Several studies prove the efficiency of our products. Our clinical experts provide the review of the latest scientific publications dedicated to our area of expertise in Neuromonitoring and Hydrocephalus. Find the links to the PubMed webpages below.

Sophy® Mini SM8 and Polaris®

Management of Neonatal Hydrocephalus: Feasibility of Use and Safety of Two Programmable (Sophy® and Polaris®) Valves.

Authors: Martínez-Lage JF, Almagro M-J, Del Rincón IS, Pérez-Espejo MA, Piqueras C, Alfaro R, Ros de

Citation: San Pedro J. Childs Nerv Syst. 2008 May;24(5):549-56

Background: Neonates represent a unique group of pediatric patients with special peculiarities. Hydrocephalus valves have not always been designed to meet the requirements of these small children. Few series have addressed the problem of cerebrospinal fluid shunting in newborn babies.

Objectives: We aimed (1) to evaluate the feasibility of the use of two programmable valves (Sophy® and Polaris®) in hydrocephalic neonates and (2) to ascertain complications and safety issues arising from their use.

Materials and methods: We performed a prospective study of 100 consecutive preterm and term babies (<2 months of age) given a programmable valve. Valves’ settings were readjusted at different pressure levels as required. Outcomes were obtained from the records of our Outpatient Clinic.

Results: The study group was formed by 60 term and 40 preterm infants (average weight 2.440 g, mean age of 25 days). Mean follow-up was 55 months. Only one fifth deaths was shunt-related. In 70 babies, no complications occurred, and hydrocephalus was successfully controlled. Proximal catheter obstruction presented in 20% and infection in 5% of cases. Several external adjustments of the valves apparently avoided several surgical shunt revisions.

Conclusions: (1) Both programmable valves (Sophy® and Polaris®) can be safely used for treatment of neonatal hydrocephalus, introducing some technical modifications. (2) Both valves are comparable to other shunts with regard to indications, performance, and safety. (3) The possibility of modifying their working pressure seems to constitute their main advantage. Prevention of late overdrainage syndromes with these valves needs a longer follow-up.

Sophysa’s comments:  The results of this study demonstrate that the design of Sophysa’s programmable valves (Sophy® Mini SM8 and Polaris®) allows a safely use in high-risk populations which includes neonates and preterm infants. For this specific population, the surgical technique used was essentially the same as the routine one used at the Authors’ Service, except for minor modifications. For all patients, valves were placed through a posterior parietal burr hole and a 16mm reservoir and a 5- to 6-cm ventricular catheter were implanted. The valves were initially set at a pressure of 70 mmH2O and then adjusted according to the patients’ clinical evolution.

In this study, no child given the Polaris® valve required a readjustment of the valve after MR or by any other accidental pressure-level variation, confirming the in vitro study results and the efficacy of the device magnetic lock.




Magnetic toys: forbidden for pediatric patients with certain programmable shunt valves?

Authors: Zuzak TJ, Balmer B, Schmidig D, Boltshauser E, Grotzer MA

Citation: Childs Nerv Syst. 2009 Feb;25(2):161-4

Background: Inadvertent adjustments and malfunctions of programmable valves have been reported in cases in which patients have encountered powerful electromagnetic fields such as those involved in magnetic resonance imaging, but the potential effects of magnetic toys on programmable valves are not well known.


Materials and methods: The magnetic properties of nine toy magnets were examined. To calculate the effect of a single magnet over a distance, the magnetic flux density was directly measured using a calibrated Hall probe at seven different positions between 0 and 120 mm from the magnet. Strata II small (Medtronic Inc.), Codman Hakim (Codman & Shurtleff), and Polaris (Sophysa) programmable valves were then tested to determine the effects of the toy magnets on each valve type.


Results: The maximal flux density of different magnetic toys differed between 17 and 540 mT, inversely proportional to the distance between toy and measurement instrument. Alterations to Strata and Codman valve settings could be affected with all the magnetic toys. The distances that still led to an alteration of the valve settings differed from 10 to 50 mm (Strata), compared with 5 to 30 mm (Codman). Valve settings of Polaris could not be altered by any toy at any distance due to its architecture with two magnets adjusted in opposite directions.


Conclusion: This is the first report describing changes in the pressure setting of some adjustable valves caused by magnetic toys in close contact. Parents, surgeons, neurologists, pediatric oncologists, and paramedics should be informed about the potential dangers of magnetic toys to prevent unwanted changes to pressure settings.


Sophysa’s comments:  The unique feature of the Polaris® valve is its magnetic lock which holds the rotor in the selected position, thus preventing any accidental change in operating pressure in patient’s daily life. The result of this report is a proof-of-concept with Polaris® valve pressure not being altered by any toys at any distances whereas it was shown that the magnetic properties of magnetic toys are of sufficient strength to alter programmable Strata and Codman valves.




Reliability of a new adjustable shunt device without the need for readjustment following 3-Tesla MRI

Authors: Lüdemann W, Rosahl SK, Kaminsky J, Samii M

Citation: Childs Nerv Syst. 2005 Mar;21(3):227-9.

Introduction: 3-Tesla (T) magnetic resonance imaging (MRI) offers high resolution imaging with improved signal quality. It also allows for improved functional investigations, most prominently with respect to fiber tracts and their relation to pathological lesions. Up to now, patients with adjustable shunt systems were not eligible for high field power magnetic resonance imaging. We have evaluated the effects of this technique upon a newly developed adjustable shunt valve.

Method: Ten adjustable shunt devices were examined during routine and functional 3-T high field MRI examinations. Pressure settings were checked after 17 examinations each for all valves. There were no changes in pressure setting at all possible levels in any of the tested devices. No problems with the adjusting mechanism were observed during 340 examinations.

Conclusion: This new shunt device offers the diagnostic benefit of high field magnetic resonance imaging in shunt-dependent patients who need an adjustable valve. The valve is not affected by higher magnetic field power and does not require readjustment of the pressure settings after MRI examination.

Sophysa’s comments:  The present results demonstrate the reliability of the Polaris® valve in 3-T MRI with respect to the stability of the previously adjusted level and the adjustment mechanism thanks to the two micro-magnets in the device. Polaris® valve allows safe MRI examination for patients.




Programmable shunt valves: in vitro assessment of safety of the magnetic field generated by a portable game machine

Authors: Nakashima K, Nakajo T, Kawamo M, Kato A, Ishigaki S, Murakami H, Imaizumi Y, Izumiyama H

Citation: Neurol Med Chir (Tokyo) 51, 635~638, 2011.

Background: Cerebrospinal fluid (CSF) shunts are frequently used to treat hydrocephalus. The use of a programmable shunt valve allows physicians to easily change the opening pressure. Since patients with adjustable CSF shunt valves may use portable game machines, the permanent magnets in these machines may alter the shunt valve programmed settings or permanently damage the device.


Objective: This study investigated the risk of unintentional valve adjustment associated with the use of game machines in patients with programmable CSF shunt valves.


Material and Methods: Four adjustable valves from 4 different manufacturers, Sophysa Polaris® model SPV (Polaris® valve), Miethke proGAV (proGAV), Codman Hakim programmable valve (CHPV), and Strata II small valve (Strata valve), were evaluated. Magnetic field interactions were determined using the portable game machine, Nintendo DS Lite (DS). The maximum distance between the valve and the DS that affected the valve pressure setting was measured by x-ray cinematography.


Results: The Polaris® valve and proGAV were immune to unintentional reprogramming by the DS. However, the settings of the CHPV and Strata valves were randomly altered by the DS.


Conclusion: Patients with an implanted shunt valve should be made aware of the risks posed by the magnetic fields associated with portable game machines and commonly used home electronics.


Sophysa’s comments: Results of this in vitro study confirm the efficacy of Polaris® magnetic lock, thus preventing any accidental change in operating pressure in patient’s daily life when using portable game machines.


Investigation of the hydrodynamic properties of a new MRI-resistant programmable hydrocephalus shunt

Authors: Allin DM, Czosnyka M, Richards HK, Pickard JD, Czosnyka ZH

Citation: Cerebrospinal Fluid Research 2008, 5:8

Background: The Polaris® valve is a newly released hydrocephalus shunt that is designed to drain cerebrospinal fluid (CSF) from the brain ventricles or lumbar CSF space. The aim of this study was to bench test the properties of the Polaris shunt, independently of the manufacturer.


Methods: The Polaris® Valve is a ball-on-spring valve, which can be adjusted magnetically in vivo. A special mechanism is incorporated to prevent accidental re-adjustment by an external magnetic field. The performance and hydrodynamic properties of the valve were evaluated in the UK Shunt Evaluation Laboratory, Cambridge, UK.


Results: The three shunts tested showed good mechanical durability over the 3-month period of testing, and a stable hydrodynamic performance over 45 days. The pressure-flow performance curves, operating, opening and closing pressures were stable. The drainage rate of the shunt increased when a negative outlet pressure (siphoning) was applied. The hydrodynamic parameters fell within the limits specified by the manufacturer and changed according to the five programmed performance levels. Hydrodynamic resistance was dependant on operating pressure, changing from low values of 1.6 mmHg/ml/min at the lowest level to 11.2 mmHg/ml/min at the highest performance level. External programming proved to be easy and reliable. Even very strong magnetic fields (3 Tesla) were not able to change the programming of the valve. However, distortion of magnetic resonance images was present.


Conclusion: The Polaris® Valve is a reliable, adjustable valve. Unlike other adjustable valves (except the Miethke ProGAV valve), the Polaris® cannot be accidentally re-adjusted by an external magnetic field.


Sophysa’s comments:  Many valves on the market have very low hydrodynamic resistance but, without siphon-preventing mechanisms, thus potentially causing over-drainage.

Polaris® valve’s hydrodynamic resistance increases with the pressure performance level which is consistent with Sophysa’s recommendations to use a high pressure setting at the initial stage of the treatment, in order to minimize the risk of overdrainage and shunt dependency. This allows a stable drainage over time.


Laboratory testing of the Pressio® intracranial pressure monitor

Authors: Allin D, Czosnyka M, Czosnyka Z

Citation: Neurosurgery. 2008 May;62(5):1158-61; discussion 1161

Objective: The Sophysa Pressio® (Sophysa Ltd., Orsay, France) is a new intracranial pressure monitoring system. This study aimed to evaluate its accuracy and compare it with the popular Codman intracranial pressure transducer (Codman/Johnson & Johnson, Raynham, MA) in vitro.

Methods: A computerized rig was used to test the Pressio® and Codman transducers simultaneously. Properties that were tested included drift over 7 days, the effect of temperature on drift, frequency response, the accuracy of measurement of static and pulsatile pressures, and connectivity of the system.

Results: Long-term (7 d) relative zero drift was less than 0.05 mmHg. The temperature drift was low (0.3 mmHg/207C). Absolute static accuracy was better than 0.5 mmHg over the range of 0 to 100 mmHg. Pulse waveform accuracy, relative to the Codman transducer, was better than 0.2 mmHg over the range of 1 to 20 mmHg. The frequency bandwidth of the Pressio® transducer was 22 Hz. The Pressio® monitor can transmit data directly to an external computer without the use of a pressure bridge amplifier.

Conclusion: The new Pressio® transducer proved to be accurate for measuring static and dynamic pressure during in vitro evaluation.

Sophysa’s comments: The metrological properties of the Pressio®® ICP monitoring system are satisfactory and allow accurate readings of pressure during testing conditions.

User comments:

This in vitro study suggests acceptable performance parameters for this new intracranial pressure monitor. Given the direct interface with existing bedside monitors without the need for a pressure bridge amplifier, there should be a significant cost advantage of this new technology. It is hoped that clinical studies will demonstrate similar reliability.” (Jack E. Wilberger Pittsburgh, Pennsylvania)



In vivo accuracy of two intraparenchymal intracranial pressure monitors

Authors: Lescot T, Reina V, Le Manach Y, Boroli F, Chauvet D, Boch A-L, Puybasset L

Citation: Intensive Care Med. 2011 May;37(5):875-9.

Purpose: To evaluate the in vivo accuracy of the new Pressio® device for intraparenchymal monitoring of intracranial pressure (ICP) versus the Codman® device and intraventricular measurement external ventricular drainage (EVD).

Methods: Data were collected retrospectively for 30 consecutive patients admitted into a 25-bed neurosurgical intensive care unit of a university hospital between January and December 2009. Patients received both intraventricular and intraparenchymal ICP monitoring with Pressio® (n = 15) or Codman® (n = 15).

Results: We obtained 3,089 data points from the 30 patients. Mean difference between intraparenchymal and EVD pressure (bias) was −0.6 mmHg, and limits of agreement (1.96 SD of the bias) were −8.1 to 6.9 mmHg with Pressio® and 0.3 mmHg with limits of agreement of −6.7 to 7.1 mmHg with Codman® (NS). The temporal difference was −0.7 ± 1.6 mmHg/100 h of monitoring with Pressio® and 0.1 ± 1.6 mmHg/100 h of monitoring with Codman® over the study period (NS).

Conclusions: Intraparenchymal pressure measured with both transducers approximates intraventricular cerebrospinal fluid pressure with an accuracy of ±7 mmHg.

Sophysa’s comments: The difference may be explained in part by measurement of the ICP at two different levels (tensor at the tip of the catheter for Intraparenchymal systems and at the level of the external transducer for ICP values obtained by EVD).


Pressio® 2

Laboratory Testing of Pressio® 2 Intracranial Pressure Monitor

Authors: Czosnyka M, Smielewski P, Czosnyka Z

Citation: Promedics 20/02/2017

Objectives: The aim of this evaluation is to provide extensive bench testing to evaluate the Pressio® 2 Monitoring system. Where it was possible absolute accuracy was assessed, otherwise comparison to Codman Express ICP transducer and monitor was studied.

Design: Drift of pressure measurement over 7 days, drift with temperature, frequency response and accuracy of measurement of both static and pulsatile pressures have been tested simultaneously in Pressio® 2 and Codman transducers using a standard laboratory rig. Connectivity of the systems was also assessed.


Results: Long-term (10 days) zero drift was less than 2mmHg in both transducers. Temperature drift of Pressio® 2 was low (0.2mmHg per 20°C). The frequency bandwith of the Pressio® 2 was 20Hz (relative to Codman transducer). Absolute static accuracy of Pressio® 2 was better than 2mmHg over the range from -30 to 120mmHg. Pulse waveform accuracy (relative to Codman) was better than 0.2mmHg over the range from 1mmHg to 20mmHg. The frequency bandwith of the Pressio® 2 was 17Hz (relative to Codman transducer). Long-term (10 days) zero drift was less than 2mmHg in both transducers. Temperature drift of Pressio® 2 was low (0.2mmHg per 20°C). Pressio® 2 ICP Monitor can transmit data directly to external computer without use of pressure transducer bridge amplifier with the resolution of 0.1mmHg. It is “ICM+” compatible.


Conclusion: The new Pressio® 2 ICP Monitor has good accuracy as far as both static and dynamic ICP measurement is concerned, low zero and temperature drift and excellent frequency properties. The monitor is absolutely comparable with Codman Express Monitor and may be, from metrological point of niew, used as an alternative in clinical ICP monitoring.


Sophysa’s comments: Our catheter Pressio® has a zero drift less than 2 mmHg (10 days) and a low temperature drift (0.2mmHg per 20°C). Our Pressio® 2 monitor is ICM+ compatible by direct transmission of data on the external laptop (without use of amplifier).