Programmable Shunt Research Articles

Smartphone Magnetometers for Assessing Programmable Shunt Valve Settings: A Proof-of-Concept Study.

Programmable shunt valves (PSVs) used to treat hydrocephalus require specialized valve-specific devices that determine their setting. However, these devices are typically only accessible in major medical centers. This study explores the feasibility of using smartphone magnetometers to assess PSV settings. We investigated 2 PSVs, the Codman Certas Plus and Medtronic Strata II, using 3 different smartphones. Free open-source software was used to measure magnetic flux densities of the shunts, and PSV-specific algorithms were developed to interpret these measurements. All measurements were performed ex vivo. We demonstrated that this method could accurately determine PSV settings with 100% accuracy in ex vivo blinded trials. The technique was effective even with a scalp analog simulating different skin thicknesses. This proof-of-concept study suggests that smartphones can be used for PSV assessment. However, further development and validation are needed to refine this method for clinical use. This technology could enhance PSV management accessibility, allowing for remote or at-home evaluations by trained individuals or caregivers, thus improving patient care in underserved areas.

Shunt options for normal pressure hydrocephalus: a comparison of complications, overdrainage rates and neurological outcomes between integra low flow regulated and Codman Hakim programmable shunts

Aims: Shunt surgery is the most commonly performed treatment for idiopathic normal pressure hydrocephalus, and shunt systems with different operating principles are employed. This study aimed to retrospectively compare programmable ventriculoperitoneal shunts and flow-regulated shunts in terms of complications, overdrainage rates, and neurological outcomes. Methods: Between January 2020 and May 2022, 44 patients who underwent shunt operation with a diagnosis of idiopathic normal pressure hydrocephalus at our clinic were retrospectively analyzed. Patients were categorized into two groups: the programmable ventriculoperitoneal shunt and the flow-regulated shunt group. Demographic characteristics, complications, rates of insufficient drainage/overdrainage, and surgical outcomes were compared. Results: There were 26 patients in the programmable ventriculoperitoneal shunt group and 18 patients in the flow-regulated shunt group. In the programmable ventriculoperitoneal shunt group, 14 patients (53.8%) required 27 shunt setting adjustments owing to excessive or inadequate drainage. Subdural effusion was observed in five patients (19.2%), and shunt revision was performed in one patient (3.8%). Subdural effusion was observed in two (11.1%) patients in the flow-regulated shunt group. One of these patients (5.5%) underwent shunt revision. There was no significant difference between the groups in terms of the development of subdural effusion and need for shunt revision (p>0.05). The rate of improvement in at least one of the symptoms was 53.8% in the programmable ventriculoperitoneal shunt group at the 1st-month postoperative outpatient follow-up. In the flow-regulated shunt group, this rate was 72.2% and there was no statistically significant difference. Both groups showed similar clinical improvement at the 1-year follow-up. Conclusion: There was no difference between the groups in terms of neurological outcomes and the need for shunt revision. However, the use of flow-regulated shunts has demonstrated earlier rates of clinical improvement without the need for reprogramming.

Toward the "Perfect" Shunt: Historical Vignette, Current Efforts, and Future Directions.

As a concept, drainage of excess fluid volume in the cranium has been around for more than 1000 years. Starting with the original decompression-trepanation of Abulcasis to modern programmable shunt systems, to other nonshunt-based treatments such as endoscopic third ventriculostomy and choroid plexus cauterization, we have come far as a field. However, there are still fundamental limitations that shunts have yet to overcome: namely posture-induced over- and underdrainage, the continual need for valve opening pressure especially in pediatric cases, and the failure to reinstall physiologic intracranial pressure dynamics. However, there are groups worldwide, in the clinic, in industry, and in academia, that are trying to ameliorate the current state of the technology within hydrocephalus treatment. This chapter aims to provide a historical overview of hydrocephalus, current challenges in shunt design, what members of the community have done and continue to do to address these challenges, and finally, a definition of the "perfect" shunt is provided and how the authors are working toward it.

Optimizing shunt integrity during acute subdural hematoma evacuation.

Even mild head trauma can cause severe intracranial hemorrhage in patients with cerebrospinal fluid (CSF) shunts for hydrocephalus. CSF shunts are considered a risk factor for subdural hematoma (SDH). The management of acute SDH (ASDH) in shunted patients with normal pressure hydrocephalus can be challenging. Addressing the hematoma and the draining function of the shunt is important. To preserve the shunt, we set the shunt valve pressure to the highest and perform hematoma evacuation for ASDH. In this study, we report the surgical cases of ASDH in patients with shunts. Between 2013 and 2019, five patients with ASDH and CSF shunts underwent hematoma evacuation at our hospital. We retrospectively analyzed data regarding their clinical and radiological presentation, hospitalization course, the use of antithrombotic medications, and response to different treatment regimens. The patients presented with scores of 5-14 in the Glasgow coma scale and severe neurological signs, consciousness disturbance, and hemiparesis. Most patients were elderly, taking antithrombotic medications (four of five cases), and had experienced falls (4 of 5 cases). All patients underwent hematoma evacuation following resetting their programmable shunt valves to their maximal pressure setting and shunt preservation. ASDH enlargement was observed in only one patient who underwent burr-hole drainage. Glasgow outcome scale scores at discharge were 1 and 3, respectively. In hematoma evacuation, increasing the valve pressure may reduce the bleeding recurrence. To preserve the shunt, setting the shunt valve pressure to the highest level and performing endoscopic hematoma evacuation with a small craniotomy could be useful.

Transventricular transforaminal endoscopic fenestration with cysto-ventriculoperitoneal shunt to manage a third ventricular arachnoid cyst: a case report

Regular ventriculoperitoneal (VP) shunt is commonly used as the first option to manage a third ventricular arachnoid cyst due to the lack of facilities, unfamiliarity with endoscopic techniques, or misdiagnosis as purely obstructive hydrocephalus. A 9-year-old girl with obstructive hydrocephalus due to a third ventricular arachnoid cyst was treated with a VP shunt. 2 months later, the previous shunt device was removed due to an infection. Following a sterile cerebrospinal fluid analysis culture, we conducted a navigation-assisted transventricular transforaminal endoscopic fenestration and cysto-VP programmable shunt placement. A decrease in ventricular dilatation was seen on follow-up. This approach was justified due to the possibility of establishing communication with normal cisterns, the high rate of cyst elimination, and the potential for achieving shunt independence. Performing an endoscopic fenestration followed by cysto-VP shunt placement could be an optimal option for managing this condition.

Programmable Versus Differential Pressure Ventriculoperitoneal Shunts for Pediatric Hydrocephalus: A 20-Year Single-Center Experience From Saudi Arabia.

Background Shunt malfunction is the most common complication after ventriculoperitoneal shunt (VPS) insertion for pediatric hydrocephalus. The incidence of shunt malfunction and the need for VPS revision may be related to the type of valve used in the shunt. Therefore, we aimed to compare the outcome of VPS in the pediatric age group stratified by differential pressure valves (DPV) and programmable shunt valves (PSV). Materials and methods This ethics-approved retrospective study was conducted at a tertiary care hospital in Saudi Arabia. We included 175 children with congenital hydrocephalus who underwent a shunt insertion or revision between 2003 and 2018 and followed them up to December 2022. The VPS complication and revision rates were compared with the patient's demographics and shunt valve types. The Kaplan-Meier method, log-rank test, and univariate and multivariate Cox proportional hazards regression were used to analyze several variables and subsequent shunt revisions. Results Females represented 52% of the study participants, and the mean age of the patients was 21.7 ± 38.4 months. The main indication for VPS was congenital hydrocephalus due to aqueductal stenosis (40%). The differential shunt valve was used in 78.9% and the PSVin 21.1% of the patients. Surgical complications occurred in 33.7% of the patients. Shunt malfunction and infection occurred in 16% and 11.4% of the patients, respectively. The VPS revision rate was significantly lower when PSV was used (odds ratio = 0.39, P < 0.05). Conclusion Overall, one-third of the studied pediatric cohort required shunt revision at some point during the 15-year follow-up. However, children with PSV had fewer revision rate-related complications compared to children with DPV during the first five years of follow-up.

Noninvasive intracranial pressure monitoring throughout brain compliance guiding a ventriculoperitoneal shunt replacement in hydrocephalus-case report.

Ventriculoperitoneal (VP) shunt is the primary therapy for hydrocephalus in children; however, this technique is amenable to malfunctions, which could be detected through an assessment of clinical signs and imaging results. Furthermore, early detection can prevent patient deterioration and guide clinical and surgical treatment. A 5-year-old female with a premedical history of neonatal IVH, secondary hydrocephalus, multiple VP shunts revisions, and slit ventricle syndrome was evaluated using a noninvasive intracranial pressure monitor device at the early stages of the clinical symptoms, evidencing increased intracranial pressure and poor brain compliance. Serial MRI images demonstrated a slight ventricular enlargement, leading to the use of a gravitational VP shunt, promoting progressive improvement. On the follow-up visits, we used the noninvasive ICP monitoring device to guide the shunt adjustments until symptom resolution. Furthermore, the patient has been asymptomatic for the past 3years without requiring new shunt revisions. Slit ventricle syndrome and VP shunt dysfunctions are challenging diagnoses for the neurosurgeon. The noninvasive intracranial monitoring has allowed a closer follow-up assisting early assessment of brain compliance changes related to a patient's symptomatology. Furthermore, this technique has high sensitivity and specificity in detecting alterations in the intracranial pressure, serving as a guide for the adjustments of programmable VP shunts, which may improve the patient's quality of life. Noninvasive ICP monitoring may lead to a less invasive assessment of patients with slit ventricle syndrome and could be used as a guide for adjustments of programmable shunts.

Preterm-related posthemorrhagic hydrocephalus: Review of our institutional series with a long-term follow-up

IntroductionPreterm-related posthemorrhagic hydrocephalus is a major cause of neurological impairment and a common indication for a ventriculoperitoneal shunt in infants that are prone to diverse complications. Protocols of diagnosis and treatment are in continuous evolution and require evaluation of their results. ObjectiveTo review the clinical characteristics and results of a series of preterm-related posthemorrhagic hydrocephalus needing a definitive shunt from 1982 to 2020 in our institution. As a secondary objective we evaluated the safety of the changes in our protocol of treatment from 2015. MethodsRetrospective review, clinical investigation. Results133 patients were implanted a shunt in the study period. Shunt infection was diagnosed in 15 patients. Proximal shunt obstruction as the first complication was diagnosed in 30% of cases at one year, 37% at two years and 46% at five years. 61 patients developed very small or collapsed ventricles at last follow-up. Two thirds of our patients achieved normal neurological development or mild impairment. Changes in protocol did not significantly modify clinical results although improvement in most outcomes was observed. Mean follow-up was over nine years. ConclusionsClinical outcomes are comparable to previous reported data. Changes in protocol proved to be safe and improved our results. Programmable shunts can be used safely in preterm patients although they may not prevent tendency towards ventricular collapse, which is very common after long follow-up.

Approach to Cochlear Implantation in Patients With Ventriculoperitoneal Shunts.

To evaluate the safety and outcomes of cochlear implantation (CI) in patients with ventriculoperitoneal (VP) shunts to inform clinical practice. Historical cohort study. Tertiary referral centers. A multi-institutional historical cohort of patients with VP shunts and CI was identified and analyzed. A total of 46 patients (median age 8 years [interquratile range, IQR: 2-46]) with VP shunts and CI were identified. Of these, 41 (89%) patients had a VP shunt prior to CI. Based on institutional preference and individual patient factors, CI was performed contralateral to a pre-existing VP shunt in 24 of these 41 cases (59%) and ipsilateral in 17 (41%). Furthermore, pre-CI relocation of the VP shunt was performed in 3 cases (7%), and 2 patients (5%) underwent planned revision of their VP shunt concurrent with CI. In total, 2 of 27 pediatric patients (7%) required unanticipated revision shunt surgery, both contralateral to CI device placement, given VP shunt malfunction. One of 19 adult patients (5%) required shunt revision during CI due to shunt damage noted intraoperatively. Among 43 patients with available follow-up, 38 (88%) are regular CI users, with a median consonant-nucleus vowel-consonant word: score of 58% (IQR: 28-72). CI can be performed at low risk, either contralateral or ipsilateral, to a VP shunt, and does not mandate shunt revision in most cases. Additional considerations regarding CI receiver-stimulator placement are necessary with programmable shunts to mitigate device interaction. Preoperative planning, including coordination of care with neurosurgery, is important to achieving optimal outcomes.

Effects Of Shunt Types Used In Idiopathic Normal Pressure Hydrocephalus On Patients' Clinical Outcomes

Background: Idiopathic normal pressure hydrocephalus (iNPH) is a surgically reversible neurological disorder in adults. It is a neurological condition characterized by ventricular enlargement detected on cranial imaging as well as gait disturbance, cognitive decline and urinary incontinence, with no other reason to explain the clinical findings. Ventricular shunting, predominantly ventriculoperitoneal (VP) shunt, has been shown to be successful in relieving symptoms in patients. In this study, we aimed to investigate the effects of two VP shunts used in the iNPH patients treated in our clinic. Methods: Clinical and laboratory records of 28 patients who underwent VP shunting due to iNPH were reviewed retrospectively via the Enlyl system. A programmable shunt was inserted in 9 (32.1%) and a medium-pressure shunt was inserted in 19 (67.9%) patients. Results: There was no significant difference between the two shunt types with regard to patient age, gender, and preoperative tests (p&gt;0.05). However, the prevalence of ataxic gait was significantly higher in the Programmable Shunt group compared to the Medium-Pressure Shunt group (p&lt;0.05). On the other hand, no significant difference was found between the shunt types with regard to postoperative examination findings and additional neurological disorders (p&gt;0.05 for both). Conclusion: In the present study, no significant difference was observed between the shunt types with regard to clinical outcomes and thus both types of shunts were revealed as viable options.

The Effects of Using Hearing Aids and Hearing Assistive Technologies on Programmable Ventriculoperitoneal Shunt.

To investigate interaction between behind-the-ear (BTE) hearing aids, hearing assistive technologies, and programmable shunt valve to understand how use of BTE hearing aids in patients who underwent ventriculoperitoneal shunt (VPS) surgery affects the settings of a programmable shunt valve. In this study, we investigated the magnetic field (MF) generation of 3 BTE hearing aids made by different companies, 1 frequency modulated system using telecoil technology, and 1 wireless microphone technology and their interactions with 2 programmable shunt valves. All measurements were made in a silent booth using 2 different models. The influence of MF strength in the distance modeling was investigated based on the distance from source auditory prostheses. The measurements were recorded using a Gauss meter. In the anatomical modeling, the change in the settings and interaction of the valve in a bust mannequin were investigated. No MF created by BTE hearing aids was detected in the distance modeling. The highest value measured was 32.67 μT (<90 dB noise) when BTE hearing aids and frequency modulated systems were used, and this value decreased as the distance increased. No MF generation was observed at measurements done for distances >10 mm. In the anatomical modeling, the settings of both programmable valves did not change under all acoustic conditions. This is the first study to our knowledge examining the MF created by hearing aids and hearing assistive technologies and its impact on programmable valves and variations in their settings. Our findings showed that it is safe to use BTE hearing aids, frequency modulated systems, and wireless microphone technologies in patients with a programmable VPS.

Cochlear Implants: What the Neurosurgeon Needs to Know.

Patients with cochlear implants (CIs) commonly undergo neurosurgical interventions for concurrent pathologies. The neurosurgeon must be aware of the limitations these devices place on treating these patients and all pertinent interactions CIs have with common neurosurgical instruments and procedures. A literature search was performed utilizing the terms "cochlear implant" and "neurosurgery" or "neurosurgical" and all associated iterations. We reviewed the abstracts of 146 generated reports and eight published papers discussing the interaction and limitations of CI use in different neurosurgical procedures. Five realms were identified in which a CI may potentially interfere with standard neurosurgical care: Magnetic resonance imaging (MRI), radiotherapy, deep brain stimulation (DBS),intraventricular shunt placement, andintraoperative neuromonitoring (IONM). First, MRI use with CIs is limited due to thermal injury risk, imaging disruption, and implant damage. Secondly, high-dose >50 Gysingle-fraction linear accelerator-based radiosurgery has been demonstrated to result in a loss of radio frequency link range in CIs, interfering with their function. Next, during surgery for DBS, the need for MRI and microelectrode recording requires CI magnet removal by neurotology and the surgeon must communicate with a non-hearing patient. Tunneling of shunts must accommodate CI position retroauricularly, if ipsilateral, and programmable valves must be placed >2 cm from the CI to prevent interference. Intraoperative neuromonitoring may produce voltages that interfere with CIs, and while monopolar cautery may pose the same risk, no study has proven this to date. Generally, bipolar cautery is safe and favored >1 cm from CIs. MRI use is limited in CI patients, although MRI-safer devices are in production. DBS electrodes may be successfully placed after CI magnet removal. Programmable shunt valves may be placed >2 cm away from CIs and radiosurgery <50 Gy has not demonstrated harm to these devices. IONM and monopolar cautery have not been demonstrated to directly affect CIs; however, more research is needed.

TU-178. Maladjustment of pressure settings of programmable shunt valves by weak magnetic fields

TU-178. Maladjustment of pressure settings of programmable shunt valves by weak magnetic fields

The Prognostic Impacts of Body Mass Index and Distance to the Peritoneal Bottom on Laparoscopic Ventriculoperitoneal Shunt Placement

Laparoscopic ventriculoperitoneal shunt surgery has been reported to have several advantages in selected patients. However, the prognostic factors have been understudied specifically for this surgery. We sought to investigate the factors influencing the complications after the laparoscopic ventriculoperitoneal shunt placement. All surgeries in this prospective study were performed by the same team of neurosurgeons and general surgeons. Clinical parameters as well as potential risk factors for postoperative complications were analyzed. The endpoint was overall complications requiring surgical revision within the follow-up period after surgery. Ninety-nine patients (51 male and 48 female) scheduled for laparoscopic-assisted ventriculoperitoneal shunt surgery between 2019 and 2021 were included. Overall shunt complication rate was 9% (9 of 99 cases), and there was 1 patient (1%) who had distal dysfunction among them. Body mass index ≥27 kg/m2 (hazard ratio 4.87; 95% confidence interval 1.05-22.57; P= 0.043), and nonprogrammable shunts (hazard ratio 7.91; 95% confidence interval 1.51-41.50; P= 0.014) were significantly associated with an increased risk of complications. Among 75 patients who received programmable shunts, the vertical distance from the distal tip to the presumed bottom of peritoneal cavity was significant positively associated with the number of pressure adjustments (R2 0.511, adjusted R2 0.504, and P < 0.001). Ventriculoperitoneal shunt surgery provided benefits with little complication rate, whereas patients treated with nonprogrammable shunts and obese patients had less favorable outcome. A positive correlation between the vertical distance from the distal tip to the bottom of peritoneal cavity and pressure adjustments inferred to the advantage of the laparoscopic method.

An In Vitro Study of Magnetic Field Interference with an Electronic Shunt Programmer

Programmable shunts play a valuable role in the treatment of hydrocephalus. However, the use of magnets in programming these valves has caused obstacles in today's magnetized world. Previous studies have reported problems with magnetic toys and electronics unintentionally reprogramming shunt valves. This study investigated how an Apple Watch can interfere with the Codman CERTAS Plus electronic programmer. In this invitro study, we tested the magnetic field emitted by Apple Watch Series 3, 4, 5, and 6 using an electromagnetic field tester at distances of 0-50 mm. We conducted 20 trials of shunt programming and shunt setting reading with and without each watch. All 4 watches generated significant magnetic fields. Maximum magnetic fields were Series 3, 165.73 millitesla (mT); Series 4, 144.91 mT; Series 5, 131.09 mT; and Series 6, 130.68 mT. All 4 watches interfered with the programmer's ability to correctly read and program the valve setting. The Codman CERTAS Plus electronic programmer detects the magnetic field emitted from an Apple Watch and mistakes it for the valve, rendering programming difficult. These smartwatches and similar electronic devices should be kept away from the programmer and not worn by health care providers to avoid inappropriate readings and setting changes.

Maladjustment of pressure settings of a programmable shunt valve by electromagnetic door locks in Forensic Psychiatry – a case report

IntroductionMaladjustments and failures of programmable ventriculo-peritoneal shunts have been reported in patients encountering powerful electromagnetic fields, e. g. MRI.We describe the case of a 53-year old man treated for hydrocephalus with a programmable Codman-Hakim shunt valve. During his hospitalization in Forensic Psychiatry, the patient’s valve pressure setting changed randomly despite frequent reprogramming and surveillance.ObjectivesMaladjustments and failures of programmable ventriculo-peritoneal shunts have been reported in cases in which patients have encountered powerful electromagnetic fields, e.g., MRI. Through a case, this study shows easy maladjustment of a Codman-Hakim programmable valve also by small magnetic fields from everyday life.MethodsA 53-year old man presented with periventricular hydrocephalus due to aqueductal stenosis. The patient was treated with a left ventriculo-peritoneal Codman-Hakim programmable shunt valve. During his hospitalization in Forensic Psychiatry, the patient’s valve pressure setting changed randomly, presumably by walking through electromagnetically controlled doors of a hospital ward. With a test dummy, changes in pressure settings were tracked.ResultsBoth - pressure settings of the patient’s Codman-Hakim programmable valve as well as pressure settings of a new valve - were unwantedly modified simply by walking through standard doors in a hospital ward.ConclusionsThus already weak magnetic fields (&lt; 200 mT) might cause changes in the pressure settings of programmable shunt valves and therefore lead to maladjustment. Patients should be informed and pay attention to using everyday life’s devices, like rod magnets or mobile phones.DisclosureNo significant relationships.

P 68 Unintentional maladjustment of a shunt valve due to electromagnetic door locks – A case report

Normal-pressure hydrocephalus is caused by dilatation of the internal cerebrospinal fluid spaces at normal intracranial pressure. The resulting progressive accumulation of CSF in the brain space can cause permanent damage and, if left untreated, complete loss of brain tissue [2, 4]. The standard treatment for hydrocephalus in children and adults is the implantation of a ventriculo-peritoneal shunt (VP shunt). Most of the currently used shunt systems have a valve to control pressure and drain CSF if necessary [4]. In recent years, malfunction of programmable VP shunts has been reported in patients exposed to strong electromagnetic fields, such as those generated during magnetic resonance imaging (MRI) [1, 3]. However, little is known about the effects of weak magnetic fields on VP shunts. We present the case of a 53 -year-old forensic psychiatric patient in whom the pressure setting of an implanted Codman-Hakim programmable shunt valve changed during passage through various ward doors, leading to the onset of psychiatric symptoms. During the inpatient stay, the valve's pressure setting changed at least six times randomly despite frequent reprogramming and monitoring. References 1 Akbar M, Aschoff A, Georgi JC, Nennig E, Heiland S, Abel R, Stippich C (2010) Adjustable Cerebrospinal Fluid Shunt Valves in 3.0-Tesla MRI: a Phantom Study using Explanted Devices. Rofo 182(7):594-602 2 Kahle KT, Kulkarni AV, Limbrick DD, Warf BC (2016) Hydrocephalus in children. Lancet 387(10020):788–799 3 Mirzayan MJ, Klinge PM, Samii M, Goetz F, Krauss JK (2012) MRI safety of a programmable shunt assistant at 3 and 7 Tesla. Br J Neurosurg 26(3):397-400 4 Portillo Medina SA, Franco JVA, Ciapponi A, Garotte V, Vietto V (2017) Ventriculo-peritoneal shunting devices for hydrocephalus. Cochrane Database Syst Rev. 2017(7): CD012726 Figure 1. Scetch of a Codman-Hakim shunt valve. Figure 2. Image of a Codman-Hakim VP shunt before and after passing a door.

Maladjustment of Pressure Settings of Programmable Shunt Valves by Weak Magnetic Fields – A Case Report

Maladjustment of Pressure Settings of Programmable Shunt Valves by Weak Magnetic Fields – A Case Report

Programmable shunt valve affected by behind-the-ear hearing device: A case report and literature review

Background: It is known that interactions between programmable Ventriculoperitoneal Shunt (VPS) valves and electromagnetic and hearing devices may change the valve settings. We reported a patient using programmable VPS valves and hearing devices and reviewed the literature.&#x0D; Case Description: A 71-year-old man was implanted with a programmable VPS valve with the diagnosis of Normal Pressure Hydrocephalus. A hearing device (behind-the-ear) was proposed because of hearing difficulties, but it was suggested that it be discontinued because it did not help. However, the patient used it twice because of his current dementia, forgetting the doctor’s recommendations. The setting of the valve has changed in these two different times that this behind-the-ear hearing device is used. Long-term follow-ups showed no change in valve settings except those two situations.&#x0D; Conclusion: It is important to note that patients using hearing devices and programmable VPS valves are a unique group of patients. There are not enough studies showing the relationship between the behind-the-ear hearing devices and programmable VPS. It should be kept in mind that hearing devices with magnetic field strength may change the setting of the valves.

Determination of Programmable Shunt Setting Using CT: Feasibility Study.

Background: Programmable shunts can be adjusted to optimize CSF diversion in patients with hydrocephalus without the need for re-operation. Currently, all shunts incorporate radiopaque markers so that their setting can be determined on skull X-ray images. The purpose of this study was to evaluate whether the shunt setting could also be determined ex vivo and in vivo using the data from a standard head CT scan since one is nearly always obtained when patients with VP shunts present with new symptoms that could be due to shunt malfunction. Materials and Methods: Four commonly used programmable shunts were attached to a dried skull and scanned using a variety of CT techniques. The shunts imaged were the CertasTM Plus (Codman, Raynham, Massachusetts), Polaris® (Sophysa, Orsay, France), proGAV 2.0® (Braun, Bethlehem, Pennsylvania), and Hakim® (Codman, Raynham, Massachusetts). Each shunt was scanned at two different valve settings using multiple CT techniques: CTDIvol 75, 140kVp, 330mAs, CTDIvol60, 120kVp 390mAs, CTDIvol40, 80kVp with 430mAs, 140kVp with 215mAs. Image reconstruction with and without CT metal suppression software was used for all scans, and the data was reconstructed into volume-rendered images. We enlisted ten observers to review the volume-rendered images only. After a short set of training slides viewed by all observers, they were asked to predict the shunt setting for each valve along with their level of confidence. One clinical case of a patient with a programmable valve was evaluated on a CT scan.Results: Using the volume-rendered images only, the two shunt settings of the Polaris shunt were correctly predicted by all the observers and in nine of 10 settings for the CertasTM Plus valve. For the Hakim® shunt and the proGAV 2.0® shunt, setting prediction accuracy was 0% and 10%, respectively. In one clinical case, the programmable valve setting could be determined from the CT scan data.Conclusion: The valve setting of at least two currently available programmable shunts can be determined using volume-rendered images generated from CT data. Reconstructions using metal suppression software were rated as superior and may be necessary for some valve designs.