Pseudo shunt malfunction caused by the use of a portable cassette player
EANS Academy. Wu P. 09/25/19; 275484; EP08001
Pin-Hui Wu
Pin-Hui Wu

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Abstract
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Background: Programmable ventriculoperitoneal (VP) Shunts have revolutionized the management of hydrocephalus. We present a case where the use of a cassette player, inadvertently modified shunt valve pressure settings causing transient symptoms of blocked shunt. Interestingly, programmable shunts were introduced in the 1980s when portable cassette players were popular, yet a case like this has yet to be reported.
Case Presentation: A 33 year-old male patient with spina bifida, learning difficulties and a programmable VP shunt in situ presented with symptoms of a blocked shunt. Examination of the shunt showed no obvious cause and subsequent imaging demonstrated a 3rdventricle cyst without features suggestive of shunt malfunction. The cyst was fenestrated and resulted in an improvement of symptoms. His inpatient stay was complicated by recurrence of symptoms attributed to spontaneous changes in the valve setting.
The frequent use and attachment to a cassette player in close proximity to the valve was eventually identified as the cause. The magnet within this technology repeatedly and inadvertently adjusted the valve settings.
Discussion and conclusions: A cassette player usually contains two small magnets, each only the size of a flattened pea. The two magnets combined sum up to approximately half the width of the tape of a cassette. These created a magnetic field that changed the patient's valve settings, causing recurrent symptoms.
It is therefore advised to keep in mind that any device with magnets, no matter how small, should be avoided near patients with programmable VP shunts. This may prove to be challenging in patients with brain insults, that develop difficult behaviours and find relief in devices containing magnets.


[Fig 1. A Demonstration of the Cassette Player's Magnetic Pull]

Background: Programmable ventriculoperitoneal (VP) Shunts have revolutionized the management of hydrocephalus. We present a case where the use of a cassette player, inadvertently modified shunt valve pressure settings causing transient symptoms of blocked shunt. Interestingly, programmable shunts were introduced in the 1980s when portable cassette players were popular, yet a case like this has yet to be reported.
Case Presentation: A 33 year-old male patient with spina bifida, learning difficulties and a programmable VP shunt in situ presented with symptoms of a blocked shunt. Examination of the shunt showed no obvious cause and subsequent imaging demonstrated a 3rdventricle cyst without features suggestive of shunt malfunction. The cyst was fenestrated and resulted in an improvement of symptoms. His inpatient stay was complicated by recurrence of symptoms attributed to spontaneous changes in the valve setting.
The frequent use and attachment to a cassette player in close proximity to the valve was eventually identified as the cause. The magnet within this technology repeatedly and inadvertently adjusted the valve settings.
Discussion and conclusions: A cassette player usually contains two small magnets, each only the size of a flattened pea. The two magnets combined sum up to approximately half the width of the tape of a cassette. These created a magnetic field that changed the patient's valve settings, causing recurrent symptoms.
It is therefore advised to keep in mind that any device with magnets, no matter how small, should be avoided near patients with programmable VP shunts. This may prove to be challenging in patients with brain insults, that develop difficult behaviours and find relief in devices containing magnets.


[Fig 1. A Demonstration of the Cassette Player's Magnetic Pull]

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