Endoscopic third ventriculostomy and choroid plexus cauterization
While ventriculoperitoneal shunt (VPS) insertion is the standard treatment for myelomeningocele-associated hydrocephalus (MAH), it can be complicated by shunt infection and shunt malfunction. As such, endoscopic third ventriculostomy (ETV), with or without choroid plexus coagulation (CPC), has been proposed as an alternative.
ETV+CPC was associated with a higher success rate than ETV alone for MAH in a meta-analysis of published studies. ETV, with or without CPC, was technically feasible and safe for this patient population 1).
In the twenty-first century, choroid plexus cauterization (CPC) in combination with endoscopic third ventriculostomy (ETV) has emerged as an effective treatment for some infants with hydrocephalus, leading to the favourable condition of ‘shunt independence‘.
Coulter et al. provide a narrative technical review considering the indications, procedural aspects, morbidity and its avoidance, postoperative care and follow-up. The CP has been the target of hydrocephalus treatment for more than a century. Early eminent neurosurgeons including Dandy, Putnam and Scarff performed CPC achieving generally poor results, and so the procedure fell out of favour. In recent years, the addition of CPC to ETV was one of the reasons greater ETV success rates were observed in Africa, compared to developed nations, and its popularity worldwide has since increased. Initial results indicate that when ETV/CPC is performed successfully, shunt independence is more likely than when ETV is undertaken alone. CPC is commonly performed using a flexible endoscope via septostomy and aims to maximally cauterize the CP. Success is more likely in infants aged >1 month, those with hydrocephalus secondary to myelomeningocele and aqueductal obstruction and those with >90% cauterized CP. Failure is more likely in those with post-haemorrhagic hydrocephalus of prematurity (PHHP), particularly those <1 month of corrected age and those with prepontine scarring. High-quality evidence comparing the efficacy of ETV/CPC with shunting is emerging, with data from ongoing and future trials offering additional promise to enhance our understanding of the true utility of ETV/CPC 2).
In the quest to identify the optimal means of cerebrospinal fluid diversion free of shunt dependency, endoscopic third ventriculostomy (ETV) with choroid plexus cauterization (CPC) has been proposed as a promising procedure in select children. Supplementing traditional ETV with obliteration of the choroid plexus has been shown to decrease the likelihood of ultimate shunt dependency by roughly 20%. Originally devised to treat hydrocephalus in infants in sub-Saharan Africa, ETV/CPC has gained eager attention and cautious support in the developed world 3).
Diagnosing treatment failure is dependent on infantile hydrocephalus metrics, including head circumference, fontanel quality, and ventricle size.
Systematic review was performed using four electronic databases and bibliographies of relevant articles, with no language or date restrictions. Cohort studies of participants undergoing ETV/CPC that reported outcome were included using MOOSE guidelines. The outcome was time to repeat CSF diversion or death. Forest plots were created for pooled mean and its 95 % CI of outcome and morbidity.
Of 78 citations, 11 retrospective reviews (with 524 total participants) were eligible. Efficacy was achieved in 63 % participants at follow-up periods between 6 months and 8 years. Adverse events and mortality was reported in 3.7 and 0.4 % of participants, respectively. Publication bias was detected with respect to efficacy and morbidity of the procedure. A large discrepancy in success was identified between ETV/CPC in six studies from sub-Saharan Africa (71 %), compared to three studies from North America (49 %).
The reported success of ETV/CPC for infantile hydrocephalus is higher in sub-Saharan Africa than developed nations. Large long-term prospective multi-center observational studies addressing patient-important outcomes are required to further evaluate the efficacy and safety of this re-emerging procedure 4).
It is not clear to what degree these metrics should be expected to change after ETV/CPC. Using these clinical metrics, Dewan et al., present and analyze the decision making in cases of ETV/CPC failure.
Infantile hydrocephalus metrics, including bulging fontanel, head circumference z-score, and frontal and occipital horn ratio (FOHR), were compared between ETV/CPC failures and successes. Treatment outcome predictive values of metrics individually and in combination were calculated.
Forty-four patients (57% males, median age 1.2 months) underwent ETV/CPC for hydrocephalus; of these patients, 25 (57%) experienced failure at a median time of 51 days postoperatively. Patients experiencing failure were younger than those experiencing successful treatment (0.8 vs 3.9 months, p = 0.01). During outpatient follow-up, bulging anterior fontanel, progressive macrocephaly, and enlarging ventricles each demonstrated a positive predictive value (PPV) of no less than 71%, but a bulging anterior fontanel remained the most predictive indicator of ETV/CPC failure, with a PPV of 100%, negative predictive value of 73%, and sensitivity of 72%. The highest PPVs and specificities existed when the clinical metrics were present in combination, although sensitivities decreased expectedly. Only 48% of failures were diagnosed on the basis all 3 hydrocephalus metrics, while only 37% of successes were negative for all 3 metrics. In the remaining 57% of patients, a diagnosis of success or failure was made in the presence of discordant data.
Successful ETV/CPC for infantile hydrocephalus was evaluated in relation to fontanel status, head growth, and change in ventricular size. In most patients, a designation of failure or success was made in the setting of discordant data 5).
A study retrospectively reviewed medical records of 27 premature infants with intraventricular hemorrhage (IVH) and hydrocephalus treated with ETV and CPC from 2008 to 2011. All patients were evaluated using MRI before the procedure to verify the anatomical feasibility of ETV/CPC. Endoscopic treatment included third ventriculostomy, septostomy, and bilateral CPC. After ETV/CPC, all patients underwent follow-up for a period of 6-40 months (mean 16.2 months). The procedure was considered a failure if the patient subsequently required a shunt. The following factors were analyzed to determine a relationship to patient outcomes: gestational age at birth, corrected age and weight at surgery, timing of surgery after birth, grade of IVH, the status of the prepontine cistern and cerebral aqueduct on MRI, need for a ventricular access device prior to the endoscopic procedure, and scarring of the prepontine cistern noted at surgery.
Seventeen (63%) of 27 patients required a shunt after ETV/CPC, and 10 patients did not require further CSF diversion. Several factors studied were associated with a higher rate of ETV/CPC failure: Grade IV hemorrhage, weight 3 kg or less and age younger than 3 months at the time of surgery, need for reservoir placement, and presence of a normal cerebral aqueduct. Two factors were found to be statistically significant: the patient’s corrected gestational age of less than 0 weeks at surgery and a narrow prepontine cistern on MRI. The majority (83%) of ETV/CPC failures occurred in the first 3 months after the procedure. None of the patients had a complication directly related to the procedure.
Endoscopic third ventriculostomy/CPC is a safe initial procedure for hydrocephalus in premature infants with IVH and hydrocephalus, obviating the need for a shunt in selected patients. Even though the success rate is low (37%), the lower rate of complications in comparison with shunt treatment may justify this procedure in the initial management of hydrocephalus. As several of the studied factors have shown influence on the outcome, patient selection based on these observations might increase the success rate 6).
A total of 710 children underwent ventriculoscopy as candidates for ETV as the primary treatment for hydrocephalus. The ETV was accomplished in 550 children: 266 underwent a combined ETV-CPC procedure and 284 underwent ETV alone. The mean and median ages were 14 and 5 months, respectively, and 443 patients (81%) were younger than 1 year of age. The hydrocephalus was postinfectious (PIH) in 320 patients (58%), nonpostinfectious (NPIH) in 152 (28%), posthemorrhagic in five (1%), and associated with myelomeningocele in 73 (13%). The mean follow up was 19 months for ETV and 9.2 months for ETV-CPC. Overall, the success rate of ETV-CPC (66%) was superior to that of ETV alone (47%) among infants younger than 1 year of age (p < 0.0001). The ETV-CPC combined procedure was superior in patients with a myelomeningocele (76% compared with 35% success, p = 0.0045) and those with NPIH (70% compared with 38% success, p = 0.0025). Although the difference was not significant for PIH (62% compared with 52% success, p = 0.1607), a benefit was not ruled out (power = 0.3). For patients at least 1 year of age, there was no difference between the two procedures (80% success for each, p = 1.0000). The overall surgical mortality rate was 1.3%, and the infection rate was less than 1%.
The ETV-CPC was more successful than ETV alone in infants younger than 1 year of age. In developing countries in which a dependence on shunts is dangerous, ETV-CPC may be the best option for treating hydrocephalus in infants, particularly for those with NPIH and myelomeningocele 7).