Can e-stim actually work for chronic pain conditions with a non-musculoskeletal cause?

Although Transcutaneous Electrical Nerve Stimulation (TENS) has been used as an analgesic of acute pain for many years, its use for chronic pain, especially of a non-musculoskeletal nature, has been sparing and unfortunately there remains limited evidence to support the effectiveness of TENS to mitigate chronic non-musculoskeletal pain.

Fibromyalgia (FM) is one such non-musculoskeletal condition. Patients with FM experience global, migrating chronic pain that is thought to be caused by alterations in the central nervous system or peripheral mechanisms. Changes to these mechanisms can results in abnormal pain processing, with lowered mechanical and thermal pain thresholds and altered temporal summation of pain stimuli .TENS aims to alleviate the FM symptoms of  pain and as such assist patients to develop long term management strategies. Current studies predicate the pain relief from TENS may only be of a temporary nature. For this reason self-administration devices have become common use with patients using the machines at home on a discretionary basis when pain presents.

A dichotomy exists between the ambiguity revolving around the effectiveness of TENS for pain relief of chronic conditions, and the fact TENS is considered to be the “gold standard” from a therapeutic view point. TENS can be used at varying frequencies, but the most common treatment for chronic pain interventions include, (i) a steady high frequency between 50 and 120 Hz, or (ii) bursts of a high frequency delivered at a low frequency between 1 and 4 Hz.

TENS has shown to be effective to reduce pain in FM patients, however the duration of pain relief is only maintained in the short term. FM patients can accomplish both a similar analgesic effect and pain relief duration with other means of treatment including, superficial warmth devices and sham TENS, when using comparable treatment times. Studies have shown there is a non-significant difference between TENS and sham TENS to reduce chronic pain symptoms, suggesting a placebo effect can be achieved and sustained for a similar pain relief period. TENS, sham TENS and superficial warmth are all appropriate e-stim methods that can significantly reduce chronic pain in FM patients compared to their base-line values. These e-stim modalities are self-administered, inexpensive and can be safely combined with other FM treatment options.




References

Arendt-Nielsen L, Graven-Nielsen T. Central sensitization in fibromyalgia and other musculoskeletal disorders. Curr Pain Headache Rep 2003; 7: 355–361.

Elvin A, Siosteen AK, Nilsson A, Kosek E. Decreased muscle blood flow in fibromyalgia patients during standardised muscle exercise: a contrast media enhanced colour Doppler study. Eur J Pain 2006; 10: 137–144.

Kosek E, Ekholm J. Modulation of pressure pain thresholds during and following isometric contraction. Pain 1995; 61: 481–486.

Staud R, Cannon RC, Mauderli AP, Robinson ME, Price DD, Vierck CJ, Jr. Temporal summation of pain from mechanical stimulation of muscle tissue in normal controls and subjects with fibromyalgia syndrome. Pain 2003; 102: 87–95.

Pain relief in women with fibromyalgia: a cross-over study of superficial warmth stimulation and transcutaneous electrical nerve stimulation. Monika Löfgren and Cecilia Norrbrink.