Recent analysis of the effect that treatment parameters of TENS have on pain relief clearly demonstrates that it is possible to optimize those parameters to achieve more pain relief. The importance of treatment amplitude, pulse frequency and treatment location have all been shown in recent literature and even in articles dated as far back as 1975 (Melzack et al) .

Based upon my experience of the benefit of InterX therapy and the successful treatment of very difficult conditions including CRPS, Allodynia, Phantom Pain and others , I suggest that the technology of TENS which has barely evolved in the last 30 yrs limits the ability of a therapist to optimize treatment parameters for the effective relief of pain from CRPS. The protocols used with InterX dictate both an extra segmental and segmental approach for the treatment of CRPS. This includes contralateral treatment, treatment of the whole spine and the face and scalp. The crucial technological aspect of InterX is that it allows the identification of optimal treatment points within chosen treatment areas while also delivering a significant dose of stimulation (typically 45mA). The identification of treatment points is based upon patients’ physiological response (increased sympathetic skin response) , and not arbitrary or anatomical points. The dose is an important factor and the InterX amplitude is approximately three times higher than Bjordal et al considered high amplitude and thus important for the success of a treatment.

If this scientific application of a modality excludes InterX from the classification of TENS then so be it, but it does not fall into the category of electroacupuncture either as points of low impedance are not always acupuncture points. As such InterX (Interactive Neurostimulation) may be considered in any of the above categories or in one of its own as a scientific delivery of high amplitude stimulation to points relating to a patients sympathetic nerve activity. Either way, it should be noted that even if “TENS” is not indicated for the treatment of CRPS, it does not mean that TENS-like technologies when scientifically and correctly applied cannot offer sufferers of CRPS significant relief of their pain. This relief can bring them back into functional rehabilitation and ultimately to achieve long term relief with the aid of an integrated approach. With spinal cord stimulation considered the next best option, surely a non-invasive, evidence based approach to transcutaneous neurostimulation should be offered first.

Check out this review: http://mrw.interscience.wiley.com/cochrane/clsysrev/articles/CD004598/frame.html
This is what the New Zealand Accident Compensation Corporation
says:
“One guideline, three systematic reviews and one experimental study provided information on the effectiveness of sympathetic ganglion nerve block for complex regional pain syndrome (CRPS).

One high quality systematic review was identified evaluating the use of stellate and lumbar sympathetic ganglion blocks (Cepeda, 2002). It included 29 studies, three of which were randomised controlled trials. The majority of case series were retrospective and included small numbers of participants. The review included a meta-analysis of pain outcomes pooled from a sub-group of 14 studies in which the magnitude of treatment effects was quantified. Less than one third of people with CRPS (29%) obtained pain relief by three quarters of pre-treatment levels. The authors noted that the rate of success may be acceptable to many patients and practitioners but was consistent with a placebo response. Two other systematic reviews concluded that the limited amount and quality of the available evidence did not allow definite conclusions on the treatment’s effectiveness (Forounzanfar, 2002; Kingery, 1997). The guideline (Sanders, 1999) concluded that nerve blocking procedures should be limited to those patients in whom functional capacity can also be improved.

One randomised controlled trial was identified which was not included in the above Cepeda review (Tran, 2000). Seventeen people with CPRS I or II received a lumbar sympathetic nerve block using bupivacaine with iohexol (a contrast dye) or one using bupivacaine with saline. Both types of blocks resulted in significant pain relief from baseline to 1 hour post-block, and for six (iohexol / bupivacaine group) or three (saline / bupivacaine group) days afterwards.”