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. 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.