BEUDAMED
    FDA Adverse Event Malfunction Summary report: N

    ELEKTA NEUROMAG® WITH MAXFILTER

    MDR report key: 3828984 · Received May 23, 2014

    Report

    Report Number
    9680891-2014-00001
    Event Type
    Malfunction
    Date Received
    May 23, 2014
    Date of Event
    April 30, 2014
    Report Date
    October 22, 2014
    Manufacturer
    ELEKTA OY
    Product Code
    OLX
    PMA / PMN Number
    K091393
    Product Problem
    Yes
    Report Source
    Manufacturer report
    Reporter Location
    TX, US
    Reporter Occupation
    PHYSICIAN

    Narratives

    Additional Manufacturer Narrative · 1

    THE MANUFACTURER'S INVESTIGATION IS ON-GOING. ELEKTA WILL PROVIDE FURTHER INFORMATION WHEN THE INVESTIGATION IS COMPLETE.

    Additional Manufacturer Narrative · 1

    THE MANUFACTURER'S INVESTIGATION CONCLUDED THAT THE PROBLEM WAS THAT BOTH AUTOMATIC BAD CHANNEL DETECTION AND THE TEMPORAL SSS (TSSS) FAILED TO RECOGNIZE SHORT-DURATION JUMPING ARTEFACTS ON A SINGLE MEG CHANNEL. THEREFORE, MAXFILTER TSSS PROCESSING CAUSED SPREADING OF SUCH SUDDEN JUMPS ON SINGLE CHANNEL AS ARTEFACTS TO SEVERAL MEG CHANNELS. THE CHARACTERISTICS OF THE BAND-PASS FILTERED ARTIFACT RESEMBLED AN EPILEPTIC SPIKE. THE USER PERFORMED TYPICAL ANALYSIS OF LOCALIZATION OF EPILEPTIC ACTIVITY ON THE DATA. THE MEG RESULTS WERE IN ACCORDANCE WITH THE CLINICAL PICTURE OF THE PATIENT, AND NO OTHER (REAL) EPILEPTIC ACTIVITY WAS FOUND IN THE DATA. HOWEVER, USER SUSPECTED THE VALIDITY OF THE RESULTS BY USING NORMAL CLINICAL PRACTICES AND BY FOLLOWING INSTRUCTIONS, E.G. LACK OF CORRESPONDING ACTIVITY IN THE EEG DATA MEASURED SIMULTANEOUSLY WITH MEG DATA. USER CONSULTED ELEKTA PERSONNEL, AND THE ACTIVITY WAS CONFIRMED TO BE AN ARTIFACT BY REVIEWING THE RAW DATA TO WHICH MAXFILTER PROCESSING WAS APPLIED, AS DESCRIBED IN MAXFILTER USER MANUAL AND ACNS AND ACMEGS GUIDELINES. AFTER MANUALLY SELECTING THE ILL-BEHAVING CHANNEL, AND OMITTING IT FROM MAXFILTER PROCESSING, NO ARTIFACT REMAINED IN THE PROCESSED DATA. NO HARM WAS REALIZED TO THE PATIENT. EVEN IF THE ANALYSIS HAD BEEN ACCEPTED BY THE CLINICAL USER, THE RESULT WOULD NOT HAVE BEEN TYPICALLY USED ALONE FOR THE PRESURGICAL PLANNING, BUT ONLY IN AGREEMENT WITH OTHER IMAGING MODALITIES AND IN REFERRING PHYSICIAN'S CAREFUL CONSIDERATION. THE ROOT CAUSE WAS THAT MAXFILTER DID NOT RECOGNIZE THE PROBLEMATIC CHANNEL MEG1023 AS A BAD ONE, BECAUSE: 1. THE AUTOMATIC BAD CHANNEL SCANNING DID NOT FIND THE ARTIFACT DUE TO LARGE DISTURBANCES CREATED BY THE VNS DEVICE. 2. THE JUMPS HAVE SHORT DURATION (<100 MS) AND OCCURRED INFREQUENTLY. THEREFORE, TSSS-PROCESSING IN MAXFILTER DID NOT INCLUDE THE ARTIFACT SHAPE IN THE DISTURBANCE WAVEFORMS WHICH WERE PROJECTED OUT WHEN USING DEFAULT PARAMETER SETTINGS. THUS, MAXFILTER PROCESSING DID NOT REMOVE THE ARTIFACT. FIELD CORRECTIVE ACTION (FCO 145 036 01 113) WAS RELEASED TO CUSTOMERS JUNE 2014. USER NOTICE RELEASED TO CUSTOMERS CLARIFIES THE GUIDANCE PROVIDED BY THE INSTRUCTIONS FOR USE, PROVIDING SPECIFIC GUIDANCE ON HOW TO INSPECT THE OUTPUT DATA IN ORDER TO DETECT SIMILAR ARTIFACTS. THIS IS A VERY RARE COMBINATION OF INDIVIDUAL EVENTS THAT TOGETHER CAUSED THE ARTEFACT TO RESEMBLE POTENTIALLY PATHOLOGICAL ACTIVITY. NO HARM OR RISK OF HARM WAS REALIZED TO THE PATIENT.

    Description of Event or Problem · 1

    CHANNEL ARTEFACT SPREAD BY FILTERING TO RESEMBLE EPILEPTIC ACTIVITY. THE CUSTOMER REPORTED THAT ONE CHANNEL HAS LOW-AMPLITUDE (ORDER OF NEURONAL SOURCE) ARTEFACT OCCURING EVERY NOW AND THEN. TSSS PROCESSING USING MAXFILTER-2.2 DID NOT REMOVE THIS ARTEFACT, BUT SPREAD IT TO CLOSE-BY CHANNELS. ADDITIONAL TEMPORAL FILTER IN GRAPH (4-30 HZ) SMOOTHED THE TIME COURSE OF THE ARTEFACTS TO RESEMBLE EPILEPTIC INTER-ICTAL SPIKES. THE ARTEFACTS LOCALIZED TO THE FRONTAL CORTEX, TO THE LOCATION THAT WELL MATCHED WITH THE CLINICAL PROFILE OF THE PATIENT. OTHER EPILEPTIC ACTIVITY WAS NOT FOUND. WITHOUT LOOKING AT THE RAW DATA, THIS ARTEFACTUAL SOURCE COULD HAVE BEEN ASSUMED TO BE EPILEPTIC SOURCE. THE CASE DISPLAYS KNOWN BUT RARE BEHAVIOUR OF MAXFILTER PREPROCESSING: IF BAD CHANNEL IS NOT MARKED/DETECTED AND THE ARTEFACT IS LOW IN AMPLITUDE, SO THAT IT DOES NOT HAVE ENOUGH POWER TO BE DETECTED BY THE TEMPORAL EXTENSION OF TSSS, THE SPATIAL FILTER (I.E. SSS) WILL SMOOTH THE ARTEFACT TO RESEMBLE REAL MAGNETIC FIELD. TYPICALLY THE ARTEFACT IS SUPPRESSED BY EITHER DETECTING THE CHANNEL AS BAD OR BY TERMPORAL PROJECTION (IN TSSS).

    Devices

    Seq Brand Generic Product Code Manufacturer Model Lot UDI-DI
    307594 ELEKTA NEUROMAG® WITH MAXFILTER SOURCE LOCALIZATION SOFTWARE FOR ELECTROENCEPHALOGRAPH OR MAGNETOENCEPHALOGRAPH OLX ELEKTA OY

    Patients

    Seq Age Sex Outcome Treatment
    1