Hydrodynamic properties of hydrocephalus shunts: United Kingdom Shunt Evaluation Laboratory.

Czosnyka, Marek; Czosnyka, Zofia; Whitehouse, Helen; Pickard, John D.

doi:10.1136/jnnp.62.1.43

Cited by 63 publications

(56 citation statements)

References 17 publications

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“…4,15 However, prospective studies of the effect of an ASD at different opening pressures are scarce. The objective of this study was not to evaluate the effect of the ASD on shunt complications, overdrainage symptoms, or clinical outcome.…”

Section: Antisiphon Devicementioning

confidence: 99%

A randomized controlled dual-center trial on shunt complications in idiopathic normal-pressure hydrocephalus treated with gradually reduced or “fixed” pressure valve settings

Sæhle

Farahmand

Eide

et al. 2014

JNS

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I dIopathIc normal pressure hydrocephalus (iNPH) is a treatable condition, first described by Hakim in 1965. 10 It is characterized clinically by gait disturbance, cognitive impairment, and urinary incontinence and radiologically by ventriculomegaly. The condition is typically diagnosed in the elderly and most often treated by insertion of a ventriculoperitoneal (VP) shunt with either a fixed or an adjustable pressure valve. Adjustable valves were designed to lower the complication rate and optimize the effect of shunting. 26 After shunt surgery in iNPH patients, improvement rates between 61% and 90% have been reported, 6,[11][12][13][14]16,18,23 with recent studies revealing a rate above 80%. 13,24 The complication rates are high, up to 50%, 3,8,22 although a rate of 20% is evident in recent studies. 8,26 The major complications are mechanical obstruction, infection, and subdural hematoma (SDH); the frequency of SDH is between 2% and 16%. 7,13,23 A Dutch NPH study recommended the use of a low A randomized controlled dual-center trial on shunt complications in idiopathic normal-pressure hydrocephalus treated with gradually reduced or "fixed" pressure valve settings Object. This study was undertaken to investigate whether a gradual reduction of the valve setting (opening pressure) decreases the complication rate in patients with idiopathic normal-pressure hydrocephalus (iNPH) treated with a ventriculoperitoneal (VP) shunt.Methods. In this prospective double-blinded, randomized, controlled, dual-center study, a VP shunt with an adjustable valve was implanted in 68 patients with iNPH, randomized into two groups. In one group (the 20-4 group) the valve setting was initially set to 20 cm H 2 O and gradually reduced to 4 cm H 2 O over the course of the 6-month study period. In the other group (the 12 group), the valve was kept at a medium pressure setting of 12 cm H 2 O during the whole study period. The time to and type of complications (hematoma, infection, and mechanical problems) as well as overdrainage symptoms were recorded. Symptoms, signs, and outcome were assessed by means of the iNPH scale and the NPH grading scale.Results. Six patients in the 20-4 group (22%) and 7 patients in the 12 group (23%) experienced a shunt complication; 9 had subdural hematomas, 3 mechanical obstructions, and 1 infection (no significant difference between groups). The frequency of overdrainage symptoms was significantly higher for a valve setting ≤ 12 cm H 2 O compared with a setting > 12 cm H 2 O. The 20-4 group had a higher improvement rate (88%) than the 12 group (62%) (p = 0.032). There was no significant relationship between complications and body mass index, the use of an antisiphon device, or the use of anticoagulants.Conclusions. Gradual lowering of the valve setting to a mean of 7 cm H 2 O led to the same rate of shunt complications and overdrainage symptoms as a fixed valve setting at a mean of 13 cm H 2 O but was associated with a significantly better outcome. (http://thejns.org/doi/abs/10.3171/2014.7.JNS14283) Key Wo...

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Section: Antisiphon Devicementioning

confidence: 99%

A randomized controlled dual-center trial on shunt complications in idiopathic normal-pressure hydrocephalus treated with gradually reduced or “fixed” pressure valve settings

Sæhle

Farahmand

Eide

et al. 2014

JNS

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“…The CSF flow (Q) through the internal drainage system is governed by the pressure gradient between the ventricle and the peritoneal area (∆P) and the resistance (R) imposed by the neurological valve and the cylindrical ducts through which the fluid passes (Czosnyka et al, 1997;Drake and Sainte-Rose, 1994;Gusmão et al, 2000;Maset et al, 2009;Pudenz and Foltz, 1991), as shown in Equation 1.…”

Section: Methodsmentioning

confidence: 99%

“…Changes in the shunt components can modify the neurological valve pressure class and interfere in the treatment of hydrocephalus. Allin et al (2008), Czosnyka et al (1997Czosnyka et al ( , 2002 and Suriano et al (2012) presented their results with statistical analyses. However, there was no evidence of evaluation of the testing rigs used in the tests or the analysis of experimental uncertainties.…”

Section: Introductionmentioning

confidence: 99%

“…Cerebrospinal fluid (CSF) is a transparent fluid with density (Wood, 1980) and viscosity (Czosnyka et al, 1997;Lavinio et al, 2008) similar to those of water and is found in the interior of the human skull and the spinal column. This fluid is produced in the choroid plexuses through a filtration mechanism similar to that of renal glomeruli (Schimer, 1995), and it exits the central nervous system through holes covering the spinal cord and is absorbed in the brain by specialized veins that take up the spinal fluid in the bloodstream.…”

Section: Introductionmentioning

confidence: 99%

“…To perform pressure-flow tests and evaluate the valves' opening and closing, Allin et al (2008) and Czosnyka et al (1997;2002), employed a testing rig containing pressure transducers, a water reservoir at a constant level, an infusion pump, a pulse generator and an electronic balance, with an additional apparatus that allowed the testing of shunts in a pressurized environment. Suriano et al (2012), determined the relative pressure-flow rate of a shunt on a testing rig to show that changes to the original diameter and length of the peritoneal catheter, during installation of the implant or surgical revision, change the hydrodynamic behavior of the drainage system and can induce errors in the clinical evaluation of the patient by the neurosurgeon.…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of flow rate accuracy and pressure measurements of testing rig for neurological valve hydrodynamic tests

Pinto¹,

Maset²,

Andrade³

et al. 2014

RBEB

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Introduction: Increased production and disorders in the circulation or absorption of cerebrospinal fluid (CSF) leads to increased intracranial pressure and causes a condition called hydrocephalus. The most common treatment for this disorder is the implantation of a ventricle-peritoneal shunt, which consists of the insertion of a ventricular catheter in the cerebral ventricle, a neurological valve for drainage control and a peritoneal catheter that leads the CSF to the abdominal region. The International Organization for Standardization (ISO) 7197 introduced requirements for the design and production of the shunts and neurological valve, including in vitro hydrodynamic tests, which are indispensable for evaluating the performance of the CSF drainage systems. Methods: A testing rig built in accordance with ISO 7197 was evaluated for the uncertainty of flow and opening and closing pressure measurements, the pressure-flow relationship and reflux neurological valve resistance. The infusion pump and pressure measurement system were evaluated for calibration, hysteresis behavior and stability to determine the experimental uncertainties from hydrodynamic testing of two commercial products. Results: The equipment showed uncertainties of less than 1% in the infusion pump, less than 4% in the pressure sensor and adequate performance for the hydrodynamic tests. Conclusion: The hydrodynamic test rig allowed the opening and closing pressures and the resistance to reflux to be obtained, and it also allowed the determination of the pressure and flow rate characteristics of two neurological commercial valves with experimental uncertainties that do not impact the results and the evaluation of in vitro performance of a shunt.

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Hydrocephalus, Tools for Diagnosis and Treatment of

Alperin

Eklund

Sood

2006

Encyclopedia of Medical Devices and Instrumentation

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Hydrodynamic properties of hydrocephalus shunts: United Kingdom Shunt Evaluation Laboratory.

Cited by 63 publications

References 17 publications

A randomized controlled dual-center trial on shunt complications in idiopathic normal-pressure hydrocephalus treated with gradually reduced or “fixed” pressure valve settings

A randomized controlled dual-center trial on shunt complications in idiopathic normal-pressure hydrocephalus treated with gradually reduced or “fixed” pressure valve settings

Evaluation of flow rate accuracy and pressure measurements of testing rig for neurological valve hydrodynamic tests

Hydrocephalus, Tools for Diagnosis and Treatment of

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