Freehand stereotactic ventricular catheter insertion for ventriculoperitoneal shunts based on individualized radio-anatomical landmarks

Acta Neurochirurgica (2021) 163:1103–1112

The accurate placement of the ventricular catheter (VC) is critical in reducing the incidence of proximal failure of ventriculoperitoneal shunts (VPSs). The standard freehand technique is based on validated external anatomical landmarks but remains associated with a relatively high rate of VC malposition. Already proposed alternative methods have all their specific limitations. Herein, we evaluate the accuracy of our adapted freehand technique based on an individualized radio-anatomical approach. Reproducing the preoperative imaging on the patient’s head using common anatomical landmarks allows to define stereotactic VC coordinates to be followed at surgery.

Material and methods Fifty-five consecutive patients treated with 56 VPS between 11/2005 and 02/2020 fulfilled the inclusion criteria of this retrospective study. Burr hole coordinates, VC trajectory, and length were determined in all cases on preoperative computed tomography (CT) scan and were accurately reported on patients’ head. The primary endpoint was to evaluate VC placement accuracy. The secondary endpoint was to evaluate the rate and nature of postoperative VC-related complications.

Results Our new technique was applicable in all patients and no VC-related complications were observed. Postoperative imaging showed VC optimally placed in 85.7% and sub-optimally placed in 14.3% of cases. In all procedures, all the holes on the VC tip were found in the ventricular system.

Conclusions This simple individualized technique improves the freehand VC placement in VPS surgery, making its accuracy comparable to that of more sophisticated and expensive techniques. Further randomized controlled studies are required to compare our results with those of the other available techniques.

Readmission and reoperation for hydrocephalus: a population-based analysis across the spectrum of age

J Neurosurg 134:1210–1217, 2021

Hydrocephalus is a common, chronic illness that generally requires lifelong, longitudinal, neurosurgical care. Except at select research centers, surgical outcomes in the United States have not been well documented. Comparative outcomes across the spectrum of age have not been studied.

METHODS Data were derived for the year 2015 from the Nationwide Readmissions Database, a product of the Healthcare Cost and Utilization Project of the Agency for Healthcare Research and Quality. In this data set patients are assigned state-specific codes that link repeated discharges through the calendar year. Discharges with diagnostic codes for hydrocephalus were extracted, and for each patient the first discharge defined the index admission. The study event was readmission. Observations were censored at the end of the year. In a similar fashion the first definitive surgical procedure for hydrocephalus was defined as the index operation, and the study event was reoperation for hydrocephalus or complications. Survival without readmission and survival without reoperation were analyzed using life tables and Kaplan- Meier plots.

RESULTS Readmission rates at 30 days ranged between 15.6% and 16.8% by age group without significant differences. After the index admission the first readmission alone generated estimated hospital charges of $2.25 billion nationwide. Reoperation rates at 30 days were 34.9% for infants, 39.2% for children, 47.4% for adults, and 32.4% for elders. These differences were highly significant. More than 3 times as many index operations were captured for adults and elders as for infants and children. Estimated 1-year reoperation rates were 74.2% for shunt insertion, 63.9% for shunt revision, but only 34.5% for endoscopic third ventriculostomy. Univariate associations with survival without readmission and survival without reoperation are presented.

CONCLUSIONS In the United States hydrocephalus is predominantly a disease of adults. Surgical outcomes in this population-based study were substantially worse than outcomes reported from research centers. High reoperation rates after CSF shunt surgery accounted for this discrepancy.

Free-hand stereotactic ventricular catheter insertion technique based on radio-anatomical landmarks

Acta Neurochirurgica (2021) 163:1097–1102

Accurate ventricular catheter (VC) placement plays an important role in reducing the risk of ventriculoperitoneal shunt failure. Free-hand VC insertion is associated with a significant misplacement rate. Consequently, several expensive alternative methods that are unfortunately not available worldwide have been used. To overcome these limitations, we developed a simple surgical technique based on radio-anatomical landmarks aimed at reducing VC’s misplacements.

Method We reproduce the preoperative imaging on the patient’s head using common anatomical landmarks. This allows defining stereotactic VC coordinates to be followed during the surgical procedure.

Conclusion This simple and cost-effective method improves VC insertion accuracy.

The endoscopic supraorbital translaminar approach

Acta Neurochirurgica (2021) 163:635–641

Resection of lesions located within the third ventricle presents a surgical challenge. Several approaches have been developed in an attempt to obtain maximal resection, while minimizing brain retraction. In this work, we assess the surgical exposure and maneuverability of the endoscopic supraorbital translaminar approach (ESTA), a potential alternative to fenestrate the lamina terminalis and approach the third ventricle by using the endoscope through a keyhole supraorbital-eyebrow craniotomy.

Methods Five cadaveric heads were used to assess the corridor depth, area of exposure, and viewing angles offered by the ESTA. One additional utilized specimen provided a stepwise dissection of the approach.

Results The ESTA was successfully performed in all specimens. Depth of the surgical corridor from the craniotomy to the ipsilateral internal carotid artery (ICA), lamina terminalis, and contralateral carotid were 70.7 ± 2.9 mm, 73.2 ± 2.9 mm, and 78.9 ± 4.1 mm, respectively. Viewing angle referenced to the ipsilateral ICA was 6.5 ± 4.2°, while the viewing angle for the lamina terminalis was 25.8 ± 4.3°. The surgical exposure provided by the ESTA was 1655 ± 255 mm2.

Conclusions The ESTA provides a wide surgical view of the lamina terminalis and may be potentially used to approach lesions located in the anterior third of the third ventricle. As a pure endoscopic approach, the ESTA requires minimal brain retraction, while affords good visualization of targeted lesions around the lamina terminalis. The ESTA uses an anterolateral approach and so provides a short and straightforward approach to these structures.

Risk factors for developing subdural hematoma: a registry-based study in 1457 patients with shunted idiopathic normal pressure hydrocephalus

J Neurosurg 134:668–677, 2021

Subdural hematomas and hygromas (SDHs) are common complications in idiopathic normal pressure hydrocephalus (iNPH) patients with shunts. In this registry-based study, patients with shunted iNPH were screened nationwide to identify perioperative variables that may increase the risk of SDH.

METHODS The Swedish Hydrocephalus Quality Registry was reviewed for iNPH patients who had undergone shunt surgery in Sweden in 2004–2014. Potential risk factors for SDH were recorded preoperatively and 3 months after surgery. Drug prescriptions were identified from a national pharmacy database. Patients who developed SDHs were compared with those without SDHs.

RESULTS The study population consisted of 1457 patients, 152 (10.4%) of whom developed an SDH. Men developed an SDH more often than women (OR 2.084, 95% CI 1.421–3.058, p < 0.001). Patients on platelet aggregation inhibitors developed an SDH more often than those who were not (OR 1.733, 95% CI 1.236–2.431, p = 0.001). At surgery, shunt opening pressures had been set 5.9 mm H2O lower in the SDH group than in the no-SDH group (109.6 ± 24.1 vs 115.5 ± 25.4 mm H2O, respectively, p = 0.009). Antisiphoning devices (ASDs) were used in 892 patients but did not prevent SDH. Mean opening pressures at surgery and the follow-up were lower with shunts with an ASD, without causing more SDHs. No other differences were seen between the groups.

CONCLUSIONS iNPH patients in this study were diagnosed and operated on in routine practice; thus, the results represent everyday care. Male sex, antiplatelet medication, and a lower opening pressure at surgery were risk factors for SDH. Physical status and comorbidity were not. ASD did not prevent SDH, but a shunt with an ASD allowed a lower opening pressure without causing more SDHs.

Congress of Neurological Surgeons Systematic Review and Evidence-Based Guidelines on the Treatment of Pediatric Hydrocephalus: Update of the 2014 Guidelines

Neurosurgery 87:1071–1075, 2020

The Congress of Neurological Surgeons reviews its guidelines according to the Institute of Medicine’s recommended best practice of reviewing guidelines every 5 yrs. The authors performed a planned 5-yr review of the medical literature used to develop the “Pediatric hydrocephalus: systematic literature review and evidence-based guidelines” and determined the need for an update to the original guideline based on new available evidence.

OBJECTIVE: To perform an update to include the current medical literature for the “Pediatric hydrocephalus: systematic literature review and evidence-based guidelines”, originally published in 2014.

METHODS: The Guidelines Task Force used the search terms and strategies consistent with the original guidelines to search PubMed and Cochrane Central for relevant literature published between March 2012 and November 2019. The same inclusion/exclusion criteria were also used to screen abstracts and to perform the full-text review. Full text articles were then reviewed and when appropriate, included as evidence and recommendations were added or changed accordingly.

RESULTS: A total of 41 studies yielded by the updated search met inclusion criteria and were included in this update.

CONCLUSION: New literature resulting from the update yielded a new recommendation in Part 2, which states that neuro-endoscopic lavage is a feasible and safe option for the removal of intraventricular clots and may lower the rate of shunt placement (Level III). Additionally a recommendation in part 7 of the guideline now states that antibiotic- impregnated shunt tubing reduces the risk of shunt infection compared with conventional silicone hardware and should be used for children who require placement of a shunt (Level I). <https://www.cns.org/guidelines/browse-guidelines-detail/pediatric- hydrocephalus-guideline>

Diagnostic Accuracy of Non-Invasive Thermal Evaluation of Ventriculoperitoneal Shunt Flow in Shunt Malfunction

Neurosurgery 87:939–948, 2020

Thermal flow evaluation (TFE) is a non-invasive method to assess ventriculoperitoneal shunt function. Flow detected by TFE is a negative predictor of the need for revision surgery. Further optimization of testing protocols, evaluation in multiple centers, and integration with clinical and imaging impressions prompted the current study.

OBJECTIVE: To compare the diagnostic accuracy of 2 TFE protocols, with micropumper (TFE+MP) or without (TFE-only), to neuro-imaging in patients emergently presenting with symptoms concerning for shunt malfunction.

METHODS: We performed a prospective multicenter operator-blinded trial of a consecutive series of patients who underwent evaluation for shunt malfunction. TFE was performed, and preimaging clinician impressions and imaging results were recorded. The primary outcome was shunt obstruction requiring neurosurgical revision within 7 d. Noninferiority of the sensitivity of TFE vs neuro-imaging for detecting shunt obstruction was tested using a prospectively determined a priori margin of −2.5%.

RESULTS: We enrolled 406 patients at 10 centers. Of these, 68/348 (20%) evaluated with TFE+MP and 30/215 (14%) with TFE-only had shunt obstruction. The sensitivity for detecting obstruction was 100% (95% CI: 88%-100%) for TFE-only, 90% (95% CI: 80%-96%) for TFE+MP, 76% (95% CI: 65%-86%) for imaging in TFE+MP cohort, and 77%(95% CI: 58%- 90%) for imaging in the TFE-only cohort. Difference in sensitivities between TFE methods and imaging did not exceed the non-inferiority margin.

CONCLUSION: TFE is non-inferior to imaging in ruling out shunt malfunction and may help avoid imaging and other steps. For this purpose, TFE only is favored over TFE+MP.

In vitro performance of six combinations of adjustable differential pressure valves and fixed anti-siphon devices with and without vertical motion

Acta Neurochirurgica (2020) 162:2421–2430

Adjustable differential pressure (DP) valves in combination with fixed anti-siphon devices are currently a popular combination in counteracting the effects of cerebrospinal fluid overdrainage following implantation of a ventriculoperitoneal shunt system. The study examined the flowperformance of three DP valves in successive combination with an anti-siphon device in an in vitro shunt laboratory with and without vertical motion.

Methods We analyzed three DP valves (Codman Hakim Medos programmable valve [HM], Codman CertasPlus [CP], and Miethke proGAV [PG], in combination with either Codman SiphonGuard [SG] or Miethke ShuntAssistant [SA]), resulting in the evaluation of six different valve combinations. Defined DP conditions between 4 and 40 cmH2O within a simulated shunt system were generated and the specific flow characteristics were measured. In addition, combinations with SA, which is a gravitydependent valve, were measured in defined spatial positions (90°, 60°). All device combinations were tested during vertical motion with movement frequencies of 2, 3, and 4 Hz.

Results All valve combinations effectively counteracted the siphon effect in relation to the chosen DP. Angulation-related flow changes were similar in the three combinations of DP valve and SA in the 60° and 90° position. In CP-SA and PG-SA, repeated vertical movement at 2, 3, and 4 Hz led to significant increase in flow, whereas in HM-SA, constant increase was seen at 4 Hz only (flow change at 4Hz, DP 40 cm H2O: PG (opening pressure 4 cm H2O) 90°: 0.95 ml/min, 60°: 0.71 ml/min; HM (opening pressure 4 cmH2O) 90°: 0.66 ml/min, 60°: 0.41ml/min; CP (PL 2) 90°: 0.94ml/min, 60°: 0.79 ml/min; p < 0.01); however, HMSA showed relevant motion-induced flow already at low DPs (0.85 ml/min, DP 4 cm H2O). In combinations of DP valve with SG, increase of flow was far less pronounced and even led to significant reduction of flow in certain constellations. Maximum overall flow increase was 0.46 ± 0.04ml/min with aHM(opening pressure 12 cm H2O) at 2 Hz and a DP of 10 cmH2O, whereas maximum flow decrease was 1.12 ± 0.08 with a PG (opening pressure 4 cm H2O) at 3 Hz and a DP of 10 cmH2O.

Conclusion In an experimental setup, all valve combinations effectively counteracted the siphon effect in the vertical position according to their added resistance. Motion-induced increased flow was consistently demonstrated in combinations of DP valve and SA. The combination of HM and SA especially showed relevant motion-induced flow already at low DPs. In combinations of DP and SG, the pattern of the motion induced flow was more inconsistent and motion even led to significant flow reduction, predominantly at DPs of 10 and 20 cmH2O.

 

Single center experiences with telemetric intracranial pressure measurements in patients with CSF circulation disturbances

Acta Neurochirurgica (2020) 162:2487–2497

Hydrocephalus may present with heterogeneous signs and symptoms. The indication for its treatment and the optimal drainage in complex cases may be challenging. Telemetric intracranial pressure measurements (TICPM) may open new perspectives for those circumstances. We report our experiences using the Neurovent-P-tel and the Sensor Reservoir in a retrospective study.

Methods A series of 21 patients (age range 10–39.5 years) treated in our Pediatric Neurosurgical Unit receiving a TICPM was analyzed. In 8 patients, a Neurovent-P-Tel was implanted; 13 patients received a Sensor Reservoir, 6 of which as a stand-alone implant, while 7 were already shunted. TICPM were performed on an outpatient basis. Possible complications, follow-up surgeries, and TICPM were analyzed.

Results Concerning the complications, one infection was seen in each group and one postoperative seizure was observed in the Ptel group. TICPM-assisted shunt adjustments lead to clinical improvements in six patients in the P-tel group and six patients in the Sensor Reservoir group. In four out of six non-shunted patients, TICPMcontributed to the indication toward shunt implantation.

Conclusions TICPM seems to be a promising tool to improve clinical management of shunted patients with complex hydrocephalus. The two available systems will need further technical improvements, concerning implantation time, measurements, and data analysis in order to optimize handling and interpretation of the data.

Cerebrospinal fluid disturbances after transcallosal surgery: incidence and predictive factors

J Neurosurg 133:979–987, 2020

CSF dynamics after transcallosal resection of intraventricular lesions can be altered, and the need for shunt implantation complicates the management of these patients. Because the pathophysiological mechanism and contributing factors are poorly understood and the incidence has largely not been described, the authors conducted a study to elucidate these factors.

METHODS The authors retrospectively reviewed data from patients who had been operated on at their institution via a transcallosal approach between March 2002 and December 2016. They evaluated the need for a shunt implantation up to 3 months after surgery by assessing clinical variables. These variables were age at surgery, the need for perioperative external CSF drainage, histology of the lesion, and the following radiological parameters: pre- and postoperative Evans index, maximal postoperative extension of subdural effusions (SDEs) measured on axial images, and maximal interhemispheric fissure (IHF) width measured on coronal images assessed at 4 different points in time (preoperatively, day 1, days 2–4, and days 4–8 after surgery). To identify potential risk factors, univariate and multivariate regression models were constructed. Receiver operating characteristic (ROC) curves for significant predictors, as well as the area under the curve (AUC), were calculated.

RESULTS Seventy-four patients (40 female and 34 male) were identified; their median age at surgery was 17.6 years (range 4 months to 76 years). Shunt implantation was necessary in 13 patients (ventriculoperitoneal [VP] shunt, n = 7; subdural peritoneal [SDP] shunt, n = 6) after a median interval of 24 days (range 10 days to 3 months). Univariate logistic regression models revealed a significant effect of IHF width on days 4–8 (OR 1.31, 95% CI 1.03–1.66; p = 0.027), extension of SDE on days 2–4 (OR 1.33, 95% CI 1.11–1 0.60; p = 0.003), and age (OR 0.932, 95% CI 0.88–0.99; p = 0.02). In the multiple regression model, the effect of the independent variable extension of the SDE remained significant. ROC curves for the predictors IHF width on days 4–8 and extension of SDE on days 2–4 revealed an AUC equal to 0.732 and 0.752, respectively. Before shunt implantation, the ventricles were smaller compared to the preoperative size in 9 of the 13 patients (SDP shunt, n = 5; VP shunt, n = 4).

CONCLUSIONS The rate of shunt-dependent hydrocephalus 3 months after surgery in this heterogeneous group of patients was 17.6% (95% CI 9.7%–28.2%). The authors identified as predictive factors the variables extension of the convexity space, IHF 1 week after surgery, and younger age.

 

Neural and vascular architecture of the septum pellucidum: an anatomical study and considerations for safe endoscopic septum pellucidotomy

J Neurosurg 133:902–911, 2020

The septum pellucidum is a bilateral thin membranous structure representing the border between the frontal horns of the lateral ventricles. Its most examined components are the septal veins due to their surgical importance during endoscopic septum pellucidotomy (ESP), which is a well-accepted method for surgical treatment of unilateral hydrocephalus. It is widely accepted that the septum pellucidum contains nerve fibers as well, but interestingly, no anatomical study has been addressed to its neural components before. The aim of the present study was to identify these elements as well as their relations to the septal veins and to define major landmarks within the ventricular system for neurosurgical use.

METHODS Nine formalin-fixed human cadaveric brains (18 septa pellucida) were involved in this study. A central block containing both septa pellucida was removed and frozen at -30°C for 2 weeks in 7 cases. The fibers of the septum pellucidum and the adjacent areas including the venous elements were dissected under magnification by using homemade wooden spatulas and microsurgical instruments. In 2 cases a histological technique was used to validate the findings of the dissections. The blocks were sliced, embedded in paraffin, cut in 7-μm-thick slices, and then stained as follows: 1) with H & E, 2) with Luxol fast blue combined with cresyl violet, and 3) with Luxol fast blue combined with Sirius red.

RESULTS The septum pellucidum and the subjacent septum verum form the medial wall of the frontal horn of the lateral ventricle. Both structures contain nerve fibers that were organized in 3 groups: 1) the precommissural fibers of the fornix; 2) the inferior fascicle; and 3) the superior fascicle of the septum pellucidum. The area directly rostral to the postcommissural column of the fornix consisted of macroscopically identifiable gray matter corresponding to the septal nuclei. The histological examinations validated the findings of the authors’ fiber dissections.

CONCLUSIONS The nerve elements of the septum pellucidum as well as the subjacent septum verum were identified with fiber dissection and verified with histology for the first time. The septal nuclei located just anterior to the fornix and the precommissural fibers of the fornix should be preserved during ESP. Considering the venous anatomy as well as the neural architecture of the septum pellucidum, the fenestration should ideally be placed above the superior edge of the fornix and preferably dorsal to the interventricular foramen.

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.

Anterior third ventricular height and infundibulochiasmatic angle: two novel measurements to predict clinical success of endoscopic third ventriculostomy in the early postoperative period

J Neurosurg 132:1764–1772, 2020

The authors sought to develop a set of parameters that reliably predict the clinical success of endoscopic third ventriculostomy (ETV) when assessed before and after the operation, and to establish a plan for MRI follow-up after this procedure.

METHODS This retrospective study involved 77 patients who had undergone 78 ETV procedures for obstructive hydrocephalus between 2010 and 2015. Constructive interference in steady-state (CISS) MRI evaluations before and after ETV were reviewed, and 4 parameters were measured. Two well-known standard parameters, fronto-occipital horn ratio (FOHR) and third ventricular index (TVI), and 2 newly defined parameters, infundibulochiasmatic (IC) angle and anterior third ventricular height (TVH), were measured in this study. Associations between preoperative measurements of and postoperative changes in the 4 variables and the clinical success of ETV were analyzed.

RESULTS Of the 78 ETV procedures, 70 (89.7%) were successful and 8 (10.3%) failed. On the preoperative MR images, the mean IC angle and anterior TVH were significantly larger in the successful procedures. On the 24-hour postoperative MR images of the successful procedures, the mean IC angle declined significantly from 114.2° to 94.6° (p < 0.05) and the mean anterior TVH declined significantly from 15 to 11.2 mm (p < 0.05). The mean percentage reduction of the IC angle was 17.1%, and that of the anterior TVH was 25.5% (both p < 0.05). On the 1-month MR images of the successful procedures, the mean IC angle declined significantly from 94.6° to 84.2° (p < 0.05) and the mean anterior TVH declined significantly from 11.2 to 9.3 mm (p < 0.05). The mean percentage reductions in IC angle (11%) and anterior TVH (16.9%) remained significant at this time point but were smaller than those observed at 24 hours. The 6-month and 1-year postoperative MR images of the successful group showed no significant changes in mean IC angle or mean anterior TVH. Regarding the unsuccessful procedures, there were no significant changes observed in IC angle or anterior TVH at any of the time points studied. Reduction of IC angle and reduction of anterior TVH on 24-hour postoperative MR images were significantly associated with successful ETV. However, no clinically significant association was found between FOHR, TVI, and ETV success.

CONCLUSIONS Assessing the IC angle and anterior TVH on preoperative and 24-hour postoperative MR images is useful for predicting the clinical success of ETV. These 2 measurements could also be valuable as radiological follow-up parameters.

Shunt infusion studies: impact on patient outcome, including health economics

Acta Neurochirurgica (2020) 162: 1019–1031

The diagnosis of shunt malfunction is often not straightforward. We have explored, in symptomatic shunted patients with hydrocephalus or pseudotumour cerebri syndrome (PTCS), the accuracy of CSF infusion tests in differentiating a functioning shunt from one with possible problems, and the health economic consequences.

Methods Participants: hydrocephalus/PTCS patients with infusion tests performed from January 2013 until December 2015. We followed patients up after 6 and 12 months from the test to determine whether they had improved, had persisting symptoms or had required urgent revision. We calculated the total cost savings of revision versus infusion tests and standard protocol of revision and ICP monitoring versus infusion tests.

Results Three hundred sixty-five shunt infusion tests had been performed where a shunt prechamber/reservoir was present. For hydrocephalus patients, more than half of the tests (~ 55%, 155 out of 280) showed no shunt malfunction versus 125 with possible malfunction (ages 4 months to 90 years old). For PTCS patients aged 10 to 77 years old, 47 had possible problems and 38 no indication for shunt malfunction. Overall, > 290 unnecessary revisions were avoided over 3 years’ time. Two hundred fifty eight (> 85%) of those non-surgically managed, remained well, did not deteriorate and did not require surgery. No infections were associated with infusion studies. For Cambridge, the overall savings from avoiding revisions was £945,415 annually.

Conclusions Our results provide evidence of the importance of shunt testing in vivo to confirm shunt malfunction. Avoiding unnecessary shunt revisions carries a strong health benefit for patients that also translates to a significant financial benefit for the National Health Service and potentially for other healthcare systems worldwide.

Treatment Options for Hydrocephalus Following Foramen Magnum Decompression for Chiari I Malformation: A Multicenter Study

Neurosurgery 86(4): 500-508, 2020

New-onset hydrocephalus following foramen magnum decompression (FMD) for Chiari I malformation (CM-I) is rare; its natural history and pathophysiology are poorly understood.

OBJECTIVE: To describe a series of patients who developed hydrocephalus following FMD for CM-I, provide possible explanations of this phenomenon, and outline treatment options.

METHODS: Out of patients undergoing FMD for CM-I from 6 different tertiary centers, we evaluated patients presenting with new-onset hydrocephalus following FMD. The retrospectively collected data included demographics, clinical, and radiological findings of the CM-I and hydrocephalus patients. Time from FMD and hydrocephalus onset, treatment, and surgical techniques were assessed.

RESULTS: Of 549 patients who underwent FMD for CM-I, 28 (5.1%) subsequently developed hydrocephalus (18 females, 10 males), with a mean age of 11.7 ± 11.9 yr (range 6 mo to 52 yr). Hydrocephalus occurred on average 2.2 ± 2.6 mo after FMD (range 1 wk to 8 mo). Four patients did not have a violation of the arachnoid during the FMD surgery. Main presenting symptoms of hydrocephalus were headaches (17, 41%), vomiting (10, 24.4%), and cerebrospinal fluid (CSF) leak or pseudomeningocele (7, 17%). Overall, 23 patients (82.1%) underwent CSF shunting, 1 patient (3.5%) had an endoscopic third ventriculostomy, 3 patients (10.7%) temporary CSF diversion only, and 1 patient (3.5%) was treated with acetazolamide.

CONCLUSION:Hydrocephalus following FMDforCM-I is uncommon,but important. Based on our series and literature review, its incidence is about 5% to 7% and most likely will require further surgery. Shunting appears to be the favored treatment option.

Cerebrospinal Fluid Shunting Improves Long-Term Quality of Life in Idiopathic Normal Pressure Hydrocephalus

Neurosurgery, Volume 86, Issue 4, April 2020: 574–582

The short- and long-term impact of cerebrospinal fluid shunting on quality of life (QoL) in idiopathic normal pressure hydrocephalus (INPH) is poorly understood.

OBJECTIVE: To investigate QoL in shunted INPH patients compared to the population and to investigate which factors influence QoL in INPH.

METHODS: INPH patients consecutively shunted in Sweden during 2008-2010 were scrutinized. Population-based controls were age- and sex-matched to the patients. Included participants were the following:176 INPH patients and 368controls.QoLwas assessed using the EuroQol 5-dimension 5-level (EQ5D5L) instrument, which measures overall QoL and health status in 5 dimensions. Independency (accommodation and/or need for in-home care) and comorbidities were assessed. Patients were followed up 6-45 mo after surgery (mean follow-up time: 21 mo).

RESULTS: Shunting improved QoL (P < .001) and health status in all dimensions (P < .005). Shunted INPH patients had lower QoL than controls (P < .001). The patients’health status in mobility, self-care, daily activities, and anxiety/depression was worse than the controls both before and after surgery (P < .001). The main predictors of low QoL in INPH were symptoms of depression (P < .001) and severity of gait disturbance (P = .001). Fewer INPH patients than controls lived independently (45% vs 85%, P < .001). Time after shunting had no influence on QoL.

CONCLUSION: QoL remains improved in shunted INPH patients at a mean follow-up time of 21 mo, but the patients do not reach the same QoL as the population. Symptoms of depression and severity of gait disturbance are the strongest predictors of low QoL in INPH.

Natural history of ventriculomegaly in adults: a cluster analysis

J Neurosurg 132:741–748, 2020

Chronic ventriculomegaly in the absence of raised intracranial pressure (ICP) is a known entity in adult hydrocephalus practice. The natural history and indication for treatment is, however, poorly defined. A highly heterogeneous group, some adults with ventriculomegaly are asymptomatic, while others have life-threatening deteriorations. The authors hypothesized that the various presentations can be subtyped and represent different stages of decompensation. A cluster analysis was performed on a cohort of patients with chronic ventriculomegaly with the aim of elucidating typical clinical characteristics and outcomes in chronic ventriculomegaly in adults.

METHODS Data were collected from 79 patients with chronic ventriculomegaly referred to a single center, including demographics, presenting symptoms, and 24-hour ICP monitoring (ICPM). A statistical cluster analysis was performed to determine the presence of subgroups.

RESULTS Four main subgroups and one highly dissimilar group were identified. Patients with ventriculomegaly commonly have a perinatal event followed by one of four main presentations: 1) incidental ventriculomegaly with or without headache; 2) highly symptomatic presentation (including reduced consciousness) and raised ICP; 3) early presenting with symptoms of headache and nausea (with abnormal pulsatility); and 4) late presenting with features common to normal pressure hydrocephalus. Each symptomatic group has characteristic radiological features, ICPM, and responses to treatment.

CONCLUSIONS Cluster analysis has identified subgroups of adult patients with ventriculomegaly. Such groups may represent various degrees of decompensation. Surgical interventions may not be equally effective across the subgroups, presenting an avenue for further research. The identified subtypes provide further insight into the natural history of this lesser studied form of hydrocephalus.

Comparative Analysis of Subventricular Zone Glioblastoma Contact and Ventricular Entry During Resection in Predicting Dissemination, Hydrocephalus, and Survival

Neurosurgery, Volume 85, Issue 5, November 2019, Pages E924–E932

Ventricular entry during glioblastoma resection and tumor contact with the subventricular zone (SVZ) have both been shown to associate with development of hydrocephalus, leptomeningeal dissemination, distant parenchymal recurrence, and decreased survival. However, prior studies did not analyze these variables together in a single-patient population; therefore, it is unknown which is an independent predictor of these outcomes.

OBJECTIVE: To conduct a comparative outcome analysis of surgical ventricular entry and SVZ contact by glioblastoma in a retrospective cohort of 232 patients.

METHODS: Outcomes studied included hydrocephalus, leptomeningeal dissemination, distant tumor recurrences, and progression-free (PFS) and overall (OS) survival. The Cox proportional regression analyses were adjusted for age at diagnosis, preoperative Karnofsky performance status score, extent of resection, temozolomide and radiation treatments, and tumor molecular status (specifically, IDH1/2 mutation and MGMT promoter methylation).

RESULTS: Surgical ventricular entry, SVZ-contacting glioblastoma, hydrocephalus, leptomeningeal dissemination, and distant recurrences were observed in 85 (36.6%), 114 (49.1%), 19 (8.2%), 78 (33.6%), and 59 (25.4%) patients, respectively. Multivariate, adjusted analysis revealed SVZ tumor contact—but not ventricular entry—associated with hydrocephalus (hazard ratio, HR, 4.20 [1.13-15.7], P = .03), leptomeningeal dissemination (HR 1.93 [1.14-3.28], P = .01), PFS (HR 2.10 [1.53-2.88], P < .001), and OS (HR 1.90 [1.35-2.67], P < .001). Distant recurrences were not associated with either. No interaction between the 2 variables was statistically noted.

CONCLUSION: SVZ contact by glioblastoma was independently associated with the development of hydrocephalus, leptomeningeal dissemination, and decreased survival. SVZ tumor contact was associated with ventricular entry during surgical resections, which did not independently correlate with these outcomes.

Noninvasive Thermal Evaluation of Ventriculoperitoneal Shunt Patency and Cerebrospinal Fluid Flow Using a Flow Enhancing Device

Neurosurgery, Volume 85, Issue 2, August 2019, Pages 240–249

While a noninvasive flow determination would be desirable in the diagnosis of cerebrospinal fluid shunt malfunction, existing studies have not yet defined a role for thermal flow detection.

OBJECTIVE: To evaluate a revised test protocol using a micropumper designed to transiently enhance flow during thermal testing to determine whether thermal detection of flow is associated with progression to shunt revision surgery.

METHODS: Eighty-two unique tests were performed in 71 shunts. The primary outcome, need for revision within 7 d of testing, was compared with results of micropumper-augmented thermal flow detection. Statistical analysis was based on blind interpretation of test results and raw temperature data recorded during testing.

RESULTS: The test was sensitive (73%) and specific (68%) in predicting need for revision, with 5.6-fold higher probability of revision when flow was not detected. Negative predictive value in our sample was 94.2%. The probability of not requiring revision increased with increasing total temperature drop. Analysis of various possible thresholds showed that the optimal temperature cutoff may be lower than suggested by the manufacturer (0.125◦C vs 0.2◦C).

CONCLUSION: This is the first study to report a strong association between thermal flow evaluation and a clinical impression that a shunt is not malfunctioning. The current recommended threshold may increase the false positive rate unnecessarily, and as clinicians gain experience with the method, they may find value in examining the temperature curves themselves. Multicenter studies are suggested to further define a role for this diagnostic test.

Ruptured PICA aneurysms: presentation and treatment outcomes compared to other posterior circulation aneurysms

Acta Neurochirurgica (2019) 161:1325–1334

Aneurysms of the posterior inferior cerebellar artery (PICA) are relatively uncommon and evidence is sparse about patients presenting with ruptured PICA aneurysms. We performed an analysis of the Swiss SOS national registry to describe clinical presentation, treatment pattern, and neurological outcome of patients with ruptured PICA aneurysms compared with other ruptured posterior circulation (PC) aneurysms.

Methods This was a retrospective analysis of anonymized data from the Swiss SOS registry (Swiss Study on Aneurysmal Subarachnoid Hemorrhage; 2009–2014). Patients with ruptured PC aneurysms were subdivided into a PICA and non-PICA group. Clinical, radiological, and treatment-related variables were identified, and their impact on the neurological outcome was determined in terms of modified Rankin score at discharge and at 1 year of follow-up for the two groups.

Results Data from 1864 aneurysmal subarachnoid hemorrhage patients were reviewed. There were 264 patients with a ruptured PC aneurysm. Seventy-four PICA aneurysms represented 28% of the series; clinical and radiological characteristics at admission were comparable between the PICA and non-PICA group. Surgical treatment was accomplished in 28% of patients in the PICA group and in the 4.8% of patients in the non-PICA group. No statistically significant difference was found between the two groups in terms of complications after treatment. Hydrocephalus requiring definitive shunt was needed in 21.6% of PICA patients (p = 0.6); cranial nerve deficit was present in average a quarter of the patients in both PICA and non-PICA group with no statistical difference (p = 0.3). A more favorable outcome (66.2%) was reported in the PICA group at discharge (p < 0.05) but this difference faded over time with a similar neurological outcome at 1-year follow-up (p = 0.09) between both PICA and non- PICA group. The Kaplan-Meyer estimation showed no significant difference in the mortality rate between both groups (p = 0.08).

Conclusions In the present study, patients with ruptured PICA aneurysms had a favorable neurological outcome in more than two thirds of cases, similar to patients with other ruptured PC aneurysms. Surgical treatment remains a valid option in a third of cases with ruptured PICA aneurysms.