TheHistoryoftheDevelopmentoftheImplantableSpinalCordStimulatorPainbytes Staff

ThefirstportablebatterypoweredelectricalstimulatorcommerciallyproducedtobeusedasatreatmentwastheElectreatattheturnofthe20thcentury.Itwas

patentedin1919byC.W.Kent,anaturopathfromPeoria,Illinois,andremainedonthemarketthroughthe1940s,despiteintenseattackbytheFDAandrejectionbythemedicalprofession,largelybecauseoftheoutrageousclaimsmadebythemanufacturerofbeingabletocureavarietyofmaladies.ThemanufacturercalledtheElectreatthe“artificialheart”indeferencetoitsinvigoratingcapabilities.TheFDAwasformedin1938andtheElectreatbecamethefirstproductprosecutedforfraudulentadvertising,thereafterbeingforcedtolimititscurativeclaimstopainalone.Over250,000weresoldandwasusedclinicallyupuntilthecompanywasboughtin1993.Thedeviceoperatedon2-Dbatteriesandhadarollerasonepoleandaspongepadastheother.However,theElectreatwasusedbyphysiciansadministeringavarietyoftreatmentstopatientsintheearly1900stostimulatevitality,increasemusclemass,andtoincreasebodytemperature.Itwasespeciallyusedtotreatneurasthenia,adiagnosisofthetimethateffectivelymeantwomenwereoverstressed,werefatigued,andhadavarietyofachesandpains,andneededtorest,andnottroublethemselveswithissuesoftheworld,education,orbooks.DrS.WeirMitchellusedtheElectreataspartofhis“RestCure”inadditiontomassage(whichwasthebeginningofmassagetherapyintheUS).Unfortunately,neurastheniawassimplyaVictorianerabeliefoftheinherent“weakness”ofwomen(meaningemotionallyweak)andservedasadevicetopreventwomenfromphysicallystrainingthemselves,movingforwardintheirstationinlifeorbecomingeducated,effectivelymakingthemmoresubservienttotheheadofthehouse.Some

physiciansincludingShealy,thefatherofthespinalcordstimulator,maintainedElectreatwasnotasimpleDCdevice,buthadoutputinthegigahertzrange(SoulMedicine,DawsonChurchandNormanShealy),butthisclaimhasnotbeenindependentlysubstantiated.ShealyhadacquiredanElectreatforuseinhispatients.

EarlBakkenbeganMedronicwithhisbrotherinlawinhisgaragein1949.Hewasagraduatestudentatthetime,tryingtomakeextramoneybyrepairinghospitalequipmentforNorthwesternHospital.Hebecamesosuccessfulatthisthathequitgraduateschool.Initiallyhewasarepresentativefor3equipmentcompanies,andhadmanyinteractionswithphysicianswhodesiredsomecustomengineeringandinventionwork.Hebegantomodifyormakeequipmentrequestedbythephysiciantobeusedclinically.Bakkenmademorethan100customapplicationsduringtheearlyyears,nonewasFDAapproved,andnonewerepatented.HedidrunintodifficultywiththeFDAwhen

theyultimatelyrequiredapprovalforsomeofhiscustomproductshewasselling.Bakkenworkedtodeveloppacemakersanddefibrillatorsinthe1950sonward.Thisgavehimtheexpertiseinminiaturization,externalandinternalbatterysupplies,andinleadconstructthatwouldultimatelybeusefulinspinalcordstimulationconstruction.

In1954,Heathelectricallystimulatedacancerpatient’sseptumpellucidumatintervalsof15mindailytoweeklyandderivedcancerpainalleviation.

Alsoin1954TexasInstrumentsfirstcommerciallyproducedsilicontransistorthathadbeendevelopedbyBellLabscientistsearlierinthesameyear.Thecommercialproductionmadeitincreasinglypossibletoprovideminiaturecircuitry.

Alsoin1954,Poolusedfrontallobestimulationtotreatpsychiatricdiseases.

Thefirstintegratedcircuitwasdevelopedafewyearslaterin1958andunderwentrapidimprovement.

THEFIRSTIMPLANTABLEPACEMAKER:SIEMANS1958

In1958thefirstpacemakerwasdevelopedbySiemans.Thepacemakerwasusedasthemodelforthetechnologyforthespinalcordstimulator.Pacemakershavethesameparametersthatmaybeadjustedasthespinalcordstimulatorgeneratorsoftwodecadeslater.

Theamplitude,frequency,andpulsewidthareadjustable.Themajordifferenceisthatthepowerrequirementsarehigherforspinalcordstimulationcomparedwithcardiacpacing.

Thefirstimplantedpacemakerlasted3hoursbeforeitfailed.

Alsoin1958,Heathimplantedseptumpellucidumelectrodes(inthebrain)asatreatmentforcancerpain.Thepatienthadrelieffortheirlast7monthsofhislife.

1963BarostatwasanelectricalstimulatordevicemanufacturedbyMedtronicandusedtostimulatethecarotidsinus(locatedintheneck)forthetreatmentofhighbloodpressure.In1965AngiostatwascreatedbyMedtronictostimulatethecarotidsinusforanginatreatment.

1965GatetheoryMelzack-Wallwasproposed.Painperceptioninvolvesagatethatcanbeopenedorclosedtoallowpainsensationtopassthroughortoblockit.Iftheactivityofsmallpainfiberspredominates,thenthegatewillopen.Ontheotherhandlargepainfibersthatpredominate(touch,positionsense)willclosethegateandnotallowasmuchpainthroughtothebrain.Thiscreatedtheideathatpaincouldbeblockedbyopeningandclosingthesegates.

1966J.ThomasMortimer,atthetimeagraduatestudentinengineeringatCaseWesternUniversity(graduatestudent)wasrecruitedbyNormShealytobeginworkingonaspinalcordstimulatorprototype.Shortlyafterwardsin1967,NormShealy,theChiefofNeurosurgeryattheGundersonClinic,Mortimer,andothercollaborators,begantoperformexperimentsoncatstoprovethegatetheoryandstimulationofthedorsalcolumnsasreportedintheJournalAnesthesia&AnalgesiaMay/Juneedition1967.ThefollowingeditionJuly/Aug1967wasthereportofthefirstpatientuseasoutlinedbelow.

1967Thegatetheorywastestedin1967byWallandSweetwhostimulatedtheirowninfraorbitalnervesundertheeyes.SubsequentlySweetrecruitedRogerAvery,acolleagueinengineeringatMIT,tomakeanimplantablestimulator.SweetandWepsicusedthestimulatortoprovideperipheralnervestimulationforpainmanagement.

Alsoin1967,NormShealytheneurosurgeonstimulatedthelargenervesofthespinalcordinthedorsalcolumninthelabandfounditwaspossibletoblocksensation.

1967Thefirsthumandorsalcolumnstimulator(latertermedspinalcordstimulator)wasimplantedinApril1967byC.NormanShealy,M.D.oftheGundersonClinicinLaCrossWisconsinanddesignedbyMortimerafterexperimentationinafelinemodel.Thefirstpatientsufferedthoracicchestwallandabdominalpainfromwidespreadmetastaticcancerfromaprimarycancerof

carcinomaofthelung.Hehadasinglecathodeelectrodeimplanted"approximatingthedorsalcolumns"bysuturingtheelectrodestotheduraafterlaminectomyatT2-3forexposure.Theanodewasintramuscular,bothelectrodesbeingmadeofVitallium.Thestimulatorwasexternalandconnectedtotheimplantedleadsviahypodermicneedlesthatwereplacedthroughtheskinintotheleadjacks.Thestimulatorwasturnedononlyforanhourthefirstday,changingthefrequencywhenthepatientbegantoexperiencepainagain.Theseconddaythepatientusedthedorsalcolumnstimulatorfor10outof12hours,againchangingthefrequencywhenhebegantoexperiencepain.Thefollowingday,thepatientwastooillforstimulationanddiedthatnight.Laterpublicationsmistakenlypurportedthedevicewasusedforthelastseveralmonthsofthepatient’slife,wheninactualitywasforonly11hoursoverthelast3daysofthepatient'slife.Theautopsydemonstratedthepatientsufferedfromendocarditiswithcerebralembolismthatresultedinparaparesisanddeath.Thefirstspinalcordstimulatorcouldnotbemeasuredasasuccessgiventheshortamountoftimeusedinstimulationandtheunrelateddeathofthepatientwithcancer,butitspurredfurtherinterestsincetherewasareductioninpainduringthestimulation.Buthavingtoplugintojacksthatwerebeingaccessedwithneedlesplacedthroughtheskinwasnotanoptimalwaytodeliverpowertoastimulationsystem.Mortimerknewthis,andsetouttoimprovehissystem.

Mortimersubsequentlycontactedanengineer,NormHagforsofMedtronic,wherehehadinterviewedtwoyearsbeforeforajob.MortimersurmisedtheMedtronicradiofrequency(external)poweredcardiacgeneratorcouldbeusedtopoweraspinalcordstimulator.ThesecondstimulatorpoweredbytheMedtroniccardiacgeneratormodifiedBarostat,providedpainreliefforfouryearsfromchronicpain.ThesecondelectrodewasdesignedbyMortimertoworkwith

theBarostatradiofrequencytechnology.Theleadsonthesecondimplantwereplatinumiridiumofthesameshapeasthefirststimulatorwithanexternalcoilforthetransmissionofpower.Aportablecontrolboxwithadjustablerate,amplitude,andthe

rateoffrequencychangewasconnectedtotheexternalcoil.Therateandamplitudeweregeneratedinthe

controllerthentranslatedintoradiofrequencywavespickedupbythereceiver,thatre-assembledtheRFsignalintothefinalstimulationparameters.Parametersofamplitudeandfrequencywerepatientcontrolled.Thissecondpatienthadadequatestimulationforpelviccarcinomalasting4years.Theleadsweresealedinsilastic.Shealyattemptedtopublishhisoutcomes,butthepublicationwasrejectedbytheJournalofNeurosurgeryandinsteadpresentedthisataneurosurgerymeetingandpublishedinthejournalAnesthesia&Analgesia.Hesubsequentlywentontoimplantdorsalcolumnstimulatorsfor7yearsbeforeabandoningtheseduetocomplications,andinsteadswitchedhisenergiestodevelopmentofTENSunits.

1968Myelostatwasthefirstcommerciallyavailablespinalcordstimulator,andwasbasedontheimplantsofShealyandtheBarostatmodifiedinput-outputcharacteristics.ShealysuggestedthisconcepttoMedtronic.

TheMyelostatwasaradiofrequency(RF)poweredunitwithanexternalgeneratorworninapocketoronabelt,andaRFtransmitterantennaringwasplacedovertheimplantedreceiver.Thestimulationpowerallresidedinbatteriesinthecontrollerunit.Thereceiverwasprimarilyanantenna/receiveronly.ThisunitwasapredecessortoseveralotherRFunitsusedinspinalcordstimulation,includingXtrel,Mattrix,andRenewsystemsdevelopedmuchlater.

Alsoin1968,RogerAveryreportedintheliteraturetheimplantationofperipheralnervestimulatorsforpain.HewasanengineeratMITandacontemporaryofSweet,whohadprovedthegatetheoryviastimulationoffacialnerves.Hedevelopedhisownimplantableperipheralnervestimulatorsystemin1968.HissystemwasalsoaRFsystem.

1969TimmandtheRegentsoftheUniversityofMinnesotafiledapatentapplicationwiththeUSPatentOfficefor“ImplantableElectronicStimulatorElectrodeandMethod”.Itdescribedinvaguedetailaprogrammablestimulator,coupler,andelectrodesforstimulationof“amassofelectricallyexcitabletissuewithoutstimulatingnearbytissuestructures”.Thepatent3,646,940wasapprovedinMarch,1972.Alsoin1969,NormShealypresentedtheresultsofspinalcordstimulationtotheHarveyCushingSociety,aprestigiousneurosurgicalmeeting,afterhavingapaperrejectedpreviouslybytheJournalofNeurosurgeryonthesubject.

1970-TheIntraduralpocketwascreatedforplacementofspinalcordstimulatorplateleads(theonlykindavailable)sincesubarachnoidplacement(themostcommonlyused)wascausingspinalcordtrauma(directinjurytothespinalcordduringplacementorafterwardsduetopressureexertedbythedorsalcolumnpaddleelectrodes),bleeding,arachnoiditis(achronicpermanentinflammationofthespinalnerverootsresultinginclumpingandstickingofnervestogetherandultimatelypainandmotordysfunction),andparaplegia(lossofmotorfunctionfromthewaistdown)duetothethicknessoftheleads.Theduramateristhethickmembranesurroundingthespinalcord.Creationofasplitinthismembranetoallowforplacementofthestimulatorleadinsidetheduraratherthanundertheduraprotectedthespinefromsomeofthecomplications,butepidural(ontopofthedura)wassafest.Howevertherewasnowaytosecurethepaddleleadsoitdidnotmigratethereforetheintraduralroutewasacompromise,butwastechnicallydifficulttoperform.

1971AveryLabsdevelopedthesingleleadRFsystemforspinalcordstimulation.AnarticlepublishedinPopularMechanicsJuly1971featuredthespinalcordstimulationsystem.UnliketheMedtronicsystemthatusedsubarachnoidorintraduralleads,theAverysystemusedanepiduralleadandwasmoreflexible.RogerAverystartedthecompanyinhisgaragein1968.ThePopularMechanicsarticlewaswildlypopularandsignificantlyincreasedsalesforAveryLabs.

Avery'sradiofrequencyspinalcordstimulatorsystemwasdevelopedwiththegeneratortobecarriedinthepocket(arrow)andtheantennaleadconnectedtothetransmittingantennalocateddirectlyovertheimplantedradiofrequency

receiver.Thereceiverwasconnectedsubcutaneouslytothedorsalcolumnelectrodes,implantedinthethoracicspine.Fromtheearly1970sthrough1990,thereceiverwasprimarilylocatedintheanteriorabdomentoallowthetransmitterantennatobeeasilyplaced.Thisbecamethebasisforthelocationoftheearlyimplantablebatteryunitsthatwereplacedintheanteriorabdomen.TherewasreallynootherreasonforthisotherthanasinglestudybyMedtronicdemonstratingpossiblylessleadfracturingwithananteriorimplantationsite.

In1971theonlyunitsonthemarketwereAvery'smodel100AandtheMyelostatbyMedtronic.ByJuly1971Neurosurgeonsaroundthecountryhadimplantedover200dorsalcolumnstimulators.

1972AveryLaboratories,foundedinitiallytodevelopphrenicnervepacemakersasatreatmentfordiaphragmaticparalysis,beganmarketingheavilytheirspinalcordsystemin1972.AverymarketedtheDCSsystemtoneurosurgeonsbeginninginthatyear.

1973FirstdeepbrainstimulatorforchronicpainbyHosobuchiwhoimplantedastimulatorelectrodeinthesomatosensorythalamusfortreatmentofdenervationpainwithanesthesiadolorosa

1974ThefirstpatientwornTENSunitwascreatedandpatented.Shealycontinuedtousespinalcordstimulationfor7years,thenconcludedtherisksweretoohighforitsuse.However,hecontinuedusingtheElectreatduringthattimeonpatientsthatwerecandidatesforspinalcordstimulation,andsubsequentlyapproachedMedtronic,whohadmadehisinitialdorsalcolumnimplantabledevicein1967,butMedtronicatthetimehadnointerestintranscutaneoususesofelectricity,beingtheworldleaderincardiacpacemakerimplantabledevices.ShealythenspokewithaMedtronicengineerwholeftthecompanyintheearly1970stoformanewcompanyStim-Tech,thatintroducedthefirstsolid-statemodernskinstimulator,alsocalledtheStim-Tech.Theinitial

stim-techmodelwasnearlyafootlongand4inchesthick,andusedasquarewavewithanoutputofonly3mA(modernTENSunitshaveupto90mAoutput).Shealy,aproponentoftheancientElectreatsystem,believedtheStim-TechwasnotaseffectiveasthespikewavesproducedbytheElectreat,andsubsequentlyconvincedMedtronictobeginmanufacturingspikewavetranscutaneousstimulators.

Pre-operativeTENSseemedtoreducetheperceptionofpainalmostaswellasthedorsalcolumnimplant(Hymes1984).Whiletheoriginalgoaloftranscutaneousstimulationwasscreeningofpatientsforspinalcordstimulators,itbecameapparentquicklythatstimulationoftheskinwasoftensufficienttoprovidepaincontrolalone(Long1991).Subsequentlyprivateindustryhaddevelopedmorethan200TENSunitsandbiofeedbackdevicesbythe1980s.By1991,therewereover600publishedpapersonTENSincludingbasicscienceresearch.In2013,TENSunitswereavailablewithoutphysicianprescription,andthecostoftheseunitsdroppedbyupto95%.

1976Cordis(lateracquiredbyJohnsonandJohnson)introducedthefirsttotallyimplantablespinalcordstimulator,madeinepoxyandcontainingamercurybattery.Itwasamodifiedcardiacpacemaker.Thisdevicehadexternallychangeableamplitudeandrate.

1977MedicaldeviceswereaddedtotheumbrellaofFDAregulatorypower,requiringapprovalbytheFDAbeforemarketing.

1978Medtronicintroducedapercutaneouslyinsertedelectrodeforpermanentuse.

1979NeuromedCompanywasformedandintroducedMultistem(aportmanteauformultiprogrammablespinalcordstimulator),anexternalquadrupoleonasinglelead(novelforthetime)andRFreceiverpower/programmingdevice.

1980Cordismanufacturedthe900X-MKI,thefirstspinalcordstimulatordevicetoachieveFDAapprovalforpainrelief.Thiswasaunipolardevice.

1980,NeuromedreleasedtheRFQuatrodesystem.

Alsoin1980,MyelostatbyMedtronicdorsalcolumnstimulatorwasapprovedbytheFDAK801384.IthadbeenonthemarketformanyyearsbythispointbutwasreleasedbeforetheFDAwasrequiredtoapproveimplantablemedicaldevices.

1981Medtronicreleasedafourelectrodepercutaneouslead,thePisces(acronymforpercutaneouslyinsertedspinalcordelectricalstimulation).

1981Averyretired,theirsalesandmarketingofdorsalcolumnstimulationceased,andthecompanycontinuedtheirconcentrationindiaphragmaticandphrenicnervestimulation.

Alsoin1981,Cordisreleasedthemodel904MK-IIunipolarandbipolarimplantableprogrammablegenerator(IPG).Ithadalithiumbatteryandwaspatientcontrolledviaanexternalmagnetwithupto8.5mAcurrent,fixedpulsewidth,andvariablefrequencyofupto115hzwithatitaniumhousing.

1984MedtronicreceivedapprovalfromtheFDAtomarketItrel,aprimarycell(non-rechargeable)totallyimplantablespinalcordstimulationsystem.ThiswasMedtronic'sfirstimplantablesystemwithinternallycontainedbattery(IPG).TheItrelwasa4electrodesystemonasinglelead.SeveralmodificationsweremadetotheItrelovertimewithseveralgenerationsofthisprimarycellonthemarketfordecades.TheplatformforallsubsequentMedtronicproductswasbuiltontheconstantvoltagesystemadoptedbyMedtronic.

1986Neuromedmanufacturedan8electrodeleadfortheirsingleleadRFsystem(Octrode).

1988MedtronicreleasedtheXtrelRFsystem.4totalcontacts,model3470.Thiswasadualleadsystemwith2contactsoneachlead.ItwasthesuccessortotheMyelostatsystem.Ithassincebeendiscontinuedfromproduction.Itfeaturedanimprovedimplantedmodulewithanenhancedantennaandimprovedleadthroughs(wheretheleadsinsertintotheunit).

1991MedtronicreleasedItrelIIIPGwith4totalelectrodesandimprovedbatterylifefromthisprimarycellunit.TheItrelcontinuedtouseatotalofonly4electrodes,makingprogrammabilityverylimited,albeitimprovedovertheItrelI.TheItrelIIbecameincreasinglypopular.Alithiumbatterywasused.

1991NeuromedintroducedintoclinicaltrialstheTIME(acronymfortotallyimplantablemultistimelectronics)implantablespinalcordstimulatorinboththeUSandEurope.However,by1993thedevicewaspulledfromthemarketbytheFDAaftertheagencycancelledtheinvestigationaldeviceexemption(IDE)andrescindedtheexportauthorityforNeuromedafterallegedviolationsbytheformermanagementofthecompany.Theallegationsincludedviolationofapplicablerulesandregulationsincludinggoodmanufacturingpractices.Theclinicaltrialswerediscontinuedandtheproductwaswithdrawnfromthemarket.(Source:SECFilingQuest

Medical1995)

1993AdvancedBionicswasformedbyspinningoffMiniMed,aleaderinimplantablediabeticmicroinfusionpumps.AdvancedBionicsdevelopedaverypopularHiResolutioncochlearimplantandinthelate1990selectedtoenterthespinalcordstimulatormarket.ThecompanysubmittedanapplicationtotheFDAin2000foraradicallynewspinalcordstimulatorsystem:arechargeablesystem.TheFDAwaitedseveralyearstoapprovethedevice.

1994NeuromedreceivedFDAapprovaltomarketthedualoctrodeleadradiofrequencycoupledspinalcordstimulatorsystem.ThissmallcompanyhadtheonlyproductonthemarketatthetimetocompetewithMedtronic,andwithdoublethenumberofelectrodes.

1995QuestMedicalacquiredNeuromed.

1995Medtronicreleasedthe8electrodeMattrixRFspinalcordstimulatorsystem.TheRFsystemwasthesuccessortotheExtrelsystemandacompetitoroftheNeuromedRFCoupledsystem.TheMattrixwasnotheavilymarketedbyMedtronicsincetheyhadaprimarycellthatrequiredreplacementevery3yearsandprovidedasteadyrecurringrevenuesourceforMedtronic.Thesystemwasalso

notpatientfriendlycomparedtotheprimarycellsystems.Itwasaradiofrequencycoupledsysteminwhichthestimulationparameterswereachievedinthegeneratorthatconvertedthesignalintoaradiofrequencysignalinordertotransmitboththepowerandprogrammingparametersthroughtheskintothereceiver.Thereceiverwasaradioantennawithfrequency

converterthatusedthepowerbeingtransmittedtodrivetheenergyneededtopowertheelectrodesbutalsoconverttheRFenergyintospecificallydefinedstimulationparameters.ThesystemusedanexternalbatterythatwasinitiallyNiCd(didnotworkwell)andultimatelyaNiMHrechargeableexternalbattery.Patientsdidnotlikethesystemverywell,couldnotuseitintheshowerorwhenswimming,itrequiredpreciseplacement(withadhesive)ofthetransmittingcoildirectlyoverthereceivingcoil.ItfinallyfellintoobscurityasultimatelydidalltheRFsystemsduetotheinconvenienceofuse.

1995MedtronicreleasedItrel3,thenextgenerationintheItrelsystem.ItwasfirstimplantedinBelgiumin1994andwasreleasedintheUSin1995.ThebatterylifewasextendedcomparedtotheItrelII,theonlyotherprimarycellonthemarketin1995.Ithad4totalelectrodessplittablebetween2leads.Howeverwithonly2electrodesperlead,anyleadmovement(commonwiththeleadsystemsofthetime)wouldlosestimulation.The8and16electrodesystemshadsignificantadvantagesduetothisfactandbecauseoflead

anchorsthatfrequentlyfailedandallowedleadmovementorwereuncomfortable.Thebatterylifewastoutedasupto5yearsbutfrequentlylasted2-3years.Thesizeofthetitaniumcanwas22ml,itweighed42g,wasprogrammableatafrequencyof2-130Hz,pulsewidthof60-210mS,andamplitudeof0-10.5V.

1998QuestMedicalchangedtheirnametoAdvancedNeuromodulationSystems(ANS)

1999-ANSRenewSystemreleased.ThiswasasuccessortotheNeuromedSystem.Italsowasadualoctrode(thefirst16totalelectrode)system.Itwasaradiofrequencycoupledsystem.Animprovedprogrammerthatwaseasytousewastheprimaryprovement.Thesystemwasaneconomical"lifetime"system

butultimatelythesystemdidhaveitsproblemswithleakageinthesealsofthesystem(thethroughputs)withshortingoutandmalfunctionafteryearsofuse.ThecumbersomenessoftheRFpowerringhavingtobeexactlypositionedoverthereceiverwasanissueforpatients.Howeverthesystemwasappealingsinceithadroundandpaddleleadsavailableandiftherewereaslightmovementofthelead,reprogrammingratherthansurgeryrecapturedthestimulationparametersforpaincontrol.

1999SynergyprimarycellbyMedtronicmodel7427wasreleased.Thesystemhaddualquadelectrodes,doublingthenumberofelectrodespreviouslyavailableinaprimarycell.Thebatterysizewasthereforealsoincreasedtoaccommodatetheincreasednumberofelectrodes.Ithad8electrodes,volumeof51cc,weight83g,rate3-130Hz,pulsewidth90-450microseconds,0-10.5Vamplitude.Itusedacombinedsilvervanadiumoxide3.2Vbattery.

2001AdvancedNeuromodulationSystems(ANS)broughttomarkettheirfirstprimarycellnon-rechargeableimplantableprogrammablegenerator(IPG)amidmuchfanfaresinceitwastheonlyproductonthemarkettocompetewiththeMedtronicprimarycell(non-rechargeable)systems.WhenANSreleasedtheirrechargeableversionofthecellseveralyearslater,GenesiswasrenamedGenesis

PrimeCell.ItwasstillbeingimplantedinsuccessorGenesisproductsaslateas2012.Itsvolumewas29ml,weight53g,frequency50-1200Hz,pulsewidth50-500mS,amplitude0-25.5mA.Thebatterywas3.7voltlithiumthionylchloride.

2002ANSreleasedanentirefamilyofprimarycellgeneratorstocompetewithMedtronic.TheGenesisXPmodel3609,GenesisXPDualmodel3644,andGenesisG4(effectivelytheoriginalGenesis)model3604.Theyhadlargerbatterysizeswithexternaldimensionsizesthatwerehuge.TheXPhadnearlydoublethevolumeandwasveryheavycomparedtotheGenesis.Withlargerbatterysizesavailable,thelongevityoftheseprimarycellswaslongerthantheGenesisorMedtronichoweverpatient

discomfortwasbecomingarealissuewiththelargeIPGs(ImplantableProgrammableGenerators).

2002MedtronicreleasedtheSynergyVersitrelmodel7427Vwith4or8contactsavailable(tocompetewithGenesisXPDual).Thevolumewas40ml,weight65g,frequencyrate3-130Hz,pulsewidth60-450Hz,Amplitude0-10.5V.SamebatteryastheSynergy.Primarydifferenceisthesizeisslightlysmallerandweighsless.

2004AdvancedBionicsreceivedFDAPMAapprovaltomarketthefirstrechargeable(secondarycell)IPGgenerator(thePrecision)andleadsystem.ThiswasamuchsmallersystemthantheprimarycellunitsonthemarketbyANSandMedtronic.Thevolumewas22ml,weight33g,frequency0-1200Hz,pulsewidth0-1000microseconds,powerupto20mA@15Volts,16programs,fractionalchargedelectrodes,and16totalelectrodes(doublethoseavailablewithotherunits).Thebatterycapacitywas200mA-hrs.Itwasa

constantcurrentproductliketheANSprimarycellsystems.

Thissystemquicklybecameagame-changer,forcingothercompaniestoscrambletodeveloparechargeablesystem.Theengineeringonthisproductwasextraordinarilygoodfortheirfirstforayintothespinalcordstimulatormarket,andwithonlysometweakssincethattime,thesameprinciplesusedintheoriginalunitsarestillemployedtoday.

2004TheANSGenesisRCwasthesecondrechargeableIPGreleasedandwassignificantlylargerthanthePrecision.Italsohadaplasticsurfaceononesidethatifaccidentallywascutorincisedduringimplantation,coulddisabletheIPG.ItwasavailablelaterthantheAdvancedBionicssystem,butdidofferanalternative.

2005St.JudeMedicalpurchasedAdvancedNeuromodulationSystems

2005EonRechargeablesecondarycellIPGreleasedbySt.JudeMedical(ANS).Itwasadualoctrodesystem,42ccvolume,constantcurrentsystem.Italsohadaplasticcoatingoverthefaceofthedevicethatcouldnotbeincisedorscratchedwithoutpotentiallydamagingthedevice.Thedevicehasoutputof0-25.5mA,50-500microsecondpulsewidth,frequency2-1200Hz,24programs,andcapacityof325mA-hr(morethan50%morethanthePrecision).

2005St.JudeMedical(ANS)releasedtheGenesisdual4channelprimarycellIPGmodel3643FDAapproved.

2005Synergyplus+model7479andSynergycompact+primarycellIPGswerereleasedbyMedtronic.TheserepresentedexpandedandcontractedsizesoftheSynergy.Theywerediscontinedinafewyears.TheSynergycompactandversitrelbatteriesareabouthalfthesizeofthesynergy.

2005RestorerechargeablespinalcordstimulatorwasreleasedbyMedtronic.Thiswastheirfirstsecondarycell(rechargeable)IPGandwasmodelnumber37711.TherewasaclassIrecallonthestimulatorissuedNovember2005.Implantscontinueduntilatleasttheendof2011butwassupercededbyotherRestoremodels.Thefrequencyrangewas0-130Hz,pulsewidth60-450microseconds,amplitude0-10.5V,capacity300mA-hr.

2006BostonScientificacquiredAdvancedBionics.

2006RestorePRIME,anon-rechargeableMedtronicspinalcordstimulatorsystemwasreleasedin2006.Ithad16electrodeswith32programs.Modelnumber

37701.Itsvolumewas39ml,weight67g,pulsewidth3-130Hz,pulsewidth60-450microseconds.Amplitude0-10.5V.Theimplantdepthis<4cm.

Alsoreleasedin2006wastheMedtronicPrimeADVANCED.ThiswasaprimarycellIPGthathadalongerlifebattery.Themodelwas37702.Thevolumeis39cc,16electrodes,rate3-130Hz,pulsewidth60-450microseconds,amplitude0-10.5V.Ithas32programs.Italsohasanimplantdepthof<4cm.

ThereappearstobelittledifferencecomparingthisIPGwiththeRestorePrimeinsize,weight,programs,andparameters.ItappearsMedtronicclaimsalongerbatterylifewiththePrimeAdvancedbattery.

2007St.JudereceivedFDAapprovalforthemodel3688Eon-C,aprimarycellnon-rechargeable,withextendedbatterylife,and16contacts.Itadjustspoweroutputautomaticallybasedonimpedencechanges.Ithadmoreand40%morebatterycapacitythantheMedtronicRestoreandcouldcontrolupto8painareasindependently.Thevolumewas49ml.Frequencyrangeis50-1200Hz,pulsewidth50-500microseconds.Theamplitudeis25.5mAandthereare24programs.Thevolumeis49cccomparedto42ccfortheEon.ThisisthefirstextendedlifeprimarycellreleasedbySt.Jude/ANS.

2008MedtronicreleasedRestoreUltramodelnumber37712approvedbytheFDAwithprovisionalhead1.5TMRIundercertainconditions.Ithas16electrodes.Volume22cc,weight45g,rate2-1200Hz,pulsewidth60-1000microsecondswith16programs.

2008St.Jude(ANS)receivedapprovalfortheEon-mini,amineaturized16electrodesecondary(rechargeable)cellthatissmallerthanotherunitsonthemarket.Volume18ml,weight29g,0-25.5mAcurrentat12Volts;50-500microsecondpulsewidth,2-1200Hzfrequencywith24programs.Formediumcurrentuse,therechargeintervalis22daysvs56fortheEon.TheminiEonis40%ofthevolumeoccupiedbytheEon.

2011MedtronicreceivedapprovalfortheRestoreSensor,arechargeableIPGwithanaccelerometer(electronicgyroscope)model37714.Theaccelerometerisameanstochangetheoutputoftheconstantvoltagesystembychangingthecurrentdependingonthepositionofthebody.Theaccelerometerdetectsthepositionofthebodyandautomaticallychangesthisvalue.ThishasbeenaproblemfortheMedtronicconstantvoltagesystemplatformforyearswhereasbothSt.JudeandBostonScientificsystemshavesomeautomaticadjustmentoftheoutputbasedonimpedence.TheMedtronicsystemisapprovedforprovisionalMRI1.5T.Thevolumeis22cc,weight45g,batterylife9+years(rechargeable),16contact,2-1200Hzstimulationfrequency,60-1000microsecondpulsewidth,0-10.5V.

2012MedtronicreleasedtheItrel4models37703and37704.Itisa4electrodesystemusableasaprimarycellsystem(non-rechargeable)usedforsinglelimbpain.ItisprovisionallyapprovedforheadMRI.Thevolumeofthe37703is28mland44gweight.Thefrequencyofstimulationisadjustablefrom2to130Hz,pulsewidth60-450microseconds,amplitude10.5vmax.

2013MedtronicreceivedapprovalinMarch2013forRestoreSensorSurescan.TheFDAmanyyearsofdesignchangesasinstitutedbytheFDAinordertohavefullbodyMRIcapability.OnMay10,2005,theFDAsentoutapublichealthnotificationthateffectivelybannedphysiciansfromperformingMRIsonpatientswithspinalcordstimulators.TherehadnotbeenanyreportedinjuriesfromMRIperformanceinpatientswithspinalcordstimulators,howevertheFDAlackedthesophisticationormedicalknowledgetounderstandthedifferencesbetweenspinalcord

stimulationanddeepbrainstimulation.Deepbrainstimulatorshavetheleadsimplanteddirectlyintoneuraltissueofthebrainwhereasspinalcordstimulatorleadsareseparatedfrombothspinalfluidandthespinalcordbyathickmembranecalledtheduramater.Unfortunatelyduetoignorance,theFDAconfabulatedthetwousesandsimplyreactedtoacoupleofreportsfromdeepbrainstimulationinjuriesinMRIandeffectivelybannedallMRIsforanyonewithanyimplantabledevicesincludingpacemakers,sacralstimulators,vagusstimulators,etc.YearsofsubsequentresearchdemonstratingpreandpostbansafetywerepresentedinscientificmeetingsandtotheFDAtonoavail.MedtronichadpetitionedyearsbeforeforapprovaloftotalbodyMRIforsubmittedsystemsbutcouldnotsatisfytheFDAsafetydemonstrationrequirements.SuddenlytheFDAapprovedtherequestafterredesignoftheleadsbyshieldingthemwithcoilsplacedaroundtheactiveleads,andtoshieldtheleadthroughs(placethestimulatortransmitsenergytotheleads).Thecompanywasnotreadyfortheapprovalanddidnothaveanyproductgenerallyavailablefor5monthsaftertheFDAannouncedtheapproval.TheSurescantechnologyallowsforscansofanypartofthebodywithanimplantedspinalcordstimulatorsystemsubjecttocertainlimitations.ThestimulationparametersareidenticaltothatoftheRestoreSensorIPG.

2013inAprilBostonScientificLaunchedPrecisionSpectraintheUS.32electrodesindependentlyprogrammablewithpositive,neutral,ornegativefullorfractionalcharges.Thepatientcanhave4x8electrodeleadsor2x16leadsoracentral16electrodeleadflankedbyan8electrodeleadoneithersideorothercombinations.TheIPGrechargeableamplitudeisupto25.5mAwhilethestimulationrateis2-1200Hz.Thepulsewidth

rangeis20-1000microseconds.Thereare16availableprograms.

2014AprilProtegespinalcordstimulatorbySt.Judewasreleased.ThisIPGrechargeableisthesmallestonthemarket(17.7ml)withalithiumionbatteryrechargeable.ItisthefirstsoftwareupgradablespinalcordstimulatorprogrammerassoftwareisapprovedbytheFDA.Amplitudeupto25.5mA,pulsewidthtonic50-500microseconds,frequency2-1200Hz,StimulationmodeTonic.IthasthepotentialtoupgradetoBurststimulationviasoftwareupgradewhenapprovedbytheFDA.Thebatterylifeis10yearsonHighSetting.Warrantyis7yearswithamaximumoutofpocketcosttothepatientof$1250.

2015St.JudeProdigymodel3799hasreceivedCEMarkinEuropeandisawaitingFDAapprovalintheUS.Itisasecondary(rechargeable)Lithiumioncellwithupgradablesoftwareandpulsebursttechnology.Itispartofasystemthatincludesarapidprogrammerandchargermodules.Italsohasapatientprogrammer.Specificationsincludevolumeof18ml,weight29g,amplitude0-25.5mA,50-500microsecondspulsewidth,pulsewidthburstmode50-1000

microseconds,frequency2-1200Hz,stimulationmodestonicorburst.

2015ApprovedbytheFDA:NevroSenzahighfrequencyspinalcordstimulationsystem.TheSenzasystemhashadexcellentresultsinEuropeandisnowintrialsintheUS.Unlikeothersystems,theSenzaisoperatingatupto10,000Hz(8timesfasterthanothersystemsapprovedbytheFDA)thatthepatientdoesnotfeelthestimulation,butachievespainrelief.

2016BostonScientificwasapprovedbytheFDAtoreleasethePrecisionMontagespinalcordstimulator(MRICompatible)withthermallyshieldedleads,makingBostonScientificonlythesecondcompanytohaveafullyMRIcompatiblesystemfor1.5TMRIscanners(themostcommontype).

SPINALCORDSTIMULATIONCOMESOFAGEAftertheinitialexperimentin1967onthelungcancerpatientwithwidelydisseminatedmetastasis(wouldbeaverypoorcandidateforspinalcordstimulationtoday),Shealycontinuedimplantationofdorsalcolumnplatesandelectrodesthatwereverylarge,requiredalaminectomy,andwereconnectedtoanexternaldevice.By1970,sixpatientshadundergonethistreatment.By1972,seriesofpatientshavingthesedorsalcolumnimplants(thatwerequiteprimitivehavingonlyonebipolar(2electrodes)contactsetononelead,weredescribedintheliteraturewitha30patientseriesshowingthemostsuccessinburningpainfromnervoussysteminjury.In1972,dorsalcolumnstimulatorswereinitiallymarketedtoneurosurgeonsintheUS,andthedeviceswerelaternamedspinalcordstimulators.In1974,casereportsofseriouscomplicationswerepublishedincludingdelayedintraspinalhemorrhageandspinalcordtranssection,bothostensiblyduetotheextremelylargeelectrodesbeingusedatthetime.By1976,cardiacpacemakertechnologybatteryandprogrammeradvancesledtothedevelopmentofthefirstcompletelyimplantableneurostimulator(Medtronic).Slowadvancesweremadeinthe1970sand1980sduetoconstraintsinthebatterysizeandcontinueddevelopmentinleaddesign.Thenumberofelectrodeswasverylimitedduringthistime,andthedeviceswereexpensiveandfrequentlyrequiredrevision.Withonly2electrodes,programmingwasextremelylimitedandtherewasfrequentlymotorstimulationofthelegsgiventheunitsofthetime.Therewereultimatelyseveral

advancesintechnologiesthatbeganinthe1990sandcontinuestoaccelerate,inpartduetoextremecompetitionbetweenthethreemanufacturersofspinalcordstimulation,andnowdeepbrainstimulationsystems.Theadvanceshavecomeaboutpartiallyduetopatientconvenienceandacceptanceoftheproductbutsomehavecomethroughbasicresearchdesignchangestomakeabetterproductwithfewerfailures.Theseadvancescanbecategorizedintoseveralareas:1.Batterylife.Usingmorecontactsonleadsbroughtaboutgreaterprogrammabilityandenhancedpaincontrolbutalsotheimplantableprogrammablestimulators(IPG)expandedprogrammingparameterstendedtochewuptheearlystimulatorimplantedbatteriesquickly.Theuseofhigherstimulationfrequencies,increasedpulsewidths,andmoreactivecontactscausedhigherdrainonthebatterylifeoftheseunits.TheItrelwouldsometimesonlylastafewmonthsbeforebatterydepletion.TheItrelIIIwithbetterprogrammingcapacityandalargerbatterymaylastonly1-2yearsbeforereplacementwasnecessary.Becauseofthislimitation,bothMedtronicandANSbegandevelopingeverlargerbatteriesuntilthepatientsbegancomplainingofthephysicalsizeofthegeneratorbeingalimitingfactor.IPGsthatweretwicethesizemayonlylast50%longerthanthesmallerIPGsandthecostcontinuedtoescalatewitheachgenerationoflargerbatteriesbutalsowiththecostofnotinfrequentreplacementoftheIPG.Thebatteriesaresealedinsidetheimplantedgeneratorandthereforewhendepleted,requirereplacementoftheentireIPG.Thereforesomethinghadtobedoneabouttheincreasingsizeofthebatteriesandtheincreasingpowerrequirementsduetoenhancedprogrammingsophistication.Theexternalpowersuppliedunits(RF)attemptedtosolvetheproblembyusingapowerpackhungonthepatient’sbeltandaRFtransmitterringwassecuredtotheskindirectlyovertheverysmallimplantedRFreceiver.Muchgreaterpowerwasavailableusingthissystem,andthereceivertheoreticallywouldnothavetobechanged.Howevertheseunitsprovedtobecumbersometomanypatients,notbeingabletowearthemintheshowerorwhenswimming,andtheRFtransmitterringwouldoftendislodgefromtheskin,causinganinterruptioninpowertothereceiverandanincreaseinpain.TherechargeablebatteriesofthetimewereNickelCadmiumbatteries,thatheldachargeforoftenlessthanaday.Thefrequentrechargingofbatteriesandthefinickynatureofthedevicefinallydrovesomepeopleawayfromthesystems.OtherreasonspeoplemovedawayfromtheRFsystemwasatendencytoformleakysealsinthereceiver,causingtheunittoshortoutandbenon-functional.TherechargeableRFsystemswerecomingontothemarketforotherapplications,anditbecamereadilyapparentthisdesignwouldpermitbatteryandIPGminiaturizationforpatientcomfort,butretaintheprogrammabilityandpowerneededforcomplexprogramminguseswithchronicpain.ThePrecisionrechargeablewasthefirstrechargeableIPGonthemarketin2004,followedbytheGenesisRC(ANS)andRestore(Medtronic).Themanufacturershavecontinuedtouseimprovedlithiumionbatterytechnologyandhavecreatedextremelysmallspinalcordstimulatorsthatweighjustoveranounce.2.Leaddesign.Thespinalcordstimulatorleadshaveadvancedfromthepurelysurgicallyimplantableleadsinthe1960storoundpercutaneousleadsinthe1990stocomplexsurgicalleaddesignswith16andsoon32electrodes,anduseofcombinationsof2or3roundleadstogivebettercoverage.Theleadscontinueto

becomesmallerandthinnerwithradicallydifferingleaddesignsusedbythethreemanufacturers.However,someofthemanufacturershaveconversionssystemstopermitanalreadyindwellingleadtobeconnectedtotheirIPG.Theleadsaretypicallymultistrandedstraightwireswitheachofthe4to8bundlesenclosedinaflexibleplasticsheath.Thewiresextendinternallyfromoneendtotheother,connectingtotheplatinum-irridiumelectrodesattheendofthelead.Thespacingoftheleadcontactsisnowselectablebythephysicianbasedontheanticipatedneedsandareaofcoverage.Theoldcoiledleadsarenotusedasoftennow.Becauseoftheimprovementsinleads,thebreakagefactorismuchlessthaninthepast,andtheultralowimpedancespreservethebatterylife.Theleadconfigurationhasalsobeenshowntohelpwithcertaintypesofpain.Forinstance,lowbackpainmaybebesttreatedwithatripole(3leadssidebyside)astreatmentforlowbackpain.3.IPGProgrammability.Fromtheoriginsofspinalcordstimulationwheneffectivelyagivenwaveformwasavailableandtheamplitudeofvoltagewastheonlyadjustableparameter,wenowhaveaplethoraofchoicesinprogramming.Eachcontactcanbepositive,negative,orneutral.Onesystempermitsindependentfractionalchargeforeachof32electrodes.Thepulsewidth,frequency,servicetimeon,andscanningacrossleadsareallprogrammableusinganexternalprogrammer.Themultipleprogramsavailable(4-32)dependentonthemanufacturer,permitselectionofthemostsoothingprogramfordifferentactivities.Thelatestadvancewilluseapositionsensortochangethestimulationpatternwhenthepatientchangesfromsittingtostandingorlyingdowntostandingpositions,therebyreducingtheshockpotentialwhenchangingpositions.Therearenowmillionsofprogrammingcombinationsavailableforeachstimulator.

Someofthemostexcitingadvancesincludetheuseofhighfrequencystimulationandtheuseofburststimulation(smallburstsoffrequencywithnothinginbetween)bothofwhicharehelpingreducetheacclimationofthespineandbraintothestimulator,resultinginbetterpaincontrol.

4.Anchordesign.Theleadscontainingthecontactelectrodesmustbesecuredpermanentlytosomestructure.Typicallyselectedarethethickfascialplanesoutsidethespinalbackmusclesortotheligamentsbetweenthespinalbones.Aseriesofanchoringdeviceshavebeendevelopedandcontinueinrapidlyadvancementtopermitsecureplacementofleadssothatthetraditional15%leadmigrationrate(movementawayfromtheoptimalplacementforstimulation)iseradicated.NeweranchorsincludedtheTitanbyMedtronicandlateranchorsandSynchanchorbyStJude.ThereisanewtwistlockanchorbyStJudethatmakesmovementoftheleadvirtuallyimpossibleoutsideofmajortraumatotheback.Bostonhasdevelopedascrewsystemanchorthatisalsoexcellent.Theanchordesignshavereducedthenumberofsurgicalrevisionsoftheleadsandthereforehascuttheoverallexpensesignificantly.5.Externalprogrammerfunction.Boththepatientprogrammersandtheindustryrepresentativeprogrammershaveadvancedfeaturesthatdrasticallyreducetheamountoftimerequiredtoprogramoptimallythespinalcordstimulatorsystem.

BostonScientifichasaveryimpressivesystemforthis,andtheothermanufacturershavedramaticallyimprovedtheirprogrammingcapabilities.6.Companysupport.Intheolddaysofthe70s-90s,itwasnotalwayseasytofindthecompanyrepresentativetosupporttheproductandhavethemreadilyavailableincasearevisionortroubleshootingwasrequired.Thisisnolongerthecase,aseachcompanyhasmultipletiersofrepresentativesmakingthemvirtuallyalwaysavailablebyphonetopatientsorphysicians.

7.MRICompatibility.Theultimategoalofspinalcordstimulationsystemsistobeaspatientfriendlyaspossible.ThechancesofapatientneedinganMRIatsomepointintheirlifetimeisveryhigh.StimulatorsystemswereusedforyearswithoutissuewithMRIandtherewerehundredsofthousandsofMRIscansinpatientswithspinalcordstimulatorsystemswithoutcomplicationsorinjury.TheFDAinwhatwasaclearoverregulationwithoutevidenceofinjurybutbasedonthetheoreticalpossibilityofinjurynearlyovernightstoppedMRIscansofpatientswithspinalcordstimulationsystemsin2005withtheirunwarrantedwarningletter.ManypatientswereinjuredbecauseofcontinuingpainandtissueinjuryduetoinabilitytoMRIimage,haddelayedsurgeries,hadersatzimagingbyCTresultinginsometimeswrongsurgicalprocedures,orhadthespinalcordstimulatorsystemexplantedduetotheneedforaMRIthenreimplantedlater.TheFDAreluctantlyagreedtoallowsomestimulatorswithleadsimplantedinthethoracicspinetobeeligibleforheadMRIundercertainconditions.HoweverfullMRIcompatibilitywasforwholebodyMRIwasfirstgrantedtoMedtronicin2013thentoBostonScientificin2016.Asof2016,neitherNevroorSt.JudehavefullMRIcompatibility.Withtwocompaniesonthemarketasof2016withfull1.5TMRIcompatibilityandgiventheextremelyhighchanceofneedinganMRIsomewhereinthebodyotherthanthehead,itisillogicaltocontinuetoimplantnon-MRIcompatibleunitsinpatients.Formanyyears,painphysiciansinparticularwereinsoucianttothepotentialfutureneedsoftheirpatients,andwillynillyimplantednon-MRIcompatibleunitsbasedontheirownpreferenceforastimulatorratherthanwhatwasbestforthepatients.

COMPLICATIONSOFSPINALCORDSTIMULATIONNoimplanteddevice,whetheritbeapacemakerordeepbrainstimulatororinsulinpumporartificialhiparewithoutcomplications.Certainfactorsincreaseriskssuchasbeingadiabeticincreasestheinfectionriskbyupto10timesthatofanon-diabeticpatient.Mostrisksarerelatedtothesurgeryandnottothedevices.InaMedtronicregistryofcomplicationsreportedtoMedtronicin2009fromalloftheirpreviouslyimplantedspinalcordstimulators,thefollowingwerenoted:5eventsrelatedtotheneurostimulatormalfunction,157eventsrelatedtoleaddysfunction(halfofthesewereduetoleadmigrationbeforethenewanchorswereintroduced),11eventsduetoleadextensionbreakageandissues.Therewerealso60complicationssurroundingtheIPGpocket(mainlyinfectionandpainatthesite),14leadtractissues,109patientrelatedcomplications(2/3ofthesewereforfailuretomeetpatientexpectationsandlossofeffect),and140spinalcordstimunitswerereplacedduetoexpectedbatterydepletion.Thesesameratioswouldbeexpectedforothermanufacturersproducts,andareonlyasmallfractionofthehundredsof

thousandsofspinalcordstimulatorsthathavebeenimplantedthusfar.Statisticsinthescientificliteraturecollectedeven3yearsagoarenowobsoletecomparedtothosewithnewIPGandleadsandleadanchorimplants,thereforethecomplicationratecontinuestoimprove.Therecanalwaysbeneurologicaldisastersfromplacementofspinalcordstimulators,buttheseareexceedinglyrare.

HISTORYOFSPINALCORDSTIMULATORCOMPANIESHISTORYOFMEDTRONICSPINALCORDSTIMULATIONMedtronicwastheoriginalofthespinalcordstimulatorcompaniesandwaspresentattheverybeginningofdevelopmentin1967,makingthedevicesimplantedbyShealy.TheItrelimplantableprogrammablegenerator(IPG)wasaneurostimulator(4totalelectrodes)approvedbytheFDAin1984.Thisunitwastobeusedforspinalcordstimulationinwhichaseriesofelectrodesonasingleleadwereplacedintotheepiduralspaceoverthedorsalcolumnofthespinalcord,thusthemoniker“dorsalcolumnstimulator”.TheItrelIIwasadrasticallyimprovedversionoftheItrelwithFDAapprovalbeingachievedin1992(8electrodes),andtheItrelIIIwasapprovedin1995.SynergywasthenextgenerationofIPGbyMedtronic,receivingFDAapprovalinNovember1999.ThisunithadtwicethebatterycapacityastheItrelIIIbutthesizewasalsomuchlarger.TheRestorerechargeablesystemwasapprovedbytheFDAin2005andaminiatureversion,theRestoreUltrawasFDAapprovedin2008.TheRestoresystemcontinuedtoadvancewithFDAapprovaloftheirRestoreSensorsystemwithbuiltinpositiondetectionaccelerometerin2011andtheadditionofSureScan(TotalBodyMRICompatible)in2013.TheMattrixsystem,wasnotanIPG,butwasaradiofrequencypoweredunitapprovedbytheFDAin1992.Itwasadevicethatusedanexternalpowersourcethatwasplacedonabeltloopoutsidethebody,withaRFantennausedtotransmitenergythroughtheskinandtotheimplantedsmallreceiverunit.

HISTORYOFADVANCEDNEUROMODULATIONSYSTEMS(ANS)-STJUDETheprecursortoAdvancedNeuromodulationSystems(ANS)wasincorporatedinMay1979asMedicor,Inc.byveteransofthemedicaldevicefield,includingitspresident,ThomasC.Thompson,whohadearlierfoundedacompanythatmadeintravenouscatheters.AftertheintravenouscathetercompanywassoldtoBaxterTravenol,ThompsonjoinedforceswithseasonedexecutiveswhohadworkedatJohnson&Johnson,EliLilly'sIVACunit,andIMDE,aWarner-Lambertsubsidiary.ThepartnersgotintobusinessinOctober1979throughacquisition,pickingupafour-year-oldDallascompanycalledMed-ProLtd.,whichmadeitsmoneysellingsurgicaltapebutharboredagreatdealofpotentialintheintravenous(IV)tubesandelectronicIVdevicesithadunderdevelopment.Afewmonthslater,inJanuary1980,MedicorchangeditsnametoQuestMedical,Inc.Asmallcompany,Neuromed,in1991developedaradiofrequencypoweredspinalcordstimulationsystemthatusedasmallimplantablereceiverandanexternalpowerunittocontrolthespinalcordstimulator.UltimatelyNeuromedwasacquiredbyQuestin1995for$15millionplusstocks,whodivestedtheircompanyofothernon-profitableproducts

overseveralyears,thenchangedtheirnametoAdvancedNeuromodulationSystems(ANS)in1998asspinalcordstimulationbecamethemostprofitableelementinthecompany.LedbyChrisChavez,aformerJohnsonandJohnsonexecutiveandaHarvardBusinessSchoolGraduate,thecompanybegantoleapforwardintroducingtheRenewRFsystemin1999(16totalelectrodes)andcapturing50%oftheRFmarketthatyear.Subsequently,throughaseriesofpartnershipsandacquisitions,ANSdevelopedtheirfirstimplantableprogrammablegenerator(Genesis)in2002intheUSandlatein2002,theGenesisXPwithalargerbatterysize.In2005,theGenesisRC(rechargeablebattery)wasintroducedintheUS,followedbytheEonrechargeableandin2008themini-Eon,averysmallrechargeable16electrodegenerator.ThecompanywasacquiredbyStJudeMedicalin2005.

HISTORYOFADVANCEDBIONICS-BOSTONSCIENTIFICAdvancedBionicsreceivedPMAforitsPrecisionspinalcordstimulatorasanaidinmanagementofchronic,intractabletrunkandlimbpainin2004.Allarefullyimplanteddevices.Thecompanyhadapprovalforcochlearimplantationstimulatorsin1998.AdvancedBionicshadthefirstrechargeablegeneratorandthefirstindependentcurrentcontrolledcontactsontheirleads.TheirPrecisionspinalcordstimulatorhasbeenimplantedthroughouttheworldintochronicpainpatients.ThecompanywasultimatelyacquiredbyBostonScientific.

NEVROisthelatestcompanytoenterthemarketin2015withtheirhighfrequencystimulatorsystemwithheadonlyMRIcompatibility.Thedownsideoftheirunitisitssizeandthefactthatveryfrequentrechargesoftheunitarenecessary.

OTHERSTIMULATORHISTORY

TheCordis900AprogrammableneurostimulatorfromCordis,Corp.wasapprovedin1981.CordiswasultimatelyacquiredbyJohnsonandJohnsonandstoppedmanufacturingspinalcordstimulators.Cordishadthefirstimplantableselfcontainedstimulatoronthemarketin1976.

AveryLabswasestablishedin1968inagarage.ThecompanymarketedRFsystemspinalcordstimulatorsystemsbeginningin1971.By1981,theirchairmanretired,andAverystoppedmakingspinalcordstimulators.

Medtronicwasalsostartedinagaragein1949.Apparentlygaragesareexcellentlocationstodevelopgreatideasandtoactuallymakethemintosomething.