Endoscopic third ventriculostomy (ETV) provides a physiological restoration of cerebrospinal fluid and a shunt-free option for pediatric hydrocephalus. Continuous developments in techniques and instruments have improved ETV as the first-line treatment.
More patients undergo ETV with a better outcome, identifying a new era of hydrocephalus treatment. Deeper understanding of ETV will improve a better shunt-free survival for pediatric hydrocephalus patients 1).
Also in elderly, ETV is a safe and efficient procedure, with success rates similar to the younger population. Further research is required to set up a prognostic scoring system for this age group 2).
see Endoscopic third ventriculostomy success score (ETVSS)
A role for endoscopic third ventriculostomy (ETV) in myelomeningocele (MM) has provoked much debate, principally due to anatomical variants described, which may complicate the procedure.
Perez da Rosa et al. present 7 cases of children with MM and hydrocephalus undergoing a total of 10 ETV procedures. All patients demonstrated clinical improvement (in acute/subacute cases) or stabilization (in chronic cases). Three patients requiring a second ETV have shown clinical stability and renewed radiological evidence of functioning ventriculostomies in follow-up since reintervention. ETV can be used, albeit cautiously, in selected cases of hydrocephalus associated with MM. However, the frequency with which anatomical variation is encountered and the difficulty of the assessment of success make the procedure more challenging than usual 3).
The only randomized trial of endoscopic third ventriculostomy (ETV) for idiopathic normal pressure hydrocephalus (iNPH) compares it to an intervention which is not a standard practice (VP shunting using a non-programmable valve). The evidence from this study is inconclusive and of very low quality. Clinicians should be aware of the limitations of the evidence. There is a need for more robust research on this topic to be able to determine the effectiveness of ETV in patients with iNPH 4).
ETV success or failure may be influenced by numerous factors.
An absence or weakness of pulsation of the third ventricle floor at etV completion was significantly related to etV failure (p < 0.0001). The presence of thickened or scarred membranes in the subarachnoid space was significantly related to etV failure (p < 0.04) as well as the Liliequist membrane opening in a second endoscopic maneuver (p < 0.008) 5).
In infants with hydrocephalus, a greater 1-year CSF diversion failure rate may occur after ETV compared with shunt placement. This risk is most significant for procedures performed within the first 90 days of life. Further investigation of the need for multiple reoperations, cost, and impact of surgeon and hospital experience is necessary to distinguish which treatment is more effective in the long term 6).
Closure of the stoma can be associated with symptom recurrence and need for further surgical intervention.
Adult patients with obstructive hydrocephalus secondary to aqueductal stenosis exhibited a low rate of stoma closure with the use of a side-cutting aspiration device, and a rate of complications comparable to the known literature. Likewise, patients treated with a side-cutting aspirator may have lower symptom recurrence post-ETV and require fewer revisions in comparison with the known literature. As such, a side-cutting aspirator may be considered as a useful adjunct to traditional ETV for the treatment of obstructive hydrocephalus secondary to aqueductal stenosis 7).
Adult patients with obstructive hydrocephalus secondary to aqueductal stenosis exhibited a low rate of stoma closure with the use of a side-cutting aspiration device, and a rate of complications comparable to the known literature. Likewise, patients treated with a side-cutting aspirator may have lower symptom recurrence post-ETV and require fewer revisions in comparison with the known literature. As such, a side-cutting aspirator may be considered as a useful adjunct to traditional ETV for the treatment of obstructive hydrocephalus secondary to aqueductal stenosis 8)
A study aims to develop and establish the content validity of multiple expert rating instruments to assess performance in endoscopic third ventriculostomy (ETV), collectively called the Neuro-Endoscopic Ventriculostomy Assessment Tool (NEVAT).
The important aspects of ETV were identified through a review of current literature, ETV videos, and discussion with neurosurgeons, fellows, and residents. Three assessment measures were subsequently developed: a procedure-specific checklist (CL), a CL of surgical errors, and a global rating scale (GRS). Neurosurgeons from various countries, all identified as experts in ETV, were then invited to participate in a modified Delphi survey to establish the content validity of these instruments. In each Delphi round, experts rated their agreement including each procedural step, error, and GRS item in the respective instruments on a 5-point Likert scale.
Seventeen experts agreed to participate in the study and completed all Delphi rounds. After item generation, a total of 27 procedural CL items, 26 error CL items, and 9 GRS items were posed to Delphi panelists for rating. An additional 17 procedural CL items, 12 error CL items, and 1 GRS item were added by panelists. After three rounds, strong consensus (>80% agreement) was achieved on 35 procedural CL items, 29 error CL items, and 10 GRS items. Moderate consensus (50-80% agreement) was achieved on an additional 7 procedural CL items and 1 error CL item. The final procedural and error checklist contained 42 and 30 items, respectively (divided into setup, exposure, navigation, ventriculostomy, and closure). The final GRS contained 10 items.
We have established the content validity of three ETV assessment measures by iterative consensus of an international expert panel. Each measure provides unique assessment information and thus can be used individually or in combination, depending on the characteristics of the learner and the purpose of the assessment. These instruments must now be evaluated in both the simulated and operative settings, to determine their construct validity and reliability. Ultimately, the measures contained in the NEVAT may prove suitable for formative assessment during ETV training and potentially as summative assessment measures during certification 9).
Sanchez Rodriguez et al., conducted a retrospective cohort study of the videos and records of 150 hydrocephalic patients chosen randomly who underwent ETV (and other endoscopic procedures) with a flexible endoscope. The patients were classified into two groups based on the neuroendoscopic findings. The first group included patients with a permeable subarachnoid space (SAS), and the second group included patients with a nonpermeable SAS. A normal SAS or one with slight arachnoiditis was considered permeable. Adhesive arachnoiditis and immature or mechanically obliterated SASs were considered nonpermeable.
They found a success rate of 70% in patients with a permeable SAS versus 33% in patients with a nonpermeable SAS. The baseline characteristics of both groups were homogeneous. They obtained a statistically significant difference (p < 0.0001) with hazard ratio (HR) 3.42 (95% confidence interval [CI], 1.88-6.22). Another important factor involved was age that showed a statistically significant difference (p < 0.0018) with HR 3.28 (95% CI, 1.55-6.93).
The permeability of the SAS is an important prognostic factor in the resolution rate of hydrocephalus after ETV (and other endoscopic procedures) using flexible neuroendoscopes. Therefore they recommend that the characteristics of the SAS be examined following every endoscopic procedure for hydrocephalus to identify patients at risk of recurrence 10).
Grand et al., conducted a retrospective review of adult ETV procedures performed at a center between 2000 and 2014.
The overall rate of success (no further cerebrospinal fluid diversion procedure performed plus clinical improvement) of 243 completed ETVs was 72.8%. Following is the number of procedures with the success rate in parentheses: aqueduct stenosis, 56 (91%); communicating hydrocephalus including normal pressure hydrocephalus, nonnormal pressure hydrocephalus, and remote head trauma, 57 (43.8%); communicating hydrocephalus in postoperative posterior fossa tumor without residual tumor, 14 (85.7%); communicating hydrocephalus in subarachnoid hemorrhage without intraventricular hemorrhage, 23 (69.6%); obstruction from tumor/cyst, 42 (85.7%); VPS obstruction (diagnosis unknown), 23 (65.2%); intraventricular hemorrhage, 20 (90%); and miscellaneous (obstructive), 8 (50%). There were 9 complications in 250 intended procedures (3.6%); 5 (2%) were serious.
Use of ETV in adult hydrocephalus has broad application with a low complication rate and reasonably good efficacy in selected patients 11).
Kulkarni et al., report prospective, multicenter results from the Hydrocephalus Clinical Research Network (HCRN) to provide the most accurate determination of morbidity, complication incidence, and efficacy of ETV in children and to determine if intraoperative predictors of ETV success add substantially to preoperative predictors.
All children undergoing a first ETV (without choroid plexus cauterization) at 1 of 7 HCRN centers up to June 2013 were included in the study and followed up for a minimum of 18 months. Data, including detailed intraoperative data, were prospectively collected as part of the HCRN's Core Data Project and included details of patient characteristics, ETV failure (need for repeat hydrocephalus surgery), and, in a subset of patients, postoperative complications up to the time of discharge.
Three hundred thirty-six eligible children underwent initial ETV, 18.8% of whom had undergone shunt placement prior to the ETV. The median age at ETV was 6.9 years (IQR 1.7-12.6), with 15.2% of the study cohort younger than 12 months of age. The most common etiologies were aqueductal stenosis (24.8%) and midbrain or tectal lesions (21.2%). Visible forniceal injury (16.6%) was more common than previously reported, whereas severe bleeding (1.8%), thalamic contusion (1.8%), venous injury (1.5%), hypothalamic contusion (1.5%), and major arterial injury (0.3%) were rare. The most common postoperative complications were CSF leak (4.4%), hyponatremia (3.9%), and pseudomeningocele (3.9%). New neurological deficit occurred in 1.5% cases, with 0.5% being permanent. One hundred forty-one patients had documented failure of their ETV requiring repeat hydrocephalus surgery during follow-up, 117 of them during the first 6 months postprocedure. Kaplan-Meier rates of 30-day, 90-day, 6-month, 1-year, and 2-year failure-free survival were 73.7%, 66.7%, 64.8%, 61.7%, and 57.8%, respectively. According to multivariate modeling, the preoperative ETV Success Score (ETVSS) was associated with ETV success (p < 0.001), as was the intraoperative ability to visualize a “naked” basilar artery (p = 0.023).
The authors' documented experience represents the most detailed account of ETV results in North America and provides the most accurate picture to date of ETV success and complications, based on contemporaneously collected prospective data. Serious complications with ETV are low. In addition to the ETVSS, visualization of a naked basilar artery is predictive of ETV success 12)
Isaacs et al., performed a retrospective chart review of all adult patients (age ≥ 18 years) with symptomatic hydrocephalus treated with ETV in Calgary, Canada, over a span of 20 years (1994-2014). Patients were dichotomized into a primary or secondary ETV cohort based on whether ETV was the initial treatment modality for the hydrocephalus or if other CSF diversion procedures had been previously attempted respectively. Primary outcomes were subjective patient-reported clinical improvement within 12 weeks of surgery and the need for any CSF diversion procedures after the initial ETV during the span of the study. Categorical and actuarial data analysis was done to compare the outcomes of the primary versus secondary ETV cohorts.
A total of 163 adult patients with symptomatic hydrocephalus treated with ETV were identified and followed over an average of 98.6 months (range 0.1-230.4 months). All patients presented with signs of intracranial hypertension or other neurological symptoms. The primary ETV group consisted of 112 patients, and the secondary ETV consisted of 51 patients who presented with failed ventriculoperitoneal (VP) shunts. After the initial ETV procedure, clinical improvement was reported more frequently by patients in the primary cohort (87%) relative to those in the secondary ETV cohort (65%, p = 0.001). Additionally, patients in the primary ETV group required fewer reoperations (p < 0.001), with cumulative ETV survival time favoring this primary ETV cohort over the course of the follow-up period (p < 0.001). Fifteen patients required repeat ETV, with all but one experiencing successful relief of symptoms. Patients in the secondary ETV cohort also had a higher incidence of complications, with one occurring in 8 patients (16%) compared with 2 in the primary ETV group (2%; p = 0.010), although most complications were minor.
ETV is an effective long-term treatment for selected adult patients with hydrocephalus. The overall ETV success rate when it was the primary treatment modality for adult hydrocephalus was approximately 87%, and 99% of patients experience symptomatic improvement after 2 ETVs. Patients in whom VP shunt surgery fails prior to an ETV have a 22% relative risk of ETV failure and an almost eightfold complication rate, although mostly minor, when compared with patients who undergo a primary ETV. Most ETV failures occur within the first 7 months of surgery in patients treated with primary ETV, but the time to failure is more prolonged in patients who present with failed previous shunts 13).
Eighty-five patients (45 boys) with a mean age of 4.3 months (range 1 day to 20 months) underwent endoscopic third ventriculostomy (ETV) with choroid plexus cauterization (CPC). Etiology included intraventricular hemorrhage of prematurity in 44 patients (51.7%), myelomeningocele (MMC) in 7 (8.2%), congenital aqueductal stenosis in 12 (14.1%), congenital communicating hydrocephalus in 6 (7.1%), Dandy-Walker complex in 6 (7.1%), postinfectious hydrocephalus in 5 (5.8%), and other cause in 5 (5.8%). Six procedure-related complications occurred in 5 (5.8%) patients, including 2 hygromas, 1 CSF leak, and 3 infections. There were 3 mortalities in this cohort. ETV/CPC was successful in 42.1%, 37.7%, and 36.8% of patients at 6, 12, and 24 months follow-up, respectively. The median (95% CI) time to ETV/CPC failure was 4.0 months (0.9-7.1 months). In univariate analyses, both the ETVSS (hazard ratio [HR] 1.03; 95% CI 1.01-1.05; p = 0.004) and CCHU ETVSS (HR 1.48; 95% CI 1.04-2.09; p = .028) were predictive of outcome following ETV/CPC. In multivariate analysis, the presence of prepontine scarring was associated with ETV/CPC failure (HR 0.34; 95% CI 0.19-0.63; p < 0.001). Other variables, such as radiological criteria (prepontine interval, prepontine space, aqueductal stenosis, Third Ventricular Morphology Index) and intraoperative findings (ventriculostomy pulsations, extent of CPC), did not predict outcome. CONCLUSIONS ETV/CPC is a feasible alternative to ETV and ventriculoperitoneal shunt in infants with hydrocephalus. Both the ETVSS and CCHU ETVSS predicted success following ETV/CPC in this single-center North American cohort of patients 14).
412 patients from July 2006 to October 2012 at Dhaka Medical College Hospital (a government hospital) and other private hospitals in Dhaka, Bangladesh. The authors attempted some previously undescribed simple maneuvers that may help to overcome the difficulties of managing complications.
The complication rate was determined by recording intraoperative changes in pulse and blood pressure, bleeding episodes, serum electrolyte abnormalities, CSF leakage, and neurological deterioration in the immediate postoperative period.
Intraoperative complications included hemodynamic alterations in the form of tachycardia, bradycardia, and hypertension. Bleeding was categorized as major in 2 cases and minor in 68 cases. Delayed recovery from anesthesia occurred in 14 cases, CSF leakage from the wound in 11 cases, and electrolyte imbalance in 5 cases. Postoperatively, 2 patients suffered convulsions and 1 had evidence of third cranial nerve injury. Three patients died as a result of complications.
Complications during endoscopy can lead to serious consequences that may sometimes be very difficult to manage. The authors have identified and managed a large number of complications in this series, although the rate of complications is consistent with that in other reported series. These complications should be kept in mind perioperatively by both surgeons and anesthesiologists, as prompt detection and action can help minimize the risks associated with neuroendoscopic procedures 15).