Predictors of shunt responsiveness and outcomes in idiopathic normal pressure hydrocephalus: a retrospective cohort study

Acta Neurochirurgica (2026) 168:80

This retrospective cohort study from Tel-Aviv Medical Center evaluates predictors of clinical improvement after shunt placement in patients with idiopathic normal pressure hydrocephalus (iNPH) assessed between 2020–2022. The authors analyze clinical presentation, standardized gait testing, MRI features (including DESH), CSF biomarkers (notably total tau and protein), and PET findings to determine associations with lumbar puncture (LP) responsiveness and one-year post-shunt outcomes.

Key findings show 37% LP responsiveness among 167 patients, 38 underwent shunting, and 55% of shunted patients had favorable one‑year outcomes. Lower CSF total tau and presence of a DESH imaging pattern correlated with LP response and improved one‑year outcomes, while greater immediate post‑LP gait improvement predicted sustained benefit; vascular comorbidities and standard MRI metrics were less predictive.

Objective Identify clinical, imaging, and CSF biomarkers linked to favorable outcomes after shunt placement in suspected idiopathic normal pressure hydrocephalus (iNPH).

Cohort & pathway 183 patients were evaluated (2020–2022); 167 underwent high-volume lumbar puncture (≥30 mL removed); LP responders were referred for shunting and followed for 1 year.

LP responsiveness rate 62/167 (37%) improved after CSF drainage and were referred for shunt surgery; 38/62 (61%) ultimately underwent shunt placement.

Clinical pattern Gait disturbance was the most common presenting symptom (68%) and was more frequent in LP responders, while cognitive symptoms were more common among non-responders (29.5% vs 10%).

CSF biomarkers (LP response) LP responders had lower CSF total tau (t-tau) and protein than non-responders.

Imaging marker (LP response) The DESH pattern was more common in LP responders (73% vs 46%).

Shunt outcomes (1 year) 21/38 (55%) shunted patients had a favorable outcome at one year; favorable outcome was associated with more frequent DESH and lower t-tau (trend).

Overall takeaway Combining post-LP clinical response with DESH imaging and CSF t-tau may help refine selection for shunting and predict better outcomes.

Revision and complication rates in adult shunt surgery

Acta Neurochirurgica (2021) 163:447–454

CSF diversion with shunt placement is frequently associated with need for later revisions as well as surgical complications. We sought to review revision and complication rates following ventriculoperitoneal, ventriculoatrial and cystoperitoneal shunt placement in adult patients, and to identify potential risk factors for revision surgery and postoperative complications.

Method Included patients were adults (≥ 18 years) who underwent primary shunt insertion at St. Olavs Hospital in Trondheim, Norway, from 2008 through 2017. The electronic medical records and diagnostic imaging from all hospitals in our catchment area were retrospectively reviewed. Follow-up ranged from 1 to 11 years. Complications were graded according to the Landriel Ibañez classification system.

Results Of the 227 patients included, 47 patients (20.7%) required revision surgery during the follow-up. In total, 90 revision surgeries were performed during follow-up. The most common cause for the first revision was infection (5.7%) and for all revisions proximal occlusion (30.0%). A total of 103 patients (45.4%) experienced ≥ 1 complication(s). Mild to moderate complications (grade I and II) were detected in 35.0% of all procedures. Severe or fatal complications (grade III and IV) were observed in 8.2% of all procedures. Urinary tract infections and pneumonia were common postoperatively (13.9% and 7.3%, respectively), and the most common IIb complication was shunt misplacement (proximally or distally). Two out of fourteen deaths within 30 days were directly associated with surgery. We did not find that aetiology/indication, age or gender influenced the occurrence of revision surgery or a grade III or IV complication.

Conclusions Shunt surgery continues to be a challenge both in terms of revision rates and procedure-related complications. However, the prediction of patients at risk remains difficult. A multidimensional focus is probably needed to reduce risks.

Shunt Failure—The First 30 Days

Neurosurgery 87:123–129, 2020

Incontrovertible predictors of shunt malfunction remain elusive.

OBJECTIVE: To determine predictors of shunt failure within 30 d of index surgery.

METHODS: This was a single-center retrospective cohort study from January 2010 through November 2016. Using a ventricular shunt surgery research database, clinical and procedural variables were procured. An “index surgery” was defined as implantation of a new shunt or revision or augmentation of an existing shunt system. The primary outcome was shunt failure of any kind within the first 30 days of index surgery. Bivariate models were created, followed by a final multivariable logistic regression model using a backward-forward selection procedure.

RESULTS: Our dataset contained 655 unique patients with a total of 1206 operations. The median age for the cohort at the time of first shunt surgery was 4.6 yr (range, 0-28; first and third quartile, .37 and 11.8, respectively). The 30-day failure rates were 12.4% when analyzing the first-index operation only (81/655), and 15.7% when analyzing all-index operations (189/1206). Small or slit ventricles at the time of index surgery and prior ventricular shunt operations were found to be significant covariates in both the “first-index” (P < .01 and P=.05, respectively) and “all-index”(P=.02 and P<.01, respectively) multivariable models. Intraventricular hemorrhage at the time of index surgery was an additional predictor in the all-index model (P = .01).

CONCLUSION: This study demonstrates that only 3 variables are predictive of 30-day shunt failure when following established variable selection procedures, 2 of which are potentially under direct control of the surgeon.

Shunting of the over 80s in normal pressure hydrocephalus

Acta Neurochir (2017) 159:987–994

Idiopathic normal pressure hydrocephalus is predominantly a disease of the elderly. By its nature, many of those who present to clinic are in advanced old age with multiple comorbidities. Majority of patients treated are younger than 80 years old. We present the clinical outcomes and complication rates of patients over the age of 80 years at the time of operation, during the past 11 years at a single institution.

Methods Retrospective analysis of clinical records of all patients over the age of 80 years, who presented to our institution between 2006 and 2016.

Results were analysed for co-morbidities, immediate and delayed complications, change in mobility/cognitive function post shunting of hydrocephalus.

Results 39 patients (24 male, 15 female) met criteria. Mean [SD] age at the time of shunt insertion was 84 years (+/− 3.22) (range 80–94). No patients developed immediate CSF infection or sub-dural collection, or extended length of stay due to surgical or anaesthetic complications. There were no perioperative or anaesthetic complications. 4 patients required a delayed surgical revision to encourage greater CSF drainage. 3 patients went on to develop delayed subdural haematoma, 1 of which was associated with trauma, 2 through overdrainage. 1 patient experienced poor post-operative wound healing and subsequently underwent removal of shunt. Of the 34 patient followed up, 27 patients (79.4%) improved in their mobility. (64.7%) patients/families reported symptomatic improvement in their cognition and memory. 6 (17.7%) patients did not experience an improvement in either mobility or cognitive function.

Conclusions Our data supports the assertion that, with proper patient selection, shunting of the over 80s with iNPH is a safe and effective procedure.

Clinical effect of different shunt valve settings in iNPH

Hydrocephalus

J Neurosurg 124:359–367, 2016

The study aim was to examine the effect of gradually reducing the opening pressure on symptoms and signs in the shunt treatment of idiopathic normal pressure hydrocephalus (iNPH).

Methods In this prospective double-blinded, randomized, controlled, double-center study on patients with iNPH, a ventriculoperitoneal shunt with an adjustable Codman Medos Valve was implanted in 68 patients randomized into 2 groups. In 1 group (the 20–4 group) the valve setting was initially set to 20 cm H2O and gradually reduced to 4 cm H2O over the course of the 6-month study period. In the other group (the 12 group), the valve was kept at a medium level of 12 cm H2O during the whole study period. All patients were clinically evaluated using 4 tests preoperatively as well as postoperatively at 1, 2, 3, 4, and 6 months. The test scores between the 2 groups (20–4 and 12) were compared for each clinical evaluation.

Results Fifty-five patients (81%) were able to complete the study. There were no significant differences between the 2 groups (20–4 and 12) preoperatively or at any time postoperatively. Both groups exhibited significant clinical improvement after shunt insertion at all valve settings compared with the preoperative score, with the greatest improvement observed at the first postoperative evaluation. The clinical improvement was significant within the first 3 months, and thereafter no significant improvement was seen in either group.

Conclusions Gradual reduction of the valve setting from 20 to 4 cm H2O did not improve outcome compared with a fixed valve setting of 12 cm H2O. Improvement after shunt surgery in iNPH patients was evident within 3 months, irrespective of valve setting.

Ventriculoperitoneal Shunt Surgery Outcome in Adult Transition Patients With Pediatric-Onset Hydrocephalus

Neurosurgery 70:380–389, 2012 DOI: 10.1227/NEU.0b013e318231d551

Ventriculoperitoneal shunting remains the most widely used neurosurgical procedure for the management of hydrocephalus, albeit with many complications.

OBJECTIVE: To review and assess the long-term clinical outcome of ventriculoperitoneal shunt surgery in adult transition patients with pediatric-onset hydrocephalus.

METHODS: Patients 17 years or older who underwent ventriculoperitoneal shunt placement for hydrocephalus during their pediatric years (younger than 17 years) were included. Medical charts, operative reports, imaging studies, and clinical follow- up evaluations were reviewed and analyzed retrospectively.

RESULTS: A total of 105 adult patients with pediatric-onset hydrocephalus were included. The median age of the patients was 25.9 years. The median age at the time of the initial ventriculoperitoneal shunt placement was 1.0 year. The median follow-up time for all patients was 17.7 years. The incidence of shunt failure at 6 months was 15.2%, and the overall incidence of shunt failure was 82.9%. Single shunt revision occurred in 26.7% of the patients, and 56.2% had multiple shunt revisions. The cause of hydrocephalus was significantly associated with shunt survival for patients who had shunt failure before the age of 17 years. Being pediatric at first shunt revision, infection, proximal shunt complication, and other causes were independently associated with multiple shunt failures.

CONCLUSION: The findings of this retrospective study show that the long-term ventriculoperitoneal shunt survival remains low in adult transition patients with pediatric-onset hydrocephalus.

Management of Adult Hydrocephalus With Ventriculoperitoneal Shunts: Long-term Single- Institution Experience

Neurosurgery 69:774–781, 2011 DOI: 10.1227/NEU.0b013e31821ffa9e

Ventriculoperitoneal shunting is the most widely used neurosurgical procedure for the management of hydrocephalus.

OBJECTIVE: To evaluate our long-term single-institution experience in the management of adult hydrocephalus patients with ventriculoperitoneal shunts.

METHODS: Adult patients who underwent ventriculoperitoneal shunt placement for hydrocephalus from October 1990 to October 2009 were included. Medical charts, operative reports, imaging studies, and clinical follow-up evaluations were reviewed and analyzed retrospectively for clinical outcome in adult hydrocephalus patients.

RESULTS: A total of 683 adult patients were included in the study. The most common etiologies of hydrocephalus include idiopathic (29%), tumors and cysts (20%), postcraniotomy (13%), and subarachnoid hemorrhage (13%). The overall shunt failure rate was 32%, and the majority (74%) of shunt revisions occurred within the first 6 months. The median time to first shunt revision was 9.31 months. Etiology of hydrocephalus showed a significant impact on the incidence of shunt revision/failure and on the median time to shunt revision. Similarly, the type of hydrocephalus had a significant effect on the incidence of shunt failure and the median time to shunt revision.

CONCLUSION: A large proportion of patients (32%) experience shunt failure after shunt placement for hydrocephalus. Although the overall incidence of shunt revision was comparable to previously reported studies, the fact that a large proportion of adult populations with shunt placement experience shunt failure is a concern.