Pun, 44 (1991) 231-234 1 1991 Elsevier Science Publishers ADONIS 03043959Y100082Y
231 B.V. 0304.3959/91/$03.50
PAIN 01717
The consistency of pulse frequencies and pulse patterns of transcutaneous electrical nerve stimulation (TENS) used by chronic pain patients M.I. Johnson, Chnrcul Ps_vc’hophurmucolog
Unrt, Depurtment
C.H. Ashton
and J.W. Thompson
of Phurmawlog~cul Sciences, The Medrcal School, Unic;emt.) of Newcostle Newcastle upon Tyne NE2 4HH (U.K.)
(Received
6 July 1990, accepted
upon Qne,
24 July 1990)
This study records the consistency of transcutaneous electrical nerve stimulation (TENS) pulse Summary frequency and pulse pattern used by 13 chronic patients over a 1 year period. The results show that patients prefer specific pulse frequencies and pulse patterns unique to the individual and that they turn to such frequencies and patterns on subsequent treatment sessions. Pulse frequencies and pulse patterns were not related to the cause and site of pain, a finding consistent with previous study in this laboratory. This observation, coupled with the large variability in pulse frequencies and pulse patterns used between individuals, implies that patients prefer such frequencies and patterns for reasons of comfort which may not be related to mechanisms specific to the pain system. Key words: Transcutaneous Pulse pattern
electrical
nerve stimulation
Introduction Although it has been well documented that TENS efficacy is dependent upon pulse frequency [1,5,7,10, 11,15,16], there have been few reports of the actual pulse frequencies used by patients. Linzer and Long [lo] monitored the electrical characteristics of stimulation and electrode locations in 23 patients who received satisfactory relief of pain with TENS. Stimulator settings which gave best pain relief were recorded and it was found that 74% of patients utilised frequencies below 60 Hz. In this laboratory, Johnson et al. [9] found that 75% of patients utilised frequencies between 1 and 70 Hz, although examination of the output characteristics of the machines suggested that this was partly due to stimulator design. Although no relationships between TENS pulse frequency, the cause and site of pain and TENS efficacy were found, the results implied that patients utilised specific pulse frequencies which were unique to the individual.
Correspondence IO: Prof. J.W. Thompson, Clinical Psychopharmacology Unit, Dept. of Pharmacological Sciences, The Medical School, University of Newcastle upon Tyne. Framlington Place, Newcastle upon Tyne NE2 4HH, U.K.
(TENS);
Analgesia;
Chronic
pain patients;
Pulse frequency;
The study by Johnson et al. [9] found that patients expressed strong preferences for the pattern of pulse delivery. For example 23% of patients found burst mode TENS to be more beneficial than continuous mode TENS in reducing their pain and 56% found continuous mode TENS more beneficial. New patients issued with TENS at Pain Relief Clinics in the U.K. are generally instructed as follows: (1) initially use continuous mode TENS; (2) set all controls (pulse intensity (mA) and pulse frequency) to minimum setting; (3) increase pulse intensity to the ‘strong but comfortable’ level; (4) increase pulse frequency to maximal comfortable level; (5) hunt for the most appropriate setting during each treatment session: (6) if insufficient relief of pain is obtained, try using burst mode TENS. The patient is encouraged to experiment with all stimulator settings. It must be stressed that these instructions are issued to the majority of new patients although under certain circumstances burst mode TENS utilised as acupuncture-like TENS (AL-TENS) [2,3,14,16] is the first treatment choice. All of the patients who participated in the present study had experimented with the variety of settings available on the stimulator and none were utilising AL-TENS. The studies by Linzer and Long [lo] and Johnson et al. [9] only recorded the electrical characteristics of
TENS during one treatment session. To our knowledge no study has recorded the consistency of pulse frequency and pulse pattern used by patients during a series of treatment sessions over a long period of time. Thus, the aim of the present study was to record TENS pulse frequencies and pulse patterns used by chronic pain patients over 1 year.
1‘ABLI- I
Patient
I
Thirteen patients (age range = 39-66 years old; mean f S.D. = 54.1 f 9.8; female n = 8; male n = 5) attended the research unit on 3 separate occasions (approximately 4 months apart over a 1 year period) to participate in a variety of TENS experiments. Prior to the start of each experiment patients were instructed to apply TENS as they would to treat their chronic pain condition. All patients applied electrodes directly over, or immediately proximal to, the site of pain and TENS pulse frequency was recorded using a Type 4000 Frye analyser. Patients set their stimulators to a ‘strong but comfortable’ intensity level and hunted for the most suitable pulse frequency. Patients were in possession of 1 of 4 types of stimulator (i.e., Tiger Pulse, Tiger Burst, MICROTENS or Spembly). Pulse width was fixed at 200 psec in all stimulators and electrode impedance was below 1.5 kS2. Of these 13 patients, 10 returned for a fourth visit. Patients were categorised according to the classification of chronic pain prepared by the International Association for the Study of Pain (IASP) [6]. The patient population had a range of chronic pain conditions including 2 deafferentations, 3 nerve entrapments, 3 neuralgias, 3 spondylosis, 1 sympathetic and 1 ‘other.’ Five of these patients had low back pain in either ‘trauma’ or ‘degenerative/ mechanical’ aetiology. All patients had been successfully controlling their pain condition with TENS for over 1 year prior to this study. Twelve of the 13 patients found that TENS generally reduced their pain by over half, as measured on a visual analogue scale.
12ICI
B
140 [B]
136 [B]
(0 1)
124 [C] 47 1W
(W
8 [Cl
Results Of the 13 patients, 4 were in possession of a Tiger Pulse stimulator (no burst mode option available), 3 a Tiger Burst, 3 a Spembly 9000 and 3 a MICROTENS 7577. Patients utilised pulse frequencies between 3 and 176 Hz (mean = 60 Hz; median = 47 Hz; n = 39; 3 visits per subject). All stimulators possess a frequency control dial with logarithmic output characteristics [7,9]. Therefore logarithmic transformation of pulse frequency data was performed before statistical analysis (Table I). Two-way analysis of variance (2-way ANOVA) showed no significant differences between the frequency
F
92 [Cl
G H I J W) L
lb IC] 104 [B] 24 ICI 5x [C] 10 ICI 55 ICI
M
136 [B]
_.._” .-..- --- --- .? 1 .____._. .~ .___~_
~__.____
2 _____ 28 ICI
CA) Methods
Visit ___..--__-
7’ [(‘I
56 LB1 11 [Cl
12 [C]
i 76 [C‘] ! 24 [
231 B.V. 0304.3959/91/$03.50
PAIN 01717
The consistency of pulse frequencies and pulse patterns of transcutaneous electrical nerve stimulation (TENS) used by chronic pain patients M.I. Johnson, Chnrcul Ps_vc’hophurmucolog
Unrt, Depurtment
C.H. Ashton
and J.W. Thompson
of Phurmawlog~cul Sciences, The Medrcal School, Unic;emt.) of Newcostle Newcastle upon Tyne NE2 4HH (U.K.)
(Received
6 July 1990, accepted
upon Qne,
24 July 1990)
This study records the consistency of transcutaneous electrical nerve stimulation (TENS) pulse Summary frequency and pulse pattern used by 13 chronic patients over a 1 year period. The results show that patients prefer specific pulse frequencies and pulse patterns unique to the individual and that they turn to such frequencies and patterns on subsequent treatment sessions. Pulse frequencies and pulse patterns were not related to the cause and site of pain, a finding consistent with previous study in this laboratory. This observation, coupled with the large variability in pulse frequencies and pulse patterns used between individuals, implies that patients prefer such frequencies and patterns for reasons of comfort which may not be related to mechanisms specific to the pain system. Key words: Transcutaneous Pulse pattern
electrical
nerve stimulation
Introduction Although it has been well documented that TENS efficacy is dependent upon pulse frequency [1,5,7,10, 11,15,16], there have been few reports of the actual pulse frequencies used by patients. Linzer and Long [lo] monitored the electrical characteristics of stimulation and electrode locations in 23 patients who received satisfactory relief of pain with TENS. Stimulator settings which gave best pain relief were recorded and it was found that 74% of patients utilised frequencies below 60 Hz. In this laboratory, Johnson et al. [9] found that 75% of patients utilised frequencies between 1 and 70 Hz, although examination of the output characteristics of the machines suggested that this was partly due to stimulator design. Although no relationships between TENS pulse frequency, the cause and site of pain and TENS efficacy were found, the results implied that patients utilised specific pulse frequencies which were unique to the individual.
Correspondence IO: Prof. J.W. Thompson, Clinical Psychopharmacology Unit, Dept. of Pharmacological Sciences, The Medical School, University of Newcastle upon Tyne. Framlington Place, Newcastle upon Tyne NE2 4HH, U.K.
(TENS);
Analgesia;
Chronic
pain patients;
Pulse frequency;
The study by Johnson et al. [9] found that patients expressed strong preferences for the pattern of pulse delivery. For example 23% of patients found burst mode TENS to be more beneficial than continuous mode TENS in reducing their pain and 56% found continuous mode TENS more beneficial. New patients issued with TENS at Pain Relief Clinics in the U.K. are generally instructed as follows: (1) initially use continuous mode TENS; (2) set all controls (pulse intensity (mA) and pulse frequency) to minimum setting; (3) increase pulse intensity to the ‘strong but comfortable’ level; (4) increase pulse frequency to maximal comfortable level; (5) hunt for the most appropriate setting during each treatment session: (6) if insufficient relief of pain is obtained, try using burst mode TENS. The patient is encouraged to experiment with all stimulator settings. It must be stressed that these instructions are issued to the majority of new patients although under certain circumstances burst mode TENS utilised as acupuncture-like TENS (AL-TENS) [2,3,14,16] is the first treatment choice. All of the patients who participated in the present study had experimented with the variety of settings available on the stimulator and none were utilising AL-TENS. The studies by Linzer and Long [lo] and Johnson et al. [9] only recorded the electrical characteristics of
TENS during one treatment session. To our knowledge no study has recorded the consistency of pulse frequency and pulse pattern used by patients during a series of treatment sessions over a long period of time. Thus, the aim of the present study was to record TENS pulse frequencies and pulse patterns used by chronic pain patients over 1 year.
1‘ABLI- I
Patient
I
Thirteen patients (age range = 39-66 years old; mean f S.D. = 54.1 f 9.8; female n = 8; male n = 5) attended the research unit on 3 separate occasions (approximately 4 months apart over a 1 year period) to participate in a variety of TENS experiments. Prior to the start of each experiment patients were instructed to apply TENS as they would to treat their chronic pain condition. All patients applied electrodes directly over, or immediately proximal to, the site of pain and TENS pulse frequency was recorded using a Type 4000 Frye analyser. Patients set their stimulators to a ‘strong but comfortable’ intensity level and hunted for the most suitable pulse frequency. Patients were in possession of 1 of 4 types of stimulator (i.e., Tiger Pulse, Tiger Burst, MICROTENS or Spembly). Pulse width was fixed at 200 psec in all stimulators and electrode impedance was below 1.5 kS2. Of these 13 patients, 10 returned for a fourth visit. Patients were categorised according to the classification of chronic pain prepared by the International Association for the Study of Pain (IASP) [6]. The patient population had a range of chronic pain conditions including 2 deafferentations, 3 nerve entrapments, 3 neuralgias, 3 spondylosis, 1 sympathetic and 1 ‘other.’ Five of these patients had low back pain in either ‘trauma’ or ‘degenerative/ mechanical’ aetiology. All patients had been successfully controlling their pain condition with TENS for over 1 year prior to this study. Twelve of the 13 patients found that TENS generally reduced their pain by over half, as measured on a visual analogue scale.
12ICI
B
140 [B]
136 [B]
(0 1)
124 [C] 47 1W
(W
8 [Cl
Results Of the 13 patients, 4 were in possession of a Tiger Pulse stimulator (no burst mode option available), 3 a Tiger Burst, 3 a Spembly 9000 and 3 a MICROTENS 7577. Patients utilised pulse frequencies between 3 and 176 Hz (mean = 60 Hz; median = 47 Hz; n = 39; 3 visits per subject). All stimulators possess a frequency control dial with logarithmic output characteristics [7,9]. Therefore logarithmic transformation of pulse frequency data was performed before statistical analysis (Table I). Two-way analysis of variance (2-way ANOVA) showed no significant differences between the frequency
F
92 [Cl
G H I J W) L
lb IC] 104 [B] 24 ICI 5x [C] 10 ICI 55 ICI
M
136 [B]
_.._” .-..- --- --- .? 1 .____._. .~ .___~_
~__.____
2 _____ 28 ICI
CA) Methods
Visit ___..--__-
7’ [(‘I
56 LB1 11 [Cl
12 [C]
i 76 [C‘] ! 24 [
