Tag: Overdrainage

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Initial Clinical Experience and Biomechanical Analysis of a Novel Gravity Unit–Assisted Valve (M.blue) in Pediatric Patients With Hydrocephalus

Neurosurgery 93:555–562, 2023

Overdrainage is a widely reported complication representing common indication for shunt revision. Despite recent advances in valve design, repeated shunt revisions represent burden on healthcare systems.

OBJECTIVE: To investigate the efficiency of a novel gravity unit–assisted programmable valve “M.blue” in pediatric hydrocephalus using clinical and biomechanical analyses.

METHODS: This retrospective single-center study included pediatric patients who received M.blue valve between April 2019 and 2021. Several clinical and biomechanical parameters were documented including complications and revision rates. Flow rate, functional assessment in vertical and horizontal positions, and extent of depositions inside valve were analyzed in explanted valves.

RESULTS: Thirty-seven M.blue valves in 34 pediatric patients with hydrocephalus (mean age 2.82 ± 3.91 years) were included. Twelve valves (32.4%) were explanted during a follow-up period of 27.3 ± 7.9 months. One-year survival rate of 89% and overall survival rate of 67.6% with a valve survival average of 23.8 ± 9.7 months were observed. Patients with explanted valves (n = 12) were significantly younger, with 0.91 ± 0.54 years of age in average (P= .004), and showed significantly more adjustments difficulties (P= .009). 58.3% of explanted valves showed deposits in more than 75% of the valve surface despite normal cerebrospinal fluid findings and were associated with dysfunctional flow rate in vertical, horizontal, or both positions.

CONCLUSION: The novel M.blue valve with integrated gravity unit is efficient in pediatric hydrocephalus with comparable survival rate. Deposits inside valves could affect its flow rate in different body positions and might lead to dysfunction or difficulties in valve adjustments.

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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.

 

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A counterforce to diversion of cerebrospinal fluid during ventriculoperitoneal shunting: the intraperitoneal pressure

Acta Neurochirurgica (2018) 160:519–524

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.

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Comparison of anti-siphon devices—how do they affect CSF dynamics in supine and upright posture?

Acta Neurochir (2017) 159:1389–1397

Three different types of anti-siphon devices (ASDs) have been developed to counteract siphoning induced overdrainage in upright posture. However, it is not known how the different ASDs affect CSF dynamics under the complex pressure environment seen in clinic due to postural changes. We investigated which ASDs can avoid overdrainage in upright posture best without leading to CSF accumulation.

Methods Three shunts each of the types Codman Hakim with SiphonGuard (flow-regulated), Miethke miniNAV with proSA (gravitational), and Medtronic Delta (membrane controlled) were tested. The shunts were compared on a novel in vitro setup that actively emulates the physiology of a shunted patient. This testing method allows determining the CSF drainage rates, resulting CSF volume, and intracranial pressure in the supine, sitting, and standing posture.

Results The flow-regulated ASDs avoided increased drainage by closing their primary flow path when drainage exceeded 1.39 ± 0.42 mL/min. However, with intraperitoneal pressure increased in standing posture, we observed reopening of the ASD in 3 out of 18 experiment repetitions. The adjustable gravitational ASDs allow independent opening pressures in horizontal and vertical orientation, but they did not provide constant drainage in upright posture (0.37 ± 0.03 mL/min and 0.26 ± 0.03 mL/min in sitting and standing posture, respectively). Consequently, adaptation to the individual patient is critical. The membrane-controlled ASDs stopped drainage in upright posture. This eliminates the risk of overdrainage, but leads to CSF accumulation up to the volume observed without shunting when the patient is upright.

Conclusions While all tested ASDs reduced overdrainage, their actual performance will depend on a patient’s specific needs because of the large variation in the way the ASDs influence CSF dynamics: while the flow-regulated shunts provide continuous drainage in upright posture, the gravitational ASDs allow and require additional adaptation, and the membrane-controlled ASDs show robust siphon prevention by a total stop of drainage.

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Female gender predisposes for cerebrospinal fluid overdrainage in ventriculoperitoneal shunting

Female gender predisposes for cerebrospinal fluid overdrainage in ventriculoperitoneal shunting

Acta Neurochir (2016) 158:1273–1278

Gravitational valves (GVs) prevent overdrainage in ventriculoperitoneal shunting (VPS). However, there are no data available on the appropriate opening pressure in the shunt system when implementing a GV. We performed a retrospective analysis of hydrocephalic patients who were successfully treated with VPS which included one or more GV.

Method In this retrospective study in adult VPS patients with GVs, we analysed all available data, including the most recent computed tomography (CT) scans, to determine the best adjustments for alleviating any symptoms of overdrainage and underdrainage. Vertical effective opening pressure (VEOP) of the entire shunt system, including the differential pressure valve, was determined.

Results One hundred and twenty-two patients were eligible for the study. Of these, female patients revealed a higher VEOP compared with males (mean, 35.6 cmH2O [SD ± 2.46] vs 28.9 cmH2O [SD±0.87], respectively, p=0.0072, t-test). In patients older than 60 years, lower VEOPs, by a mean of 6.76 cmH2O± 2.37 (p = 0.0051), were necessary. Mean VEOP was found to be high in idiopathic intracranial hypertension (IIH; 41.6 cmH2O) and malresorptive and congenital HC (35.9 and 36.3), but low in normal pressure HC (27.5, p =0.0229; one-way ANOVA). In the total cohort, body mass index (BMI) and height did not correlate with VEOP. Twelve patients required a VEOP of more than 40 cmH2O, and in eight of these patients this was accomplished by using multiple GVs. All but one of these eight patients were of female gender, and none of the latter were treated for normal pressure hydrocephalus (NPH) (p = 0.0044 and p = 0.0032, Fisher’s exact test).

Conclusions In adult VPS patients, female gender increases the risk of overdrainage requiring higher VEOPs. Initial implantation of adjustable GV should be considered in female patients treated with VP shunts for pathology other than NPH.

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Overdrainage shunt complications in idiopathic normal-pressure hydrocephalus and lumbar puncture opening pressure

Shunt complications of overdrainage

J Neurosurg 119:1498–1502, 2013

Management of idiopathic normal-pressure hydrocephalus (iNPH) is hard because the diagnosis is difficult and shunt surgery has high complication rates. An important complication is overdrainage, which often can be treated with adjustable–shunt valve manipulations but also may result in the need for subdural hematoma evacuation. The authors evaluated shunt surgery overdrainage complications in iNPH and their relationship to lumbar puncture opening pressure (LPOP).

Methods. The authors reviewed the charts of 164 consecutive patients with iNPH who underwent shunt surgery at their institution from 2005 to 2011. They noted age, sex, presenting symptoms, symptom duration, hypertension, body mass index (BMI), imaging findings of atrophy, white matter changes, entrapped sulci, LPOP, valve opening pressure (VOP) setting, number of valve adjustments, serious overdrainage (subdural hematoma requiring surgery), radiological overdrainage (subdural hematomas or hygroma seen on postoperative imaging), clinical overdrainage (sustained or postural headache), other complications, and improvements in gait, urine control, and memory.

Results. Eight patients (5%) developed subdural hematomas requiring surgery. All had an LPOP of greater than 160 mm H2O and an LPOP-VOP of greater than 40 mm H2O. Radiological overdrainage was more common in those with an LPOP of greater than 160 mm H2O than in those with an LPOP of less than 160 mm H2O (38% vs 21%, respectively; p = 0.024). The BMI was also significantly higher in those with an LPOP of greater than 160 mm H2O (median 30.2 vs 27.0, respectively; p = 0.005).

Conclusions. Serious overdrainage that caused subdural hematomas and also required surgery after shunting was related to LPOP and LPOP-VOP, which in turn were related to BMI. If this can be replicated, individuals with a high LPOP should have their VOP set close to the LPOP, or even higher. In doing this, perhaps overdrainage complications can be reduced.

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Shunting with gravitational valves—can adjustments end the era of revisions for overdrainage-related events?

overshunting with gravitational valves—can adjustments end the era of revisions for overdrainage-related events?

J Neurosurg 117:1197–1204, 2012

Overdrainage of CSF remains an unsolved problem in shunt therapy. The aim of the present study was to evaluate treatment options on overdrainage-related events enabled by the new generation of adjustable gravityassisted valves.

Methods. The authors retrospectively studied the clinical course of 250 consecutive adult patients with various etiologies of hydrocephalus after shunt insertion for different signs and symptoms of overdrainage. Primary and secondary overdrainage were differentiated. The authors correlated the incidence of overdrainage with etiology of hydrocephalus, opening valve pressure, and patient parameters such as weight and size. Depending on the severity of overdrainage, they elevated the opening pressure, and follow-up was performed until overdrainage was resolved.

Results. The authors found 39 cases (15.6%) involving overdrainage-related problems—23 primary and 16 secondary overdrainage. The median follow-up period in these 39 patients was 2.1 years. There was no correlation between the incidence of overdrainage and any of the following factors: sex, age, size, or weight of the patients. There was also no statistical significance among the different etiologies of hydrocephalus, with the exception of congenital hydrocephalus. All of the “complications” could be resolved by readjusting the opening pressure of the valve in one or multiple steps, avoiding further operations.

Conclusions. Modern adjustable and gravity-assisted valves enable surgeons to set the opening pressure relatively low to avoid underdrainage without significantly raising the incidence of overdrainage and to treat overdrainagerelated clinical and radiological complications without surgical intervention.

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Use of the proGAV Shunt Valve in Normal-Pressure Hydrocephalus

Neurosurgery 68[ONS Suppl 2]:ons245–ons249, 2011 DOI: 10.1227/NEU.0b013e318214a809

Overdrainage is a common complication associated with shunt insertion in normal-pressure hydrocephalus (NPH) patients. Using adjustable valves with antigravity devices has been shown to reduce its incidence. The optimal starting setting of an adjustable shunt valve in NPH is debatable.

OBJECTIVE: To audit our single-center practice of setting adjustable valves.

METHODS: We performed a retrospective review of clinical records of all NPH patients treated in our unit between 2006 and 2009 by the insertion of shunts with a proGAV valve, recording demographic and clinical data, shunt complications, and revision rates. Radiological reports of postoperative follow-up computed tomography scans of the brain were reviewed for detected subdural hematomas.

RESULTS: A proGAV adjustable valve was inserted in 50 probable NPH patients between July 2006 and November 2009. Mean 6 SD age was 76 6 7 years. Mean follow-up was 15 months. The initial shunt setting was 6 6 3 cmH2O, and the final setting was 4.9 6 1.9 cm H2O. Nineteen patients required 24 readjustment procedures (readjustment rate, 38%; readjustment number, 0.48 times per patient). One patient (2%) developed delayed bilateral subdural hematoma after readjustment of his shunt valve setting as an outpatient.

CONCLUSION: Starting with a low opening pressure setting on a proGAV adjustable shunt valve does not increase the chances of overdrainage complications and reduces the need for repeated readjustments.

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