Endoscopic third ventriculostomy: can we predict success during surgery?

Endoscopic Endonasal Transsphenoidal Approach for Third Ventriculostomy in the Management of Obstructive Hydrocephalus

ABSTRACT

Endoscopic third ventriculostomy (ETV) is a safe and effective method for the management of obstructive hydrocephalus. Traditional approach is a transfrontal trajectory through the foramen of Monro to access and open the third ventricle floor. Though endoscopic endonasal transsphenoidal approach (EETA) for pituitary and skull base tumors has become increasingly popular, no published literature has explored its utility in performing an ETV. Here, the authors reported a successful ETV for obstructive hydrocephalus through the EETA. A 57-year-old male presenting with progressive headache and gait disturbance for 3 months was diagnosed with obstructive hydrocephalus. Brain MRI revealed an obstruction of cerebrospinal fluid (CSF) flow at the cerebral aqueduct and supratentorial hydrocephalus, accompanied with dilatation and downward herniation of the third ventricle floor. Considering the displacement of the third ventricle floor and the indication for surgery, an ETV was successfully performed through the EETA. No postoperative complication was observed. Both radiological and clinical evaluation postoperatively confirmed ETV success with decreased ventricular size, increased CSF flow across the floor of the third ventricle, and improved clinical signs. EETA is a feasible approach for ETV in selected cases of obstructive hydrocephalus. This approach provides a short trajectory to directly visualize and open the Liliequist's membrane and the displaced floor of the third ventricle, while minimizes damage to normal brain tissue. Skull base repair with nasoseptal flap ensures the success rate by preventing postoperative CSF leak and infection.

The role of the Liliequist membrane in the third ventriculostomy

Endoscopic third ventriculostomy (ETV) is a hydrocephalus treatment procedure that involves opening the Liliequist membrane (LM). However, LM anatomy has not been well-studied neuroendoscopically, because approach angles differ between descriptive and microsurgical anatomical explorations. Discrepancies in ETV efficacy, especially among children age 2 and younger, may be due to incomplete LM opening. The objective of this study was to characterize the LM anatomically from a neuroendoscopic perspective to better understand the impact of anatomical features during LM ostomy and the ETV success rate. Additionally, the ETV success score was tested to predict patient outcome after the intraoperatively difficult opening of LM. Fifty-four patients who underwent ETV were prospectively analyzed with a mean follow-up of 53.1 months (1-90 months). The ETV technical parameters of difficulty were validated by seven expert neurosurgeons. The pediatric population (44) of this study represents the majority of patients (81.4%). The overall ETV success rate was 68.5%. Anomalies on the IIIVT floor resulted in an increased rate of ETV failure. The IIIVT was anomalous, and LM was thick in 33.3% of cases. Fenestration of LM was difficult in 39% of cases, and the LM and TC were opened separately in 55.6% of cases. The endoscopic third ventriculostomy success score (ETVSS) accurately predicted the level of difficulty opening the LM (p = 0.012), and the group with easy opening presented greater durability in ETV success. Neurosurgeons should be aware of the difficulty level of the overture of LM during ETV and its impact on long-term ETV effectiveness.

Endoscopic management of an intrasellar arachnoid cyst through the tuber cinereum in an adult: a case report

The transventricular endoscopic approach is an effective less invasive method for the management of symptomatic intrasellar arachnoid cysts in adults. The open area of the brain tissue defect in the infundibular recess caused by the upward compression of the cyst is a common target site for fenestration from the third ventricle. This report highlighted an alternative approach through the tuber cinereum (denoted as "trans-tuberal"), which enabled the treatment of symptomatic cases with a small opening for cyst fenestration in the infundibular recess.

Does pre-resection endoscopic third ventriculostomy prevent the need for post-resection CSF diversion after pediatric posterior fossa tumor excision? A historical cohort study and review of the literature

OBJECTIVE

Children with posterior fossa tumors (PFTs) may present with hydrocephalus. Persistent (or new) hydrocephalus is common after PFT resection. Endoscopic third ventriculostomy (ETV) is sometimes performed prior to resection to 1) temporize hydrocephalus prior to resection and 2) prophylactically treat post-resection hydrocephalus. The objective of this study was to establish, in a historical cohort study of pediatric patients who underwent primary craniotomy for PFT resection, whether or not pre-resection ETV prevents the need for post-resection CSF diversion to manage hydrocephalus.

METHODS

The authors interrogated their prospectively maintained surgical neuro-oncology database to find all primary PFT resections from a single tertiary pediatric neurosurgery unit. These data were reviewed and supplemented with data from case notes and radiological review. The modified Canadian Preoperative Prediction Rule for Hydrocephalus (mCPPRH) score was retrospectively calculated for all patients. The primary outcome was the need for any form of postoperative CSF diversion within 6 months of PFT resection (including ventriculoperitoneal shunting, ETV, external ventricular drainage [EVD], and lumbar drainage [LD]). This was considered an ETV failure in the ETV group. The secondary outcomes were time to CSF diversion, shunt dependence at 6 months, and complications of ETV. Statistical analysis was done in RStudio, with significance defined as p < 0.05.

RESULTS

A total of 95 patients were included in the study. There were 28 patients in the ETV group and 67 in the non-ETV group. Patients in the ETV group were younger (median age 5 vs 7 years, p = 0.04) and had more severe preoperative hydrocephalus (mean frontal-occipital horn ratio 0.45 vs 0.41 in the non-ETV group, p = 0.003) and higher mCPPRH scores (mean 4.42 vs 2.66, p < 0.001). The groups were similar in terms of sex and tumor histology. The overall rate of post-resection CSF diversion of any kind (shunt, repeat ETV, LD, or EVD) in the entire cohort was 25.26%. Post-resection CSF diversion was needed in 32% of patients in the ETV group and in 22% of the patients in the non-ETV group (p > 0.05). Shunt dependence at 6 months was seen in 21% of the ETV group and 16% of the non-ETV group (p > 0.05). The median time to ETV failure was 9 days. ETV failure correlated with patients with ependymoma (p = 0.02). Children who had ETV failure had higher mCPPRH scores than the ETV success group (5.67 vs 3.84, p = 0.04).

CONCLUSIONS

Pre-resection ETV did not reliably prevent the need for post-resection CSF diversion. ETV was more likely to fail in children with ependymoma and those with higher mCPPRH scores. Based on the findings of this study, the authors will change the practice at their institution; pre-resection ETV will now be performed based on a newly defined protocol.

Predicting endoscopic third ventriculostomy success in adult hydrocephalus: preliminary assessment of a modified ETV success score for adults (ETVSS-A) in a series of 47 patients

BACKGROUND

Endoscopic third ventriculostomy is an established treatment for noncommunicating hydrocephalus. In carefully selected patients, it can be adopted for the management of communicating variant; however controversy exists in regards to the definition of the appropriate candidates. Predictive score of Endoscopic Third Ventriculostomy Success (ETVSS) has been reported for pediatric and mixed populations only. Our purpose was to define a ETV success score for adult population (ETVSS-A), measuring the strength of correlation between preoperative score retrospectively evaluated and the success rates achieved in a class of adult patients.

METHODS

A retrospective analysis of 47 cases which received ETV procedure at our Institution between 2015 and 2018 was run. Demographic data,clinical history,preoperative and postoperative signs were reviewed and ETVSS-A was calculated. Thereafter ETVSS-A results were compared with the actual success rates.

RESULTS

29 patients(61,7%) presented unchanged or improvedclinical status with a mean ETVSS-A of 54.5%;18 patients(38,3%) worsened with mean ETVSS-A of 37,7%. We found that age,type of hydrocephalus and symptoms of admission are each apart important factors in predicting ETV success:older patients and those with non-obstructive hydrocephalus had the lowest predicted ETV success. In patients in whom ETV was actually successful, the pre-operative ETVSS-A was significantly higher as compared to those patients in whom we observed a poor surgical outcome.

CONCLUSIONS

From the results of this series, though small and retrospectively analyzed, it seems that ETVSS-A can be considered as a useful instrument to help neurosurgeon in predicting the ETV success and though define a more accurate surgical strategy in cases of hydrocephalus. Wider series and prospective studies are attended to validate these preliminary results.

A New Optimal Marker to Evaluate the Effectiveness of Endoscopic Third Ventriculostomy During Operation: "Folding Sign"

OBJECTIVE

Endoscopic third ventriculostomy (ETV) remains the mainstay of treatment for noncommunicating hydrocephalus these days. However, there has been no adequate clue for the intraoperative assessment of ETV efficacy until now. This time, we propose a newly defined finding, "folding sign," which is visible and enables us to confirm penetration of both the third ventricle floor and the Liliequist membrane (LM) during operation. In this report, we describe consecutive ETV cases and discuss the mechanism of folding sign and its clinical meanings.

METHODS

A folding sign is a formation of a sequence of folds at the tectal region, which is easily detectable. A total of 30 patients with newly diagnosed hydrocephalus between October 2014 and February 2018 at Tokyo Women's Medical University were enrolled in our case series (age range, 3 months to 74 years). The difference between proportions was analyzed by the χ² method.

RESULTS

In all, 12 patients (40%) showed a folding sign: congenital hydrocephalus including aqueductal stenosis (AS) and isolated fourth ventricle in 4 patients, and brain tumor-associated noncommunicating hydrocephalus in 8 patients. Statistical analysis showed that the emergence of a folding sign was related to successful ETV, indicating it as an optimal intraoperative sign to assess the effectiveness of this procedure (P = 0.0298).

CONCLUSION

The folding sign is a newly defined sign to predict the success of ETV during operation. This optimal finding appears only when the LM is sufficiently opened; therefore, it could be a good candidate for an intraoperative assessment tool.

Endoscopic third ventriculostomy in children with a fiber optic neuroendoscopy

OBJECTIVE

Endoscopic third ventriculostomy (ETV) provides a shunt-free treatment for obstructive hydrocephalus children. With rapidly evolving technology, the semi-rigid fiber optic neuroendoscopy shows a potential application in ETV by blunt fenestration. A retrospective analysis of our experience is reviewed.

METHODS

The authors review infants and children who underwent ETV using this technique from June 2004 to June 2016 with radiological and clinical follow-up done by a single surgeon. Patients who underwent ETV with channel scope were excluded. Demographic variables and operative reports were collected. Improvement of preoperative symptoms and avoidance of additional cerebrospinal fluid (CSF) diversion procedures were considered a success. The ETV success score (ETVSS) was used to correlate with clinical outcomes.

RESULTS

A total of 79 patients were included with a mean age of 8.3 ± 5.5 years, and 40.5% were female. The mean clinical and radiographic follow-up was 38.6 ± 40.9 months. The overall complication rate was 6.3%, while 73.4% were considered successful. The ETV failure cases received conversion to ventriculoperitoneal shunt or redo of ETV with a median time of 2 months. The mean ETV success score was 74.3 ± 11.8 with positive correlation between success rate (P < 0.05). Kaplan-Meier failure-free survival rates of 30-day, 90-day, 6-month, 1-year, and 2-year were 89.9, 83.5, 78.5, 75.9, and 74.6%. Eight patients required redo ETV, and five of these patients required eventual shunt placements. Approximately 61.9% of failure occurred within 3 months. Patients with post-intraventricular hemorrhage (IVH) /infection, and age younger than 12 months had the poorest outcome (P < 0.05).

CONCLUSIONS

Blunt dissection of the third ventricle floor under endoscopic vision with the stylet tip of a fiber optic neuroendoscopy is safe and requires less equipment in the pediatric population. This technique is successful with an optimistic long-term outcome except for infants and the post-IVH and infectious subgroups.

Update on Endoscopic Third Ventriculostomy in Children

Endoscopic third ventriculostomy (ETV) provides a physiological restoration of cerebrospinal fluid and a shunt-free option for hydrocephalus children. Continuous developments in techniques and instruments have improved ETV as the first-line treatment. This paper focuses on the recent advances in surgical techniques, instruments, predictive models, imaging tools, and new cohort studies. The efficacy, safety, indications, and remaining challenges of ETV are discussed. 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.

Endoscopic third ventriculostomy and repeat endoscopic third ventriculostomy in pediatric patients: the Dutch experience

OBJECTIVE After endoscopic third ventriculostomy (ETV), some patients develop recurrent symptoms of hydrocephalus. The optimal treatment for these patients is not clear: repeat ETV (re-ETV) or CSF shunting. The goals of the study were to assess the effectiveness of re-ETV relative to initial ETV in pediatric patients and validate the ETV success score (ETVSS) for re-ETV. METHODS Retrospective data of 624 ETV and 93 re-ETV procedures were collected from 6 neurosurgical centers in the Netherlands (1998-2015). Multivariable Cox proportional hazards modeling was used to provide an adjusted estimate of the hazard ratio for re-ETV failure relative to ETV failure. The correlation coefficient between ETVSS and the chance of re-ETV success was calculated using Kendall's tau coefficient. Model discrimination was quantified using the c-statistic. The effects of intraoperative findings and management on re-ETV success were also analyzed. RESULTS The hazard ratio for re-ETV failure relative to ETV failure was 1.23 (95% CI 0.90-1.69; p = 0.20). At 6 months, the success rates for both ETV and re-ETV were 68%. ETVSS was significantly related to the chances of re-ETV success (τ = 0.37; 95% bias corrected and accelerated CI 0.21-0.52; p < 0.001). The c-statistic was 0.74 (95% CI 0.64-0.85). The presence of prepontine arachnoid membranes and use of an external ventricular drain (EVD) were negatively associated with treatment success, with ORs of 4.0 (95% CI 1.5-10.5) and 9.7 (95% CI 3.4-27.8), respectively. CONCLUSIONS Re-ETV seems to be as safe and effective as initial ETV. ETVSS adequately predicts the chance of successful re-ETV. The presence of prepontine arachnoid membranes and the use of EVD negatively influence the chance of success.

Endoscopic Third Ventriculostomy: Outcome Analysis of an Anterior Entry Point

BACKGROUND

Endoscopic third ventriculostomy (ETV) is a safe and effective treatment for hydrocephalus. An entry point located 4 cm anterior to the coronal suture, 3 cm anterior to Kocher point, and approximately 9 cm from the pupil at the midpupillary line has been used successfully for the last 20 years in our center. We aimed to evaluate this alternative anterior entry point routinely used for ETV, with or without concurrent endoscopic biopsy.

METHODS

Patients undergoing this proposed entry point were examined to evaluate its safety and efficacy. Factors such as patients' age, sex, hydrocephalus etiology, tumor location and pathology, and complication rate were examined through regression analyses to evaluate their impact on tumor biopsy and ETV success rates, and the need for subsequent ventricular shunting.

RESULTS

A total of 131 patients were included in the study. ETV was successful in 125 (95.4%) patients. Of these, 26 (19.8%) patients required a biopsy, which was successful in 21 (80.8%) cases. A complication was observed in 10 (7.6%) patients, with a trend toward complications occurring after ETV failure. There was no association between ETV success rate and patients' age (P = 0.5) or sex (P = 0.99).

CONCLUSIONS

The anterior entry point is a safe and effective method for ETV, especially when considering concurrent ventricular tumor biopsy. This entry point may be considered as a more minimally invasive procedure when using rigid endoscopy and may also eliminate the need for a flexible scope.

Stented endoscopic third ventriculostomy—indications and results

OBJECTIVE

In patients with risk of reclosure of a performed opening in the floor of the third ventricle, a stented endoscopic third ventriculostomy (sETV) was performed to maintain continuous cerebrospinal fluid (CSF) diversion in patients with occlusive hydrocephalus. A retrospective analysis of a patient series is presented.

METHODS

A cohort of nine patients (median age 12 years and 9 months; range 1 month to 25 years and 9 months) was studied retrospectively. Etiology of hydrocephalus was aqueduct stenosis due to tumorous occlusion and tumorous infiltration of the third ventricular floor in seven of nine patients. For two patients with simple aqueductal stenosis, a sETV was performed because of young age of 1 month in one and because of previous ETV failure in the other.

RESULTS

Correct placement of the implanted stent was demonstrated in all treated patients. There was no operative morbidity after the performed sETV. Resolution or improvement of symptoms was achieved in eight of nine patients (88.9%), and failure to control clinical symptoms was observed in one patient (11.1%), who needed subsequent shunt insertion. Decreased ventricular dimensions were seen after the sETV procedure. The median fronto-occipital horn ratio (FOHR) decreased from 0.46 (range 0.43-0.58) to 0.45 (range 0.37 to 0.59) after a median of 3 months and to a median of 0.40 (range 0.30 to 0.50) after 17 months. The median fronto-occipital horn width ratio FOHWR decreased from 0.31 (range 0.22 to 0.52) to 0.28 (range 0.14 to 0.52, p = 0.06) after a median of 3 months and to a median of 0.21 (range 0.09 to 0.36, p < 0.05).

CONCLUSION

sETV is a feasible and safe alternative procedure which when performed with an appropriate trajectory allows treatment of occlusive hydrocephalus with altered anatomy of the third ventricular floor. sETV has been demonstrated to resolve or improve clinical and radiological signs of disturbed CSF circulation.

Predicting success of endoscopic third ventriculostomy: validation of the ETV Success Score in a mixed population of adult and pediatric patients

OBJECT

Endoscopic third ventriculostomy (ETV) has become the first line of treatment in obstructive hydrocephalus. The Toronto group (Kulkarni et al.) developed the ETV Success Score (ETVSS) to predict the clinical response following ETV based on age, previous shunt, and cause of hydrocephalus in a pediatric population. However, the use of the ETVSS has not been validated for a population comprising adults. The objective of this study was to validate the ETVSS in a "closed-skull" population, including patients 2 years of age and older.

METHODS

In this retrospective observational study, medical charts of all consecutive cases of ETV performed in two university hospitals were reviewed. The primary outcome, the success of ETV, was defined as the absence of reoperation or death attributable to hydrocephalus at 6 months. The ETVSS was calculated for all patients. Discriminative properties along with calibration of the ETVSS were established for the study population. The secondary outcome is the reoperation-free survival.

RESULTS

This study included 168 primary ETVs. The mean age was 40 years (range 3-85 years). ETV was successful at 6 months in 126 patients (75%) compared with a mean ETVSS of 82.4%. The area under the receiver operating characteristic curve was 0.61, revealing insufficient discrimination from the ETVSS in this population. In contrast, calibration of the ETVSS was excellent (calibration slope = 1.01), although the expected low numbers were obtained for scores < 70. Decision curve analyses demonstrate that ETVSS is marginally beneficial in clinical decision-making, a reduction of 4 and 2 avoidable ETVs per 100 cases if the threshold used on the ETVSS is set at 70 and 60, respectively. However, the use of the ETVSS showed inferior net benefit when compared with the strategy of not recommending ETV at all as a surgical option for thresholds set at 80 and 90. In this cohort, neither age nor previous shunt were significantly associated with unsuccessful ETV. However, better outcomes were achieved in patients with aqueductal stenosis, tectal compressions, and other tumor-associated hydrocephalus than in cases secondary to myelomeningocele, infection, or hemorrhage (p = 0.03).

CONCLUSIONS

The ETVSS did not show adequate discrimination but demonstrated excellent calibration in this population of patients 2 years and older. According to decision-curve analyses, the ETVSS is marginally useful in clinical scenarios in which 60% or 70% success rates are the thresholds for preferring ETV to CSF shunt. Previous history of CSF shunt and age were not associated with worse outcomes, whereas posthemorrhagic and postinfectious causes of the hydrocephalus were significantly associated with reduced success rates following ETV.

Development and preliminary assessment of a robotic platform for neuroendoscopy based on a lightweight robot

BACKGROUND

Ventriculostomy is a widely performed neurosurgical procedure; some risk factors can be mitigated by computer/robot-assisted approaches. Platforms fostering synergistic robot-surgeon integration are pursued, for which lightweight robots with compliant controlled joints must be assessed (because compliance hampers accuracy).

METHODS

We developed a platform encompassing, in particular, a lightweight robot and an optical tracker also used to enhance robot accuracy. Based on specifications by neurosurgeons, we designed a neuroendoscope-handling interface and assessed targeting accuracy in a model ventriculostomy where the robot was operated both autonomously and in hands-on (i.e. co-operative) mode.

RESULTS

Targeting errors were systematically below the procedure accuracy threshold (1 mm); the rms targeting errors were 0.51 and 0.54 mm for autonomous and hands-on control, respectively. No significant difference was observed between the considered control modes. Very positive feedback was gathered from neurosurgeons.

CONCLUSIONS

Accurate tool targeting under both autonomous and hands-on control was achieved.