Acquired Chiari type I malformation: a late and misunderstood supratentorial over-drainage complication.

PURPOSE: Acquired Chiari I malformation is an uncommon but possible late complication of supratentorial shunting in children. This condition can be caused by an abnormal thickening of the cranial vault and consequent reduction of the posterior cranial fossa (PCF) volume especially in children with already a small PCF volume. The management of Acquired Chiari I malformation is very challenging, and several options have been proposed for this condition. These are aimed to expand the PCF volume both through decompression and PCF remodeling in order to relieve symptoms of acquired Chiari I malformation. A cranial vault remodeling or a standard Chiari decompression is two proposed techniques aimed to expand the PCF volume thus relieving symptoms . METHODS: We describe the case of a 16-year-old girl undergone surgical removal of sellar-suprasellar glioneuronal tumor and ventriculo-peritoneal shunting, who developed an acquired symptomatic Chiari type I malformation some years after ventricular-peritoneal shunting. For this condition, she underwent successful standard Chiari decompression with C0-C1 craniectomy and duroplasty. RESULTS: We retrospectively analyzed MRI and CT scan performed during follow-up, in order to evaluate the volume of the posterior cranial fossa and to measure the variation of skull thickness at different periods. MRI and CT scan analysis showed a progressive thickening of the calvaria, in particular of the occipital bone, leading to a progressive reduction of PCF volume with the establishment of acquired Chiari type I malformation. In this case, standard C0-C1 Chiari decompression was effective in restoring PCF volume and relieving symptoms. CONCLUSION: Acquired Chiari I malformation due to chronic overhunting could be a severe and late complication in patient undergone supratentorial shunting. These patients require careful clinical and radiological follow-up to avoid over-drainage. According to our analysis, a careful selection of pediatric patients for supratentorial shunting should be made according to pre-operative PCF volume in order to foresee higher odds of possible late complications from over-drainage.

Programmable (proSA®) vs. fixed (SHUNTASSISTANT®) gravitational valves in pediatric patients with hydrocephalus: a 16-year retrospective single-center comparative study with biomechanical analysis.

PURPOSE: In pediatric hydrocephalus (HC) treatment, programmable gravitational valves offer greater flexibility to manage overdrainage during children's growth. However, it remains unclear whether these devices provide better outcomes rather than their precursors. The study assessed the benefit from programmability of gravitational valve, i.e., programmable-SHUNTASSISTANT (proSA®) vs. SHUNTASSISTANT® (SA®). METHODS: Clinical records and imaging of pediatric patients with hydrocephalus of non-tumoral etiology treated with fixed (SA®) or programmable (proSA®) gravitational valves between January 2006 and January 2022 were analyzed in a retrospective single-center study. Valve survival was compared in relation to age and etiology. Lately explanted valves received biomechanical analysis. RESULTS: A total of 391 gravitational valves (254 SA® and 137 proSA®) were inserted in 244 patients (n = 134 males). One hundred thirty-three SA® (52.4%) and 67 proSA® (48.9%) were explanted during a follow-up of 81.1 ± 46.3 months. Valve survival rate at 1 and 5 years with proSA® was 87.6% and 60.6% compared to 81.9% and 58.7% with SA®, with mean survival time 56.4 ± 35.01 and 51.4 ± 43.0 months, respectively (P = 0.245). Age < 2 years at implantation correlated with significantly lower valve survival rates (P < 0.001), while HC etiology showed no significant impact. Overdrainage alone accounted for more SA® revisions (39.8% vs. 3.1%, P < 0.001), while dysfunctions of the adjustment system represented the first cause of valve replacement in proSA® cohort (45.3%). The biomechanical analysis performed on 41 proSA® and 31 SA® showed deposits on the valve's internal surface in 97.6% and 90.3% of cases. CONCLUSION: Our comparative study between proSA® and SA® valves in pediatric HC demonstrated that both valves showed similar survival rates, regardless of etiology but only with young age at implantation. The programmability may be beneficial in preventing sequelae of chronic overdrainage but does not reduce need for valve revision and proSA® valve should be considered in selected cases in growing children older than 2 years.

How to define CSF overdrainage: a systematic literature review.

PURPOSE: Overdrainage (OD) is one of the most frequent complications related to drainage of the cerebrospinal fluid (CSF). It is mostly associated with valve-bearing shunt systems but should probably be considered as a risk factor in any type of CSF diversion procedure. There is extreme variation in the reported incidence of OD due to the lack of consensus on defining criteria and an unclear perception of the pathophysiology. Hence, OD is probably underreported and underestimated. The objective of this paper was to establish a definition of OD, based on a systematic review of the literature. METHODS: A systematic search was conducted in MEDLNE and EMBASE. Studies providing a definition or a description of diagnostic findings related to OD in ventriculoperitoneal shunt treated hydrocephalus were included. Non-English titles, abstracts and manuscripts were excluded. Extracted descriptions were graded into five groups (class I-V studies) based on how precise the terminology used to describe OD was. Class I studies were included for further analysis and characteristics of OD were extracted. The quality of included descriptions was assessed by a clinical expert panel. RESULTS: A total of 1309 studies were screened, 190 were graded into groups, and 22, which provided specific definitions or descriptions of OD, were graded as class I studies. We extracted 32 different characteristics consistent with OD (e.g., clinical symptoms, radiological signs, and syndromes). CONCLUSION: There was an overall agreement that CSF overdrainage following implantation of a ventriculoperitoneal shunt in a mixed pediatric and adult population is characterized as a persistent condition with clinically manifestations as postural dependent headache, nausea, and vomiting and/or radiological signs of slim ventricles and/or subdural collections.

A case of recurrent flight-induced cerebrospinal fluid shunt overdrainage.

Shunted patients often complain of headaches after flights. The effect of air travel on shunt systems is unknown. We describe the case of a patient with longstanding hydrocephalus, who suffered flight-induced clinical deterioration and shunt overdrainage in two independent occasions. The patient, clinically stable for 1.5 and 5 years before each episode, reported severe headaches starting during the descent stages of the air travel. On both occasions, brain MRI imaging demonstrated pronounced ventricular size reduction. This case suggests that flight-induced shunt overdrainage can occur and should be suspected in patients with prolonged headaches and/or clinical deterioration triggered by air travel.

Retrospective single-center historical comparative study between proGAV and proGAV2.0 for surgical revision and implant duration.

OBJECTIVE: Cerebrospinal fluid (CSF) diversion shunt systems remain to be the most common treatment for pediatric hydrocephalus. Different valve systems are used to regulate CSF diversion. Preventing complications such as occlusions, ruptures, malpositioning, and over- or underdrainage are the focus for further developments. The proGAV and proGAV2.0 valve system are compared in this retrospective study for revision-free survival and isolated valve revision paradigms. METHODS: In the first part of the study, the shunt and valve revision-free survival rates were investigated in a retrospective historical comparison design for a period of 2 years in which each valve was used as standard valve (proGAV: July 2012-June 2014; proGAV2.0: January 2015-December 2016) with subsequent 30-month follow-up period, respectively. In the second part of the study, the implant duration was calculated by detecting isolated valve (valve-only) revisions together with another valve explantation during the entire period of the first study and its follow-up period. RESULTS: Two hundred sixty-two patients (145 male and 117 female, mean age 6.2 ± 6.1 years) were included in the cohort of revision-free survival. During the 30-month follow-up period, 41 shunt revisions, including 27 valve revisions (shunt survival rate: 72.1%, valve survival rate: 81.6%) were performed in the proGAV cohort and 37 shunt revisions, including 21 valve revisions (shunt survival rate: 74.8% and valve survival rate: 85.0%) were performed in the proGAV2.0 cohort without showing statistically significant differences. In the second part of the study, 38 cases (mean age 4.0 ± 3.9 years) met the inclusion criteria of receiving a valve-only-revision. In those patients, a total of 44 proGAV and 42 proGAV2.0 were implanted and explanted during the entire study time. In those, a significantly longer implant duration was observed for proGAV (mean valve duration 961.9 ± 650.8 days) compared to proGAV2.0 (mean length of implantation period 601.4 ± 487.8 days; p = 0.004). CONCLUSION: The shunt and valve revision-free survival rates were found to be similar among the groups during 30 month follow-up. In patients who received "valve only" revisions and a subsequent explanation, the implant duration was significantly longer in the proGAV. Although the amount of patients with valve-only-revisions are small compared to the entire cohort certain patients seem to be at higher risk for repeated valve revisions.

Shunt Over-drainage, Slit Ventricle Syndrome, Programmable Valves and Anti-Siphon Devices. A Narrative Review of a Multifactorial and Intractable Problem.

The current management strategy of hydrocephalus mainly involves the insertion of a ventriculoperitoneal shunt and is inherently related with a complication widely known as shunt over-drainage. Albeit this is a well-recognized complication, the true incidence and severity of this phenomenon remains undefined and most probably underdiagnosed, necessitating a more comprehensive pathophysiologic and therapeutic consideration. The slit ventricle syndrome is intimately related with the entity of shunt over-drainage, although who's the definition of the former is implicated by a lack of universally accepted inclusion criteria. Another point of controversy is related with the absence of widely accepted criteria that would be able to discriminate the existing differentiations between these two entities. This is reflected in the fact that there are many proposed, relevant, treatment protocols. The background for all this data is based on the uncertainty and ambiguity regarding the pathophysiological mechanisms that are implicated. Current efforts are centered on the implementation of precautionary measures, as well as on treatment of both of these entities. Currently, there are enough evidence that support the concept that prevention of siphoning via the use of gravitational valves or antisiphon devices is the most efficacious means contained in our current therapeutic armamentarium. We attempt to present an overview of this complex entity, emphasizing on the hydrodynamics of the cerebrospinal fluid circulation in conditions harboring a ventriculoperitoneal shunt, the effect of the siphoning effect and the role of programmable valves and anti-siphon devices in our effort to eliminate this phenomenon. Based on an extensive literature review and on expert opinion, we concluded that the insertion of an anti-siphon device (gravitational shunt valves) could reliably address the issue of over-drainage, when a patient assumes a vertical position. Besides that, there are ongoing prospective studies centered on the safety and efficacy of adjustable gravitational valves, whose results are of ultimate importance. It is of paramount importance to be recognized that, due to the complexity of the pathophysiology of shunted hydrocephalus, lifelong follow-up of patients with ventriculoperitoneal shunts is necessary.

Efficacy and safety of the Miethke programmable differential pressure valve (proGAV®2.0): a single-centre retrospective analysis.

PURPOSE: Achieving decompression without CSF over-drainage remains a challenge in hydrocephalus. Differential pressure valves are a popular treatment modality, with evidence suggesting that incorporation of gravitational units helps minimise over-drainage. This study seeks to describe the utility of the proGAV®2.0 programmable valve in a paediatric population. METHODS: Clinical records and imaging of all patients fitted with proGAV®2.0 valves and Miethke fixed-pressure valves between 2014 and 2019 at our tertiary centre were analysed. Patient demographics, indication for shunt and valve insertion/revision and time to shunt/valve revision were collected. Ventricular linear metrics (fronto-occipital horn ratio (FOHR) and fronto-occipital horn width ratio (FOHWR)) were collected pre- and post-valve insertion. Microsoft Excel and SPSS v24 were used for data collection and statistical analysis. RESULTS: Eighty-eight proGAV®2.0 valves were inserted in a population of 77 patients (n = 45 males (58%), mean age 5.1 years (IQR: 0.4-11.0 years)). A total of 102 Miethke fixed-pressure valves were inserted over the same time period. Median follow-up was 17.5 months (1.0-47.3). One (1.1%) proGAV®2.0 was revised due to over-drainage, compared to 2 (1.9%) fixed-pressure valves (p > 0.05). ProGAV®2.0 insertion resulted in a significant decrease in the mean number of revisions per patient per year (1.77 vs 0.25; p = 0.01). Overall shunt system survival with the proGAV®2.0 was 80.4% at 12 months, and mean time to revision was 37.1 months, compared to 31.0 months (95%CI: 25.7-36.3) and 58.3% in fixed-pressure valves (p < 0.01). Significant decreases were seen following proGAV®2.0 insertion in both FOHR and FOHWR, by 0.014 (95%CI: 0.006-0.023, p = 0.002) and 0.037 (95%CI: 0.005-0.069, p = 0.024) respectively. CONCLUSION: The proGAV®2.0 provides effective decompression of hydrocephalic patients, significantly reduces the number of valve revisions per patient and had a significantly greater mean time to revision than fixed-pressure valves.

Posture related in-vitro characterization of a flow regulated MEMS CSF valve.

Overdrainage in upright position is one of the most prevalent issues in treating hydrocephalus with a cerebrospinal fluid (CSF) shunt. Anti-siphon devices (ASDs) are employed to reduce this problem. A novel microelectromechanical system (MEMS)-based valve, termed Chronoflow device, aims to regulate CSF drainage indifferently of the body posture. With this study, the suitability of this MEMS-based valve is evaluated regarding its use for the treatment of hydrocephalus, particularly for the prevention of overdrainage and blockage. In total, four Chronoflow devices were tested. An established in-vitro hardware-in-the-loop (HIL) test bed was used to investigate the valves regarding their pressure-flow characteristics, their behaviors towards CSF dynamics, and their capabilities to prevent CSF overdrainage in upright position. Additionally, a contamination test was conducted to evaluate the susceptibility of the device to blockage due to particles. All valves tested regulated the drainage rate at similar nominal flows and independently of posture. The pressure-flow relation measured, however, was notably higher than numerically calculated. Regarding the CSF dynamics, the first three valves tested led to a decreased steady-state intracranial pressure in supine position and showed stable drainage rate in upright position. During the transitional phase from supine to upright and vice versa, the valves continuously adjusted the outflow resistance, which resulted in a stable transitional phase preventing overdrainage. Yet, the fourth valve showed continuous overdrainage in upright position due to an increased nominal flow. However, after several test iterations the nominal flow decreased and stabilized at a level similar to that of the first three valves tested. The contamination test showed that most particles initially adhere to the pillars and spread throughout the cavity of the valve as the concentration of particles increases, thereby affecting the displacement of the membrane. The devices generally provide a stable flow regulation and prevent overdrainage in upright position. Specifically, their drainage behaviors during the posture changes are very effective. However, they also showed high hysteresis and sensitivity towards particle contamination, which resulted in initial increased and altering nominal flows after many test iterations. This result suggests that the MEMS design presented lacks robustness. Yet, an upstream filter and specific coatings on the fluid pathway may increase significantly its reliability.

Trapped fourth ventricle: a rare complication in children after supratentorial CSF shunting.

PURPOSE: Trapped fourth ventricle (TFV) is a well-identified problem in hydrocephalic children. Patients with post-hemorrhagic hydrocephalus (PHH) are mostly affected. We tried to find out predisposing factors and describe clinical findings to early diagnose TFV and manage it. METHODS: We reviewed our database from 1991 to 2018 and included all patients with TFV who required surgery. We analyzed prematurity, cause of hydrocephalus, type of valve implanted, revision surgeries, modality of treatment of TFV, and their clinical examination and MRI imaging. RESULTS: We found 21 patients. Most of patients suffered from PHH (16/21), tumor (2/21), post-meningitis hydrocephalus (2/21), and congenital hydrocephalus (1/21). Seventeen patients were preterm. Seven patients suffered from a chronic overdrainage with slit ventricles in MRI. Thirteen patients showed symptoms denoting brain stem dysfunction; in 3 patients, TFV was asymptomatic and in 5 patients, we did not have available information regarding presenting symptoms due to missing documentation. An extra fourth ventricular catheter was the treatment of choice in 18/21 patients. One patient was treated by cranio-cervical decompression. Endoscopic aqueductoplasty with stenting was done in last 2 cases. CONCLUSION: Diagnosis of clinically symptomatic TFV and its treatment is a challenge in our practice of pediatric neurosurgery. PHH and prematurity are risk factors for the development of such complication. Both fourth ventricular shunting and endoscopic aqueductoplasty with stenting are effective in managing TFV. Microsurgical fourth ventriculostomy is not recommended due to its high failure rate. Early detection and intervention may help in avoiding fatal complication and improving the neurological function.

A comparison between flow-regulated and adjustable valves used in hydrocephalus during infancy.

INTRODUCTION: Ventriculoperitoneal shunt insertion during the neonatal period and early infancy is associated with a high rate of shunt failure when compared to the adult population. Furthermore, the function of flow-regulated valves and differential pressure valves may be different in neonatal hydrocephalus. METHODS: A retrospective case series of all primary shunt procedures carried out during or immediately following the neonatal period, from August 2011 to February 2018 at Sheffield Children's Hospital. The total sample size was 55. This included 34 patients with adjustable valves (Miethke ProGav) and 21 with flow-regulated valves (Orbis-Sigma); however, only 53 had adequate follow-up. RESULTS: The overall 1 year shunt survival was 34% (18/53), and there was no significant difference depending on which shunt valve was implanted. The primary shunt infection rate was 11% (6/53) with S. aureus being the most common causative organism. During the first year of life, clinical signs of shunt overdrainage were seen more frequently in patients with adjustable valves than in those with flow-regulated valves (59% [19/32] versus 24% [5/21], p = 0.02). Furthermore, 2 patients in the adjustable valve group developed sagittal craniosynostosis secondary to shunt overdrainage. CONCLUSION: Shunt failure is high when inserted during or immediately following the neonatal period. Overdrainage may be less common in patients with flow-regulated valves. However, if overdrainage is observed, adjusting the setting of a differential pressure valve can effectively treat the overdrainage without the need for invasive shunt revision surgery.

Management of paediatric hydrocephalous with Miethke fixed pressure gravitational valves. The Alder Hey Children's Hospital experience.

OBJECTIVE: The management of paediatric hydrocephalous remains challenging with the complication and revision rates being consistent in the literature. We hypothesise that the use of a fixed pressure gravitational valve for all de novo shunt insertions decreases the rate of functional revisions and that by implementing the routine use of gravitational valves in children, we would see a reduction in over-drainage and slit ventricle syndrome. METHODS: Retrospective data collection in a single centre, between February 2010 and August 2018. All patients undergoing fixed pressure gravitational Miethke valve insertion were included. We collected data on patients' demographics, reason for shunt insertion, type of valve and time to and reason for first revision. Data analysis was done with SPSS. RESULTS: A total of 235 patients were included in our study (124 males, 111 females), aged from 0 to 18.6 years (median 0.28). A total of 99 shunt revisions were documented, 30 of which secondary to ventricular catheter malfunction and 28 secondary to infection. The overall mechanical valve survival rates were 88.5%, 86.4% and 85.5% at 1, 2 and 5 years, respectively. Shunt revision due to over-drainage was documented in only 3 cases (1.3%). CONCLUSION: Our results are in agreement with existing literature regarding shunt failures secondary to all extrinsic factors to the valve (infection and mechanical failure). We have shown that the use of a Miethke fixed pressure valve for all de novo shunt insertions in paediatric hydrocephalus decreases the need for functional revisions with valve survival rates being superior to the ones described for other types.

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

OBJECTIVE: 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 flow performance 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 cm H2O within a simulated shunt system were generated and the specific flow characteristics were measured. In addition, combinations with SA, which is a gravity-dependent 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 cm H2O) 90°: 0.66 ml/min, 60°: 0.41 ml/min; CP (PL 2) 90°: 0.94 ml/min, 60°: 0.79 ml/min; p < 0.01); however, HM-SA 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 ± 0.04 ml/min with a HM (opening pressure 12 cm H2O) at 2 Hz and a DP of 10 cm H2O, 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.

In vitro performance of combinations of anti-siphon devices with differential pressure valves in relation to the spatial position.

BACKGROUND: Programmable differential pressure (DP) valves combined with an anti-siphon device (ASD) represent the current standard of care in preemtping overdrainage associated with ventriculoperitoneal shunting for hydrocephalus. OBJECTIVE: We aimed to provide comparative data of four combinations of two ASDs of different working principles in combination with two DP valves in an in vitro model in order to achieve a better understanding of the flow characteristics and potential clinical application. METHODS: We analyzed the flow performance of four possible combinations of two DP valves (CHPV [HM]; proGAV 2.0[PG]) in combination with either a gravity-regulated (Shuntassistant [SA]) or a flow-regulated (SiphonGuard [SG]) ASD in an in vitro setup. A DP between 4 and 60 cmH2O was generated, and the specific flow characteristics were measured. In addition, the two combinations with gravity-regulated ASDs were measured in defined spatial positions. RESULTS: Flow characteristics of the SA combinations corresponded to the DP in linear fashion and to the spatial position. Flow characteristics of the SG combinations were dependent upon the DP in a non-linear fashion and independent of the spatial position. Highest mean flow rate of the PG-SG- (HM-SG-) combination was 1.41 ± 0.24 ml/min (1.16 ± 0.06 ml/min). The mean flow rates sharply decreased with increasing inflow pressure and subsequently increased slowly up to 0.82 ± 0.26 ml/min (0.77 ± 0.08 ml/min). CONCLUSION: All tested device combinations were able to control hydrostatic effect and prevent consecutive excessive flow, to varying degrees. However, significant differences in flow characteristics can be seen, which might be relevant for their clinical application.

Flow-regulated versus differential pressure valves for idiopathic normal pressure hydrocephalus: comparison of overdrainage rates and neurological outcome.

BACKGROUND: To compare flow-regulated (FR) and differential pressure (DP) valves for treatment of patients with idiopathic normal hydrocephalus (iNPH) focusing on overdrainage and neurological outcome. METHODS: This is a retrospective study of patients with iNPH treated with FR and DP valves at a single institution between 2008 and 2018. The neurological status was evaluated retrospectively with the Kiefer scale at baseline, after shunt placement and at the 6-month follow-up. Groups were compared using inverse probability of treatment weighting based on propensity scores. RESULTS: The study cohort consisted of 38 patients treated with FR valves and 49 with DP valves. The mean patient age was 72.0 ± 7.6 years. Based on the Kiefer scale score, neurological improvement at the 6-month follow-up was recorded in 79.6% in the DP group and 89.5% in the FR group (p = 0.252). The overdrainage rates were higher among DP valves (10.2%) than among FR valves (2.6%, adjusted p = 0.002). Valve malfunction occurred in 2.0% in the DP group and 5.3% in the FR group (adjusted p = 0.667). CONCLUSIONS: The current study demonstrates a comparable neurological improvement between DP and FR valves, with potentially lower overdrainage rates among FR valves. Long-term studies will be necessary to draw a definite conclusion on FR valves for treatment of iNPH patients.

In NPH, setting valve opening pressure close to lumbar puncture opening pressure decreases overdrainage.

BACKGROUND: The management of normal pressure hydrocephalus (NPH) can be difficult, partly because there are frequent treatment complications such as overdrainage which, when serious, may require surgical intervention. We previously reported a correlation between the difference of lumbar puncture opening pressure minus the valve opening pressure setting (LPOP-VOP) (which we refer to as the delta) and increased rates of overdrainage. This led to a modification in our practice, whereby we now set the VOP equal to, or close to, the LPOP, resulting in lower deltas. OBJECTIVE: In this new study, our aim was to compare the rate of overdrainage in our patients with higher and lower deltas and assess the significance of setting the VOP equal, or close, to the patient's LPOP. METHODS: 1. We reproduced the association between delta and overdrainage. 2. We compared the incidence of overdrainage in those whose VOP was set close to LPOP (low delta) versus those with VOP setting distant from the LPOP (higher delta). 3. We compared symptom improvement in those with a low versus higher delta. RESULTS: We confirmed the relation between high delta and an increased rate of overdrainage, lower rates of overdrainage in those whose VOP was set close to the LPOP (Delta Adjusted Practice), and better improvement of symptoms when the VOP was set closer to the LPOP. CONCLUSION: We propose that the initial VOP should be set as close as possible to the patient's LPOP to decrease overdrainage without compromising symptom improvement.

Conservative and operative management of iatrogenic craniocerebral disproportion-a case-based review.

INTRODUCTION: Craniocerebral disproportion (CCD) can occur as a sequela after shunting in early infancy. It can be understood as a disorder closely related to slit ventricle syndrome and chronic overdrainage syndrome. Here, we present two exemplary cases and summarize the pathophysiological, diagnostic, and therapeutic approaches to CCD. CLINICAL PRESENTATION: Two premature babies underwent shunting for posthemorrhagic hydrocephalus and presented in later childhood with recurrent episodes of symptomatic raised intracranial pressure (ICP) at 2 and 8 years of age, respectively. DIAGNOSIS AND MANAGEMENT: Both patients had unchanged ventricular size on cranial imaging and fulfilled the clinical diagnostic criteria of CCD. After confirming shunt patency, ICP monitoring was performed to diagnose intermittent intracranial hypertension. Different treatment pathways were pursued: While readjustment of a programmable shunt valve was sufficient to alleviate the raised ICP in the first case, a cranial expansion surgery was necessary in the second case. OUTCOME AND CONCLUSIONS: Both children were treated successfully after thorough assessment and careful choice of treatment approaches. This review provides detailed insight into CCD and highlights the importance of individual and critical decision-making in these complex patients.

Refractory epilepsy associated with ventriculoperitoneal shunt over-drainage: case report.

Epilepsy and intracranial pressure (ICP) can be interrelated. While shunt malfunction is recognized as a cause of seizures, shunt over-drainage is seldom reported as such. We report a child who had undergone ventriculoperitoneal shunt insertion at the age of 6 months following an excision of a left ventricle choroid plexus papilloma, who developed refractory epilepsy since the age of 3 years. An MRI showed small ventricles. The child presented with acute hydrocephalus due to proximal shunt malfunction at the age of 11 years and was treated with an endoscopic third ventriculostomy. Following the procedure, the seizures abated. Our case suggests that intractable epilepsy may be related to intracranial hypotension. Potential treatments for shunt over-drainage may be indicated even in the absence of classic over-drainage symptoms, in the presence of refractory epilepsy.

Shunt independence in paediatric hydrocephalus: our 16-year experience and review.

PURPOSE: Shunt independence remains a matter of debate for neurosurgeons, and little information on this subject is available in the literature. The aims of the study were to analyse the incidence of shunt removal in a series of paediatric patients and to describe our experience with attempts at shunt removal. METHODS: Thirty of 212 paediatric patients shunted between 2000 and 2016 at our institution were studied for shunt independence. Variables related to hydrocephalus aetiology, shunt complications, independence trial peculiarities and follow-up were recorded and a descriptive analysis of the data was performed. RESULTS: Two patients (0.94%) refused to be included in a shunt independence trial and were analysed separately. In the other 28 patients, 29 shunt independence trials were performed, of which 19 (65.52%) were successful, giving a global rate of shunt independence of 8.96% (19/212) in our population. Secondary endoscopic third ventriculostomy was the most frequent type of independence trial and achieved the highest success rate (75%). Spontaneous independence was achieved in just 4/7 cases (57.14%). Planned removal of the shunt in overdrainage cases had a 50% success rate, with transient measures to control intracranial pressure frequently required. CONCLUSIONS: Shunt independence trials should be considered for selected patients in a closely monitored setting. Secondary endoscopic third ventriculostomy at the time of shunt malfunction has the highest success rate whereas planned removal of the shunt in overdrainage is an invasive procedure with more likelihood of failure. Shunt independence should not be presumed.

Chronic overdrainage syndrome: pathophysiological insights based on ICP analysis: a case-based review.

INTRODUCTION: Chronic overdrainage affects shunted patients producing a variety of symptoms that may be misdiagnosed. The best known symptoms are so-called shunt-related headaches. There is mounting evidence that changes in cerebrospinal venous system dynamics are a key factor to the pathophysiology of chronic overdrainage syndrome. CLINICAL PRESENTATION: We report the case of a 29-year-old woman with a shunt since the postnatal period suffering from chronic but the most severe intermittent headache attacks, despite an open shunt and with unchanged ventricular width during attacks. Intracranial pressure (ICP) recordings were performed during headache attacks and thereafter. DIAGNOSIS AND MANAGMENT: Massively increased ICPs, a continuous B wave "storm," and severely compromised intracranial compliance despite an open shunt were found, a scenario that was always self-limiting with the resolution of symptoms after several hours. When mobilized to the upright position, her ICPs dropped to - 17 mm Hg, proving shunt overdrainage. OUTCOME AND CONCLUSIONS: Symptomatology can only be explained by sudden venous entrapment following chronic venous distention as a result of chronic overdrainage. Subsequent therapeutic management with an overdrainage preventing shunt and satisfying clinical outcome with complete ceasing of headache attacks adds insight into the pathophysiology of chronic overdrainage syndrome.

A counterforce to diversion of cerebrospinal fluid during ventriculoperitoneal shunting: the intraperitoneal pressure. An observational study.

BACKGROUND: Intraperitoneal pressure (IPP) counteracts the diversion of cerebrospinal fluid (CSF) from the cranial to the peritoneal compartment during ventriculoperitoneal shunting. Animal studies suggest that the intrinsic IPP exceeds the intraperitoneal hydrostatic pressure. The intrinsic IPP in mobile patients is relevant for shunt therapy, but data about it is not available. METHODS: The IPP was measured indirectly in 25 mobile subjects (13 female) by applying a standard intravesical pressure measurement technique. Measurements were carried out in reference to the navel (supine position) and the xiphoid (upright position). Results were adjusted for the intraperitoneal hydrostatic pressure and correlated afterward with general body measures. RESULTS: The corrected mean (SD) IPP measured in the supine position was 4.4 (4.5) cm H2O, and the mean (SD) upright IPP was 1.6 (7.8) cm H2O (p = 0.02). A positive correlation was found between the body mass index (BMI) and the IPP in the upright (r = 0.51) and supine (r = 0.65) body positions, and between the abdominal circumference and the IPP in the supine position (r = 0.63). CONCLUSIONS: The intrinsic IPP in mobile subjects exceeds the intraperitoneal hydrostatic pressure. Thus, the intrinsic IPP counteracts the diversion of CSF into the peritoneal compartment. The intrinsic IPP is correlated with mobile patients' general body measures.