Home Disentangling ‘sciatica’ to understand and characterise somatosensory profiles and potential pain mechanisms
Article Publicly Available

Disentangling ‘sciatica’ to understand and characterise somatosensory profiles and potential pain mechanisms

  • Brigitte Tampin EMAIL logo , Christopher Lind , Angela Jacques and Helen Slater
Published/Copyright: August 2, 2021
Download Article (PDF)
Become an author with De Gruyter Brill
Author Information Explore this Subject
Scandinavian Journal of Pain
From the journal Scandinavian Journal of Pain Volume 22 Issue 1

Abstract

Objectives

The study aimed to investigate if patients with lumbar radicular pain only and those with combined lumbar radicular pain + radiculopathy differ in their somatosensory profiles and pain experiences.

Methods

Quantitative sensory testing (QST) was performed in 26 patients (mean age 47 ± 10 years, 10 females) with unilateral leg pain in the L5 or S1 distribution in their main pain area (MPA) and contralateral mirror side, in the relevant foot dermatome on the symptomatic side and in the hand dorsum. Pain experience was captured on the painDETECT.

Results

Eight patients presented with lumbar radicular pain only and 18 patients with combined radicular pain + radiculopathy. Patients with radicular pain only demonstrated widespread loss of function (mechanical detection) bilaterally in the MPA (p<0.003) and hand (p=0.002), increased heat sensitivity in both legs (p<0.019) and cold/heat sensitivity in the hand (p<0.024). QST measurements in the dermatome did not differ compared to HCs and patients with radiculopathy. Patients with lumbar radiculopathy were characterised by a localised loss of function in the symptomatic leg in the MPA (warm, mechanical, vibration detection, mechanical pain threshold, mechanical pain sensitivity p<0.031) and dermatome (mechanical, vibration detection p<0.001), consistent with a nerve root lesion. Pain descriptors did not differ between the two groups with the exception of numbness (p<0.001). Patients with radicular pain did not report symptoms of numbness, while 78% of patients with radiculopathy did.

Conclusions

Distinct differences in somatosensory profiles and pain experiences were demonstrated for each patient group, suggesting differing underlying pain mechanisms.

Keywords: radicular pain; radiculopathy; quantitative sensory testing; sciatica; sensory profiles

Introduction

The prevalence of ‘sciatica’, commonly referred to as pain radiating from the lower back into the leg, varies significantly between studies and is estimated to range between 1.6 and 43%, depending on the time points used (lifetime/period/point prevalence) and investigated populations (general population, specific occupations) [1] with up to 30% of patients having pain and disability for one year or longer [2, 3]. Evidence for the benefit of conservative management is inconclusive, with some cohorts reportedly responding to treatment, and not others [4], [5], [6], [7], [8], [9]. Understanding clinical care pathways and treatment outcomes is muddied, with a number of challenges to interpretation of condition and appropriate care. These challenges include:

  1. Heterogeneity of patients diagnosed with ‘sciatica’, and subgroups with differing somatosensory profiles [10, 11].

  2. The case definition of ‘sciatica’ varies significantly between studies [12].

  3. A lack of consistent operational definition with the application of standardised classification criteria for diagnosing ‘sciatica’.

  4. The terms radicular pain and radiculopathy are commonly used interchangeably [6, 7, 13], even though they have been proposed as discrete conditions [14]. Radiculopathy is defined as a neurological condition characterized by a nerve conduction block, clinically manifesting with objective neurological deficits [14]. Radicular pain is defined as pain generated by ectopic firing from nerve roots and their ganglia [14], is not necessarily accompanied by signs of a nerve root lesion (i.e. radiculopathy) [14], [15], [16], [17].

  5. In terms of pain types, radicular pain would be classified as nociceptive pain [15] rather than neuropathic pain (i.e. pain caused by a lesion or disease of the somatosensory nervous system [18], however patients with radicular pain often present with co-morbid characteristics of neuropathic pain, i.e. electric shocks, shooting pain and paraesthesia [17, 19, 20].

To add further confusion, in a group of patients with ‘sciatica’, some patients may have radicular pain alone while others presenting with radicular pain co-morbid with radiculopathy. The aim of our study was to investigate, if there are differences in somatosensory profiles between these two patient groups and to characterize these differences based on somatosensory profiles. We applied comprehensive quantitative sensory testing (QST) in patients’ main pain area (MPA), as required for the assessment of neuropathic pain [21], in the distal dermatome for the assessment of a nerve root lesion and in the hand as a remote control site, and compared measurements to age, gender and body region matched healthy control (HC) data.

Methods

The study was approved by the Sir Charles Gairdner Group Human Research Ethics Committee (HREC 2013-096). All participants gave written informed consent prior to participation and the study protocol adhered to the ethical guidelines of the Declaration of Helsinki. The study was registered with the Australian New Zealand Clinical Trials Registry (http://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=365980).

Sample size

A sample size of 23 patients was determined sufficient to detect significant differences in nerve fibre dysfunction between sides and between patients and HCs [20]. Sample size calculation was based on QST Data [22], where a sample size of 25 would be sufficient to detect a clinically significant difference in pressure pain thresholds of 36% between groups and between the symptomatic and asymptomatic side with a power of 80 and 5% level of significance [20].

Study population

Consecutive patients with leg pain in the L5 or S1 dermatomal distribution were recruited from the Neurosurgery Spinal Clinic at Sir Charles Gairdner Hospital between July 2014 and June 2016. Radicular pain was defined as pain in the specific dermatomal distribution and referring below the knee to at least the ankle. For this study, we recruited patients with radicular leg pain, some of whom presented with and some without co-morbid radiculopathy, likely undergoing conservative management. This enabled a comparison with patients who presented with combined lumbar radicular pain and radiculopathy in a parallel study who proceeded to surgery [11]. As for definitions used in this study, this patient group is referred to as the mixed patient group/cohort.

The inclusion criteria for the mixed patient cohort were: age 18–65 years; symptom duration of >3 months; unilateral radicular leg pain in L5 or S1 dermatomal distribution; intensity of leg pain is higher than intensity of low back pain. Exclusion criteria included diabetes, vascular disease; other neurological or psychiatric disease; a history of any previous disorders that potentially might affect the sensation in the contralateral side to be tested and an insufficient level of English to understand and fill out the questionnaires. Out of 64 potential participants meeting the inclusion criteria, 26 participated in the study. All potential participants underwent a clinical neurological assessment of myotomal strength, reflex responses and dermatomal sensation in order to establish if a radiculopathy was present, in addition to the presence of radicular pain. Based on the clinical findings, patients were sub-grouped into: (i) patients with radicular pain only, and (ii) patients with combined radicular pain + radiculopathy.

For each patient, an age- (±5 years) and gender-matched healthy control (HC) subject was recruited from the local community to allow comparison of QST data between patients and a healthy non-clinical cohort. Subjects with a history of current pain or a chronic pain condition or any of the exclusion criteria described for the patient group were excluded, including taking medications that influence pain perception (e.g. analgesics, non-steroidals, antidepressants).

Questionnaires

Questionnaires were used to determine the multidimensional aspects of pain, according to IMMPACT guidelines [23]. The painDETECT questionnaire was used to capture pain intensity and pain descriptors and to screen for the presence of neuropathic pain [24]. The weight of each descriptor ranges from 0 to 5, with ‘0’ indicating the person ‘never feels the sensation’, ‘1’ indicates the sensation is ‘hardly noticed’, ‘2’ the sensation is ‘slightly noticed’, ‘3’ the sensation is ‘moderately noticed’, ‘4’ the sensation is ‘strongly noticed’ and ‘5’ the sensation is ‘very strongly’ noticed. The total painDETECT score can range from −1 to 38. A score of ≤12 indicates ‘unlikely’ neuropathic pain, a score of ≥19 indicates ‘likely’ neuropathic pain while scores between 13 and 18 reflect an ambiguous result. In our study, for profiling of pain descriptors, scores ≥3 were defined as clinically relevant [11, 25].

The Oswestry Disability Index (ODI) [26] was used for the measurement of functional status. Scores range from 0–100 and are classified into the following categories: minimal disability (0–20%), moderate disability (21–40%), severe disability (41–60%) disability, crippled (61–80%) and patient is bed-bound or exaggerates symptoms (81–100%).

The presence of anxiety and depression was screened using the Hospital Anxiety and Depression Scale [27]. A maximum score of 21 can be reached for each parameter. Scores of ≤10 are considered within normal range.

Fear avoidance behaviour was assessed with the Tampa Scale for Kinesiophobia [28]. A score ≥40 is considered to indicate significant kinesiophobia.

The Pain Catastrophizing Scale [29] measured patients level of catastrophizing. The questionnaire contains 13 items reflecting past painful experiences. The degree to which a person experiences the items is indicated on a 5-point scale from 0 (not at all) to 4 (all the time). The maximum achievable score is 52. A score >30 indicates a clinically relevant level of catastrophizing [29].

Degree of nerve root compression

A neurosurgeon, blinded to the patient’s clinical presentation, reviewed the patients’ imaging and graded the degree of nerve root compression according to the grading system proposed by Pfirrmann et al. [30]. The grading system comprises the following classifications:

  1. no compromise of the nerve root;

  2. the nerve root is in contact with disc material;

  3. deviation of the nerve root and

  4. nerve root compression.

Some patients had their imaging performed prior to their initial consult at the Neurosurgery Spinal Clinic, others were referred for further imaging after the consult.

Quantitative sensory testing

QST was performed according to the QST protocol of German Research Network of Neuropathic Pain (DFNS) [22, 31]. The protocol measures various parameters in the following standardised order: cold and warm detection thresholds (CDT, WDT), the number of paradoxical heat sensations (PHS) during the procedure of alternating warm and cold stimuli; cold and heat pain thresholds (CPT, HPT); mechanical detection threshold (MDT); mechanical pain threshold (MPT); stimulus-response functions: mechanical pain sensitivity (MPS) and dynamic mechanical allodynia (DMA); wind-up ratio (WUR); vibration detection threshold (VDT) and pressure pain threshold (PPT). Detailed methodological descriptions can be obtained in Rolke et al. [22, 31].

QST measurements were taken from the MPA nominated by the patient, and the contralateral mirror side, plus thermal and mechanical detection thresholds were assessed in the relevant distal dermatome (L5, S1) on the symptomatic side to explore dermatomal sensory deficits. In addition, the full QST battery was applied to the hand dorsum ipsilateral to the symptomatic side as a remote control site [22, 31]. Testing sites in HC subjects were matched to the body regions tested in patients.

Statistical analysis

Data were analysed using the IBM SPSS statistics 26. p-Values <0.05 were considered statistically significant. Continuous data was summarised using means and standard deviations or medians, interquartile ranges and ranges, depending on normality, and compared between the mixed patient group and HCs with independent t-tests (age, QST z-scores) or non-parametric Mann Whitney U tests (questionnaire data). QST data were log-transformed prior to statistical analysis except those data which were normally distributed as raw data [31]. QST data were standardised for individual parameters using the following formula: z-score=(Mean single proband − Mean healthy controls)/SD healthy controls [31], based on HC data obtained from a database with reference data for the lower limb and hand [11]. Scores above ‘0’ indicate a gain in function i.e. the patient is more sensitive to the tested stimulus (hyperalgesia, allodynia), whilst z-scores below ‘0’ indicate a loss of function, referring to a lower sensitivity (hypoalgesia, hypoaesthesia). Standardised QST data were compared between the mixed patient cohort and HC using independent t-tests and between sides using paired t-tests.

Standardisation of QST enabled comparison of sensory profiles between patients with radicular pain only and patients with combined radicular pain + radiculopathy. Due to smaller sample sizes, non-parametric tests were used for comparison of clinical data between patient subgroups (patients with radicular pain only and patients with combined radicular pain + radiculopathy) and of QST data between sides within each group. Kruskal–Wallis test was used to compare QST data between independent patient groups and HCs; Fisher’s Exact tests were used to compare frequencies between the patient subgroups.

Results

Mixed cohort patient characteristics

Twenty-six patients (mean age 46 ± 10, years, 10 (39%) females) participated in the study (Table 1). Symptom duration ranged from 4 to 120 months, with a mean of 19 months. Twelve patients presented with leg pain in the L5 dermatomal distribution and 14 patients with leg pain in the S1 dermatomal distribution. For 10 patients, their MPA was located in the upper leg, for 14 patients in the lower leg and for two patients, the MPA was in the foot. Lumbar imaging (MRI, n=24; CT, n=2) demonstrated nerve root compression in 12 patients (46%), nerve root displacement in six patients (23%) and contact of the nerve root with disc material in eight patients (31%).

Table 1:

Demographics and clinical profiles of healthy control (HC) subjects and the mixed patient group with radicular pain with or without lumbar radiculopathy (mixed group), of patients with radicular pain only (Radicular) and of patients with radicular pain + radiculopathy (Radiculopathy).

HC (n=26) Mixed group (n=26) Radicular (n=8) Radiculopathy (n=18) p-Valuea p-Valueb
Age (years)* mean/SD 46.1(10.5) 46.5(9.9) 49.1(11.1) 45.3(9.4) 0.892 0.367
Gender (female, n) n% 10(39) 10(39) 5(63) 5(28%) 0.189###
Sleep quality during last week (VAS)# 2.0 (1.9; 0.0–7.7) 5.2(5.0; 0.0–9.5) 7.0(7.5; 0–9) 5.0(3.5; 0.5–9.5) 0.003 ## 0.834##
(0=good sleep, 10=bad sleep) (n=24) (n=16)
Hospital anxiety and depression score
 Anxiety score (HADS)# 3.0(5.5; 0–7) 8.0(5.5; 0–14) 5.5(3.5; 0–12) 8.0(5.3; 3–14) <0.001 ## 0.019 ##
 Within normal range (≤ 10), n% 25(100) 20(77) 7(88) 13(72)
 Depression score (HADS)# 0.0(1.0; 0–2) 5.5(6.5; 1–14) 5.0(4.8; 1–8) 6.5(8.3. 1–14) <0.001 ## 0.261##
 Within normal range (≤ 10), n% 25(100) 22(85) 8(100) 14(78)
Pain catastrophizing scale# 1.0(3.5; 0.0–16.0) 18.5(16.7; 6–44) 18.5(22.0; 10–35) 18.0(17.5; 6–44) <0.001 # 0.807##
 Within normal range (≤ 30), n% 26 (100) 5(73) 15(83) 6(75)
Tampa scale of kinesiophobia 45.3(9.4)* 41.8(7.3)* 46.8(10.0)* 0.311##
46.0 (9.5;27–65)# 42.5 (10.0; 27–50)# 47.5(13.3; 33–65)#
Symptom duration, months# 13.0(20; 3.5–120) 18.5(19; 4–120) 13.0(22.0; 3.5–46) 0.605##
Oswestry disability index (0–100) 16.0(7.8)* 13.4(7.8)* 17.2(7.8)* 0.285##
14.5(12.8; 1–34)# 13 (12.5; 1–24)# 15.5(12.0; 4–34)#
 Minimal disability 7(27) 3(37.5 4(22.2)
 Moderate disability 10(39) 3(37.5) 7(38.9)
 Severe disability 8(31) 2(25) 6(33.3)
 Crippled 1(3) 0 1(5.6) 0.285
painDETECT (-1-38) 15.2*(7.6) 9.4*(6.7) 17.8*(6.6) 0.008 ##
16(14.5; 4–29)# 7.0(9.5; 4–23)# 17.0(8.3; 5–29)#
 No neuropathic pain, n% 9(35) 6(75) 3(17)
 Unclear, n% 10(38) 1(12.5) 9(50)
 Neuropathic pain, n% 7(27) 1(12.5) 6(33)
Sensory radiculopathy (i.e. only sensory dermatomal deficits, no motor deficits), n 8
Motor and sensory radiculopathy (sensory and motor deficits), n 10
Straight leg raise test positive, n% 19(73) 5(62) 14(78) 0.635###
Pain now (NRS 0–10)# 2.5(2.0; 0–7) 2.0(2.0; 0–5) 3.0(2.5; 1–7) 0.683##
Average pain last week (NRS 0–10)# 4.5(4.0; 2.0–9.0) 5.6(3.8; 2–8) 4.0(4.5; 2–9) 0.196##
Maximum pain last week (NRS 0–10)# 8.0(3.3; 4.0–10.0) 8.5(2.5; 4-100 7.5(3.3; 4–10) 0.160##
Degree of nerve root compression 0.867###
 Contact of nerve root, n% 8(31) 3(37.5) 5(28)
 Nerve root displacement, n% 6(23) 2(25) 4(22)
 Nerve root compression, n% 12(46) 3(37.5) 9(50)
Patients with medication, n% 14(54) 3(37.5) 11(61) 0.401###
Current medication◊ n, %
 Tricyclic antidepressant 1(7) 1(9)
 Antiepileptics 6(43) 1(33) 5(45)
 Opioids 3(21) 1(33) 2(18)
 Analgesics 6(43) 1(33) 5(45)
 Non-steroidal anti-inflammatories 6(43) 3(100) 3(27)

  1. *Data are mean (SD); #Data are median (IQR; min-max); ##Mann Whitney-U Test; ###Fisher’s Exact Test; ◊Multiple answers possible. aComparison mixed group with healthy controls; bComparison radicular pain only with radicular pain + radiculopathy.

The mean ODI score of 16 ± 7.8 (mean/SD) (median 14.5/IQR12.8) indicated moderate disability of the mixed patient cohort (Table 1). Seven patients (27%) were classified with minimal disability, ten (38%) were classified with moderate disability, eight patients with severe disability (31%) and one patient as being crippled (4%).

Compared to HCs, the mixed patient group showed significant lower sleep quality and higher anxiety, depression and pain catastrophizing scores (Table 1). The patients’ median pain catastrophizing score of 18.5 was below the clinically relevant level of catastrophizing. The majority of patients showed anxiety (77%) and depression (85%) scores within the normal range.

Pain descriptors

The group mean painDETECT score of 15.2 ± 7.6 (mean/SD) (median 16/IQR14.5) fell below the cut-off score for classification of ‘neuropathic pain is likely’ (Table 1). Nine patients (35%) fell into the category of likely having neuropathic pain, seven patients (27%) as not having neuropathic pain and for 10 (38%) patients the results were unclear (Table 1). The most common pain descriptors felt by patients at a moderate to very strong level were burning, sudden pain attacks, numbness and tingling (Figure 1).

Figure 1: Pain descriptors in the mixed patient cohort (blue), in patients with radicular pain only (yellow) and in patients with combined radicular pain + radiculopathy (green). *Significant difference between patients with radicular pain only and patients with radicular pain + radiculopathy.
Figure 1:

Pain descriptors in the mixed patient cohort (blue), in patients with radicular pain only (yellow) and in patients with combined radicular pain + radiculopathy (green).

*Significant difference between patients with radicular pain only and patients with radicular pain + radiculopathy.

QST

For interest, the QST profile of the mixed patient group is also documented in a Supplementary file (Appendix 1). We acknowledge that the focus of this paper was the comparison of sensory profiles between patients with radicular pain only and patients with combined radicular pain and radiculopathy. However, the QST profile of the mixed patient group demonstrated that with the aggregation of the two subgroups here, any between-group QST differences are no longer evident. There is a discussion point about this in this manuscript.

Group comparison (radicular pain only compared to combined radicular pain + radiculopathy)

Patient characteristics

There were no significant difference in demographics between patients with radicular pain only and patients with combined radicular pain + radiculopathy except for anxiety (Table 1). Patients with radicular pain only were less anxious (p=0.019). Patient groups did not differ significantly in their degree of functional disability and in their frequencies of ODI classifications (p=0.831).

Pain descriptors

Patients with radicular pain only scored a significantly lower score on painDETECT (median 7.0/IQR9.5) compared to patients with combined radicular pain + radiculopathy (median 17.0/IQR 8.3) (p=0.008) (Table 1). Based on the painDETECT, the group of patients with radicular pain only were classified as not having neuropathic pain. Pain descriptors did not differ between the two groups with the exception of numbness (p<0.001) (Figure 1). Patients with radicular pain only did not report any symptoms of numbness (scored >2), while 78% of patients with radiculopathy did.

QST

Patients with radicular pain only

For the MPA, patients with radicular pain only did not show significant differences in QST measures between sides (Figure 2A). Compared to HCs, this patient group demonstrated a significant loss of function in mechanical detection in the symptomatic and asymptomatic leg (p<0.003). Patients were significantly more sensitive to heat in both legs compared to HCs (p<0.004) (Figure 2A) and compared to patients with combined radicular pain + radiculopathy (p<0.019) (Figure 3A).

Figure 2: Z-score sensory profiles of the symptomatic (red) and asymptomatic (blue) leg in patients with radicular pain only in the maximal pain area (A), dermatome (B) and hand dorsum (C) and in patients with combined radicular pain + radiculopathy in the maximal pain area (D), dermatome (E) and hand dorsum (F). Error bars indicate the standard error of measurement. CDT: cold detection threshold; WDT: warm detection threshold; TSL: thermal sensory limen; CPT: cold pain threshold; HPT: heat pain threshold; MDT: mechanical detection threshold; MPT: mechanical pain threshold; MPS: mechanical pain sensitivity; WUR: wind-up ratio; VDT: vibration detection threshold; PPT: pressure pain threshold. *statistically significant difference in the symptomatic leg compared to asymptomatic leg, #statistically significant difference in the symptomatic leg compared to healthy controls, ##statistically significant difference in the asymptomatic leg compared to healthy controls, ###statistically significant difference in the hand compared to healthy controls.
Figure 2:

Z-score sensory profiles of the symptomatic (red) and asymptomatic (blue) leg in patients with radicular pain only in the maximal pain area (A), dermatome (B) and hand dorsum (C) and in patients with combined radicular pain + radiculopathy in the maximal pain area (D), dermatome (E) and hand dorsum (F). Error bars indicate the standard error of measurement. CDT: cold detection threshold; WDT: warm detection threshold; TSL: thermal sensory limen; CPT: cold pain threshold; HPT: heat pain threshold; MDT: mechanical detection threshold; MPT: mechanical pain threshold; MPS: mechanical pain sensitivity; WUR: wind-up ratio; VDT: vibration detection threshold; PPT: pressure pain threshold.

*statistically significant difference in the symptomatic leg compared to asymptomatic leg, #statistically significant difference in the symptomatic leg compared to healthy controls, ##statistically significant difference in the asymptomatic leg compared to healthy controls, ###statistically significant difference in the hand compared to healthy controls.

Figure 3: Z-score sensory profiles of the maximal pain area (A), dermatome (B) and hand dorsum (C) in patients with radicular pain only (yellow) and in patients with combined radicular pain + radiculopathy (green). Error bars indicate the standard error of measurement. CDT: cold detection threshold; WDT: warm detection threshold; TSL: thermal sensory limen; CPT: cold pain threshold; HPT: heat pain threshold; MDT: mechanical detection threshold; MPT: mechanical pain threshold; MPS: mechanical pain sensitivity; WUR: wind-up ratio; VDT: vibration detection threshold; PPT: pressure pain threshold. *statistically significant difference between patient groups.
Figure 3:

Z-score sensory profiles of the maximal pain area (A), dermatome (B) and hand dorsum (C) in patients with radicular pain only (yellow) and in patients with combined radicular pain + radiculopathy (green). Error bars indicate the standard error of measurement. CDT: cold detection threshold; WDT: warm detection threshold; TSL: thermal sensory limen; CPT: cold pain threshold; HPT: heat pain threshold; MDT: mechanical detection threshold; MPT: mechanical pain threshold; MPS: mechanical pain sensitivity; WUR: wind-up ratio; VDT: vibration detection threshold; PPT: pressure pain threshold.

*statistically significant difference between patient groups.

For the dermatome, patients with radicular pain only did not differ significantly in any measurements compared to HCs (Figure 2B) and patients with combined radicular pain + radiculopathy (Figure 3B). In the hand, patients with radicular pain only showed a significant loss of function in mechanical detection compared to HCs (p=0.002) and increased heat and cold sensitivity compared to HCs (p<0.023) (Figure 2C) and patients with combined radicular pain + radiculopathy (p<0.024) (Figure 3C).

Patients with combined radicular pain + radiculopathy

Patients with combined radicular pain + radiculopathy demonstrated a significant loss of function in the symptomatic leg (warm detection, thermal sensory limen, mechanical, vibration detection, mechanical pain threshold, mechanical pain sensitivity) compared to the asymptomatic leg (p<0.031) (Figure 2D). Compared to HCs, there was a significant loss of function in mechanical detection (p>0.001), mechanical pain threshold (p=0.002) and mechanical pain sensitivity in the symptomatic MPA (p<0.016), but not in the asymptomatic leg (Figure 2D). Compared to patients with radicular pain only, patients with combined radicular pain + radiculopathy showed a significant loss of function in mechanical pain sensitivity in the MPA (p=0.038) (Figure 3A).

In the dermatome, a significant loss of function in mechanical and vibration detection was evident compared to HCs (p<0.001) (Figure 2E). Patients with combined radicular pain + radiculopathy displayed a larger loss of function in mechanical detection compared to patients with radicular pain only (Figure 3B); the difference in MDT approached significance (p=0.051). There were no differences in any QST measurements in the hand compared to HCs (Figure 2F).

Discussion

This is the first study to provide detailed, QST-derived multi-site sensory phenotyping in patients diagnosed with chronic ‘sciatica’ exploring differences and commonalities between those presenting with radicular pain only and those with combined radicular pain + radiculopathy. Significant differences were found in their somatosensory profiles. Patients with radicular pain only demonstrated evoked thermal hypersensitivity with largely preserved nerve fibre function, and patients with combined radicular pain + radiculopathy demonstrated large and small fibre loss of function. Some commonalities were found in regards to pain descriptors, with the exception that those patients with radicular pain only did not report any numbness. The umbrella term ‘sciatica’ encompasses all radiating leg pain as a single diagnosis, yet our findings show distinct subtypes and QST phenotypes, suggesting different underlying pain mechanisms and pointing to possibly different targeted management.

The combined radicular pain + radiculopathy group in this study was mainly characterized by a loss of function in thermal, mechanical and vibration detection in the symptomatic leg and distal dermatome, indicative of the presence of a nerve root lesion. This is comparable to findings in our surgical lumbar radiculopathy cohort [11] and in patients with cervical radiculopathy [20]. In contrast, patients with radicular pain only did not show any sensory deficits in the dermatome, and in the MPA for one parameter only, i.e. mechanical detection. It is unclear if the observed loss of function in patients presenting with radicular pain only is suggestive of a nerve root lesion. The loss of function was not observed in the distal dermatome, as commonly seen in patients with radiculopathy [32], [33], [34]. Of note, a loss of mechanical detection has been reported in patients with nociceptive pain [35], [36], [37], [38] and has been suggested to indicate altered central pain processing [35, 38], [39], [40]. In contrast to the radiculopathy subgroup, the loss of function was widespread in the radicular-only subgroup occurring both bilaterally and in the remote site of the hand. Bilateral [38] and widespread loss of mechanical detection [35] were also demonstrated in patients with non-neuropathic pain and suggests involvement of centrally mediated mechanisms (secondary tactile hypoaesthesia). Interestingly, our patients with radicular pain only did not indicate on the painDETECT that they felt numbness in their pain area. This may further suggest that the loss of mechanical detection does not reflect a ‘true’ loss of function.

Patients with radicular pain only presented with heat hypersensitivity in both legs and in the hand. This somatosensory characteristic was not evident in patients with combined radicular pain + radiculopathy in the current study, nor in our surgical radiculopathy cohort [11]. Our finding of heat hyperalgesia in the MPA correlates with the thermal hyperalgesia found in 33% of cluster 2 patients with peripheral neuropathic pain [10]. The authors reported that patients in this cluster displayed largely preserved large and small fibre function in their MPA despite the presence of neural damage. However, the specific inclusion criteria for their radiculopathy group did not necessarily reflect the presence of nerve root damage, as patients with just pain in the L5 or S1 dermatome and a positive straight-leg-raise-test, without clinical sensory or motor deficits, were included. Unfortunately, for that study the percentage of patients with radicular pain only and patients with radiculopathy was not mentioned. A subgroup analysis may be helpful to explore further, if heat hypersensitivity may be indeed a biomarker for the presentation of radicular pain only. Furthermore, their z-sore calculation had been based on HC data obtained in the foot, but not in the patients’ MPA, which may have influenced study results.

The cluster 2 heat sensitivity profile has been attributed to likely peripheral sensitisation and referred to as the ‘irritable nociceptor’ profile [10, 41], [42], [43]. While some studies have shown promising results in the stratification of pharmacological interventions, targeting the ‘irritable nociceptor’ profile [10, 41], [42], [43], [44], [45], such stratification has not been implemented in pharmacological studies for patients with radicular pain ± radiculopathy [5, 6, 13]. Demonstration of the QST profile of our mixed patient cohort, and separately the QST profiles of our patient subgroups, clearly showed that each patient subgroup was characterised by a specific somatosensory profile, but the between-group QST differences were no longer evident when subgroup data were aggregated. The loss of function in the mixed group was driven by the radiculopathy group, whereas the heat hypersensitivity seemed to be driven by the radicular pain group. This observation suggests that these groups should possibly not be pooled in intervention trials as underlying pain mechanisms may differ.

Irrespective of the mechanisms of peripheral sensitisation, the presence of the observed widespread thermal hyperalgesia including the contralateral limb and the hand in our patients with radicular pain only, points to additional central pain mechanisms which may also have to be considered in the choice of pharmaceutical products.

It remains unclear if patients with radicular pain only should be classified as having neuropathic pain. By definition [14], these patients do not have a nerve lesion, and our clinical and QST findings did not indicate the core sign of nerve root compromise, manifesting as loss of distal dermatomal sensory or myotomal function. According to the painDETECT outcome, these patients did not have neuropathic pain, although it has to be mentioned that the validity of the questionnaire in patients with radicular pain has been questioned [17, 19]. It could also be speculated, that our patients did not have radicular pain, but rather somatic referred pain, hence being classified as having ‘nociceptive’ pain on painDETECT. Nevertheless, patients reported some of the neuropathic pain descriptors which are suggested should be considered in the determination of neuropathic pain [46]. Based on the neuropathic pain grading system [46], our patients could be classified as having possible, probable or definite neuropathic pain, all depending on the interpretation of sensory alterations found in our cohort and the interpretation of imaging results. The difference in sensory profiles between the MPA and distal dermatome may suggest, that for patients with radicular pain, sensory testing could be applied in both areas for a more comprehensive diagnostic workup.

Irrespective of the differing QST somatosensory profiles between patients with radicular pain only and patients with combined radicular pain + radiculopathy, and of having neuropathic pain or not, the groups did not differ in their degree of disability and pain intensity. In fact, demographic and psychological measures of the whole mixed patient group were comparable to our surgical radiculopathy group. Our mixed patient group did not show any significant improvement on the ODI or painDETECT over three or 12 months (data not presented), indicating the need for improving patient management.

Radicular pain with or without radiculopathy has been labelled by many authors under the term ‘sciatica’ [1, 6, 47], [48], [49], [50], [51], [52], [53], [54], [55]. The ICD-11 coding system however differentiates between sciatica and radiculopathy/radicular pain. Sciatica (ME84.3) is listed as a subgroup of spinal pain under ‘Symptoms or signs of the musculoskeletal system’ without any reference to a nerve root lesion or irritation, whereby radiculopathy/radicular pain are mentioned under ‘Disorders of the nerve root, plexus or peripheral nerve’ (8B93.Z) with manifestation of chronic peripheral neuropathic pain (MG30.51). It is important to find consensus on the terminology used to define radiating leg pain, as well as on the identification of neuropathic pain in people with ‘sciatica’, in order to facilitate clinical and scientific communication and to develop optimum clinical care pathways. Future intervention studies in patients with radiating leg pain should consider patient stratification based on the underlying pathogenesis and pain mechanisms which may lead to better treatment outcomes.

In our cohort study, the main discriminating QST factors between groups were increased heat pain sensitivity (bilaterally), demonstrated only in patients with radicular pain only. In contrast, side differences in mechanical and warm detection and mechanical pain sensitivity were demonstrated in patients with combined radicular pain + radiculopathy. These findings suggests that clinical examination of these parameters and comparison to the asymptomatic side are important for distinguishing patient groups. While laboratory-based QST may not be available or feasible for use by clinicians, recent studies have shown promising results in validation of bedsides sensory testing compared to QST [56], [57], [58]. Finally, triangulation of bedside QST with outcomes from neuropathic pain screening tools combined with appropriate clinical examination (including imaging or conduction tests) likely remains a sound approach to optimizing clinical management.

Limitations

Our results should be interpreted in the light of the small patient cohorts and in this regard, a type II error cannot be excluded. We recruited patients with clear L5 or S1 dermatomal pain distribution, suggesting that these patients present with radicular pain, however there is no tool available to validate the presence of radicular pain.

Conclusion

The results in this small cohort indicate distinct differences in QST-derived somatosensory profiles and pain experiences between patients with radicular pain only and those patients with combined radicular pain + radiculopathy, suggesting differing underlying pain mechanisms. The loss of function profile in the radiculopathy group is suggestive of a nerve root lesion and associated neuropathic pain. The findings support the notion that radicular pain and radiculopathy are discrete conditions. Clinicians and researcher should be made aware of the differences between the two conditions and possible care implications. To achieve this requires clarity of the definition of ‘sciatica’, classification criteria and guidance of operationalisation of this system in the clinic.

Corresponding author: Brigitte Tampin, Department of Physiotherapy, Sir Charles Gairdner Hospital, Neurosurgery Spinal Clinic, Hospital Avenue, Nedlands, WA6009, Australia; Neurosurgical Service of Western Australia, Sir Charles Gairdner Hospital, Perth, WA, Australia; School of Allied Health, Curtin University, Perth, WA, Australia; and Faculty of Business Management and Social Sciences, Hochschule Osnabrück, University of Applied Sciences, Osnabrück, Germany, Phone: +61 8 6457 7964, Fax: +61 8 6457 3037, E-mail:

Funding source: Arthritis Australia 10.13039/501100000940

Award Identifier / Grant number: The Eventide Homes Grant

Funding source: Sir Charles Gairdner Hospital and Osborne Park Health Care Group Research Advisory Committee

Award Identifier / Grant number: RAC 2016-17/015

Funding source: Charlies Foundation for Research

Funding source: Government of Western Australia

Funding source: Department of Health and the Raine Medical Research Foundation

Acknowledgement

We thank Carly Pyne and Stefanie Glass for their assistance in participant recruitment and assessment, Anita Dening for assistance with artwork, and we thank staff at the Pain Management Department at Sir Charles Gairdner Hospital for their support.

  1. Research funding: The study was supported by Arthritis Australia (The Eventide Homes Grant), the Sir Charles Gairdner Hospital and Osborne Park Health Care Group Research Advisory Committee Grant (RAC 2016-17/015), the Charlies Foundation for Research and the Government of Western Australia, Department of Health and the Raine Medical Research Foundation.

  2. Author contributions: All authors have accepted responsibility for the entire content of this manuscript and approved its submission. BT, HS and CL conceptualized the experiment and acquired funding. BT collected data. All authors were involved in data analysis and discussed the results. BT drafted the first version of the manuscript. All authors provided input to the final version of the manuscript.

  3. Competing interests: Authors state no conflict of interest.

  4. Informed consent: Informed consent has been obtained from all individuals included in this study.

  5. Ethical approval: Research involving human subjects complied with all relevant national regulations, institutional policies and is in accordance with the tenets of the Helsinki Declaration (as amended in 2013), and had been approved by the Sir Charles Gairdner Group Human Research Ethics Committee (HREC 2013-096).

References

1. Konstantinou, K, Dunn, KM. Sciatica: review of epidemiological studies and prevalence estimates. Spine 2008;33:2464–72, https://doi.org/10.1097/brs.0b013e318183a4a2.Search in Google Scholar

2. Vroomen, PCAJ, de Krom, MCTFM, Slofstra, PD, Knottnerus, JA. Conservative treatment of sciatica: a systematic review. J Spinal Disord 2000;13:463–9, https://doi.org/10.1097/00002517-200012000-00001.Search in Google Scholar PubMed

3. Weber, H, Holme, I, Amlie, E. The natural course of acute sciatica with nerve root symptoms in a double-blind placebo-controlled trial evaluating the effect of piroxicam. Spine 1993;18:1433–8, https://doi.org/10.1097/00007632-199318110-00006.Search in Google Scholar

4. Baron, R, Freynhagen, R, Tölle, TR, Cloutier, C, Leon, T, Murphy, TK, et al.. The efficacy and safety of pregabalin in the treatment of neuropathic pain associated with chronic lumbosacral radiculopathy. Pain 2010;150:420–7, https://doi.org/10.1016/j.pain.2010.04.013.Search in Google Scholar PubMed

5. Brötz, D, Maschke, E, Burkard, S, Engel, C, Mänz, C, Ernemann, U, et al.. Is there a role for benzodiazepines in the management of lumbar disc prolapse with acute sciatica? Pain 2010;149:470–5, https://doi.org/10.1016/j.pain.2010.02.015.Search in Google Scholar PubMed

6. Mathieson, S, Maher, CG, McLachlan, AJ, Latimer, J, Koes, BW, Hancock, MJ, et al.. Trial of pregabalin for acute and chronic sciatica. N Engl J Med 2017;376:1111–20, https://doi.org/10.1056/nejmoa1614292.Search in Google Scholar PubMed

7. Saldaña, MT, Navarro, A, Pérez, C, Masramón, X, Rejas, J. A cost-consequences analysis of the effect of pregabalin in the treatment of painful radiculopathy under medical practice conditions in primary care settings. Pain Pract 2010;10:31–41, https://doi.org/10.1111/j.1533-2500.2009.00312.x.Search in Google Scholar PubMed

8. Schäfer, A, Hall, T, Müller, G, Briffa, K. Outcomes differ between subgroups of patients with low back and leg pain following neural manual therapy: a prospective cohort study. Eur Spine J 2011;20:482–90, https://doi.org/10.1007/s00586-010-1632-2.Search in Google Scholar PubMed PubMed Central

9. Jesson, T, Runge, N, Schmid, AB. Physiotherapy for people with painful peripheral neuropathies: a narrative review of its efficacy and safety. Pain Rep 2020;5:e834, https://doi.org/10.1097/pr9.0000000000000834.Search in Google Scholar PubMed PubMed Central

10. Baron, R, Maier, C, Attal, N, Binder, A, Bouhassira, D, Cruccu, G, et al.. Peripheral neuropathic pain: a mechanism-related organizing principle based on sensory profiles. Pain 2017;158:261–72, https://doi.org/10.1097/j.pain.0000000000000753.Search in Google Scholar PubMed PubMed Central

11. Tampin, B, Slater, H, Jacques, A, Lind, C. Association of quantitative sensory testing parameters with clinical outcome in patients with lumbar radiculopathy undergoing microdiscectomy. Eur J Pain 2020;24:1377–92, https://doi.org/10.1002/ejp.1586.Search in Google Scholar PubMed PubMed Central

12. Lin, CWC, Verwoerd, AJH, Maher, CG, Verhagen, AP, Pinto, RZ, Luijsterburg, PAJ, et al.. How is radiating leg pain defined in randomized controlled trials of conservative treatments in primary care? A systematic review. Eur J Pain 2014;18:455–64, https://doi.org/10.1002/j.1532-2149.2013.00384.x.Search in Google Scholar PubMed

13. Liu, C, Shaheed, CA, McLachlan, AJ, Latimer, J, Li, Q, Buchbinder, R, et al.. OASIS – a randomised, placebo-controlled trial of oral glucocorticoids for leg pain in patients with acute sciatica: trial protocol. BMJ Open 2020;10:e040559, https://doi.org/10.1136/bmjopen-2020-040559.Search in Google Scholar PubMed PubMed Central

14. Bogduk, N. On the definitions and physiology of back pain, referred pain, and radicular pain. Pain 2009;147:17–9, https://doi.org/10.1016/j.pain.2009.08.020.Search in Google Scholar PubMed

15. Attal, N, Perrot, S, Fermanian, J, Bouhassira, D. The neuropathic components of chronic low back pain: a prospective multicenter study using the DN4 questionnaire. J Pain 2011;12:1080–7, https://doi.org/10.1016/j.jpain.2011.05.006.Search in Google Scholar PubMed

16. Freynhagen, R, Rolke, R, Baron, R, Tölle, TR, Rutjes, A-K, Schu, S, et al.. Pseudoradicular and radicular low-back pain – a disease continuum rather than different entities. Answers from quantitative sensory testing. Pain 2008;135:65–74, https://doi.org/10.1016/j.pain.2007.05.004.Search in Google Scholar PubMed

17. Tampin, B, Briffa, NK, Goucke, R, Slater, H. Identification of neuropathic pain in patients with neck/upper limb pain: application of a grading system and screening tools. Pain 2013;154:2813–22, https://doi.org/10.1016/j.pain.2013.08.018.Search in Google Scholar PubMed

18. Jensen, TS, Baron, R, Haanpää, M, Kalso, E, Loeser, JD, Rice, ASC, et al.. A new definition of neuropathic pain. Pain 2011;152:2204–5, https://doi.org/10.1016/j.pain.2011.06.017.Search in Google Scholar PubMed

19. Tampin, B, Slater, H, Briffa, NK. Neuropathic pain components are common in patients with painful cervical radiculopathy, but not in patients with nonspecific neck–arm pain. Clin J Pain 2013;20:846–56, https://doi.org/10.1097/ajp.0b013e318278d434.Search in Google Scholar

20. Tampin, B, Slater, H, Hall, T, Lee, G, Briffa, NK. Quantitative sensory testing somatosensory profiles in patients with cervical radiculopathy are distinct from those in patients with nonspecific neck–arm pain. Pain 2012;153:2403–14, https://doi.org/10.1016/j.pain.2012.08.007.Search in Google Scholar PubMed

21. Haanpää, M, Attal, N, Backonja, M, Baron, R, Bennett, M, Bouhassira, D, et al.. NeuPSIG guidelines on neuropathic pain assessment. Pain 2011;152:14–27, https://doi.org/10.1016/j.pain.2010.07.031.Search in Google Scholar PubMed

22. Rolke, R, Baron, R, Maier, C, Tölle, TR, Treede, R-D, Beyer, A, et al.. Quantitative sensory testing in the German research network on neuropathic pain (DFNS): standardized protocol and reference values. Pain 2006;123:231–43, https://doi.org/10.1016/j.pain.2006.01.041.Search in Google Scholar PubMed

23. Turk, DC, Dworkin, RH, Burke, LB, Gershon, R, Rothman, M, Scott, J, et al.. Developing patient-reported outcome measures for pain clinical trials: IMMPACT recommendations. Pain 2006;125:208–15, https://doi.org/10.1016/j.pain.2006.09.028.Search in Google Scholar PubMed

24. Freynhagen, R, Baron, R, Gockel, U, Tölle, TR. painDETECT: a new screening questionnaire to identify neuropathic components in patients with back pain. Curr Med Res Opin 2006;22:1911–20, https://doi.org/10.1185/030079906x132488.Search in Google Scholar

25. Tampin, B, Briffa, K, Slater, H. Comparison of responses to the painDETECT questionnaire and responses to laboratory quantitative testing in patients with cervical radiculopathy. Schmerz 2012;26.Search in Google Scholar

26. Fairbank, JCT, Pynsent, PB. The Oswestry disability index. Spine 2000;25:2940–53, https://doi.org/10.1097/00007632-200011150-00017.Search in Google Scholar PubMed

27. Härter, M, Reuter, K, Gross-Hardt, K, Bengel, J. Screening for anxiety, depressive and somatoform disorders in rehabilitation – validity of HADS and GHQ-12 in patients with musculoskeletal disease. Disabil Rehabil 2001;23:737–44, https://doi.org/10.1080/09638280110062176.Search in Google Scholar PubMed

28. Swinkels-Meerwisse, EJCM, Swinkels, RAHM, Verbeek, ALM, Vlaeyen, JWS, Oostendorp, RAB. Psychometric properties of the Tampa scale for kinesiophobia and the fear-avoidance beliefs questionnaire in acute low back pain. Man Ther 2003;8:29–36, https://doi.org/10.1054/math.2002.0484.Search in Google Scholar PubMed

29. Sullivan, MJL, Bishop, SC, Pivik, J. The pain catastrophizing scale: development and validation. Psychol Assess 1995;7:524–32, https://doi.org/10.1037/1040-3590.7.4.524.Search in Google Scholar

30. Pfirrmann, CWA, Dora, C, Schmid, MR, Zanetti, M, Hodler, J, Boos, N. MR image–based grading of lumbar nerve root compromise due to disk herniation: reliability study with surgical correlation. Radiology 2004;230:583–8, https://doi.org/10.1148/radiol.2302021289.Search in Google Scholar PubMed

31. Rolke, R, Magerl, W, Campbell, KA, Schalber, C, Caspari, S, Birklein, F, et al.. Quantitative sensory testing: a comprehensive protocol for clinical trials. Eur J Pain 2006;10:77–88, https://doi.org/10.1016/j.ejpain.2005.02.003.Search in Google Scholar PubMed

32. Imoto, K, Takebayashi, T, Kanaya, K, Kawaguchi, S, Katahira, G, Yamashita, T. Quantitative analysis of sensory functions after lumbar discectomy using current perception threshold testing. Eur Spine J 2007;16:971–5, https://doi.org/10.1007/s00586-006-0285-7.Search in Google Scholar PubMed PubMed Central

33. Nygaard, ØP, Mellgren, SI. The function of sensory nerve fibers in lumbar radiculopathy: use of quantitative sensory testing in the exploration of different populations of nerve fibers and dermatomes. Spine 1998;23:348–52, https://doi.org/10.1097/00007632-199802010-00012.Search in Google Scholar PubMed

34. Tschugg, A, Lener, S, Hartmann, S, Neururer, S, Wildauer, M, Thome, C, et al.. Improvement of sensory function after sequestrectomy for lumbar disc herniation: a prospective clinical study using quantitative sensory testing. Eur Spine J 2016;25:3543–9, https://doi.org/10.1007/s00586-016-4770-3.Search in Google Scholar PubMed

35. Landmann, G, Dumat, W, Egloff, N, Gantenbein, AR, Matter, S, Pirotta, R, et al.. Bilateral sensory changes and high burden of disease in patients with chronic pain and unilateral nondermatomal somatosensory deficits: a quantitative sensory testing and clinical study. Clin J Pain 2017;33:746, https://doi.org/10.1097/ajp.0000000000000456.Search in Google Scholar PubMed PubMed Central

36. Leffler, A-S, Kosek, E, Hansson, P. Injection of hypertonic saline into musculus infraspinatus resulted in referred pain and sensory disturbances in the ipsilateral upper arm. Eur J Pain 2000;4:73–82, https://doi.org/10.1053/eujp.1999.0160.Search in Google Scholar PubMed

37. Pfau, DB, Rolke, R, Nickel, R, Treede, RD, Daublaender, M. Somatosensory profiles in subgroups of patients with myogenic temporomandibular disorders and fibromyalgia syndrome. Pain 2009;147:72–83, https://doi.org/10.1016/j.pain.2009.08.010.Search in Google Scholar PubMed

38. Westermann, A, Rönnau, AK, Krumova, E, Regeniter, S, Schwenkreis, P, Rolke, R, et al.. Pain-associated mild sensory deficits without hyperalgesia in chronic non-neuropathic pain. Clin J Pain 2011;27:782–9, https://doi.org/10.1097/ajp.0b013e31821d8fce.Search in Google Scholar

39. Geber, C, Magerl, W, Fondel, R, Fechir, M, Rolke, R, Vogt, T, et al.. Numbness in clinical and experimental pain – a cross-sectional study exploring the mechanisms of reduced tactile function. Pain 2008;139:73–81, https://doi.org/10.1016/j.pain.2008.03.006.Search in Google Scholar PubMed

40. Magerl, W, Wilk, SH, Treede, R-D. Secondary hyperalgesia and perceptual wind-up following intradermal injection of capsaicin in humans. Pain 1998;74:257–68, https://doi.org/10.1016/s0304-3959(97)00177-2.Search in Google Scholar PubMed

41. Demant, DT, Lund, K, Finnerup, NB, Vollert, J, Maier, C, Segerdahl, MS, et al.. Pain relief with lidocaine 5% patch in localized peripheral neuropathic pain in relation to pain phenotype. Pain 2015;156:2234–44, https://doi.org/10.1097/j.pain.0000000000000266.Search in Google Scholar PubMed

42. Demant, DT, Lund, K, Vollert, J, Maier, C, Segerdahl, M, Finnerup, NB, et al.. The effect of oxcarbazepine in peripheral neuropathic pain depends on pain phenotype: a randomised, double-blind, placebo-controlled phenotype-stratified study. Pain 2014;155:2263–73, https://doi.org/10.1016/j.pain.2014.08.014.Search in Google Scholar PubMed

43. Patel, R, Kucharczyk, M, Montagut-Bordas, C, Lockwood, S, Dickenson, AH. Neuropathy following spinal nerve injury shares features with the irritable nociceptor phenotype: a back-translational study of oxcarbazepine. Eur J Pain 2019;23:183–97, https://doi.org/10.1002/ejp.1300.Search in Google Scholar PubMed PubMed Central

44. Forstenpointner, J, Otto, J, Baron, R. Individualized neuropathic pain therapy based on phenotyping: are we there yet? Pain 2018;159:569–75, https://doi.org/10.1097/j.pain.0000000000001088.Search in Google Scholar PubMed

45. Forstenpointner, J, Rehm, S, Gierthmühlen, J, Baron, R. Stratification of neuropathic pain patients: the road to mechanism-based therapy? Curr Opin Anaesthesiol 2018;31:562–8, https://doi.org/10.1097/aco.0000000000000642.Search in Google Scholar PubMed

46. Finnerup, NB, Haroutounian, S, Kamerman, P, Baron, R, Bennett, DLH, Bouhassira, D, et al.. Neuropathic pain: an updated grading system for research and clinical practice. Pain 2016;157:1599–606, https://doi.org/10.1097/j.pain.0000000000000492.Search in Google Scholar PubMed PubMed Central

47. Atlas, SJ, Keller, RB, Wu, YA, Deyo, RA, Singer, DE. Long-term outcomes of surgical and nonsurgical management of sciatica secondary to a lumbar disc herniation: 10 year results from the maine lumbar spine study. Spine 2005;30:927–35, https://doi.org/10.1097/01.brs.0000158954.68522.2a.Search in Google Scholar PubMed

48. Fernandez, M, Hartvigsen, J, Ferreira, ML, Refshauge, KM, Machado, A, Lemes, I, et al.. Advice to stay active or structured exercise in the management of sciatica: a systematic review and meta-analysis. Spine 2015;40:1457–66, https://doi.org/10.1097/brs.0000000000001036.Search in Google Scholar

49. Fitzsimmons, D, Phillips, CJ, Bennett, H, Jones, M, Williams, N, Lewis, R, et al.. Cost-effectiveness of different strategies to manage patients with sciatica. PAIN® 2014;155:1318–27, https://doi.org/10.1016/j.pain.2014.04.008.Search in Google Scholar PubMed

50. Fjeld, O, Grotle, M, Siewers, V, Pedersen, L, Nilsen, KB, Zwart, J-A. Prognostic factors for persistent leg-pain in patients hospitalized with acute sciatica. Spine 2017;42:E272–E9, https://doi.org/10.1097/brs.0000000000001773.Search in Google Scholar PubMed

51. Jacobs, WC, van Tulder, M, Arts, M, Rubinstein, SM, van Middelkoop, M, Ostelo, R, et al.. Surgery versus conservative management of sciatica due to a lumbar herniated disc: a systematic review. Eur Spine J 2011;20:513–22, https://doi.org/10.1007/s00586-010-1603-7.Search in Google Scholar PubMed PubMed Central

52. Konstantinou, K, Dunn, KM, Ogollah, R, Lewis, M, van der Windt, D, Hay, EM. Prognosis of sciatica and back-related leg pain in primary care: the ATLAS cohort. Spine J 2018;18:1030–40, https://doi.org/10.1016/j.spinee.2017.10.071.Search in Google Scholar PubMed PubMed Central

53. Konstantinou, K, Lewis, M, Dunn, KM, Ogollah, R, Artus, M, Hill, JC, et al.. Stratified care versus usual care for management of patients presenting with sciatica in primary care (SCOPiC): a randomised controlled trial. Lancet Rheumatol 2020;2:e401–11, https://doi.org/10.1016/s2665-9913(20)30099-0.Search in Google Scholar PubMed PubMed Central

54. Ostelo, RWJG. Physiotherapy management of sciatica. J Physiother 2020;66:83–8, https://doi.org/10.1016/j.jphys.2020.03.005.Search in Google Scholar PubMed

55. Saunders, B, Konstantinou, K, Artus, M, Foster, NE, Bartlam, B. Patients’ and clinicians’ perspectives on a ‘fast-track’ pathway for patients with sciatica in primary care: qualitative findings from the SCOPiC stratified care trial. BMC Muscoskel Disord 2020;21:469, https://doi.org/10.1186/s12891-020-03483-z.Search in Google Scholar PubMed PubMed Central

56. Reimer, M, Forstenpointner, J, Hartmann, A, Otto, JC, Vollert, J, Gierthmühlen, J, et al.. Sensory bedside testing: a simple stratification approach for sensory phenotyping. Pain Rep 2020;5:e820, https://doi.org/10.1097/pr9.0000000000000820.Search in Google Scholar

57. Ridehalgh, C, Sandy-Hindmarch, OP, Schmid, AB. Validity of clinical small-fiber sensory testing to detect small-nerve fiber degeneration. J Orthop Sports Phys Ther 2018;48:767–74, https://doi.org/10.2519/jospt.2018.8230.Search in Google Scholar PubMed

58. Zhu, GC, Böttger, K, Slater, H, Cook, C, Tampin, B, Schmid, A. Concurrent validity of a low-cost and time-efficient clinical sensory test battery to evaluate sensory dysfunction. Eur J Pain 2019;23:1826–38, https://doi.org/10.1002/ejp.1456.Search in Google Scholar PubMed PubMed Central

Supplementary Material

The online version of this article offers supplementary material (https://doi.org/10.1515/sjpain-2021-0058).

Received: 2021-03-26
Accepted: 2021-07-14
Published Online: 2021-08-02
Published in Print: 2022-01-27

© 2021 Walter de Gruyter GmbH, Berlin/Boston

Articles in the same Issue

  1. Frontmatter
  2. Systematic Reviews
  3. Associations between anger and chronic primary pain: a systematic review and meta-analysis
  4. Modulation of offset analgesia in patients with chronic pain and healthy subjects – a systematic review and meta-analysis
  5. Meditation for adults with non-specific low back pain: a systematic review and meta-analysis
  6. Clinical Pain Researches
  7. Pain quality of thermal grill illusion is similar to that of central neuropathic pain rather than peripheral neuropathic pain
  8. Disentangling ‘sciatica’ to understand and characterise somatosensory profiles and potential pain mechanisms
  9. Concordance between clinician- and 2016 criteria-based diagnoses of fibromyalgia
  10. Performance of the 2016 diagnostic criteria for fibromyalgia in a tertiary care pain rehabilitation setting: a diagnostic accuracy study
  11. Translation and validation of the Norwegian version of the Injustice Experience Questionnaire
  12. Evaluating the construct validity and internal consistency of the Sickness Questionnaire in a Swedish sample of adults with longstanding pain
  13. Ketamine therapy for chronic pain in The Netherlands: a nationwide survey
  14. Obstructive sleep apnea is common in patients with high-impact chronic pain – an exploratory study from an interdisciplinary pain center
  15. Observational Studies
  16. Patterns of pain complaints and insomnia symptoms are associated with abusive supervision in the Norwegian working population: a latent class analysis
  17. Characteristics of phantom limb pain in U.S. civilians and service members
  18. Correlation of self-reported pain severity and healthcare expenditures in older United States adults
  19. Associations of health-related quality of life with sociodemographic characteristics, health, pain, and lifestyle factors, and motivation for changing lifestyle in adults living with chronic pain: a cross-sectional exploratory study
  20. Original Experimentals
  21. Spatiotemporal patterns of pain distribution and recall accuracy: a dose-response study
  22. Effect of interactive vs. passive virtual reality on pain threshold and tolerance
  23. Pain and executive function: no association between remote exercise-induced hypoalgesia and cognitive inhibition in pain-free participants
  24. Paroxetine effects on morphine analgesic tolerance in rats
  25. Pharmacological blockade of neurokinin1 receptor restricts morphine-induced tolerance and hyperalgesia in the rat
  26. Educational Case Report
  27. Hemicrania continua secondary to neurogenic paravertebral tumor- a case report
https://doi.org/10.1515/sjpain-2021-0058
Keywords for this article
radicular pain; radiculopathy; quantitative sensory testing; sciatica; sensory profiles

Articles in the same Issue

  1. Frontmatter
  2. Systematic Reviews
  3. Associations between anger and chronic primary pain: a systematic review and meta-analysis
  4. Modulation of offset analgesia in patients with chronic pain and healthy subjects – a systematic review and meta-analysis
  5. Meditation for adults with non-specific low back pain: a systematic review and meta-analysis
  6. Clinical Pain Researches
  7. Pain quality of thermal grill illusion is similar to that of central neuropathic pain rather than peripheral neuropathic pain
  8. Disentangling ‘sciatica’ to understand and characterise somatosensory profiles and potential pain mechanisms
  9. Concordance between clinician- and 2016 criteria-based diagnoses of fibromyalgia
  10. Performance of the 2016 diagnostic criteria for fibromyalgia in a tertiary care pain rehabilitation setting: a diagnostic accuracy study
  11. Translation and validation of the Norwegian version of the Injustice Experience Questionnaire
  12. Evaluating the construct validity and internal consistency of the Sickness Questionnaire in a Swedish sample of adults with longstanding pain
  13. Ketamine therapy for chronic pain in The Netherlands: a nationwide survey
  14. Obstructive sleep apnea is common in patients with high-impact chronic pain – an exploratory study from an interdisciplinary pain center
  15. Observational Studies
  16. Patterns of pain complaints and insomnia symptoms are associated with abusive supervision in the Norwegian working population: a latent class analysis
  17. Characteristics of phantom limb pain in U.S. civilians and service members
  18. Correlation of self-reported pain severity and healthcare expenditures in older United States adults
  19. Associations of health-related quality of life with sociodemographic characteristics, health, pain, and lifestyle factors, and motivation for changing lifestyle in adults living with chronic pain: a cross-sectional exploratory study
  20. Original Experimentals
  21. Spatiotemporal patterns of pain distribution and recall accuracy: a dose-response study
  22. Effect of interactive vs. passive virtual reality on pain threshold and tolerance
  23. Pain and executive function: no association between remote exercise-induced hypoalgesia and cognitive inhibition in pain-free participants
  24. Paroxetine effects on morphine analgesic tolerance in rats
  25. Pharmacological blockade of neurokinin1 receptor restricts morphine-induced tolerance and hyperalgesia in the rat
  26. Educational Case Report
  27. Hemicrania continua secondary to neurogenic paravertebral tumor- a case report
Sign up now to receive a 20% welcome discount
Institutional Access
How does access work?
Have an idea on how to improve our website?
Please write us.
© 2025 De Gruyter Brill
Downloaded on 29.9.2025 from https://www.degruyterbrill.com/document/doi/10.1515/sjpain-2021-0058/html
Scroll to top button