Transcutaneous electrical nerve stimulation for acute pain

[Therapeutic neuromodulation in primary headaches]

Neuromodulatory techniques have developed rapidly in the therapeutic management of refractory headaches. Invasive procedures comprise peripheral nerve stimulation (particularly occipital nerve stimulation), vagus nerve stimulation, cervical spinal cord stimulation and hypothalamic deep brain stimulation. Transcutaneous electrical nerve stimulation, repetitive transcranial magnetic stimulation and transcranial direct current stimulation are noninvasive variants. Based on current neuroimaging, neurophysiological and clinical studies occipital nerve stimulation and hypothalamic deep brain stimulation are recommended for patients with chronic cluster headache. Less convincing evidence can be found for their use in other refractory headaches such as chronic migraine. No clear recommendation can be given for the other neuromodulatory techniques. The emerging concept of intermittent stimulation of the sphenopalatine ganglion is nonetheless promising. Robust randomized and sham-controlled multicenter studies are needed before these therapeutic approaches are widely implemented. Due to the experimental nature all patients should be treated in clinical studies. It is essential to confirm the correct headache diagnosis and the refractory nature before an invasive approach is considered. Patients should generally be referred to specialized interdisciplinary outpatient departments which closely collaborate with neurosurgeons who are experienced in the implantation of neuromodulatory devices. It is crucial to ensure a competent postoperative follow-up with optimization of stimulation parameters and adjustment of medication.

Intravenous lidocaine reduces ischemic pain in healthy volunteers

BACKGROUND AND OBJECTIVES

Lidocaine, a local anesthetic and antiarrhythmic drug that alters depolarization in neurons by blocking the fast voltage-gated sodium (Na+) channels in the cell membrane, is used for regional anesthesia, as antiarrhythmic drug, and as analgesic for various painful conditions. It is unclear whether monotherapy with intravenous lidocaine has an analgesic effect in healthy individuals. To address this important question, we studied pain perception before, during, and after the administration of intravenous lidocaine in 16 human volunteers. Our hypothesis was that lidocaine, administered as a short intravenous infusion, does not have an analgesic effect in healthy volunteers.

METHODS

Sixteen healthy human volunteers received systemic lidocaine at plasma concentration 2 mg/mL using a computer-assisted infusion. Participants underwent a series of sensory tests-thermal, electrical, and ischemic pain and normal pinprick sensation-at baseline, during, and 30 mins after administration of a 20-min lidocaine infusion at a 2 mg/mL effect site concentration.

RESULTS

We found a sustained decrease in ischemic pain ratings and a limited analgesic effect for electrical pain, whereas thermal pain and normal sensation did not change.

CONCLUSIONS

The observed sustained analgesic effect of systemic lidocaine in the ischemic pain model suggests that lidocaine may be used to treat acute pain.

Pain relief by applying transcutaneous electrical nerve stimulation (TENS) during unsedated colonoscopy: a randomized double-blind placebo-controlled trial

Transcutaneous electrical nerve stimulation (TENS) is a noninvasive alternative to traditional pain treatments. TENS has been studied in the past as a pain reduction modality in colonoscopy with limited success. Reviews and meta-analysis have shown that the inconclusive results of TENS may be due to the lack of randomized controlled trials and the difficulty in defining precise output parameters. The objective of this double-blind randomized placebo-controlled trial was to investigate the pain-relieving effect of a new application of TENS in unsedated screening colonoscopy. Ninety patients undergoing unsedated screening colonoscopy were randomly allocated to one of three groups: a control group (n=30), a group to receive active TENS (n=30), or a group to receive placebo TENS (n=30). A visual analogue scale (VAS) and a five-point Likert scale were used to assess pain 5 min into the procedure and at the end of the procedure. The patient's bloating sensation during colonoscopy and the effect on the duration of the procedure were also evaluated. Throughout the procedure, the active TENS group experienced a VAS pain score reduction ≥50% compared to the placebo TENS group (P<0.001) and the control group (P<0.001). On the five-point Likert scale, there was also a significant reduction in pain score in the active TENS group compared to the placebo TENS and control groups (P=0.009). No significant differences were found between the study groups as to the bloating sensation and the duration of the procedure. We conclude that TENS can be used as a pain relief therapy in unsedated screening colonoscopy.

Transcutaneous electrical nerve stimulation (TENS) for phantom pain and stump pain following amputation in adults

BACKGROUND

Amputee pain may present in a body part that has been amputated (phantom pain) or at the site of amputation (stump pain), or both. Phantom pain and stump pain are complex and multidimensional and the underlying pathophysiology remains unclear. The mainstay treatments for phantom pain and stump pain are predominately pharmacological. The condition remains a severe burden for those who are affected by it. There is increasing acknowledgement of the need for non-drug interventions and Transcutaneous Electrical Nerve Stimulation (TENS) may have an important role to play. TENS has been recommended as a treatment option for phantom pain and stump pain. To date there has been no systematic review of available evidence and the effectiveness of TENS for phantom pain and stump pain is currently unknown.

OBJECTIVES

To assess the analgesic effectiveness of TENS for the treatment of phantom pain and stump pain following amputation in adults.

SEARCH STRATEGY

We searched MEDLINE, Cochrane Central Register of Controlled Trials (CENTRAL), EMBASE, PsycINFO, AMED, CINAHL, PEDRO and SPORTDiscus (February 2010).

SELECTION CRITERIA

Only randomised controlled trials (RCTs) investigating the use of TENS for the management of phantom pain and stump pain following an amputation in adults were included.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and extracted data. It was planned that where available and appropriate, data from outcome measures were to be pooled and presented as an overall estimate of the effectiveness of TENS.

MAIN RESULTS

No RCTs that examined the effectiveness of TENS for the treatment of phantom pain and stump pain in adults were identified by the searches.

AUTHORS' CONCLUSIONS

There were no RCTs on which to judge the effectiveness of TENS for the management of phantom pain and stump pain. The published literature on TENS for phantom pain and stump pain lacks the methodological rigour and robust reporting needed to confidently assess its effectiveness. Further RCT evidence is required before such a judgement can be made.

Feasibility study of Transcutaneous Electrical Nerve Stimulation (TENS) for cancer bone pain

This multicenter study assessed the feasibility of conducting a phase III trial of transcutaneous electrical nerve stimulation (TENS) in patients with cancer bone pain recruited from palliative care services. Eligible patients received active and placebo TENS for 1 hour at site of pain in a randomized crossover design; median interval between applications 3 days. Responses assessed at 30 and 60 minutes included numerical and verbal ratings of pain at rest and on movement, and pain relief. Recruitment, tolerability, adverse events, and effectiveness of blinding were also evaluated. Twenty-four patients were randomised and 19 completed both applications. The intervention was well tolerated. Five patients withdrew: 3 due to deteriorating performance status, and 2 due to increased pain (1 each following active and placebo TENS). Confidence interval estimation around the differences in outcomes between active and placebo TENS suggests that TENS has the potential to decrease pain on movement more than pain on rest. Nine patients did not consider that a placebo was used; the remaining 10 correctly identified placebo TENS. Feasibility studies are important in palliative care prior to undertaking clinical trials. Our findings suggest that further work is required on recruitment strategies and refining the control arm before evaluating TENS in cancer bone pain.

PERSPECTIVE

Cancer bone pain is common and severe, and partly mediated by hyperexcitability. Animal studies suggest that Transcutaneous Electrical Nerve Stimulation can reduce hyperalgesia. This study examined the feasibility of evaluating TENS in patients with cancer bone pain in order to optimize methods before a phase III trial.