Pain is a major complaint of patients with chronic cervical disorders (1,2). There are various treatment options, including conventional pharmacological and invasive pain therapy, physiotherapy, transcutaneous nerve stimulation, and manual treatment, as well as complementary approaches (3). Among them, acupuncture is widely available in Western chronic pain clinics (4). This traditional Chinese medicine technique dates back at least 2500 yr. The traditional theory of acupuncture is based on the concept that an imbalance of the energy flow, “Qi,” through the body in hypothesized channels called “meridians” can be corrected by manipulation of identifiable points close to the skin. In addition to the designated acupuncture points located on the “meridians,” Nogier (5) described acupuncture points on the ear. Auricular acupuncture correlates a somatotopic map on the ear with other anatomical regions (5–7). The mechanism of acupuncture analgesia remains in question, but biological responses, such as the stimulation of A-δ fibers and activation of endorphins and monoamines by the stimulating “De qi” sensation, as well as psychological aspects, seem to be involved (8–11). The stimulation of acupuncture points can be achieved by either a mechanical action of needling or electrical point stimulation.
Among nonpharmacological treatment options, acupuncture has been found to be more effective than physiotherapy (12), transcutaneous nerve stimulation therapy (13), and massage (14,15) in chronic cervical pain patients. The cumulative evidence suggests that acupuncture represents a therapeutically beneficial and cost-effective treatment option in chronic cervical pain patients (9,16). This study was performed to test the hypothesis that continuous electrical stimulation of auricular acupuncture points is more effective than conventional manual auricular acupuncture in outpatients at home.
After we obtained approval from the local Ethics Committee at the University of Vienna and written, informed consent, 23 otherwise healthy adult patients with chronic cervical pain without radicular symptoms were investigated in a double-blinded, prospective, randomized study. Inclusion criteria were cervical pain with a duration of at least 6 mo, normal neurologic function of cervical nerves as confirmed by a neurologist, and no pain radiation. Pain arose from cervical spondylosis without nerve root impingement (confirmed by magnetic resonance imaging (MRI) and neurological examination), from pathologic structures due to osteoporosis and osteoarthrosis of the intervertebral joints (radiograph and/or MRI), or from soft tissue with no evidence of skeletal or neural pathology and normal spinal structures.
Exclusion criteria were allergy to lornoxicam or tramadol, history of drug abuse, pregnancy, concomitant use of transcutaneous nerve stimulation or pacemaker, and history of acupuncture treatment.
After an initial physical and neurological examination and cessation of their previous analgesics, patients received oral pharmacotherapy with 8 mg of lornoxicam twice daily and rescue medication with up to 8 × 50 mg of tramadol daily. After 1 wk, the participants were reevaluated and asked to rate their pain intensity on a visual analog scale (VAS; 0 = no pain and 10 = worst pain imaginable). Patients were eligible for the next step in the study if, despite medication, their persisting pain intensity was at least 5 on the VAS.
All patients received Titan disposable acupuncture stimulation needles (27 gauge, 3-mm length; Fa. Biegler GmbH, Mauerbach, Austria), which were inserted on the dominant side. Standard references were consulted when choosing the following acupuncture points: cervical spine (37) shen men (55), and cushion (29, 19). These precise points were confirmed by determining the position of the least skin resistance by using electrical conductance meters (Multipoint Selection Pen™; Fa. Biegler GmbH). Needles were connected to the electrical point stimulation device P-STIM™ (Fa. Biegler GmbH, Mauerbach, Austria). This recently designed device consists of a rechargeable battery-powered stimulator (Fig. 1) that is positioned behind the ear of the patient like a hearing aid. The P-STIM™ model used in this study has a length of 49 mm, a height of 28 mm, and a weight of 11 g. The stimulator consists of a microcontroller and a bit-coded RS232 interface that produce appropriate wave forms of electrical stimuli. The constant current source guarantees equivalent stimulation energy regardless of the individual impedance of the patient’s skin.
Patients were randomized into two groups by using computer-generated random tables. In 10 patients, needles were continuously stimulated with 2 mA of constant current at a low frequency of 1 Hz for 48 h. In 11 control patients, no electrical stimulation was administered. Patients and the investigator were blinded to the treatment allocated by randomization, and the P-STIM™ device was programmed by an independent technician.
All needles were withdrawn 48 h after insertion. Acupuncture was performed once a week for 6 wk. A follow-up investigation was performed 4 wk after the last acupuncture analgesia. During the whole study period, patients had to complete a questionnaire assessing pain severity, psychological well-being, activity, sleep, and demand for rescue medication. Pain severity was scored with the VAS (0 = no pain and 10 = maximum pain). Similarly, psychological well-being, activity, and sleep were scored by the study patients by using a scale ranging from 0 (no impairment) to 10 (worst deterioration imaginable) (17). All patients received physiotherapy during the whole study period. The patients’ overall satisfaction with the acupuncture treatment was documented at the end of the study period.
Analysis of covariance for repeated measures was used to assess differences between the two groups, taking into account the baseline values of age, sex, and body mass index as covariates. Post hoc group comparisons at each week were corrected by the Bonferroni-Holm method. P values <0.05 were considered statistically significant. Data are presented as mean ± sd or by frequencies, where appropriate.
Twenty-three patients were enrolled in the study. Two patients were excluded: one control patient dropped out in the second week because of failed pain reduction, and one patient receiving electrical auricular acupuncture dropped out in the second week because of a local skin inflammation. Accordingly, 21 patients (15 women and 6 men) were analyzed. There were no significant differences in age (52 ± 12 yr versus 52 ± 9 yr), weight (68 ± 13 kg versus 76 ± 5 kg), or height (170 ± 6 cm versus 174 ± 8 cm) between the control group and the electrical acupuncture group, respectively.
There were no differences in pain duration or treatment between the two groups. Of the 21 included patients, 12 had common cervical pain, presumably of muscular origin, whereas 9 had additional severe structural changes observed on radiograph and MRI of the spine, including spondylarthrosis and localized protrusion of a disk. The mean duration of pain was 3.3 ± 1.2 yr, and most patients had experienced various treatment modalities before entering this study, including analgesic drugs, trigger point infiltrations, transcutaneous nerve stimulation, and passive physiotherapy, including massage, warmth, and galvanization. Pretreatment analgesic medication (nonsteroidal antiinflammatory drugs; NSAIDs) was the same in both groups.
The reduction in VAS pain scores was significantly larger in the electrical acupuncture group than in the conventional manual acupuncture group (Fig. 2A). No sex differences were found. Similarly, psychological well-being, activity, and sleep were significantly improved in patients receiving electrical point stimulation (Fig. 2B–D). The consumption of rescue medication was significantly more in the control group compared with the electrical acupuncture group (107 ± 5 tablets versus 47 ± 8 tablets needed during the whole investigation period).
No adverse effects of acupuncture (such as needle-induced hypotension or hematoma) were observed. Whereas, not surprisingly, all patients in the electrical auricular acupuncture group correctly identified electrical stimulation, 10 (90%) patients in the control group also believed they were receiving electrical stimulation. Nine (90%) patients in the electrical auricular acupuncture group were satisfied and would repeat the treatment if necessary, and only one (10%) patient found the P-STIM™ design unpleasant and declined possible future treatment. All patients in the control group rejected further acupuncture treatment because of insufficient benefit, not because of discomfort. The comfort of wearing the P-STIM™ device was described as suitable by 65% of the patients and as sufficient by 35%.
We found that chronic cervical pain patients treated with adjunctive auricular electroacupuncture during oral analgesic therapy with an NSAID and the weak opioid tramadol experienced a significant improvement in pain intensity, mobility, psychological well-being, and sleep (see Fig. 2). This finding is contradictory to some studies (16,18) but confirms numerous other trials that have found a beneficial effect of acupuncture (9,19–21).
As summarized in Figure 2, electrical stimulation of auricular acupuncture points by using the new electrical low-frequency stimulation device P-STIM™ further improved pain management in chronic cervical pain patients. Similarly, the analgesic effect of transcutaneous electrical stimulation of an auricular acupuncture point has recently been reported in acute pain patients (19). The mechanism of electrical auricular acupuncture analgesia is suggested to be mediated at least in part by the activation of descending inhibitory pain control systems (10,22), activation of the propriospinal heterosegmental antinociceptive system leading to the depression of long-lasting pain-induced changes of signal transduction in the spinal cord (11), and the release of endogenous opioid peptides (23). The specific electrical stimulation pattern influences the analgesic effects (24,25). Both low-frequency and high-frequency stimulation have been found to induce analgesia, but different types of endorphins are released (23,25,26). In this study, we used a preliminary model of the electrical stimulator device P-STIM™, which provided a monophasic 1-Hz stimulation. This preliminary model had to be worn like a hearing aid fixed with tape to guarantee the exact position throughout the stimulation period; despite some inconvenience, the possibility of continuous ambulatory treatment was very well received by the patients. In the meantime, a more comfortable, self-attaching design has become available. Another advantage of the second-generation P-STIM™ is the production of a biphasic low-frequency current, which avoids polarization effects.
The use of electrical auricular acupuncture is safe (25,27). Contraindications against the use of an electrical stimulator device include the concomitant use of transcutaneous electrical nerve stimulation and a pacemaker.
Difficulty with blinding is one of the major problems for adequate validation of the effectiveness of acupuncture (16). Electrical stimulation of the auricular acupuncture points permitted a fully double-blinded study protocol in this study: the stimulator was activated or not by an investigator who was not otherwise involved in the study. The results show that patients of both groups (100% electrical acupuncture versus 90% control) believed they were receiving electrical stimulation, which proves that patient blinding was effective. One limitation of this study design is that the outcome variables are subjective. Another limitation is the lack of a placebo group, and therefore the data presented cannot refute the hypothesis that all the benefits from both treatments are due to nonspecific effects of participation in the study, contact with the pain therapist, or patient expectation.
Chronic cervical pain is a common cause of suffering, disability, and consumption of medical health costs and social service utilization. Both manual and electrical acupuncture are inexpensive treatments with potential savings in analgetic drug costs. Our results clearly demonstrate the benefit of electroanalgesia, as previously documented. However—and this is the novelty—for the first time, a continuous stimulation in an outpatient setting with all the advantages of home-based therapy has been studied. Pain relief was significant, as was patient satisfaction. Furthermore, the need for analgesic drugs was considerably reduced in patients in the electrical acupuncture group, decreasing the risk of common drug-induced adverse effects of NSAIDs and opioids, such as gastrointestinal bleeding, nausea, vomiting, obstipation, and dizziness (28,29), which often lead to therapy cessation. For all these reasons, we believe that substantial savings in medical health care can be made through the adjuvant use of electroacupuncture.
Both options are demonstrably safe. According to these results, we recommend electrical stimulator acupuncture as an adjunct therapy in chronic cervical pain patients. Cumulative analgetic effects may be achieved by longer electrical stimulation periods (24). Further studies have to determine whether a stimulation period exceeding two days further improves treatment of chronic cervical pain.
The authors thank Sonja Dolezal, MD, for her support in the initial phase of this study.
1. Bland J. Disorders of the cervical spine. Philadelphia: Saunders, 1987.
2. Bovim G, Schrader H, Sand T. Neck pain in the general population. Spine 1994; 19: 1307–9.
3. Zenz M, Jurna I. Lehrbuch der Schmerztherapie [Textbook of pain]. 2nd ed. Stuttgart: Wissenschaftliche Verlagsgesellschaft, 2001.
4. Eisenberg DM, Davis RB, Ettner SL, et al. Trends in alternative medicine use in the United States, 1990–1997: results of a follow-up national survey. JAMA 1998; 18: 1569–75.
5. Nogier P. Points reflexes auriculares. Moulins-les-Metz, France: Maisonneuve, 1987.
6. Oleson T, Kroening RA. A comparison of Chinese and Nogier acupuncture points. Am J Acupunct 1983; 11: 205–23.
7. Olseon T. Auriculotherapy manual: Chinese and Western system of ear acupuncture. 2nd ed. Los Angeles: Health Care Alternatives, 1996.
8. Ezzo J, Berman B, Hadhazy VA, et al. Is acupuncture effective for the treatment of chronic pain? A systemic review. Pain 2000; 86: 217–25.
9. Lee TL. Role of acupuncture in chronic pain. J Anaesth Clin Pharmacol 1999; 15: 536–7.
10. Willer JC, Roby A, Le Bars D. Psychophysical and electrophysiological approaches to the pain-relieving effects of heterotopic nociceptive stimuli. Brain 1984; 4: 1095–112.
11. Sandkühler J. The organization and function of endogenous antinociceptive systems. Prog Neurobiol 1996; 1: 49–81.
12. David J, Modi S, Aluko AA, et al. Chronic neck pain: a comparison of acupuncture treatment and physiotherapy. Br J Rheumatol 1998; 10: 1118–22.
13. Petrie JP, Hazleman BL. A controlled study of acupuncture in neck pain. Br J Rheumatol 1986; 25: 271–5.
14. Irnich D, Behrens N, Gleditsch JM et al. Immediate effects of dry needling and acupuncture at distant points in chronic neck pain: results of a randomized, double-blind, sham-controlled crossover trial. Pain 2002; 99: 83–9.
15. Irnich D, Behrens N, Molzen H, et al. Randomised trial of acupuncture compared with conventional massage and ‘sham’ laser acupuncture for treatment of chronic neck pain. BMJ 2001; 322: 1574–7.
16. Smith LA, Oldman AD, McQuay HJ, Moore RA. Teasing apart quality and validity in systematic reviews: an example from acupuncture trials in chronic neck and back pain. Pain 2000; 86: 119–32.
17. Ghoname ESA, Craig WF, White PF, et al. Percutaneous electrical nerve stimulation for low back pain: a randomized crossover study. JAMA 1999; 281: 818–23.
18. White AR, Ernst E. A systematic review of randomized controlled trials of acupuncture for neck pain. Rheumatology 1999; 38: 143–7.
19. Greif R, Laciny S, Mokhtarani M, et al. Transcutaneous electrical stimulation of an auricular acupuncture point decreases anesthetic requirement. Anesthesiology 2002; 96: 306–12.
20. Ghoname ESA, Craig WF, White PF, et al. The effect of stimulus frequency on the analgesic response to percutaneous electrical nerve stimulation in patients with chronic low back pain. Anesth Analg 1999; 88: 841–6.
21. Hamaza MA, Ghomame ESA, White PF, et al. Effect of the duration of electrical stimulation on the analgesic response in patients with low back pain. Anesthesiology 1999; 91: 1622–7.
22. Anderson SA, Ericson T, Holmgren E, Hachisu M. Electroacupuncture: effect on pain threshold measured with electrical stimulation of teeth. Brain 1973; 63: 393–6.
23. Mayer DJ. Biological mechanisms of acupuncture. Prog Brain Res 2000; 122: 457–77.
24. Pomeraz B, Worma N. Electroacupuncture suppression of a nociceptive reflex is potentiated by two repeated electroacupuncture treatments: the first opioid effect potentiates a second non-opioid effect. Brain Res 1988; 452: 232–6.
25. White PF, Li S, Chiu JW. Electroanalgesia: its role in acute and chronic pain management. Anesth Analg 2001; 92: 505–13.
26. White PF, Craig WF, Vakharia AS, et al. Percutaneous neuromodulation therapy: does the location of electrical stimulation effect the acute analgesic response? Anesth Analg 2000; 91: 949–54.
27. Ulett GA, Han S, Han JS. Electroacupuncture: mechanisms and clinical application. Biol Psychiatry 1998; 44: 129–38.
28. Chapman SL, Byas-Smith MG, Reed BA. Effects of intermediate- and long-term use of opioids on cognition in patients with chronic pain. Clin J Pain 2003; 18: 83–90.
29. Pietzsch M, Theuer S, Haase G, et al. Results of systematic screening for serious gastrointestinal bleeding associated with NSAIDs in Rostock hospitals. Int J Clin Pharmacol Ther 2002; 40: 111–5.