Effect of 3-tesla magnetic resonance imaging on various pressure programmable shunt valves

Inoue, Takashi; Kuzu, Yasutaka; Ogasawara, Kuniaki

doi:10.3171/ped.2005.103.2.0163

Cited by 23 publications

(23 citation statements)

References 10 publications

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“…We consider major complications those requiring surgical correction, including subdural hematomas and empyemas, permanent shunt obstruction and shunt infection. We consider minor complications those in which the adjustment of pressure and clinical measures were sufficient and effective for the control, including wound dehiscence, slit ventricle syndrome, transient shunt obstruction and resetting after MRI procedures 20,21 (Table 2). …”

Section: Complicationsmentioning

confidence: 99%

Programmable valve represents an efficient and safe tool in the treatment of idiopathic normal-pressure hydrocephalus patients

Oliveira

Saad

Reis

et al. 2013

Arq. Neuro-Psiquiatr.

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Idiopathic normal pressure hydrocephalus (iNPH) is a condition characterized by gait disturbance, dementia and/or urinary incontinence without causative disorders, as well as dilation of ventricular system due to disturbance of cerebrospinal fluid (CSF) circulation with normal CSF pressure and no secondary cause [1][2][3] . It is a differential diagnosis for most of the dementia syndromes and occurs mainly in elderly populations 4 .The known incidence is approximately 6 per 100,000 and it has a prevalence of 22 per 100,000 for suspected iNPH.There are associations with hypertension, cerebrovascular and Alzheimer diseases [1][2][3] .The clinical evolution of iNPH is not clear 5 . Without surgery, most iNPH patients present early clinical deterioration. A small number of patients might improve without shunting; however, the extent of improvement is not clear 3 .Ventricular CSF shunting is the main treatment in the management of iNPH and its results in reducing the caregiver's burden when caring for iNPH patients are well-established 6 . ABSTRACTIdiopathic normal pressure hydrocephalus (iNPH) is characterized by gait disturbance, dementia and /or urinary incontinence, dilation of the ventricular system and normal opening cerebrospinal fluid pressure. Shunt surgery is the standard treatment of iNHP. Diversions with programmable valves are recommended, once drainage pressure can be changed. However, well-defined protocols still lack guiding the steps to attain proper pressure for each patient. Methods: In our study, we reported the experience of shunting 24 patients with iNPH using Strata ® (Medtronic) valve, following a protocol based on a positive Tap Test. Results: We observed clinical improvement in 20 patients and stability/ worsening in 4 patients. Complications occurred in five patients, including one death. The results display improvement, and complications occurred at a lower rate than reported in other studies. Conclusions: The Strata ® valve used in the proposed protocol represents an efficient and safe tool in the treatment of iNPH.Key words: hydrocephalus, normal pressure, cerebrospinal fluid shunts, treatment. RESUMOA hidrocefalia de pressão normal idiopática (iNPH) é caracterizada por alterações na marcha, demência e/ou incontinência urinária, além de dilatação dos ventrículos com pressão normal de abertura no líquido cefalorraquidiano. A cirurgia de derivação é o principal tratamento da iNHP. São recomendadas válvulas programáveis, pois a pressão de drenagem pode ser alterada. Embora as válvulas programáveis sejam utilizadas, não há protocolos para atingir a pressão adequada de cada paciente. Métodos: Neste estudo, relatamos nossa experiência com 24 pacientes com iNPH que usaram a válvula Strata ® (Medtronic), seguindo protocolo baseado em um Tap test positivo. Resultados: Observamos melhora em 20 pacientes e estabilidade ou piora em 4. Ocorreram complicações em cinco pacientes, tendo um deles falecido. Houve importante melhora clínica, e as complicações ocorreram em taxa mais baixa do que as relatad...

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Section: Complicationsmentioning

confidence: 99%

Programmable valve represents an efficient and safe tool in the treatment of idiopathic normal-pressure hydrocephalus patients

Oliveira

Saad

Reis

et al. 2013

Arq. Neuro-Psiquiatr.

View full text Add to dashboard Cite

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“…Authors of several studies have established that MR imaging can alter the valve settings on programmable valves regardless of their initial settings [4,6,8,9]. Accidental resetting induced by an external magnetic field other than those associated with MR imaging has been reported to be rare [11].…”

Section: Discussionmentioning

confidence: 99%

“…However, unintended pressure changes in programmable valves can also be caused by external magnetic fields. Alterations in valve settings are common after exposure to strong magnetic fields such as those involved in magnetic resonance (MR) imaging, and the need for readjustment of the valve setting after MR imaging has been emphasized in the neurosurgical and neuroradiological literature [4,6,8,9].…”

Section: Introductionmentioning

confidence: 99%

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

Zuzak

Balmer

Schmidig³

et al. 2008

Childs Nerv Syst

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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 effected 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.

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“…Earlier research completed on the safety of programmable valves in MRI demonstrated no effect on valve function at 3T. 70 More recent data, however, has demonstrated some effects due to the electromagnetic field, resulting in a ''conditional" safety classification, as no permanent damage to valve function has actually been noted. A slight increase in temperature has been reported of the order of 0.4 degrees C. However, even though the shunt valve may be safe for MRI, the valve settings can change during imaging, necessitating resetting of the valve.…”

Section: Devices and Foreign Bodiesmentioning

confidence: 95%

MRI safety; nephrogenic systemic fibrosis and other risks

Gauden

Phal

Drummond

2010

Journal of Clinical Neuroscience

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Effect of 3-tesla magnetic resonance imaging on various pressure programmable shunt valves

Abstract: The Sophy Polaris valve allows shunt-dependent patients who need a programmable valve to undergo 3-tesla MR imaging.

Cited by 23 publications

References 10 publications

Programmable valve represents an efficient and safe tool in the treatment of idiopathic normal-pressure hydrocephalus patients

Programmable valve represents an efficient and safe tool in the treatment of idiopathic normal-pressure hydrocephalus patients

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

MRI safety; nephrogenic systemic fibrosis and other risks

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