Adjustable Differential Pressure Valve Research Articles

A single center experience of adjusting valve pressure ventriculoperitoneal shunts for the treatment of hydrocephalus in infants under 6 months old.

Ventriculoperitoneal shunt (VPS) with adjustable differential pressure valves are commonly used to treat infants with hydrocephalus avoiding shunt related under- or overdrainage. The aim of this study was to analyse the influence of VPS adjustable differential pressure valve on the head circumference (HC) and ventricular size (VS) stabilization in infants with post intraventricular haemorrhage, acquired and congenital hydrocephali. Forty-three hydrocephalic infants under 6 months old were prospectively included between 2014 and 2018. All patients were treated using a VPS with adjustable differential pressure valve. HC and transfontanelle ultrasonographic VS measurements were regularly performed and pressure valve modifications were done aiming HC and VS percentiles between the 25th and 75th. The patients were divided into two groups: infants with hydrocephalus due to an intraventricular haemorrhage (IVH-H), and infants with hydrocephalus due to other aetiologies (OAE-H). The mean of pressure valve modification was 3.7 per patient in the IVH-H group, versus 2.95 in the OAE-H group. The median of last pressure valve value was higher at 8.5 cm H2O in the IVH-H group comparing to 5 cm H2O in the OAE-H group (p = 0.013). Optimal VPS pressure valve values could be extremely difficult to settle in order to gain normalisation of the HC and VS in infants. However, after long term follow up (mean of 18 months) and several pressure valve modifications, this normalisation is possible and shows that infants with IVH-H need a higher pressure valve value comparing to infants with OAE-H.

Ultra-low-pressure hydrocephalic state in NPH: benefits of therapeutic siphoning with adjustable antigravity valves.

Idiopathic normal-pressure hydrocephalus (NPH) is a condition of the elderly treated by ventriculoperitoneal shunt (VP) insertion. A subset of NPH patients respond only temporarily to shunt insertion despite low valve opening pressure. This study aims to describe our experience of patients who benefit from further CSF drainage by adding adjustable antigravity valves and draining CSF at ultra-low pressure. Single-centre retrospective case series of patients undergoing shunt valve revision from an adjustable differential pressure valve with fixed antigravity unit to a system incorporating an adjustable gravitational valve (Miethke proSA). Patients were screened from a database of NPH patients undergoing CSF diversion over 10 consecutive years (April 2008-April 2018). Clinical records were retrospectively reviewed for interventions and clinical outcomes. Nineteen (10F:9M) patients underwent elective VP shunt revision to a system incorporating an adjustable gravitational valve. Mean age 77.1 ± 7.1 years (mean ± SD). Eleven patients (58%) showed significant improvement in walking speed following shunt revision. Fourteen patients/carers (74%) reported subjective improvements in symptoms following shunt revision. Patients presenting symptoms relapse following VP shunting may represent a group of patients with ultra-low-pressure hydrocephalus, for whom further CSF drainage may lead to an improvement in symptoms. These cases may benefit from shunt revision with an adjustable gravitational valve, adjustment of which can lead to controlled siphoning of CSF and drain CSF despite ultra-low CSF pressure.

Experience in shunt management on revision free survival in infants with myelomeningocele.

Depending on the etiology of hydrocephalus in childhood, the shunt therapy still remains challenging due to frequent shunt complications leading to possible revisions such as shunt infection or shunt malfunction. In myelomeningocele (MMC) patients who often require shunt therapy, higher revisions rates were reported. In a single-center retrospective study, experiences on shunt regimen on hydrocephalus associated with MMC are presented. Data of 160 infant hydrocephalus cases younger than 1year of age at the time of implantation were retrospectively reviewed from the hospital database. These patients received an adjustable differential pressure valve with gravitational unit and antibiotic impregnated catheters as a primary or secondary implant during the time period of April 2007 to July 2015. The subgroup of infants cases with MMC (n = 44; age 50.6 ± 80.6days) were compared to the remaining cohort of other hydrocephalus etiology (control group). The shunt and valve revision free survival rates were recorded until July 2017. During the mean follow-up of 48.7 ± 19.2 (7-114) months, the shunt revision free survival was 87% at 1year and 49% at 60months in the MMC cohort. The control group showed a shunt survival rate of 68% at 1year and 39% at 60months. Similarly, the valve revision free survival rate showed a significant higher rate of 92% at 1year and 69% at 60months in the MMC group compared to the control group (75% at 1year and 51% at 60months; p < 0.05). During the entire follow-up period, 37% of the MMC infants underwent a revision operation in contrast to the control group of 40%. The presented shunt strategy showed improved revision free survival rates in infants with a MMC-related hydrocephalus in comparison to other etiologies of hydrocephalus in infants, which might relate to infection prophylaxis and high drainage resistance integrated in the shunt system.

Valve exchange towards an adjustable differential pressure valve with gravitational unit, clinical outcome of a single-center study.

Overdrainage in children is a long-term problem for shunted patients which might lead to chronic anatomical changes. In order to prevent these problems, valve exchange is performed on a regular basis in patients without hydrostatic units towards a valve with both an adjustable and a gravitational unit. The clinical outcome of these patients is reported in a retrospective study. Between 2009 and 2014, the in-house database was analyzed for patients who received a valve exchange towards an adjustable differential pressure valve with gravitational unit. The study protocol included the patients shunt history, image analysis for ventricular width, and necessity of revision surgery after valve exchange. A questionnaire was sent to the patients in order to ask for their subjective experience for symptom changes and treatment experience. Forty-six patients were identified (26 girls, mean age 11.8±6.1years) with a mean follow-up of 36.3±15months. The ventricular width did increase after valve exchange as measured in frontal and occipital horn ratio (0.364±0.032 vs. 0.402±0.09, p=0.0017). Of the patients suffering from acute symptoms, 89% improved after treatment. The shunt and valve survival rates were 88 and 95%, respectively, after 12months. Comparing the total amount of revisions before and after valve exchange, a significant reduction was seen in total but a no significant difference was analyzed in amount of revisions to time ratio. Valve exchange might be cautiously decided if patients seem to perform clinically well. In our study, we were able to show that the strategy of valve exchange to prevent chronic overdrainage is well tolerated and seem to improve patient's clinical outcome in terms of ventricular width, symptom relieve, and revision rate.

Long-term survival rates of gravity-assisted, adjustable differential pressure valves in infants with hydrocephalus.

OBJECTIVE The use of adjustable differential pressure valves with gravity-assisted units in shunt therapy of children with hydrocephalus was reported to be feasible and promising as a way to avoid chronic overdrainage. In this single-center study, the authors' experiences in infants, who have higher rates of shunt complications, are presented. METHODS All data were collected from a cohort of infants (93 patients [37 girls and 56 boys], less than 1 year of age [mean age 4.1 ± 3.1 months]) who received their first adjustable pressure hydrocephalus shunt as either a primary or secondary implant between May 2007 and April 2012. Rates of valve and shunt failure were recorded for a total of 85 months until the end of the observation period in May 2014. RESULTS During a follow-up of 54.2 ± 15.9 months (range 26-85 months), the Kaplan-Meier rate of shunt survival was 69.2% at 1 year and 34.1% at 85 months; the Kaplan-Meier rate of valve survival was 77.8% at 1 year and 56% at 85 months. Survival rates of the shunt were significantly inferior if the patients had previous shunt surgery. During follow-up, 44 valves were exchanged in cases of infection (n = 19), occlusion (n = 14), dysfunction of the adjustment unit (n = 10), or to change the gravitational unit (n = 1). CONCLUSIONS Although a higher shunt complication rate is observed in infant populations compared with older children, reasonable survival rates demonstrate the feasibility of using this sophisticated valve technology. The gravitational unit of this valve is well tolerated and its adjustability offers the flexible application of opening pressure in an unpredictable cohort of patients. This may adequately address overdrainage-related complications from early in treatment.

The Frankfurt horizontal plane as a reference for the implantation of gravitational units: a series of 376 adult patients.

The in-line combination of adjustable differential pressure valves with fixed gravitational units is increasingly recommended in the literature. The spatial positioning of the gravitational unit is thereby decisive for the valve opening pressure. We aimed at providing data on factors contributing to primary overdrainage and underdrainage of cerebrospinal fluid (CSF), with special attention paid to the implantation angle of the gravitational unit. Weretrospectively analyzed the postoperative course of 376 consecutive patients who received a ventriculoperitoneal shunt with a proGAV valve. The incidence of both primary CSF overdrainage and underdrainage was correlated with the implantation angle of the gravitational unit in regard to the Frankfurt horizontal plane and the patients' general parameters. Primary overdrainage was found in 41 (10.9 %) patients. Primary underdrainage was found in 113 (30.1 %) patients. A mean deviation of 10° (±7.8) for the gravitational unit in regard to the vertical line to the Frankfurt horizontal plane was found. In 95 % of the cases the deviation was less than 25°. No significant correlation between the implantation angle and the incidence of overdrainage or underdrainage of CSF was found. The patients' age and having single hydrocephalus entities were identified as factors significantly predisposing patients to overdrainage or underdrainage. The implantation of the gravitational unit of the proGAV valve within a range of at least 10° in regard to the vertical line to the Frankfurt horizontal plane does not seem to predispose patients to primary overdrainage or underdrainage in ventriculoperitoneal shunting. The plane may serve as a useful reference for the surgeon's orientation.

Shunt survival rates by using the adjustable differential pressure valve combined with a gravitational unit (proGAV) in pediatric neurosurgery

Overdrainage is a chronic complication in shunted pediatric patients with hydrocephalus. The use of adjustability of differential pressure (DP) valves in combination with antisiphoning devices may help to overcome this sequela and may diminish the rate of possible shunt failures. The purpose of this retrospective study is to report our experience on shunt survival and infection rate with an adjustable DP valve with integrated gravitational unit in pediatric hydrocephalus. The proGAV consists of an adjustable differential pressure (DP) valve and a gravitational unit. During the time period of July 2004 and December 2009, a total of 237 adjustable gravitational valves were used in 203 children (age, 6.5 ± 6.54; 0-27years). In the follow-up period, valve and shunt failures as well as rate of infection were recorded. Within the average follow-up time of 21.9 ± 10.3months (range, 6-72months), the valve survival rate was 83.8%. The overall shunt survival rate including all necessary revisions was 64.3%. Looking at the group of infants (<1year of age) within the cohort, the valve survival rate was 77.3% and the shunt survival rate was 60.9%. The overall infection rate was 4.6%. In a concept of avoiding chronic overdrainage by using the proGAV in hydrocephalic children, we observed a good rate of valve and shunt survival. Compared to previous reported series, we experienced the proGAV as a reliable tool for the treatment of pediatric hydrocephalus.

Experience with a gravitational valve in the management of symptomatic overdrainage in children with shunts

Symptomatic overdrainage in children with shunt-treated hydrocephalus represents one of the more difficult shunt-related diseases and may require repeated surgery. Gravity-assisted valve design has become a standard device to avoid overdrainage in many European pediatric hydrocephalus centers. However, the use of a gravitational valve for relieving symptoms associated with overdrainage has not yet been addressed. The goal of this study was to evaluate the effectiveness of a gravitational valve in the treatment of symptomatic overdrainage in children with shunts. Seventeen children with an adjustable shunt system and symptomatic overdrainage were treated by insertion of a gravitational valve. Clinical and radiological outcome were monitored for a minimum of 12 months after surgery. Implantation of a gravitational valve resulted in either resolution (n = 12) or improvement (n = 5) of the symptoms. In 1 patient, symptoms remained almost unchanged and the gravitational valve had to be upgraded, resulting in resolution of the symptoms. During follow-up, the pressure setting of the adjustable differential pressure valve had to be changed in 7 patients. The gravitational valve was effective in improving symptomatic overdrainage in the majority of patients in the present study. Because the ideal pressure setting for a given patient is hard to determine a priori, adjustable valve systems appear to be beneficial.

Early programmable valve malfunctions in pediatric hydrocephalus

The use of adjustable differential pressure valves has been recommended to improve ventriculoperitoneal (VP) shunt performance in selected patients; however, published data are scarce regarding their clinical reliability. Recently, the identification of a number of malfunctioning programmable valves during shunt revision surgery in children prompted a retrospective review of valve performance in this patient cohort. The authors performed a retrospective chart analysis of 100 patients with programmable valve shunts and 89 patients with nonprogrammable valve shunts implanted at the St. Louis Children's Hospital between April 2002 and June 2004. They noted the cause of hydrocephalus, the type of shunt malfunction, and cerebrospinal fluid (CSF) protein levels. Regular clinical follow up ranged from 1 to 26 months, with a mean follow-up time of 9.75 months for patients with programmable valves and 10.4 months for patients with nonprogrammable valves. Patient ages ranged from 2 weeks to 18 years. One hundred patients had 117 programmable valves implanted, and 35 of these patients (35%) underwent shunt revision because of malfunction. The programmable valve itself malfunctioned in nine patients who had undergone shunt revision (11.1%/year of follow up). The nonprogrammable valve group had no valve malfunctions. The overall VP shunt revision rate in the nonprogrammable valve group was 20.2%. No significant differences were identified when CSF protein levels and specific malfunction types were compared within the programmable valve and nonprogrammable valve groups. In this study the authors demonstrated an annualized intrinsic programmable valve malfunction rate of 11.1%, whereas during the same period no intrinsic valve malfunctions were noted with nonprogrammable valve systems for similar causes of hydrocephalus. The CSF protein levels did not correlate with observed valve malfunction rates. Further evaluation in a prospective, randomized fashion will elucidate specific indications for programmable valve systems and better determine the reliability of these valves in the pediatric population.