Lars-Erik Dyrehag. Eva G. Widerstrom-Noga', Per G. Aslund, Ulrika Kruse-Molander, Bodil Mannheimer, Sven A. Andersson, Dept of Physiology, Goteborg Univ, Box 432, SB-405 30 Gote-borg, Sweden, e-mail: Dyrehag@physiol.gu.se 'Current address:Miami Project, Univ of Miami, FL,LSA.

Aim of Investigation: To evaluate the effect of electro-acupuncture treatment (EA) using several different outcome variables. Further, we aimed to evaluate whether an increase of tooth pain threshold in response to EA was predictive for successful treatment outcome of a series ofEA treatments.

Methods: Fifty-five patients with long-lasting musculoskeletal pain in the neck-shoulder region were enrolled in the study. The patients were randomly selected either for eight electroacupuncture (EA) treatments or to be on a waiting-list as controls before receiving treatment 16 weeks later. The outcome variables included: muscle tenderness, grip strength, range of motion, self-reports of pain intensity, mood, anxiety, depression and somatic discomfort. The patients were evaluated before and after a four weeks treatment period and at follow-up three months later. Tooth pain thresholds were assessed in all subjects before and after EA stimulation administered in the laboratory.

Results: The EA group showed significant improvement in most of the outcome variables while none of the variables improved significantly for the control group. In comparison with the control group, the treatment group improved significantly in functional shoulder/arm mobility and somatic discomfort. Three months following cessation ofEA treatment, the same outcome variables still showed significant improvement. No significant correlation was seen between EA induced tooth pain threshold changes and any of the outcome variables.

Conclusions: The results of this study suggest that electro-acupuncture has positive effects in long-standing neck and shoulder pain assessed both with objective and subjective instruments even though the effects are discrete. Acknowledgments: The Goteborg Medical Society. Goteborg Univ.

ACTIVE VERSUS PLACEBO TRANSCUTANEOUS ELECTRICAL NERVE STIMULATION (TENS) TREATMENT IN PATIENTS WITH CHRONIC LOW BACK PAIN: A PILOT STUDY

Charles Chabal'. Sonja Carlson²', Janet Kelson³', JeffFjelstuI⁴' 'Anesthesiology Dept., Univ of Washington School of Medicine, Seattle WA, Surgery and Perioperative Care, VA Puget Sound Healthcare System, Seattle, WA, Clinical Research Dept., Empi, Inc., St. Paul, MN, "Rehabilitation Medicine Dept., VA Puget Sound Healthcare System, Seattle, WA, 98108, USA

Aim of Investigation: To investigate the effectiveness of active TENS versus placebo TENS in subjects with chronic low back pain over six weeks of treatment.

Methods: The study utilized a randomized double blind design and compared active TENS treatment (EPIX VT ®, Empi, Inc.) to treatment with an identical placebo TENS device in subjects with chronic non-radicular low back pain over a six week study period. Outcomes included repeated measures of pain relief, physical function, device utilization, and subject satisfaction. The data were analyzed using non-parametric statistics.

Results: Interim analysis revealed demographic profiles of active subjects (N= 6) and placebo subjects (N=9) were identical. Active TENS users rated TENS significantly more effective for movement induced pain (p=0.03); were more satisfied, rated TENS more effective for pain management, and were more compliant with device use as compared to the placebo group. Preliminary data also suggests that active TENS effectively reduced several other measures of reported pain versus placebo TENS, even after six weeks of treatment.

Conclusions: In this well controlled pilot study, TENS was more effective and the majority of effects were sustained over a six week study period as compared to placebo TENS.

Acknowledgments: Supported by Empi Inc., St. Paul, MN.

THE DEVELOPMENT OF AN ACTIVE PLACEBO FOR STUDIES OF TENS TREATMENT.

Mary Chakour, Stephen J. Gibson, Max Neufeld. Robert D. Helme. National Ageing Research Inst, PO Box 31, Parkville, VIC., Australia 3052.

Objective: Dead battery TENS has been used as the placebo of choice in studies involving transcutaneous electrical modes of therapy, but this sham procedure fails to reproduce the distinct physiologic sensations arising from active stimulation. The aim of the present study was to identify an active placebo TENS treatment that could be used for future research studies.

Method: Eighty subjects (mean age = 33.3 years) were randomly assigned to one of eight TENS frequency / intensity conditions (2Hz, 5Hz, 80Hz, 2000Hz delivered at either "strong but comfortable" intensity, or "strong painful pricking" intensity). Pain threshold for C02 laser stimulation was determined using a double random staircase procedure delivered to the back of the non-dominant hand. All subjects received 5 minutes of TENS stimulation along the superficial radial nerve and pain thresholds were determined again while TENS was active.

Results: A distinct cutaneous sensation was evoked by TENS treatment with "twitching" used as the most common descriptor for low frequency stimulation (2Hz, 5Hz) and "buzzing" or "vibrating" used for higher frequency stimulation (80Hz, 2000Hz). ANOVA revealed a significant reduction in pain sensitivity to C02 laser stimuli following TENS treatment and a significant interaction with TENS frequency and TENS intensity. Post hoc pairwise comparisons indicated that high intensity TENS at 5Hz, 80Hz or 2000Hz were equally effective in raising laser pain thresholds by almost 150%, whereas low intensity stimulation or high intensity TENS delivered at 2Hz were without effect.

Conclusions: The intensity parameter of TENS stimulation appears to play a major role in determining the analgesic efficacy of this mode of therapy. Low intensity TENS, particularly 2Hz stimulation, may offer a viable placebo procedure which mimics the physical sensations induced by active treatment but does not alter sensitivity to experimental pain stimuli.

REPEATED TRANSCUTANEOUS ELECTRICAL NERVE STIMULATION (TENS) PRODUCED SIMILAR CUMULATIVE ANTINOCICEPTIVE EFFECT ON CHRONIC LOW BACK PAIN AND OSTEOARTHRITIC KNEE PAIN

G.L.Y. Cheing* and C.W.Y. Hui-Chan. Dept of Rehabilitation Sciences, The Hong Kong Polytechnic Univ, Hung Horn, Hong Kong

Aim of Investigation: This study examined whether repeated TENS produced similar cumulative modulations on chronic low backpain (LBP) and chronic osteoarthritic (OA) knee pain over a 2-week period.

Methods: Eleven LBP patients and 16 OA knee patients who suffered from either condition for more than 6 months, and were stale on their medication for 3 weeks, participated in the study. "hey received 60 min of TENS for 10 sessions. TENS was applied o the lumbro-sacral region for the LBP group, and the 4 acupunc-ure points around the knee of the OA patients. Daily measures of >ack or knee pain, using the visual analogue scale (VAS), were malyzed using repeated measure ANCOVA.

Results: The VAS scores decreased linearly over the 2-week period For both patient groups. The pre-stimulation value of VAS score For the LBP group was reduced progressively from 100% in session, to 51.2% by session10 (p=0.000). The VAS score for the OA group was reduced to 68.4% by^e^ion/o(p=0.00]). There was significant difference in the magnitude of reduction between the 2 groups (p=0.024). However, the difference was not significant after adjusting for age (p=0.206).

Conclusion: TENS produced cumulative inhibition on both chronic LBP and OA knee pain, with the effect being greater in the LBP than the OA group. However, the OA patients were older than the LBP patients (63.7 vs 31.5 yrs, p=0.004), and the group difference in TENS analgesia became non-significant after controlling for age. The variation of the patients' response in the two groups could therefore be attributable to age. Although TENS was applied at different sites: at the low back for back pain, and the knee for OA pain, the time course and cumulative effect of TENS analgesia in both groups appeared to be similar.

Acknowledgments: Project supported by a grant from the Hong Kong Polytechnic Univ to CWYHC and a scholarship to GLYC.

INTRACTABEL ANGINA PECTORIS TREATED WITH TENS PRIOR TO SPINAL CORD STIMULATION.

G. JuhL H.S. Pedersen, P. Hole and C. Andersen, (SPON: T.L-Jensen), Dept ofAnestesia, Odense Univ Hospital, DK.-5000 Odense, Denmark.

Aim of Investigation: To describe the use oftranscutaneous electrical nerve stimulation (TENS) in the treatment of intractable angina pectoris prior to spinal cord stimulation (SCS).

Methods: Since 1992 we have used TENS for treatment of intractable angina pectoris as a test of the planned SCS and patient compliance. The patient is instructed at the first meeting in using TENS for prophylactic treatment for 6-8 hours per day and to use TENS when symptomatic angmal attacks occur. Over the next 3-6 months the patient has to fill out a diary concerning the effect of TENS and the use ofnitro-glycenne, opioids and daily activities.

Results: If the patient have good effect of TENS and is in a physical state that makes an implantation of spinal cord stimulator possible, the patient is offered treatment with SCS. In 46 of the patients the TENS test resulted in SCS implantation.

Conclusions: Over the last 7 years 46 patients did have a good effect and SCS was successfully implanted for further treatment of intractable angina pectoris. We find that TENS is useful for initial treatment and testing prior to SCS.

TRANSCUTANEOUS ELECTRICAL NERVE STIMULATION IN ACUTE POSTOPERATIVE PAIN (SHOULDER SURGERY): A RANDOMIZED DOUBLE BLIND PLACEBO CONTROLLED CLINICAL TRIAL.

R. Likar, M. Molnar, E. Rupacher, G. Bematzky, R. Sitti, B. Dis-selhoff, Dept. ofAnaesthesiology, Landeskrankenhaus, Klagenfurt, Austria; Pain Clinic, Univ ofErlangen, Germany

Aim of Investigation: Transcutaneous nerve stimulation provides acceptable analgesia and allows a reduction of dosage of systemic analgesics. Double blinding is possible in trials of physical treatments like TENS.

Methods: 24 patients were randomized to receive TENS (80 Hz, 6 mA) or sham TENS (80 Hz, 0 MA) for 8 hours continuously after surgery, then 5x45 min on 1. and 2. post operative days. The pair of electrodes was placed paravertebrally (C4/C5 anode on surgery side). TENS and sham TENS were both blinking and the amplitude was chosen so low (6 mA), that neither the physician nor the patient could know if the last was in the verum or in the placebo group. Pain outcomes were measured by VAS every 4 hours for 24 hours, then every hour until 72 hours. Pain quality was also registered by the patients undergoing 2 psychological tests (Nottingham Pain Scale, Hamburger Schmerz Adjektive Liste) before and after surgery.

Results: We found that TENS (80 Hz, 6 mA) is very effective with respect to VAS Score and postoperative supplemental analgesia consumption.

Conclusion: TENS therapy in the postoperative setting is easy, effective and without side effects.

PROFOUND AND LONG LASTING INHIBITION OF CHRONIC ITCH INDUCED BY STIMULATION OF THIN CUTANEOUS NERVE FIBRES.

Hans-Jorgen Nilsson. Ragnar Carstam* and Jens Schouenborg, Dept of Physiological Sciences, Section for Neurophysiology, Lund Univ, Solvegatan 19, 223 62 Lund, Sweden

Aim of the investigation: Despite that severe itch is common in many dermatological diseases the therapeutic arsenal is often inadequate. It is known that acute itch can be effectively relieved by stimulation of cutaneous nociceptors using a new technique termed Cutaneous Field Stimulation (CFS). Here, we have tested the effects ofCFS on chronic itch due to atopic dermatitis.

Methods: 27 patients were randomised to CFS (25 min, 16 electrodes, 4 Hz per electrode, up to 0.8 mA) and Transcutaneous electrical nerve stimulation (TENS, 100 Hz, up to 26 mA). Itch was measured just prior to, during, and at regular intervals up to 12 h after either type of treatment.

Results: Both treatments increased the itch during ongoing stimulation presumably reflecting an altered sensory processing in the somatosensory pathways of the chronic itch subject. After cessation of CFS, but not TENS, itch was significantly depressed for up to 7 h. Peak inhibitory effect (about 25% of control) was reached between 1 and 5 hours postconditioning. This contrasts to the acute experimental itch in healthy subjects which typically exhibits immediate peak effects. Neither treatment had any effect on allokne-sia, as measured before and 10 mm after conditioning stimulation.

Conclusion: It is concluded that CFS strongly depresses chronic itch. CFS, therefore, offers a potentially useful symptomatic treatment of itch.

Acknowledgement: Supported by MRC grant,

EFFECTIVE ANALGESIA FOR ESWL: TRANSCUTANEOUS ELECTRICAL NERVE STIMULATION (TENS)

OlafReichelt*. Heiko Wunderlich*, Jorg Schubert*, Dirk-Henrik Zermann, Dept of Urology, Univ of Jena, Jena, Jena 07740, Germany

Aim of Investigation: ESWL (Extracorporeal Shockwave Litho-tripsy) has revolutionized the treatment of urinary stone disease. However, the most appropriate analgesia offering pain free treatment, minimal side effects and adequate cost effectiveness remains to be established. This prospective study was performed to evaluate the efficacy of TENS during ESWL.

Methods: ESWL was done using a third generation lithotripter (Lithostar). Two pairs of stimulator electrodes (70 Hz, 150 us, 9 V) were placed paravertebrally at LI and near the lithotripter shock tube prior to ESWL. Treatment was carried out as follows: 1. Begin of shock wave administration (no current=sham TENS) 2. In case of severe pain TENS was turned on (20-30 mA). 3. If patients experienced no pain relief analgetic drugs were given intrave-nously.

Results: 92 (62%) out of 149 patients did not need any analgetic medication. In 42 (72%) out of the remaining 57 patients a TENS-related, pain relieving response was observed. ESWL-induced pain could be reduced by 39.2% (pain intensity 1-10:7.4±1 before vs. 4.5±1 after TENS). The degree of fragmentation assessed by two urologists (plain film) was found to be 90% (65% "good" 25% "very good disintegration") for TBNS-patients compared to a retrospectively analysed control group (94%=72% "very good", 22% "good disintegration", n=100). The average analgetic need of each patient of this group was calculated: 826 mg metamizole (NSA1D), 87.5 mg tramadole (Opioid), 2.5 mg pintramide (Opioid), 2.1 mg pethidine (Opioid) as well as 2.3 mg midazolam (Benzodiazepine), 0,8 mg diazepam (Benzodiazepine).

Conclusions: In 72% of all patients experiencing pain during ESWL sufficient pain relief was achieved reaching comparable disintegration rates. Two different theories explaining TENS-related analgesia are known: Segmental (spinal) and supraspinal (central) inhibition. Since we didn't see any analgetic effect in patients having both two pairs of electrodes attached around the shock tube (n=30) supraspinal inhibition obviously accounts for the above-mentioned pain relief. We conclude that TENS is a non-invasive, cost-effective way of side-effect-free analgesia in ESWL with 3rd generation lithotripters.

LONG TERM DEPRESSION OF HUMAN NOCICEPTIVE SKIN SENSES INDUCED BY LOW FREQUENCY STIMULATION OF THIN CUTANEOUS FIBERS

Jens Schouenborg & Hans-Jorgen Nilsson, Dept of Physiological Sciences, Section for Neurophysiology, Lund Univ Solvegatan 19, S-233 62 Lund, Sweden

Aim of Investigation: We have recently shown that stimulation of thin nerve fibers close to the dermo-epi dermal junction in the skin, through a multi electrode array, produces powerful inhibition of itch and, to a lesser degree, cutaneous pain in humans. Here we have studied the induction time and frequency dependency of the inhibitory effects on itch, mechanical and thermal pain in 20 healthy subjects.

Methods: Sixteen electrodes applied on the skin were consecutively stimulated at different frequency and duration, using a method termed Cutaneous Field Stimulation (CFS).

Results: The results show that CFS for 6-10 min suffices to induce peak inhibitory effects on the major qualities of skin pain. No significant difference in inhibitory effects between different stimulation frequencies (1,4 and 10 Hz per electrode) was found. Confirming previous studies, different nociceptive qualities were different! ally affected.

Conclusion: The induction time, duration and frequency characteristics of the inhibitory effects may suggest that the underlying mechanisms are similar to those of "memory-like" long term depression (LTD) that can be evoked by low frequency stimulation of thin primary afferent fibers in the rat dorsal hom. Acknowledgement: Sponsored by grants from MRC

CUTANEOUS FIELD STIMULATION IN TENS-RESISTANT CHRONIC PAIN.

Bengt Sjolund. Karin Martinsson*, Dept of Rehabilitation, Lund Univ Hospital, 221 85 Lund, Sweden

Aim of Investigation: Cutaneous field stimulation (CFS; Schouenborg et al., 1997) is a new sensory stimulation technique, designed to alleviate pain and itch. With a special epicutaneous electrode (cathode) containing 16 metal pins, the area of pain is stimulated randomly with single 1 ms pulses at 4 Hz for 30 min at 2X the strength at sensory threshold from a portable stimulation unit. With this technique, thin afferent fibers and receptors are activated without causing noticeable pain in the patient. We have now examined whether patients with chronic nonmalignant and nonvisceral pain, who have not benefited from conventional or acupuncture-like transcutaneous electrical nerve stimulation, may instead experience temporary pain relief from CFS.

Methods: 106 patients with chronic nonmalignant pain of more than 6 months duration, who had been referred for pain treatment to our multidisciplinary pain center were included in the present study. They had all tried high frequency (conventional) and low frequency burst (acupuncture-like) TENS in a systematic manner without adequate pain relief After consent, they were given instructions how to apply the CFS-technique for 1 hr by one of us (K.M) and asked to treat 2x30 min/day at home. After 2, 4 and 12 weeks they were evaluated at the clinic and asked to grade their relief on a four grade verbal scale: no relief, some relief, adequate relief and pain free. Those in the latter two categories were given the opportunity to continue the treatment after the study.

Results: On the basis of history and clinical findings, 67 of the 106 patients included were diagnosed as having nociceptive pain and 39 as having neuropathic pain. 24 of the patients with nociceptive pain (1/3) but only eight of those with neuropathic pain (1/5) reported adequate or complete temporary pain relief from daily CFS treatment at the three month follow up.

Conclusions: CFS is a valid alternative in TENS-resistant chronic pain, particularly of nociceptive origin.

Acknowledgment: The equipment was provided by CFS Medical Inc., Mantalskroken 8, S-22647 Lund, Sweden.

THE ANALGESIC EFFECTS OF INTERFERENTIAL CURRENTS (IFC) AND TRANSCUTANEOUS ELECTRICAL NERVE STIMULATION (TENS) ON ISCHAEMIC PAIN IN HEALTHY SUBJECTS.

Tabasam G. and Johnson M. I.. (SPON: DM Walsh) Faculty of Health & Environment, Leeds Metropolitan Univ, Calverley St, Leeds, LSI SHE, UK.

Aim of the Investigation: To examine analgesic effects ofinterfer-ential currents (IFC) and TENS on experimentally induced ischae-mic pain.

Methods: Each healthy subject volunteer (n=30) attended the laboratory on 2 separate occasions for pretreatment and during treatment recordings. During each visit ischaemic pain was induced over a 12 minute period using the submaximal effort tourniquet technique. Visual analogue scales were presented to subjects at one minute intervals to assess the self report of pain intensity and a short form McGill Pain Questionnaire (MPQ) was completed at the end of the test. Subjects were randomly allocated to receive either (a) active IFC, (b) active TENS or (c) placebo IFC. Treatment was administered throughout the ischaemic pain test via 2 electrodes applied to the forearm. Active treatment was delivered at a 'strong but comfortable' intensity. A dummy stimulator which delivered no current output was used as a placebo.

Results: 1-way ANOVA on the mean change in pain intensity across the 12 minute period for each treatment group just failed to reach statistical significance (P=0.08). However, additional analysis revealed that IFC significantly reduced pain intensity when compared to placebo (P<0.05, unpaired t-test). TENS and IFC significantly reduced present pain intensity as recorded on the MPQ when compared to placebo (P<0.05).

Conclusion: Under the present experimental conditions TENS and IFC produced greater analgesic effects than placebo. However, there were no differences in the degree of analgesia between IFC and TENS.

EFFICACY OF THERMAL BIOFEEDBACK AND RELAXATION THERAPY ON MIGRAINE TREATMENT

Preeti Gupta and Shailja Singh*, G.B. Pant Hospital, New Delhi, M.G. Kashi Vidyapith Univ, Varanasi, India.

Aim of Investigation: Studies done to date suggest a high degree of efficacy of thermal skin temperature biofeedback training in migraine treatment. This study explored comparative efficacy of thermal skin temperature biofeedback and autogenic training of relaxation on treatment of migraine.

Methods: Ten patients who were suffering from migraine, diagnosed by the neurologists according to the criteria of International Headache Society (1988) were divided into two treatment groups. First group of 5 patients was assigned 12 sessions of thermal skin temperature biofeedback training with 6 WK baseline. Second group of 5 patients was assigned 12 sessions of autogenic training for relaxation with 6 WK. baseline. Clinical effect was measured in terms of reduction in headache intensity, duration and frequency.

Results: Findings indicate significant differences between two treatment groups. Thermal skin temperature biofeedback training group was better than relaxation training group on headache severity and frequency. Relaxation treatment group performed better on reduction of headache duration than the thermal biofeedback training group.

Conclusions: Thermal skin temperature biofeedback is comparatively more effective than the autogenic training for relaxation in migraine treatment. Combination of both therapeutic techniques may provide best results for treatment of migraine.

NEUROMODULATION OF PAIN PERCEPTION THROUGH NEUROFEEDBACK TRAINING - LONG LASTING EFFECTS ON PAIN CONTROL

Victoria L. Ibric. Therapy & Prevention Center, Pasadena / UCLA Pain Medicine Center, Los Angeles, CA USA Aim of the Investigation: Follow up studies to determine the efficacy and the long lasting effects of neuro feedback training in patients with different chronic pain syndromes.

Methods: A standard evaluation procedure has been done pre training and post 20 consecutive sessions, as well as after 1 - 2 years post interruption of the training. The evaluation consisted of a Psychophysiological Profile (PPP), an electromyography (EMG) over the affected muscle groups, performed on Biocomp, and an electroencephalography (EEC) over the sensory motor area of the brain performed on Neurocybernetics. The neurofeedback training had been designed according to the peripheral localization of the chronic pain, and varied numbers of 45 minutes sessions had been done.

Results: Two of the 115 chronic pain patients, who had been referred for biofeedback by physicians at UCLA Pain Medicine Center, are presented in this poster. First is a case of Myofascial Pain Syndrome/ RSD, post spinal cord injury, and bruxism, and second is a case of Chronic Low Back and Knee Pain, associated to Parkinson's Disease. These two patients had been treated for 50 and 65 neurofeedback sessions, respectively. The symptoms presented at the intake had been gradually resolved, and had not returned after 1 or 2 years post interruption of the training. The brain waves modifications had also been consistently noticed, and maintained. Medications had been reduced or eliminated completely.

Conclusions: The effectiveness and the long lasting effects of the neurofeeback therapy are based on the neuromodulation of the pain perception, and by modifying the electrical activity of the brain accordingly, through operant conditioning.

PERCUTANEOUS ELECTRICAL NERVE STIMULATION (PENS): AN ALTERNATIVE TO ANALGESIC DRUGS FOR THE MANAGEMENT OF HEADACHE.

HE Ahmed. PF White, MA Hamza, EA Ghoname, WF Craig, (SPON: NM Gajraj) Eugene McDermott Center for Pain Management, Dept ofAnesthesiology and Pain Management, UT Southwestern Medical Center at Dallas

Aim: To evaluate the efficacy ofelectroanalgesia involving percutaneous electrical nerve stimulation (PENS) for the management of patients with three common types of headaches.

Methods: Thirty patients with tension-type, migraine or post-traumatic headache were treated with PENS at 3 different frequencies (4 Hz, alternating 15/30 Hz and 100 Hz) and sham (needles only) according to a randomized, cross-over study design. Acupuncture-like needles were placed into the soft tissue of the back of the neck and scalp in a standardized montage corresponding to dermatomal levels C 1 -T4 and connected to a low-output electrical generator. No electrical stimulation was applied to the needles during the sham treatments. Patient assessments included visual analog scales (VAS) for pain, physical activity, and quality of sleep scores (with 0=best to 10=worst). Assessments were made 24 hr before initiating the PENS or sham treatments (baseline), immediately before and after each treatment session and then 48 hr after finishing each treatment modality.

Results: Compared with the sham treatments, all three frequencies of PENS therapy were significantly more effective in decreasing pain scores (52-59% for PENS ys_l 5-21% for sham), as well as in improving the patients' activity (41-58% for PENS v.s_l 1%-21% for sham) and sleep (41-48 % for PENS ys-12-20%). There were no statistical differences in the response to PENS therapy at stimulation frequencies of 4, 15/30 or 100 Hz. Finally, the three different types of headaches also demonstrated similar responses to PENS therapy.

Conclusion: PENS appears to be a valuable "alternative therapy" for the management of patients with headache.

USE OF PERCUTANEOUS ELECTRICAL NERVE STIMULATION FOR CHRONIC NECK PAIN: EFFECT OF LOCATION OF STIMULATION.

EA Ghoname*, PF White*, HE Ahmed*, MA Hamza*, WF. Craig*, (SPON: AS Vakharia), Eugene McDermott Center for Pain Management, Dept ofAnesthesiology & Pain Management, UT Southwestern Medical Center at Dallas Aim: To evaluate the effectiveness of percutaneous electrical nerve stimulation (PENS) when applied at the dermatomes corresponding to the patient's pathology yersus.non-related dermatomes in patients with chronic neck pain secondary to degenerative disc disease.

Methods: Sixty-eight patients received PENS treatments at involved or non-related dermatomes [or sham (needles only)] in a random, cross-over sequence. All treatments were administered for 30 min (at a frequency of 15/30 Hz) 3 times per week for 3 weeks (with 1 week "off between each treatment modality). The pre-study assessments included visual analog scale (VAS) scores for pain, physical activity and quality of sleep, as well as the daily analgesic requirements.

Results: Compared to the non-related dermatomal stimulation, dermatomal stimulation produced significantly greater decreases in the degree of pain (38±17% vs 13±18%), increased physical activity, (41±21% YS_16±15%), and improved quality of sleep (34±18% YS_10±18%) compared to baseline values (p< 0.05). The need for analgesic medications was decreased by 37% and 9% over the 3-week treatment period with dermatomal and non-related dermatomal stimulation, respectively. The clinical effects of non-related dermatomal stimulation on the patient's pain relief, physical activity and quality of sleep did not differ from the placebo ("sham") effect.

Conclusion: This study suggests that electrical stimulation at the dermatomal levels corresponding to the local pathology was more effective than stimulation at remote (non-related) dermatomes in the relief of chronic neck pain. We conclude that alterations on neuromodulation is more important than central release of analgesic-like substances for producing PENS-induced analgesia.

EFFECT OF PERCUTANEOUS ELECTRICAL NERVE STIMULATION ON DIABETIC NEUROPATHIC PAIN: A SHAM-CONTROLLED, CROSSOVER STUDY.

MA Hamza*. PF White*, WF Craig*, (Spon: CE Noe), EA Ghoname*, HE Ahmed*, Eugene McDermott Center of Pain Management, Dept ofAnesthesiology and Pain Management, UT Southwestern Medical Center at Dallas, USA.

Aim: To evaluate the efficacy of percutaneous electrical nerve stimulation (PENS) for improving pain, activity and sleep scores and decreasing the need for analgesic medication in patients with diabetic peripheral neuropathy.

Methods: Fifty adult diabetic patients with peripheral neuropathic pain of more than 6 months duration involving the lower extremities received active (needles with electrical stimulation at an alternating frequency of 15/30 Hz) and sham (needles only) treatments in a random sequence for 30 minutes three times per week for three weeks according to a standardized treatment protocol. A 10-cm visual analog scale (VAS) was used to assess pain, physical activity and quality of sleep (0 = best to 10 = worst) before each treatment session. The changes in VAS scores and requirements for analgesic medication were determined over each 3-week treatment block.

Results: Compared to pain VAS scores prior to active (5.8±1.4) and sham (5.5±1.3) treatments, pain scores were reduced to 2.6±0.8 and 5.0±1.0, respectively. With active PENS treatments, the VAS for activity and sleep scores were significantly improved from 4.9±1.2 and 3.8±1.3 to 2.2±1.3 and 1.5±1.2, respectively. The VAS scores for pain, activity and sleep were unchanged from baseline values with the sham treatments. The daily oral nonopioid analgesic requirements were decreased by 48% and 14%, after active and sham treatments, respectively.

Conclusion: In patients with diabetic peripheral neuropathy, active PENS treatments decreased extremity pain, improved physical activity and quality of sleep compared to sham treatments.

9th WORLD CONGRESS ON PAIN, 1999, Vienna, Austria, p.79 - 83