What is the Evidence that Neuropathic Pain is Present in Chronic Low Back Pain and Soft Tissue Syndromes? An Evidence-Based Structured Review, Pain Medicine Vol 15, No 1, 2014, pp 4 – 15, Fishbain et al.
This study from Fishbain and colleagues out of Florida reviewed eleven papers that had addressed the diagnosis of neuropathic pain in chronic low back pain, and five papers that addressed neuropathic pain in soft tissue syndromes. The aggregated prevalence for neuropathic pain was 37% in low back pain and 41% in soft tissue syndrome, i.e. approximately 40% overall. The prevalence varied using different methods from 17% to 54% for low back pain and 13% to 43% for soft tissue syndromes.
Comment: Although much can be debated here, it’s clear that a significant proportion, perhaps a third or more, of two common conditions have an underlying component of neuropathic pain attached. This is likely to be the case with patients presenting to Pain Clinics, perhaps less so in patients presenting to primary care practice. It certainly explains the lack of response to opioids in these two common conditions based on poor response to opioids in neuropathic pain.
A Pilot Trial of Intravenous Pamidronate for Chronic Low Back Pain, Pain Vol 155, No 1, 2014, pp 108 – 117, Pappagallo et al.
This study was conducted at a number of centres in New York. This was a randomised placebo controlled study of 44 patients suffering axial low back pain for at least three months who had MRI evidence of degenerative disc disease or lumbar spondylosis and a pain score of at least 4/10. Sixteen patients received placebo and four groups each with seven patients received 30, 60, 90 or 180mg of Pamidronate (the 180mg was as two 90mg infusions separated by four weeks). There was a significant reduction in pain in the 180mg group at six months. The mean reduction in pain was 4.1 units on a numerical rating scale 0 – 10. On the responder analysis, 100% of patients in the 180mg group had a minimum of 70% reduction in pain, and of that group, in fact, 80% of them had 100% reduction in pain.
Comment: By any classification, these are remarkable results. If replicated, they are likely to lead to watershed change in how chronic low back pain is managed. Two of the authors are employees of a large pharmaceutical company and the lead author has a patent for treating chronic spinal mechanical pain by intravenous administration of Biphosphonate. At this stage, I believe replication of these results by external independent research groups is warranted before wholesale change in clinical practice is implemented. Many pain physicians have treated numerous patients with Biphosphonate therapy or 180mg of Pamidronate and anecdotally have not noticed significant improvements in low back pain.
New Daily Persistent Headache and Potential New Therapeutic Agents, Current Neurological and Neuroscience Reports, 2014, Vol 14, No 2, pp 425 – 431, Joshi et al.
This paper is a summary of different treatments that have been reported in case series to have had an effect in the refractory condition of new daily persistent headache. They have collated positive results for Topiramate, Gabapentin, Doxycyclin and daily Naratriptan use (2.5mg bd).
Comment: Whilst these findings can only lead to conjecture and hypothesis for further research, it does allow sequential trialling of possible agents for this group of patients. To date, no therapy has been found effective for this condition, although anecdotally, occipital nerve stimulation may appear to have some significant role to play as an effective treatment option.
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