Successful endoscopic third ventriculostomy in children depends on age and etiology of hydrocephalus
Updated: Aug 9, 2018
Soner Duru, Jose L Peiro, Marc Oria, Emrah Aydin, Canan Subasi, Cengiz Tuncer, Harold L Rekate
Endoscopic third ventriculostomy (ETV) has become the method of choice in the treatment of hydrocephalus. Age and etiology could determine success rates (SR) of ETV. The purpose of this study is to assess these factors in pediatric population. Methods Retrospective study on 51 children with obstructive hydrocephalus that underwent ETV was performed. The patients were divided into three groups per their age at the time of the treatment: < 6, 6–24, and > 24 months of age.
Factors indicating a potential failure of ETV were young age and etiology such as spina bifida, other than isolated aqueductal stenosis. ETV is the method of choice even in patients with former shunting. Fast healing, distensible skulls, and lower pressure gradient in younger children, all can play a role in ETV failure. Based on our experience, ETV could be the first method of choice for hydrocephalus even in children younger than 6 months of age.
The incidence of congenital hydrocephalus is estimated to be 0.2 to 0.80 per 1000 live births in the USA . Moreover, the incidence of congenital hydrocephalus is estimated to be 0.7 cases per 1000 live births in developed countries . There is no known difference in the worldwide geographic distribution of hydrocephalus. The optimal treatment for infant hydrocephalus still is not definitively determined [1, 2, 12, 15, 20, 35, 47]. Significant technological advances have been made recently in endoscopy and shunt hardware; however, the treatment of hydrocephalus remains one of the most difficult challenges faced by neurosurgeons in the decision-making process to choose the best method of hydrocephalus treatment. Shunts have long been used to divert cerebrospinal fluid (CSF) in obstructive and non-obstructive hydrocephalus. Currently, many patients with hydrocephalus are considered candidates for endoscopic third ventriculostomy (ETV) that has gained acceptance in the last 20 years .
According to previous reports, age, etiology, and experience of the surgeon are important factors that determine success rates (SRs) of ETV. Higher SRs, reaching 90%, in some papers have been reported for patients with stenosis of the aqueduct [7, 11, 19, 22–24, 26]. Lower success for patients with post infectious and post hemorrhagic hydrocephalus, and also with prior ventriculoperitoneal shunt failures were also reported [16, 22, 23, 44, 46].
The outcome seems to be worse in small children younger than 2 years of age and especially in infants and neonates. Several studies showed SR of ETV ranging from 0 to 64% [1, 2, 8, 9, 15, 20, 28, 29, 32] in this patient population. Other studies showed favorable outcomes in patients older than 6 months old . Moreover, controversies still exist whether ETV might be superior to shunt placement or not in children less than 6 months of age. Some studies reported and concluded that ETV could be the first method of choice for hydrocephalus in children younger than 6 months of age, and especially in patients older than 3 months of age . Therefore, the use of ETV in babies under age of 6 months remains controversial.
In our study, we detailed our single-surgeon experience in ETV treatment for hydrocephalus in children. Success rates in subgroups with different etiologies and different age groups of the hydrocephalus were analyzed and discussed with a de- tailed review of the literature.
This is a retrospective analysis performed between 2001 and 2016, where we detailed single-surgeon experience in a total of 51 pediatric patients, younger than 16 years old, with obstructive hydrocephalus who underwent ETV. All these procedures were performed at Duzce University Hospital and some private hospitals in Turkey by the same pediatric neurosurgeon. A rigid GAAB Storz (Tutlingen, Germ any) neuroendoscopic system equipped with a No. 8 French diameter Hopkins rod lens system with a 0° optic and a 3-Fr working channel alongside an irrigation channel was used. Procedures were performed with freehand or fixation of the endoscopic instrument after the induction of general anesthesia.
The patients were distributed into three groups. In group 1, patients were < 6 months of age, in group 2 were between 6 months and 2 years of age, and in group 3 patients were between 2 and 16 years of age. Preoperative and postoperative variables such as etiology, prior shunt application, age at surgery, success rate, and the interval between surgeries in case of failure were analyzed.
Clinical assessment and radiological studies with CT and/ or MRI during the follow-up were performed 1–3 months after ETV. These radiological tests were repeated only if symptoms of ETV failure developed. Clinical follow-up continued throughout childhood with annual examinations. According to clinical and radiological follow-up, we defined ETV success criteria: (a) when no further intervention was required to treat hydrocephalus, (b) the absence of signs or symptoms of raised intracranial pressure, and (c) shunt independence.
Statistical analysis was performed with IBM SPSS Statistics 20.0.0 software. The characteristics of the study sample were summarized by descriptive statistics, with dichotomous or ordinal data presented as percentages and continuous data as means with standard deviations. Student’s t test was used. Statistical associations were considered significant if the p value was < 0.01.
A total of 51 children patients were studied. The age of the patients ranged from 10 days to 15 years old. Follow-up peri- od ranged from 12 to 74 months, with an average of months. Male/female ratio was 26:25 (51%). Of the total group of patients, 31.4% (16/51) were younger than 6 months. Of patients, 35.3% were 6–24 months and 33.3% of patients were > 24 months of age.
The etiologies were idiopathic aqueductal stenosis in 29 patients, spina bifida associated Chiari-2 malformation in 7 patients, post hemorrhage in 5 patients, post infectious in two patients, quadrigeminal arachnoid cyst in 3 patients, tetraventricular hydrocephalus in 3 patients, Dandy-Walker syndrome in one patient, and X-related hydrocephalus in one patient (Table 1).
In all cases, ETV was performed to restore the CSF flow pathways. We considered pediatric patients who had undergone ETV as an initial treatment or following V-P shunt failure for their hydrocephalus. Moreover, after the first unsuccessful ETV attempt for some hydrocephalic cases, re-ETV was performed in 8 cases, and a V-P shunt was performed in 3 cases. In our re- ETV procedure, SR was 62.5% (n = 5/8). We observed ETV failure, especially in spina bifida cases. In spina bifida cases, SR was only 14.3% (1/7). Moreover, we demonstrated narrow prepontine cistern in spina bifida cases, intraoperatively. In re- ETV cases, we observed healed closed orifice in the floor of the third ventricle in all cases, and when we re-opened the stoma, we demonstrated thick, opaque, and also vascularized third ventricle floor membrane, whereas in first attempt cases, we demonstrated thin, bluish color membrane (Figs. 1 and 2).
Overall success of ETV was in 40 patients (80%). In the remaining 11 patients (20%), V-P shunting or re-ETV were performed (interval from ETV ranged from 5 to 63 days). Because of persisting or worsening clinical and radiological signs of hydrocephalus, V-P shunt was performed in three patients. In eight patients, re-ETV was performed; however, in three of them, both re-ETV and V-P shunt were done. According to clinical success criteria and cine mod MRI findings (ETV stoma open or closed), we decided second surgery type, either re-ETV or shunting. In case of failure, the mean length of time between surgeries was 23 days (ranging from 5 to 63 days).
In patients with V-P shunt performed prior to ETV, the SR was 76.9%. However, the overall SR at the first ETV attempt was 85.3% (Figs. 3 and 4). Table 2 shows the SR depending on patient’s age at the time of the operation and etiology of hydrocephalus (Figs. 5 and 6). In patients for all etiology younger than 6 months of age (n = 16), SR was 56.2% (Fig. 7). In patients with all etiology from 6 to 24 months of age 16/18 were successful (88.9%) (Fig. 8). In patients for all etiologies > 24 months (n = 17), SR was 94.1% (Fig. 9). Figure 3 shows the correlation between SR and age group (P = 0,001). The highest SR (100%, p = 0.000) was obtained in the group of patients with aqueductal stenosis for all of the age groups. In patients with aqueductal stenosis < 6 months of age (n = 5), SR was 100%, 6–24 months of age (n = 11) SR was 100%, and > 24 months of age (n = 13) SR was 100%. In patients with post hemorrhagic hydrocephalus (n = 5), SR was 3/5 (successful 2 cases in <6 months, 1 case in 6– 24 months). In patients with post infectious hydrocephalus (n = 2), SR was successful in 1 of 2 cases in > 24 months). In patients with spina bifida (n = 7), SR was 14% (1/7) (successful in 1 case in 6–24 months). In a patient with Dandy-Walker syndrome (n = 1), SR was 1/1(successful in 1 case in 6–24 months). In a patient with tetraventricular hydrocephalus (n = 3), SR was 3/3 (successful in 2 cases in < 6 months, successful in 1 case in 6– 24 months). In patients with a quadrigeminal arachnoidal cyst (n = 3), SR was 3/3 (successful in 1 case in 6–24 months, successful in 2 cases in > 24 months). In a patient with X-related hydrocephalus (n = 1), SR was 0/1 (no success in < 6 months, performed re-ETV attempt plus shunting).
In our study, we present a one-center experience in 51 obstructive hydrocephalus cases performed ETV by one pediatric neurosurgeon in children. The overall SR and failure rate to restore CSF circulation was 80 and 20%, respectively.
In the last century concerning the management of hydrocephalus, the issue about timing and indication of ETV and its effectiveness in children, is still controversial [9, 14, 15, 18, 20, 27, 28, 30, 42, 45]. Moreover, there is no consensus regarding the optimal age of patients to be treated with ETV.
The physics of CSF circulation differs among patients with hydrocephalus in intrauterine, early postnatal developmental period and after, neonatal, childhood, and adult period [3, 9, 38]. Moreover, skull distensibility of the skull in the under 6-month group and the pressure in the intracranial compartment cannot get high enough for the CSF to be absorbed. In the 6 months– 2 years’ group, the skull is too large for the volume of the brain. According to some report, ETV failure in young children might be explained by the poor CSF reabsorption ability of newborn infants due to the immaturity of the arachnoid granulations . The arachnoid villi inside the dural venous sinuses have been thought to be the main site of CSF absorption.
Physiological values of CSF pressure vary according to individuals and study methods between 10 and 15 mmHg in adults and 3 to 4 mmHg in infants. The pressure gradient between subarachnoid spaces and the venous sinus necessary to ensure CSF drainage is between 3 and 5 mmHg . Also, the anterior fontanelle is widely opened, and the sutures are usually displayed in infants, contributing to the maintenance of low intracranial pressure [22, 25, 38, 47]. Due to the distensible skull in the under 6-month groups, the pressure in the intracranial compartment cannot get high enough for the CSF to be absorbed in infants. Therefore, some authors have advocated that ETV has the same long-term results in children younger than 6 months than in older children and, thus, patient age should no longer be considered a contraindication to using the technique [4, 11]. In case of delayed failure (usually secondary to obstruction of the stoma), this can often be managed by repeating the procedure [11, 33, 45]. In one study, authors reported that repeat ETV was successful in 13 patients (65%). These patients did not require further shunting or other procedures during follow-up . Therefore, despite the fact that some patients suffering from occlusion of the ventricular stoma, several authors tried to repeat ETV [11, 33, 45]. In our re- ETV procedure, SR was 62.5% (n = 5/8). We found the orifice healed and closed in all cases. The fibrous and sclerotic thick- ness of the third ventricle floor makes the redo surgery a little bit more difficult with potentially more risk of bleeding but still feasible and effective. Our results were similar to other reports. Repeat ETV is a safe and effective procedure and should be an option for treatment of recurrent obstructive hydrocephalus if stoma closure or obstruction is present.
A literature review showed that SR in children under 6 months of age ranged from 32 to 44.9% and from 56 to 71% in children older than 1 year [5, 13, 31, 34, 36, 40, 43]. In our series, for all etiology younger than 6 months of age, SR was 56.2%. In patients with all etiology from 6 to 24 months of age, SR was 88.9%. In patients with all etiology > 24 months, SR was 94.1%. In our series, no major permanent morbidity or mortality was observed.
Underlying pathology, like intraventricular hemorrhage, myelomeningocele and previous CSF infection or shunt infection were also strongly associated with failure of ETV. In our series for all ages, SR of post hemorrhagic, post infectious, and spina bifida related hydrocephalus were 60, 50, and 14.3%, respectively. However, in aqueductal stenosis, the highest SR was obtained. Interestingly, spina bifida (ETV performed after meningomyelocele repair in all spina bifida cases) shows the worse success and we hypothesize a possible cause. The lack of fluid content, space, and pressure in the subarachnoid extra- axial area while the defect is open could switch to a hyper- pressure zone when the spinal defect is water-tightly closed. This effect could impair the CSF flow through the third ventricle stoma and enhance the spontaneous closure of the orifice. In our successful case with spina bifida, we performed ETV 6 months after being repaired. In contrast, in other spina bifida cases, ETV was performed in between 1 and 7 days after meningomyelocele repair. Restoration of the CSF circulation could explain the successful late ETV in this patient. Although some authors reported that shunt revisions before ETV were associated with ETV failure , other authors reported that ETV could be the method of choice for obstructive hydrocephalus treatment, if an obstruction of the ventricular systems in patients with previous V-P shunting appear . In our series, in previous V-P shunt performed patients, ETV SR was 76.9%. However, slightly lower than the overall SR at the first ETV attempt that was 85.3%.
The critical question is why the failure occurs in the younger age group. The actual cause can be that the skull is distensible in the under 6-month groups and the pressure in the intracranial compartment cannot get high enough to maintain a flow and for the CSF to be absorbed. Moreover, in the 6 months–2 years’ group, it relates more to the fact that the skull is too large for the volume of the brain. Shunts cause the brain to be pulled inward leading to increase in the cortical subarachnoid space with a decrease in ventricular size. ETV, on the other hand, requires that the brain grow to fill the skull.
According to our series, aqueductal stenosis seems to be particularly well suited to ETV, regardless of the patient’s age. Furthermore, we had perfect ETV SR in cases with tetraventricular hydrocephalus, Dandy-Walker and with quadrigeminal arachnoid cysts but we need more cases from these etiologies to reach a final conclusion. However, hemorrhage, infection, and myelomeningocele-related hydrocephalus have been associated with high failure rates. ETV offers a low risk and can be considered an effective treatment for obstructive hydrocephalus even following the dysfunction of previous VPSs and in children younger than 2 years. Moreover, instead of VP shunt, re-ETV should be an option for treatment of recurrent obstructive hydrocephalus if stoma closure or obstruction is present. Based on our experience, ETV should be considered for hydrocephalus in children even younger than 6 months of age.