8 cases of meningitis (15%) occurred following the index ETV + CPC procedure. No cases of meningitis occurred following re-endoscopy in the 6 patients who underwent repeat procedures for stoma reclosure. It was managed by antibiotics alone in three patients, while EVD and antibiotics were used for 5 patients. All patients with meningitis were later managed with VPS. There were 14 patients who received VPS during the total duration of the study. Four of them required shunt revision.

The success rate of ETV + CPC increased with age from 54% below three months, 63% for 3 to 6 months, and 67% for 6 to 12 months.

Discussion

The treatment of hydrocephalus in infants with Chiari II malformation has traditionally relied on VPS [21]. While VP shunts provide rapid relief of hydrocephalus, they are associated with significant long-term complications, including infection, malfunction, and frequent revision surgeries [32, 39, 46]. Recent advancements in neuroendoscopy have popularized ETV, particularly when combined with CPC [20, 22, 24, 42].

Although ETV is now a primary treatment for noncommunicating hydrocephalus in many cases, its use in young infants with Chiari II malformation remains controversial. The lower success rates in these patients may be attributed to unique CSF dynamics, where the major CSF pathways may not be fully developed, and minor pathways play a significant role in CSF circulation[47]. Additionally, altered ventricular and paraventricular anatomy, especially in infants with myelomeningocele, may reduce ETV effectiveness [18, 20, 26, 45].

In our series, we employed ETV + CPC for all cases. This approach has shown promising results in managing hydrocephalus, particularly in young children. Warf reported success with ETV/CPC in East African children [41], and subsequent studies have reported improved success rates compared to ETV alone [1]. The extent of CPC performed appears to correlate with success, with more extensive cauterization linked to higher success rates [42].

Below three months post-ETV-CPC, 54% of patients were symptom-free, and by 3 to 6 months, 63% remained shunt-free. These findings align with Warf and Campbell’s study, which adopted ETV + CPC as the primary treatment for hydrocephalus across all ages for economic reasons, reporting an overall success rate of 72% with a median patient age of two months. Their data showed that adding CPC to ETV increased efficacy from 49 to 75% [44]. A recent review further confirmed the effectiveness of ETV + CPC across various hydrocephalus etiologies, including MMC [28, 44].

At 6 to 12 months, the success rate in our cohort increased to 67%, consistent with findings by Warf et al. [42] and Kulkarni et al. [20], who reported 70–76% success in similar infant cohorts. Vulcu et al. [40] and Kong et al. [17] also noted success rates around 70%, with higher success in primary ETV + CPC cases compared to those with prior shunt history. All patients in our series were shunt-free, which likely contributed to the favorable outcomes.

Success rates of ETV + CPC increased with patient age, aligning with prior studies indicating that younger age is associated with higher failure rates [33, 34]. This may be due to a thicker third ventricular floor in younger infants, increasing the likelihood of stoma closure, or immature subarachnoid spaces that limit CSF absorption [7, 19, 32, 35]. Stoma reclosure was a key predictor of failure in our cohort, varying by follow-up time. This is consistent with studies noting early stoma closure in infants due to thin, reactive third ventricular membranes [11, 29]. Repeat endoscopy successfully salvaged 7 of 17 reclosure cases in our series.

We combined CPC with ETV to augment the total success rate, and our data were consistent with previous studies that found CPC substantially augments ETV efficacy in Chiari II hydrocephalus, particularly in infants younger than 6 months where isolated ETV success drops below 45%, making ETV + CPC a preferred first-line therapy in experienced centers. A 2022 meta-analysis of 13 studies encompassing 325 pediatric patients with myelomeningocele-associated hydrocephalus demonstrated an overall ETV success rate of 56%, with ETV alone achieving 48% success versus 75% when CPC was added—an absolute improvement of 27% (p < 0.05) [27]. Long-term French data (1994–2012) on 32 infants treated with ETV + CPC reported 72% shunt independence at 8-year follow-up with zero perioperative mortality [2]. Similarly, a crucial subgroup analysis focusing on African cohorts, which are known to have a high prevalence of MM-associated hydrocephalus demonstrated a significant benefit for ETV + CPC compared to ETV alone (Relative Risk 1.38, 95% CI 1.08–1.78, p = 0.01) [36]. This finding reinforces the concept that the efficacy of CPC is highly dependent on the underlying etiology, with the greatest benefit observed in the MM/Chiari II population.

The 15% postoperative meningitis rate in our series is comparable to published shunt infection rates in MMC patients, which reach up to 15% in the first year [43, 46], with an additional 30–40% risk of mechanical shunt malfunction [3, 32]. Importantly, all 8 meningitis cases followed the index ETV + CPC procedure; none occurred after re-endoscopy. While post-shunt infection can typically be managed by shunt revision, meningitis after ETV + CPC in our cohort universally resulted in shunt dependency, effectively negating the primary benefit of the endoscopic approach. Since preoperative CSF was normal in all patients, these were genuine de novo postoperative infections rather than missed preoperative ones. Contributing factors include residual lumbosacral wound flora, immune immaturity in young infants, the challenges of sterile field maintenance after prior back surgery, and the longer operative duration of ETV + CPC compared to ETV alone. These findings support mandatory preoperative CSF analysis as a standard safety step before ETV + CPC in this population.

The durability of ETV + CPC is a significant advantage. Long-term studies, such as those by Jernigan and Berry [16], have shown stable ventricular sizes and sustained clinical improvement for up to five years post-procedure. Compared to VP shunting, which often requires multiple revisions within the first few years, ETV + CPC significantly reduces reoperation rates [15, 37, 38]. This is particularly valuable in rural or resource-limited settings with limited access to emergency neurosurgical care [45].

Despite its benefits, ETV + CPC has limitations. Systematic reviews by Limbrick et al. [23] and Yadav et al. [48] note reduced success in patients under three months or with severe hindbrain herniation. Future advancements, such as image-guided flexible endoscopy and intraoperative ETV patency assessment, may improve outcomes in challenging cases. Patient selection remains critical and should consider age, anatomy, and the ETV Success Score [5, 11, 18].

This series addresses a clear gap in the ETV + CPC literature, which is dominated by sub-Saharan African [41, 42, 44] and North American cohorts [19, 36], with no data from North African or Middle Eastern centers.

Several limitations of this series must be acknowledged. The retrospective design limits causal inference, and the 12-month follow-up, while capturing the highest-risk failure window within which over 90% of ETV failures are known to occur [19, 41], does not provide data on late failure or long-term neurodevelopmental trajectory. The 6 patients who underwent re-endoscopy for stoma reclosure are continuing under active clinical and radiological surveillance beyond the study window. The use of a rigid endoscope limited the extent of CPC achievable, particularly in the temporal horns [10]; flexible endoscopes permit more thorough cauterization and may be associated with incrementally higher success rates [2]. No neurodevelopmental outcome data were collected in this series, which represents an important gap given that the primary goal of hydrocephalus treatment in this population is preservation of cognitive and motor development [14]. To address these limitations comprehensively, we have committed to a prospective continuation of this cohort incorporating standardized clinical, radiological, and neurodevelopmental assessment where institutional ethics approval permits.

Conclusion

ETV + CPC offers an effective, durable, and safe alternative to VP shunting for hydrocephalus associated with Chiari II malformation in infants. It reduces shunt dependency, lowers complication rates, and is particularly suitable for low-resource environments. Careful patient selection and technological advancements may further enhance its efficacy.

Abbreviations

ETV + CPC

Endoscopic third ventriculostomy combined with choroid plexus cauterization

FOHR

Frontal occipital horn ratio

ETV

Endoscopic third ventriculostomy

CPC

Choroid plexus cauterization

VPS

Ventriculoperitoneal shunts

MMC

Myelomeningocele

EVD

External ventricular drain

Author contribution

All authors contributed to the study conception and design and reviewed and approved the final manuscript for submission and publication. Contributions were organized as follows: • Conceptualization: Ahmed Zaher, Mohamed Badran, Mostafa Shahein. • Methodology: Ahmed Zaher, Mohamed Badran, Mohamed Mohsen Amen, Mostafa Shahein. • Formal analysis and investigation: Mohamed Badran, Mohamed Mohsen Amen. • Writing—original draft preparation: Mohamed Badran. • Writing – review and editing: Ahmed Zaher, Mohamed Badran. • Resources: Mohamed Mohsen Amen, Mohamed Badran, Ahmed Zaher. • Supervision: Mohamed Mohsen Amen, Mohamed Badran, Ahmed Zaher.

Funding

No external funding or grants were received for this study.

Data availability

Data are available upon reasonable request from the corresponding author.

Declarations

Ethical approval

This study was reviewed and approved by the Institutional Review Board of Mansoura University Faculty of Medicine (approval number: R.25.11.3449.R2). The IRB ensures that research conducted at the institution adheres to ethical standards and protects the rights and welfare of research participants. It is important to note that this article does not contain any studies involving human participants conducted by the authors.

Conflict of interest

The authors declare no competing interests.