A systematic review published in the Journal of Pain points to a dearth of evidence regarding the neuropathic etiology of low back-related leg pain (LBLP).1
Neuropathic pain appears in 6.9% to 10% in the general population, most of it related to back pain.2 However, in patients presenting with LBLP, neuropathic pain co-occurs in 19% to 80% of patients.1 Researchers in the United Kingdom sought to characterize the prevalence, characteristics, and prognosis of LBLP in patients with neuropathic pain in primary care settings, where most patients receive their initial assessment.3
Of the 24,948 citations searched for this systematic review, a total of 12 studies (n=3457 patients; median sample size, 74 patients) were included. Two quality assessment tools were used to select studies: 1 for the evidence of prevalence of neuropathic pain in LBLP, and the other for the evidence on characteristics and prognosis. Seven of the 12 studies (n=715 patients) yielded data on prevalence estimates for the presence of neuropathic pain in patients with LBLP, which tended to be higher in patients with sciatica. Three of the studies estimated possible neuropathic pain in patients with LBLP from 19% to 43% for acute and subacute sciatica and 46% for chronic sciatica.
Patients with LBLP and neuropathic pain had worse outcomes; specifically, more pain intensity, depression, anxiety, and disability. Four of the studies described pain below the knee as a common symptom for patients with LBLP and neuropathic pain.
Overall, patients with neuropathic pain and concomitant LBLP reported lower health-related quality of life, as measured with self-reported rating scales. The domains of physical function, physical role, emotional role, social function, mental health, energy/vitality, and pain were all significantly worse in patients with neuropathic pain than in those without (P <.001).
Analgesic medication use was higher in patients with neuropathic pain, particularly with opioids, than in patients without neuropathic pain. However, patients with and without neuropathic pain used the same amount of nonsteroidal anti-inflammatory drugs.
Ten of the 12 studies provided characteristics of LBLP, yet only 2 of the studies provided longitudinal data, 1 of which could be mined for prognosis data. In the study that included patients with both neuropathic and nonneuropathic pain, patients who reported the highest improvement had peripheral nerve sensitization, and those with the least improvement had neuropathic sensitization.
Summary and Clinical Applicability
This study, which was the first to review the evidence on the prevalence, characteristics, and prognosis of patients with LBLP with neuropathic pain, highlights how little is understood about the involvement of neuropathic pain in patients with LBLP. Further research is needed in primary care settings to guide clinicians’ prognosis.
- Because of the heterogeneity of the studies included in the report, it was not possible to present pooled data on prevalence and characteristics.
- The findings in this review may not be generalizable because of the primary care-only setting.
- Harrisson SA, Stynes S, Dunn KM, Foster NE, Konstantinou K. Neuropathic pain in low back-related leg pain patients: What is the evidence of prevalence, characteristics, and prognosis in primary care? A systematic review of the literature [published online June 14, 20167. J Pain. doi: 10.1016/j.jpain.2017.04.012
- VanDenKerkhof EG, Mann EG, Torrance N, Smith BH, Johnson A, Gilron I. An epidemiological study of neuropathic pain symptoms in Canadian adults. Pain Res Manag. 2016;2016:9815750. doi: 10.1155/2016/9815750
- Mills S, Torrance N, Smith BH. Identification and management of chronic pain in primary care: a review. Curr Psychiatry Rep. 2016;18(2):22. doi: 10.1007/s11920-015-0659-9