Programmable Ventriculoperitoneal Shunt Research Articles

Management of Posttraumatic Cerebrospinal Fluid Leak with Secondary Diffuse Pneumocephalus Complicated by Meningitis and Communicating Hydrocephalus – Illustrative Case Report

Rhinorrhea is a possible complication after different types of traumatic brain injury or neurosurgical procedures, such as skull base operations. Pneumocephalus is a rarely noted complication after severe traumatic brain injury, and it may be accompanied by meningitis and ventriculitis, especially when treatment has been delayed. Treatment of these entities includes conservative and surgical approaches. Pneumocephalus may result in neurologic disturbances threatening a life. Therefore, active patient management with a multidisciplinary team is required to prevent poor outcomes. In the literature, limited cases of rhinorrhea and pneumocephalus are available, including in our country. Pneumocephalus may also occur spontaneously. In 2015, Pishbin et al. identified 10 cases of spontaneous pneumocephalus. The precise incidence of diffuse pneumocephalus after traumatic brain injury is unknown, reported as <1% of cases with rare complications. In this case, a 41-year-old male patient presented at a tertiary university hospital with the chief complaint of headache. A month prior to admission, the patient was discharged from another hospital with multiple skull and facial fractures, pneumocephalus, and traumatic subarachnoid hemorrhage in the left frontal lobe due to fights (Le Fort III). During the second hospitalization, the patient’s clinical status deteriorated. A repeated brain CT demonstrated diffuse pneumocephalus. Rhinorrhea was still present. The external lumbal drainage procedure was performed without stopping the cerebrospinal fluid leak. In children, pediatric inferior turbinate hypertrophy is a frequent cause of nasal breathing difficulties. In this case, no such hypertrophy was observed. It should be considered a nasal obstructive disease not necessarily related to adult entities, frequently associated with other nasal or craniofacial disorders. Early diagnosis and endoscopic management of rhinorrhea, nasal obstruction, and associated complications is vital, as delays can lead to life-threatening issues like hydrocephalus/meningitis. Eventually, the patient developed meningitis and acute communicating hydrocephalus. Right ventriculostomy with a programmable ventriculoperitoneal shunt placement was done (pressure 110 cm H<sub>2</sub>O), stopping the rhinorrhea. This is an extremely rare case where a patient, after cerebrospinal fluid (CSF) leakage, develops severe complications, including pneumocephalus, meningitis, ventriculitis, and acute communicating hydrocephalus. In the literature, we did not come across case reports presenting all the complications as in this case. This case report will raise knowledge and awareness of such entities, adding to the rare, similar cases reported so far.

Assessing the risk of magnetic interaction between auditory implants and programmable ventriculoperitoneal shunts

Purpose This study investigated whether the magnetic field of the internal magnet of cochlear implants and bone-anchored hearing aids (BAHA) would be sufficient to affect a programmable ventriculoperitoneal (VP) shunt. Current guidelines suggest against implanting these hearing devices ipsilateral to a programmable VP shunt, but the exact nature of the interaction has not been quantified. Methods The magnetic field strength (mT) was measured at 0 and 10 mm from the edge of both the Cochlear Implant CI512 (Cochlear Corporation) magnet and BAHA Attract magnet. Next, the hearing devices were placed into their anatomical positions in a 3-D clay model, along with three different types of programmable VP shunts. The valve setting was measured before and after exposure. Results At 10 mm, neither device generated a magnetic field sufficient to adjust the VP shunt valve. In the clay model, the valve settings were not affected by the presence of any device. Conclusion Neither the cochlear implant nor the BAHA subcutaneous internal magnets generated sufficient magnetic field to reprogramme the valves of commonly used programmable VP shunts. The magnetic field from each device decreases dramatically at 10 mm. Further clinical studies to help mitigate the current restrictive guidance should consider involvement of VP shunt manufacturers to inform future shunt development and design.

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.

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.

Magnetic resonance imaging-related programmable ventriculoperitoneal shunt valve setting changes occur often.

Patients with programmable ventriculoperitoneal (VP) shunt valves undergo multiple skull radiographs to evaluate for setting changes resulting from MRI. Our purpose was to determine the rates of inadvertent, MRI-related, programmable VP shunt valve setting changes. In this retrospective cohort with a study period of January 2015-December 2018, we reviewed the pre- and post-MRI skull radiographs of patients with programmable VP shunts and collected the following data: Demographics, commercial type of the valve used, magnetic field strength of the MRI device used, and whether a setting change occurred. We used the chi-square test to identify variables associated with valve setting change. We identified 210 MRI exposure events in 156 patients, and an MRI-related valve setting change rate of 56.7%. The setting change rate was significantly higher with higher magnetic field strength (p = 0.03), and with Medtronic Strata™ valves compared to Codman Hakim™ valves (p < 0.0001). Inadvertent, MRI-related shunt valve setting changes are frequent with valves that lack a locking mechanism. Therefore, we suggest that when feasible, the clinicians could opt to manually reprogram the valves after the MRI to the preferred setting without the need for pre- and post-MRI radiographs. We believe that this protocol modification could help reduce ionizing radiation exposure and cost. Manufacturers may consider incorporating locking mechanisms into the design of such devices in order to reduce the unintended setting change rates.

Comparison of Programmable and Non-Programmable Shunts for Normal Pressure Hydrocephalus: A Meta-Analysis and Trial Sequential Analysis.

The use of programmable ventriculoperitoneal shunt (P-VPS) in idiopathic normal pressure hydrocephalus (iNPH) has increased over the last two decades, however, there is no definitive evidence to favor them over non-programmable VPS (NP-VPS). Thus, there is a growing need for studies comparing these two procedures for their efficacy and safety profile in iNPH. In this study, we attempt to quantitatively summarize the findings of all the prospective and retrospective studies that have directly compared the P-VPS and NP-VPS in terms of efficacy, complications, or overall healthcare expenditure. A systematic search was performed of PubMed, the Cochrane Library databases, and Google Scholar for studies till June 2021 comparing the outcomes of P-VPS with NP-VPS. Four studies were finally included in the quantitative analysis. A trial sequential analysis was done to evaluate the need for further studies. The total rates of subdural collection (odds ratio (OR) 1.03; 95% Confidence interval (CI): 0.73-1.46; P = 0.85; I2 = 12%) as well as surgically evacuated subdural collection (OR 0.46; 95% CI: 0.14-1.55; P = 0.21; I2 = 75%) were not significantly different for P-VPS compared to NP-VPS with pooled data. Similarly, the rate of postoperative infection was found to be similar between the two types of VPS (OR 0.98; 95% CI: 0.39-2.5; P = 0.97; I2 = 0%). The trial sequential analysis (TSA) for the need of surgical evacuation of subdural collection and shunt revision revealed that the meta-analysis of the currently accrued information is not conclusive. Though, associated with higher initial costs, P-VPS does not seem to result in increased healthcare costs in the long run while enabling the surgeon to titrate the opening pressure and avoiding additional surgical procedures like shunt revision or evacuation of subdural collection at least theoretically. However, further trials with a greater sample size are needed to confirm these findings as the current accrued information size is insufficient to reach an unequivocal verdict.

NURS-07. PROGRAMMABLE VP SHUNTS: INDICATIONS, SAFETY AND WARNINGS

Tumor-associated hydrocephalus is common in pediatric patients with brain tumors, often necessitating placement of a permanent ventriculoperitoneal (VP) shunt. The programmable VP shunt has a magnetic externally adjustable valve that provides the option of changing the opening pressure (valve setting) to regulate the outflow of cerebrospinal fluid (CSF). Maximal resistance adjustments can be used for the administration of chemotherapy or radioimmunotherapy. Integrated reservoirs also provide an easy source of diagnostic CSF sampling. Strong magnetic field interference may cause an unintended change in valve setting. Newer models have a mechanism that provides security against inadvertent readjustment caused by MRI 3 Tesla or less. At MSKCC, 52 pediatric patients with various programmable VP shunt models have been treated. Intrathecal radioimmunotherapy or chemotherapy was given to 17 (33%), all without complication. CSF sampling from the VP shunt was well tolerated without any known iatrogenic infections. The ease of shunt reprogramming varied among the different models;1 patient (2%) presented with an unintentional valve setting change. Nurse practitioners and nurses play a vital role in the successful management of patients with a programmable VP shunt. Knowledge about the indications and management of programmable shunts, associated complications, magnetic field safety, MRI safety, shunt reprogramming technique, and nursing considerations is critical.

Undiagnosed Cryptococcus gattii meningitis leading to subsequent ventriculoperitoneal shunt infection in a patient with symptoms of normal pressure hydrocephalus: case report and literature review

BackgroundCryptococcus gattii is known to be an etiologic agent of human cryptococcosis, particularly in immunocompetent persons. C. gattii infection usually involves the central nervous system, the respiratory tract, or may be disseminated. Here we report an atypical manifestation of C. gattii infection in a patient who had C. gattii meningitis complicating the ventriculoperitoneal (VP) shunt infection and concurrent infected intraabdominal VP shunt pseudocyst.Case presentationA 66-year-old Thai female was initially diagnosed with normal pressure hydrocephalus (NPH) and underwent programmable VP shunt placement. However, she still suffered from recurrent communicating hydrocephalus with in-place VP shunt, and later developed recurrent gait impairment, chronic abdominal pain and abdominal mass. Radiological studies demonstrated recurrent hydrocephalus and a very large intraabdominal VP shunt pseudocyst. C. gattii was isolated from both the cerebrospinal fluid and the pseudocyst aspiration. C. gattii meningitis complicating the VP shunt infection and concurrent infected intraabdominal VP shunt pseudocyst was diagnosed. Prolonged antifungal therapy, removal of the infected VP shunt with subsequent implant of a new shunt provided a good outcome.ConclusionChronic C. gattii meningitis should be aware in a patient presenting with normal pressure hydrocephalus. Under-diagnosed cryptococcal meningitis following VP shunt insertion for treating the hydrocephalus can render a complicated VP shunt infection including infected VP shunt pseudocyst.

Comparison of Programmable Ventriculoperitoneal Shunt Artifacts between 3.0 and 1.5 T MR Scanner : A proGAV2.0 Device (Aesculap) Study using General Electric Scanner

Comparison of Programmable Ventriculoperitoneal Shunt Artifacts between 3.0 and 1.5 T MR Scanner : A proGAV2.0 Device (Aesculap) Study using General Electric Scanner

Programmable shunt valve interactions with osseointegrated hearing devices.

OBJECTIVE Patients with ventriculoperitoneal (VP) shunts with programmable valves who would benefit from osseointegrated hearing devices (OIHDs) represent a unique population. The aim of this study was to evaluate the magnetic field strengths of 4 OIHDs and their interactions with 5 programmable VP shunt valves. METHODS Magnetic field strength was measured as a function of distance for each hearing device (Cochlear Baha 5, Cochlear Baha BP110, Oticon Ponto Plus Power, and Medtronic Sophono) in the following modes: inactive, active in quiet, and active in 60 decibels of background noise in the sound booth. The hearing devices were introduced to each shunt valve (Aesculap proGAV, Aesculap proGAV 2.0, Codman Hakim, Codman Certas, and Medtronic Strata II) also as a function of distance in these identical 3 settings. Each trial was repeated 5 times. Between each trial, the valves were assessed for a change in setting. Finally, using a skull model, the devices were introduced to each other in standard anatomical locations and the valves were assessed for a change in settings. RESULTS The maximum magnetic field strengths generated by the Cochlear Baha 5, BP110, and Oticon OIHDs were 1.1, 36.2, and 48.7 gauss (G), respectively. The maximum strength generated by the Sophono device was > 800 G. The magnetic field strength of the hearing devices decreased markedly with increasing distance from the device. The strength of the Sophono's magnetic attachment decreased to 34.8 G at 5 mm. The Codman Hakim, Codman Certas, and Medtronic Strata II valve settings changed when rotating the valves next to the Sophono abutment. No other changes in valve settings occurred in the distance or anatomical models for any other trials. CONCLUSIONS This is the first study evaluating the interaction between OIHDs and programmable VP shunt valves. The findings suggest that it is safe to use these devices together without having to switch to a nonprogrammable valve or move the shunt valve to a more distant location. Still, care should be taken if the Sophono device is used to ensure that the valve is ≥ 5 mm away from the magnetic attachment.

Prosepective Study to Evaluate Rate and Frequency of Perturbations of Implanted Programmable Hakim Codman Valve After 1.5-Tesla Magnetic Resonance Imaging

Exposure to magnetic fields may alter the settings of programmable ventriculoperitoneal shunt valves or even cause permanent damages to these devices. There is little information about this topic, none on live patients. To investigate the effects of 1.5-tesla magnetic resonance imaging (MRI) on Hakim-Codman (HC) pressure programmable valves implanted in our hospital. A single-center prospective study to assess the rate of perturbations of HC programmable valve implanted. One hundred consecutive patients implanted for different clinical reasons between 2008 and 2012 were examined. A conventional skull x-ray before and after a standard MRI on 1.5 tesla. We evaluated before and after results, analyzed modification rate, and verified eventual damages to the implanted devices. Implanted HC valves are extremely handy and durable, even if they are likely to change often due to the exposure to magnetic fields. None of the patients complained of heating effects. Oscillations range from 10-30 mm H2O with a patient who reached 50 mm H2O and 1 who reached 60 mm H2O. Global alteration rate was 40%: 10 patients (10%) experienced a 10 mm H2O change; 14 patients (14%) had a 20 mm H2O change; 6 patients (6%) had a 30 mm H2O change; 8 patients (8%) had a 40 mm H2O change; 1 patient had a 50 mm H2O change; and 1 patient had a 60 mm H2O change. HC valves presented a variable perturbation rate, with an alteration rate of 40% with 1.5-telsa MRI. We have not observed malfunctioning hardware as a result of magnetic influence. We claim ​ a cranial x-ray immediately after the MRI because of a high risk (40%) of decalibration, especially in patients with low ventricles compliance.

Management of idiopathic intracranial hypertension with a programmable lumboperitoneal shunt: Early experience

ObjectiveTo evaluate the clinical outcomes and complications rate among idiopathic intracranial hypertension (IIH) patients who underwent lumboperitoneal (LP) shunt insertion with a programmable Strata valve. MethodsWe retrospectively evaluated patients who underwent LP shunt with a programmable Strata valve insertion at the University of Ottawa Civic Hospital from November 2012 to June 2013. The demographic data, clinical symptoms, opening pressure, pre-operative and post-operative visual fields, neuroimaging, visual acuity, disc status, and complications were recorded and analyzed. ResultsSeven female patients with IIH underwent insertion of an LP shunt with a programmable Strata valve. The mean opening pressure was 35.8cm H2O. The initial valve setting was 1.5, and four patients required post-operative valve pressure adjustment. All patients showed significant improvement in objective visual testing at follow-up as well as less frequent headaches. None of the patients developed intra- or post-operative complications. ConclusionLP shunts with programmable Strata valve systems are a potential alternative to conventional LP and programmable ventriculoperitoneal shunt systems as well as optic nerve sheath fenestration, due to their potential in avoiding brain injury, lower failure and complication rates, lower intracranial hypotension incidence, and flexibility in adjusting valve pressure settings post-operatively evading under- and overdrainage complications. They should be considered for the management of IIH instead of early design LP systems and VP shunts. A randomized multi-center trial should be conducted to compare the efficacy of these surgical techniques.

Hemifacial spasm and trigeminal neuralgia in Chiari’s I malformation with hydrocephalus: Case report and literature review

Chiari’s I malformation with hydrocephalus is commonly seen in clinical experience. Trigeminal neuralgia (TN) and hemifacial spasm (HFS) are most commonly related to vascular compression of the root entry/enter zone (REZ). Until now, TN and HFS associated with hydrocephalus caused by Chiari’s malformation have not been reported. The patient was a 24-year old male with left HFS and ipsilateral TN. Arnold–Chiari’s I malformation with hydrocephalus and platybasia were found in magnetic resonance imaging (MRI) of brain. We underwent a programmable ventriculoperitoneal shunt with complete resolution of all symptoms. This is the first report of one case only presenting as coexistent ipsilateral TN and HFS secondary to Chiari’s I malformation with hydrocephalus.

One-year outcome in the European multicentre study on iNPH

To assess the 1-year outcome after shunt surgery in patients with idiopathic normal pressure hydrocephalus (iNPH). Patients (n = 142) were prospectively included in the European multicentre study by 13 centres. Diagnoses were based solely on clinical and radiological findings. All received a programmable ventriculoperitoneal shunt. Re-examinations, 12 months after surgery, were performed in 115 patients, and the outcome was assessed by the modified Rankin scale (mRs) and a new iNPH grading scale. Improvement was defined as ≥1 step on the mRs and ≥5 points on the iNPH scale. The scores on both scales were significantly improved after 1 year of shunt treatment (Ps < 0.001). Sixty-nine per cent of the patients were improved according to the mRs and 84% according to the iNPH scale. The proportion able to live independently (scores 0-2 on the mRs) was increased from 53% before to 82% 12 months after surgery (P < 0.001). Neither classification (typical or questionable) nor comorbidity affected the level of improvement. Patients not completing the study were worse off with regard to their clinical condition at entry than completers. Twenty-eight per cent of the patients experienced complications and were either conservatively (13%) or surgically (15%) treated. The results of this prospective multicentre study on patients with iNPH diagnosed solely on clinical and radiological criteria support shunt surgery in patients presenting with symptoms and signs and MRI findings suggestive of iNPH.

Establishing successful cerebrospinal fluid flow for radioimmunotherapy

Successful delivery of intraventricular radioimmunotherapy is contingent on adequate CSF flow. The authors present a patient with medulloblastoma in whom obstructed CSF flow was causing hydrocephalus, which was initially corrected by implantation of a programmable shunting device. While managing the hydrocephalus, an endoscopic third ventriculostomy (ETV) needed to be performed in a collapsed ventricular system to ensure adequate radioimmunotherapy distribution. This 18-month-old patient with medulloblastoma involving leptomeningeal dissemination presented for intraventricular radioimmunotherapy. A CSF (111)In-DTPA scintigraphy study obtained through the existing programmable ventriculoperitoneal shunt demonstrated activity in the lateral and third ventricles, but no activity over the cerebral convexities or spinal canal, consistent with obstruction at the level of the cerebral aqueduct. By maximization of ventricular size in a controlled setting, the patient was able to undergo a trial of ETV through very small ventricles. A postoperative CINE MR imaging study confirmed patent ETV. The pressure settings on the shunt were kept at the highest opening pressure (200 mm H(2)O) to maximize flow through the stoma and improve the distribution of CSF throughout the subarachnoid space. The CSF flow scintigraphy study was again performed, this time with tracer activity demonstrated down the thecal sac at 3 hours, and symmetrically over the cerebral convexities at 24 hours. The patient began weekly intraventricular administration of (131)I-3F8 therapy. Successful rerouting of CSF flow for the purpose of therapeutic radioisotope administration is possible. Endoscopic third ventriculostomy can be considered in patients with programmable shunting devices; normal or slit ventricles do not preclude successful ETV.

A Novel Method for Administering Intrathecal Chemotherapy in Patients With Leptomeningeal Metastases and Shunted Hydrocephalus

Leptomeningeal metastatic disease occurs in a minority of patients with systemic neoplastic disease. Before the initiation of intrathecal chemotherapy, hydrocephalus must be addressed with a cerebrospinal fluid (CSF)-diverting shunt. CSF diversion can theoretically prematurely divert chemotherapeutic drugs that are administered intrathecally, thereby potentially reducing the efficacy of such treatments. We report on a patient with leptomeningeal disease and hydrocephalus secondary to metastatic bladder carcinoma requiring insertion of a programmable ventriculoperitoneal shunt and intrathecal chemotherapy. A novel method was utilized to administer intrathecal chemotherapy, in which the valve pressure setting was transiently increased during a 4-hour treatment session for intrathecal chemotherapy. No clinical complications occurred. Nuclear imaging was obtained sequentially after the injection of indium tracer into the ventricular system with the programmable valve at its baseline setting as well as at a maximal pressure setting. In the maximal valve setting condition, reduced outflow of nuclear tracer was observed at 1.5 and 4 h after injection, and normalized by 24 hours after injection. Programmable shunt valves can be utilized in a safe, controlled fashion to treat hydrocephalus associated with leptomeningeal disease, as well as regulate the outflow of CSF and minimize diversion of intrathecal chemotherapeutic agents.

Programmable valve shunts: are they really better?

Programmable valve shunts allows selection of opening pressure of shunt valve. In the presented article, a unique complication pertaining to programmable shunts has been discussed. A 5-year-old boy who had tectal plate low grade glioma with obstructive hydrocephalus was managed with Codman programmable ventriculoperitoneal shunt. There was a spontaneous change in the opening pressure of the shunt valve leading to shunt malfunction. Routinely used household appliances produce a magnetic field strong enough to cause change in the setting of shunt valve pressure and may lead to valve malfunction. Other causes of programmable valve malfunction also discussed.

Effect of transcranial magnetic stimulation on four types of pressure-programmable valves

Exposure to powerful magnetic fields may alter the settings of programmable ventriculoperitoneal shunt valves or even cause permanent damage to these devices. Transcranial magnetic stimulation (TMS) and magnetic resonance imaging both generate a high-intensity, focal magnetic field. To the best of our knowledge, there is no literature data on the compatibility of TMS with neurosurgical implants. The aim of the present in vitro study was to investigate the effects of TMS on four types of pressure-programmable valves (the Strata 2 from Medtronic, the Polaris from Sophysa, the ProGAV from Miethke, and a cylindrical valve from Codman-Hakim). We used a Magpro X100 stimulator (Medtronic) for monophasic or biphasic TMS via a circular or a figure-of-eight coil. Each valve setting was tested before and after exposure to TMS. Experiment 1: The effect of the coil-valve distance (10, 5, 2.5, and 1 cm) was assessed. Experiment 2: We mimicked in situ stimulation with a human mannequin by placing the valve in a retroauricular position, the TMS circular coil on the apex, and figure-of-eight coil centered over the primary motor area site. Temperature changes were monitored throughout the experiments. Experience 3: TMS-induced valve movements were assessed by using an in-house accelerometric setup. Our results primarily demonstrated that the Strata 2 and Codman-Hakim valves' settings were perturbed by TMS. There was no heating effect for any of the valves. However, TMS induced movements of the Strata 2, Polaris, and ProGAV valves. Experiment 1: The unsetting frequencies observed for the Strata 2 and the Codman-Hakim valve showed an influence of the distance, the coil model, and the magnetic field characteristics, whereas the Polaris and ProGAV's settings remained unchanged. Experiment 2: Unsetting occurred for Strata 2 valve with the circular coil only, whereas the Polaris, ProGAV, and Codman-Hakim valves' settings remained stable. Experiment 3: The Strata 2, Polaris, and ProGAV valves showed high-amplitude oscillations during TMS under all stimulation conditions, whereas the Codman-Hakim valve did not move. Our in vitro experiments showed that TMS can interfere with programmable shunt valves by inducing unsetting or movement. This finding suggests that great care must be taken if applying TMS in hydrocephalic, shunted patients.

O.096 A novel impedance sensor to monitor and control ventricular size

To evaluate the clinical outcomes and complications rate among idiopathic intracranial hypertension (IIH) patients who underwent lumboperitoneal (LP) shunt insertion with a programmable Strata valve.We retrospectively evaluated patients who underwent LP shunt with a programmable Strata valve insertion at the University of Ottawa Civic Hospital from November 2012 to June 2013. The demographic data, clinical symptoms, opening pressure, pre-operative and post-operative visual fields, neuroimaging, visual acuity, disc status, and complications were recorded and analyzed.Seven female patients with IIH underwent insertion of an LP shunt with a programmable Strata valve. The mean opening pressure was 35.8 cm H2O. The initial valve setting was 1.5, and four patients required post-operative valve pressure adjustment. All patients showed significant improvement in objective visual testing at follow-up as well as less frequent headaches. None of the patients developed intra- or post-operative complications.LP shunts with programmable Strata valve systems are a potential alternative to conventional LP and programmable ventriculoperitoneal shunt systems as well as optic nerve sheath fenestration, due to their potential in avoiding brain injury, lower failure and complication rates, lower intracranial hypotension incidence, and flexibility in adjusting valve pressure settings post-operatively evading under- and overdrainage complications. They should be considered for the management of IIH instead of early design LP systems and VP shunts. A randomized multi-center trial should be conducted to compare the efficacy of these surgical techniques.

Acute external hydrocephalus complicating craniocervical decompression for syringomyelia–Chiari I complex

The occurrence of subdural cerebrospinal fluid collections and ventricular dilatation (external hydrocephalus) after foramen magnum decompression is extremely rare. The authors report on a 37-year-old man who developed symptomatic subdural fluid collections (SFC) after uncomplicated foramen magnum decompression for Chiari I-syringomyelia complex. Postoperative magnetic resonance imaging revealed a supratentorial SFC with prominent midline shift. In addition, bilateral infratentorial SFCs extending supratentorially through the tentorial notch, pseudomeningocele and initial shrinkage of the syrinx were observed. Few days after evacuation of supratentorial collection, the patient experienced increasing headache and a computerized tomography scan demonstrated a contralateral subdural collection as well as ventricular dilatation. A programmable ventriculoperitoneal shunt was placed with resolution of supratentorial collection and progressive improvement of infratentorial collections and pseudomeningocele. Although previous reports described the occurrence of extra-axial fluid collections and hydrocephalus after foramen magnum decompression for Chiari malformation, to our knowledge, this is the only report of acute external hydrocephalus after foramen magnum decompression requiring urgent evacuation of SFC in order to reduce the mass effect.