Medtronic Strata II / Strata NSC valves

Hazard alert - potential for MRI scans to affect valve positioning

22 February 2017

Consumers and health professionals are advised that Medtronic Australasia, in consultation with the TGA, has issued a hazard alert for Medtronic Strata II/Strata NSC Valves (including burr hole and lumbar peritoneal versions) due to the potential for a magnetic component to become 'reverse polarised' under certain circumstances involving high-strength magnetic resonance imaging (MRI) fields.

Medtronic is also undertaking a recall for product correction to update the Instructions for Use (IFU) to take account of this issue. Please note that StrataMR devices are not affected by this recall for product correction.

Medtronic Strata II/Strata NSC Valves are used in the management of hydrocephalus. They control the flow of cerebrospinal fluid being drained from the brain to relieve pressure.

If the affected magnetic component becomes reverse polarised it could lead to inaccurate pressure level readings with the Strata Indicator Tool or StrataVarius system, which are used to measure and set the position of the valve components from outside the body using magnetic fields. This may result in over or underdrainage symptoms developing and require separate confirmation of valve position/readjustment using X-rays.

Over a two-year period, Medtronic has received a total of five complaints worldwide regarding this issue. One patient was confirmed to need follow-up surgery to correct the issue. There were no reports of other instances of disease, illness or injury.

If this issue occurs the expected adverse health consequences are the same as those experienced during the course of hydrocephalus management (for example, headaches, lethargy, nausea, vomiting), or those related to follow-up surgery.

Information for consumers

If you or someone you provide care for been implanted with an affected Medtronic Strata II/Strata NSC valve, you should be contacted by your neurosurgeon regarding this issue.

If you have any questions or concerns about this issue, contact your neurosurgeon.

Information for health professionals

If you are treating someone who has received an affected Medtronic Strata II/Strata NSC valve, be aware of this issue.

Patients with any implants such as this should be followed up by their neurosurgeon if they have any questions or concerns.

Information for neurosurgeons

Medtronic has written to neurosurgeons who have implanted affected devices providing more information about this issue.

Reverse polarisation of the magnet occurs when the north direction changes to south and vice versa.

The IFU for the products will be updated to include the following sentences to reinforce the warnings/precautions:

Biological debris inside the valve may impact adjustability, and may lead to adjustment mechanism damage if exposed to 3.0 tesla MRI. If difficulty is experienced adjusting or reading the valve setting, radiographic setting confirmation should be considered. The reading from the Strata II Indicator tool or StrataVarius system may be reversed (180 degrees opposite) from the radiographic image. In this situation, radiographic imaging should be used to determine the setting of the valve.

A full list of affected products is listed in the 'Additional information' section below.

Additional information

All affected products are listed in the table below.

Number Description
27814 SHUNT ASSY., STRATA II, SML
27815 SHUNT ASSY., STRATA II, REG.
27816 SHUNT, SNAP, STRATA II, SMALL
27817 SHUNT SNAP, STRATA II, REG.,
27818 SHNT, STRATA II,SML,BIO
27819 SHNT, STRATA II,REG,BIO
27823 SNPSHNT ASSY,STRATA II,REG,BIO
27824 SHUNT, UNI, STRATA II,SML, BIO
27825 SHUNT, UNI, STRATA II,REG, BIO
42335 FP-VALVE STRATA NSC BURR HOLE
42355 FP STRATA NSC VALVE SMALL
42365 FP STRATA NSC VALVE REGULAR
42836 FP-VALVE STRATA II BURR HOLE
42856 FP-STRATA 2 VALVE, SMALL
42866 FP-STRATA 2 VALVE,REGULAR
44420 FP-LP STRATA NSC SHUNT, CLSD
44430 SHUNT STRATA KIT NSC LP ASSY
44465 FP-LP STRATA NSC VALVE
46070 FP UNI SHNT STRATA NSC SML 8CM
46075 FP UNI SHNT STRATA NSC SM 11.5
46080 FP UNI SHNT STRATA NSC REG 11
46085 FP UNI SHNT STRATA NSC RG 13.5
46635 FP-SHUNT,STRATA NSC BUR HOLE
46655 FP SHNT ASSY STRATA NSC SMALL
46665 FP SHNT ASSY STRATA NSC REG
46836 FP-SHUNT STRATA II BURR HOLE
46856 FP-STRATA 2 SHUNT ASSY,SML
46866 FP-STRATA 2 SHUNT ASSY,REG
46881 FP-STRATA 2 UNI SHUNT, REG, 11
46886 FP-STRATA 2 UNI SHUNT,REG,13.5
92856 [NG] FP STRATA 2 VALVE, SML,BG
92866 [NG] FP STRATA 2 VALVE, REG,BG

Reporting problems

Consumers and health professionals are encouraged to report problems with medical devices. Your report will contribute to the TGA's monitoring of these products. For more information see the TGA Incident Reporting and Investigation Scheme (IRIS).

The TGA cannot give advice about an individual's medical condition. You are strongly encouraged to talk with a health professional if you are concerned about a possible adverse event associated with a medical device.