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Electro-stimulation and sensori-neural hearing loss: A preliminary report
ELECTRO-STIMULATION AND SENSORI-NEURALHEARINGLOSS:APRELI~INARYREPORT J.E. MARTIN, Paul L. MJCJ-IAEL, Robert BRE:NNAN,* James PROUT and Cordon BIENVENUE 7’he Ptw~syiamia
State I
‘nhvrsity, U,riversity Park. Pa. I ciXK?
‘If‘he cffccts of clcctrc,-stimulation on pure tcbncthreshold and speech cllscrimination \I~.~w$of persons with sensori-ncurai! hearing lo\s was assc~~f uring a double-blmd ~IIW~WC. improvcment~ in speech dtscrimination cx~~ld not ho attributed to a ~IXX~XS rikct. EEG examinations revealed no harmful cffccts of the elcctru-stirnuiation prvcenuW.
Jtrtroducfiou It has been known for some time that r:ormally hearing persons can detect an AM radio frequency signal when that signal is placed directJy into the h~;td. In such cases the observer can hear :iudio frequency modulation of the r.1‘.signal. This phenon~enon will be called electrct-stimulation of hearing in thl> paper. l’uhrioh and Lawrence ( 1969) reported that cxtonsivc elcc:trrrstirnul~,tiorl crf hearing. in patients with sensori-natural hearing loss, produced improve111cn ts in pure- tone thrcshoIds and speech disc riminatim scores following mta stimulation. The pur;x~ of‘ this paper is to publish the results of an ;!ttrrnpt to replicate the Puharich and Lawrence study u tiiizing improved rllstrumen tation and ttterapcu tic techniques. The resul ts of an assessrmn t of the neurological effects of the therapy are :iIso reported.
I werlty-live persons, who had bilateral sensori-neural hearing loss, and AU raged from 12 to 80 years in age, served as subjects for this experiment. ‘\!lt!jccts were screened by a neurologist at the Pcnnsyhania State hiversity ‘~~dL:aJ&hoot to eliminate any persons who were predisposed to epilepsy. ’ Dt. f3rcnnanis located
at the Hrrshcy Medical Center,.Hershcy,
Pennsylvania.
All of the subjects had been patic:nts at the [{caring Conservation Center ot’ Lancaster. Pennsylvania, where their audiological records are on file.
Ten persons were placed into the control group (two dropped out during therapy) and 15 were placed into the experimental group. After preliminary screening. al! Ss were given EEG examinations ad audiolqical cvahations. Al] Ss were told that they were receiving cicJctro-stinl\llatiotl and that some .% were receiving different kinds and levels of’ treatment than others. A clinical audiologist (CCC-A-ASHA) did both t11c audiological prc- and post testing. Ajthough the audiologist mdxstcmd the nature of the experiment. he did 1101 know which Ss were experiment& and which were controls. The audiological evaluation consisted of taking pure tale thre&olds il! teach c3r at 250. 500. 1000. 2000. 3000. and 6000 i’ps. Spcccli reccpti0lt thresholds (SRT scores) were also taken for each ear and dis::rirllill;itiorl functions at 10. 20, 30 and 40 dB lcvcis abt,jve the speech reception thresholds f~ each ear. This produced 8 obsel-vations per S. The test materials were rvcorded versions of the CID W-22 word lists 1 and 2. Half-lists. 2’; words in length. were used. Each S received 30 sessions of treatment. The trcatmcnt scssion.5 fasted W minutes and were conducted 5 days per week. All Ss ~omplcted the treatment sessions in 7 weeks or less. After treatment. all S were rc-evaluated audiologi
The squIpmr_nt used was the model TD. 100 unit rnarlufactured by tli’b Jn2tlectron Corporation. Four units were rented for the purpost of till,. study. These units were slightly modified in order to implement the require ments of the double-blind experimental design Four stainless steel disk electrodes 1 inch in diameter wcrc placed on tilt: head of each S. The conducting surface of two of the elcc:trodcs were COVVC~&
Kcs~rltsand discussion
uted in the range from 52 76 to 80%. Further, the means of the preprogram observalions were approximately the same for both groups. Thus meaningful comparison of the groups was possible within this range. Each subject was assigned a score which was the average of his preprogram scores (obseNatians) that fell in the range from 52% to 80%. Ei&t of the placebo subjects and 14 of the experimental subjects had at lcast one such score and could thus be included in the analysis. The means of the prcprogram, individual subject scores were ti7 $L and 6W for the cxpcrimcnt.3l and cant rol groups. respectively. The post trca tmct?i observations ~orrespr~ndin~ to the pretreatment observations (i.e.. in ttic: same car ancl at the sanic degree of amplification above speech receptk~rl threshold) ww av~ragcd for each subject. Thus each subject had a pc~sttrcatrnent score as wrll as a prcfre~~trnctlf score. The means of the posttrmtment individual subject xwres were 7Wb anil 72% for the expernncntal a:ld contrul grl:_q~s, rcspet’tltely. The post trcatmcnt scores frmr the two groups differcrt significantly. [I C= WW, by the Mann Whitney C-test. Thus the control group’s average speech discrimintitiun score changed from 69% befor: treatment to 72% following placebo treatment. Ori the other hand, the experimenta.! groups average speech discrimination score changed from 07% before treatment to 79% fdiowing 30 e~cc:trc~sritnulatiot~ treatments. an average gain of 12%. A similar analysis was carried out Mng the preprogram sc’ores cjf 485 a~ fess. Three placebo and 8 experimental subjects h:J at Icast one pqrograrrl observation within that range and were included in t!le analysis. 1’11~means 01 the preprogram scores of the subjects in the tw0 groups were 43% aaId 42 ;l irl the experimental and placebo groups, respcc tively . The pjst trea tnlernt n~;lr~~~ were 73% ard 539 in the experimental and placebo proups, rcspcctivcly. Tfrt* posttreatment scores for the two groups differed significsntly. p < 0.024, h! the Mann- Whitney U-test. Again improvement uccurrcd. Fur the cc)ntrrJ grotlp. thcrc was an 1 1% improvement foliowin:: placebo trea bnen t ,. while fry the cxpenmental group there was a 30% im::>rovcment following elcct~t~ stimulation. Thus. in cases where the preprogram scorL.9 wcrc 80% or iwss, our dat:k mdicated that elec tro-stimula tion improved dkrimina tion and th;j t the ini provement was not due to a placcho effect. The main features of the Puh:nridl and kiwrence report were replicated. Subsequent investi~,ations have showry l!his improvement to last for from three to tktrr months hcf’ore dropping ot’t rather rapidly to pretherapy levels. There wcrc no dift’rences bctwcen th right and icft cars in terms of an~unt of improvement. Finally, tfll!re was II consistent evidence f’or changes in SKT or purl: fc.)ne thresholds. It 1s important tu emphasize that the nature 01’the effect we c)bsorvcd W;P an improvement in discrimination scores without a corresponding impruv+ ment in WT scores. This implies that the slope of the discrimination f’unctiijll was steepened in the expcrimcntal group more than in the control group.
ment in hearing in everyday contexts. On the other hand, subjective reports are notoriously inadequate indices of clinical change. Whether the procedure, as it now stands, should generally be used as a clinical tool, must ultimatel! be determined by research designed to answer the question raised above. Thus, these results must be considered as very preliminary. and, at th: same time, promising. They are reported in the hope that others will join ill an attempt to extend and understand them.
Reference Puharich, H.K. and J.L. Lawrence, 1969, Hearing tehabilitation by means of transdermal etectro-therapy in bunnan hearing loss of sensori-neutral origin. Acta Otolaryng. 67, 69.
State I
‘nhvrsity, U,riversity Park. Pa. I ciXK?
‘If‘he cffccts of clcctrc,-stimulation on pure tcbncthreshold and speech cllscrimination \I~.~w$of persons with sensori-ncurai! hearing lo\s was assc~~f uring a double-blmd ~IIW~WC. improvcment~ in speech dtscrimination cx~~ld not ho attributed to a ~IXX~XS rikct. EEG examinations revealed no harmful cffccts of the elcctru-stirnuiation prvcenuW.
Jtrtroducfiou It has been known for some time that r:ormally hearing persons can detect an AM radio frequency signal when that signal is placed directJy into the h~;td. In such cases the observer can hear :iudio frequency modulation of the r.1‘.signal. This phenon~enon will be called electrct-stimulation of hearing in thl> paper. l’uhrioh and Lawrence ( 1969) reported that cxtonsivc elcc:trrrstirnul~,tiorl crf hearing. in patients with sensori-natural hearing loss, produced improve111cn ts in pure- tone thrcshoIds and speech disc riminatim scores following mta stimulation. The pur;x~ of‘ this paper is to publish the results of an ;!ttrrnpt to replicate the Puharich and Lawrence study u tiiizing improved rllstrumen tation and ttterapcu tic techniques. The resul ts of an assessrmn t of the neurological effects of the therapy are :iIso reported.
I werlty-live persons, who had bilateral sensori-neural hearing loss, and AU raged from 12 to 80 years in age, served as subjects for this experiment. ‘\!lt!jccts were screened by a neurologist at the Pcnnsyhania State hiversity ‘~~dL:aJ&hoot to eliminate any persons who were predisposed to epilepsy. ’ Dt. f3rcnnanis located
at the Hrrshcy Medical Center,.Hershcy,
Pennsylvania.
All of the subjects had been patic:nts at the [{caring Conservation Center ot’ Lancaster. Pennsylvania, where their audiological records are on file.
Ten persons were placed into the control group (two dropped out during therapy) and 15 were placed into the experimental group. After preliminary screening. al! Ss were given EEG examinations ad audiolqical cvahations. Al] Ss were told that they were receiving cicJctro-stinl\llatiotl and that some .% were receiving different kinds and levels of’ treatment than others. A clinical audiologist (CCC-A-ASHA) did both t11c audiological prc- and post testing. Ajthough the audiologist mdxstcmd the nature of the experiment. he did 1101 know which Ss were experiment& and which were controls. The audiological evaluation consisted of taking pure tale thre&olds il! teach c3r at 250. 500. 1000. 2000. 3000. and 6000 i’ps. Spcccli reccpti0lt thresholds (SRT scores) were also taken for each ear and dis::rirllill;itiorl functions at 10. 20, 30 and 40 dB lcvcis abt,jve the speech reception thresholds f~ each ear. This produced 8 obsel-vations per S. The test materials were rvcorded versions of the CID W-22 word lists 1 and 2. Half-lists. 2’; words in length. were used. Each S received 30 sessions of treatment. The trcatmcnt scssion.5 fasted W minutes and were conducted 5 days per week. All Ss ~omplcted the treatment sessions in 7 weeks or less. After treatment. all S were rc-evaluated audiologi
The squIpmr_nt used was the model TD. 100 unit rnarlufactured by tli’b Jn2tlectron Corporation. Four units were rented for the purpost of till,. study. These units were slightly modified in order to implement the require ments of the double-blind experimental design Four stainless steel disk electrodes 1 inch in diameter wcrc placed on tilt: head of each S. The conducting surface of two of the elcc:trodcs were COVVC~&
Kcs~rltsand discussion
uted in the range from 52 76 to 80%. Further, the means of the preprogram observalions were approximately the same for both groups. Thus meaningful comparison of the groups was possible within this range. Each subject was assigned a score which was the average of his preprogram scores (obseNatians) that fell in the range from 52% to 80%. Ei&t of the placebo subjects and 14 of the experimental subjects had at lcast one such score and could thus be included in the analysis. The means of the prcprogram, individual subject scores were ti7 $L and 6W for the cxpcrimcnt.3l and cant rol groups. respectively. The post trca tmct?i observations ~orrespr~ndin~ to the pretreatment observations (i.e.. in ttic: same car ancl at the sanic degree of amplification above speech receptk~rl threshold) ww av~ragcd for each subject. Thus each subject had a pc~sttrcatrnent score as wrll as a prcfre~~trnctlf score. The means of the posttrmtment individual subject xwres were 7Wb anil 72% for the expernncntal a:ld contrul grl:_q~s, rcspet’tltely. The post trcatmcnt scores frmr the two groups differcrt significantly. [I C= WW, by the Mann Whitney C-test. Thus the control group’s average speech discrimintitiun score changed from 69% befor: treatment to 72% following placebo treatment. Ori the other hand, the experimenta.! groups average speech discrimination score changed from 07% before treatment to 79% fdiowing 30 e~cc:trc~sritnulatiot~ treatments. an average gain of 12%. A similar analysis was carried out Mng the preprogram sc’ores cjf 485 a~ fess. Three placebo and 8 experimental subjects h:J at Icast one pqrograrrl observation within that range and were included in t!le analysis. 1’11~means 01 the preprogram scores of the subjects in the tw0 groups were 43% aaId 42 ;l irl the experimental and placebo groups, respcc tively . The pjst trea tnlernt n~;lr~~~ were 73% ard 539 in the experimental and placebo proups, rcspcctivcly. Tfrt* posttreatment scores for the two groups differed significsntly. p < 0.024, h! the Mann- Whitney U-test. Again improvement uccurrcd. Fur the cc)ntrrJ grotlp. thcrc was an 1 1% improvement foliowin:: placebo trea bnen t ,. while fry the cxpenmental group there was a 30% im::>rovcment following elcct~t~ stimulation. Thus. in cases where the preprogram scorL.9 wcrc 80% or iwss, our dat:k mdicated that elec tro-stimula tion improved dkrimina tion and th;j t the ini provement was not due to a placcho effect. The main features of the Puh:nridl and kiwrence report were replicated. Subsequent investi~,ations have showry l!his improvement to last for from three to tktrr months hcf’ore dropping ot’t rather rapidly to pretherapy levels. There wcrc no dift’rences bctwcen th right and icft cars in terms of an~unt of improvement. Finally, tfll!re was II consistent evidence f’or changes in SKT or purl: fc.)ne thresholds. It 1s important tu emphasize that the nature 01’the effect we c)bsorvcd W;P an improvement in discrimination scores without a corresponding impruv+ ment in WT scores. This implies that the slope of the discrimination f’unctiijll was steepened in the expcrimcntal group more than in the control group.
ment in hearing in everyday contexts. On the other hand, subjective reports are notoriously inadequate indices of clinical change. Whether the procedure, as it now stands, should generally be used as a clinical tool, must ultimatel! be determined by research designed to answer the question raised above. Thus, these results must be considered as very preliminary. and, at th: same time, promising. They are reported in the hope that others will join ill an attempt to extend and understand them.
Reference Puharich, H.K. and J.L. Lawrence, 1969, Hearing tehabilitation by means of transdermal etectro-therapy in bunnan hearing loss of sensori-neutral origin. Acta Otolaryng. 67, 69.