A prospective study of BurstDR™ spinal cord stimulation for non-operated discogenic low back pain

Introduction

Chronic discogenic low back pain (CD-LBP) is caused by degeneration of the disc due to trauma to the annulus or by unprovoked degeneration, resulting in chronic pain. Spinal cord stimulation (SCS) employing the BurstDR™ waveform has been shown to be an effective treatment in a variety of chronic pain conditions. The aim of this prospective case study was to determine the effect of BurstDR™ SCS on pain relief, disability, and patient satisfaction in a population with CD-LBP.

Methods

Seventeen subjects with CD-LBP received a SCS trial with BurstDR™ stimulation. Patients with >50% pain relief after a trial period of 2 weeks were permanently implanted (n = 15). Patients then rated LBP and leg pain using the numeric rating scale (NRS), Oswestry disability index (ODI), patient global impression of change (PGIC), EQ-5D quality of life, and painDETECT for neuropathic pain at baseline following trial, 3, 6, and 12 months after permanent implantation.

Results

Treatment with BurstDR™ SCS resulted in significant reduction of LBP as the NRS was reduced from 71.7 ± 7.3 at baseline to 42.5 ± 18.1 at 12 months. Average pain relief at 12 months was 42.5%. In patients with leg pain (n = 8), pain was significantly reduced from 66.9 ± 8.2 to 11.7 ± 10.4 at 12 months. PainDETECT scores for neuropathic pain significantly reduced from 18.9 ± 4.8 at baseline, and 14.8 ± 3.2 at 12 months. Baseline ODI score significantly reduced from 41.2 ± 12.8 to 25.8 ± 8.6 at 12 months. PGIC scores remained low from 2.6 ± 1.6 at 3 months, 2.5 ± 1.0 at 6 months, and 2.5 ± 1.3 at 12 months. EQ-5D-5L rates remained constant from baseline 56.10 ± 23.9 to 68.6 ± 12.9 at 12 months.

Conclusion

BurstDR™ SCS resulted in significant reduction of back pain, leg pain, and quality of life in patients with CD-LBP and decreased the level of disability and generated positive patient satisfaction scores.     

Is Spinal Cord Stimulation an Effective Treatment Option for Discogenic Pain?

Introduction: In a prospective observational study conducted in an urban pain management center, we evaluated whether spinal cord stimulation (SCS) is effective in relieving discogenic pain of IDD origin. Methods: Thirteen patients with intractable discogenic low back pain were enrolled. Four patients never underwent permanent implantation due to insurance denial, medical reasons or failed trial and served as a control group. Nine patients underwent SCS implantation (treatment group). All patients were followed for 12 months and assessed at each interval for pain (NRS), disability (ODI), and opioid use. Results: Nine patients completed the SCS trial with > 50% pain relief. The pretrial NRS score was 7.8 ± 0.5 mm in treated patients vs. 6.5 ± 1.7 mm in control patients. At 3, 6 and 12 months, the NRS was reduced to 2.9 ± 0.7 mm, 1.7 ± 0.5 mm, and 2.9 ± 0.5 mm, respectively in treated patients. NRS was unchanged in the control patients (6.5 ± 1.9 mm). The ODI score prior to the SCS trial in treated patients was 53.1 ± 3.4% vs. 54.0 ± 20.5 in control patients. At 3, 6 and 12 months the ODI scores were 39.0 ± 8.0%, 38.7 ± 4.6%, and 41.1 ± 3.9%, respectively in the treated patients, and 48.5 ± 29.5 at 12 months in control patients. In 6 patients receiving opioids prior to the SCS trial, average consumption was reduced by 69% (P = 0.036) over 12 months of therapy as compared with a 54% increase in the control patients. SCS usage was stable over the 12‐month study. Conclusions: The current study indicates that SCS may provide effective pain relief, improve disability, and reduce opioid usage in patients with discogenic pain.     

Burst Spinal Cord Stimulation in a Patient with Complex Regional Pain Syndrome: A 2‐year Follow‐Up

Spinal cord stimulation (SCS) is an effective therapy to treat most patients with complex regional pain syndrome (CRPS); however, the effect is not always maintained over time. We present a case report of a patient successfully treated with burst SCS after a diminishing effect of conventional tonic stimulation. Burst stimulation is a novel method of SCS consisting of delivering 5 spikes at 500 Hz, 40 times/s (pulse width 1 mseconds). The current output is set to a subthreshold level for paresthesia in the supine position. Report of a case: A 65‐year‐old woman with CRPS in the left upper extremity experienced a diminishing effect of conventional tonic SCS over time, resulting in an increase of pain with a mean Numerical Rating Score (NRS) of 8. After treatment with burst SCS, the NRS declined to 2 and remained at that level for 2 years. An intermediate/brief period, due to increased CRPS activity, resulted in a higher pain score, which was successfully managed by increasing the burst stimulation to a higher level of subthreshold stimulation. Discussion: In this patient with CRPS, burst SCS was successful in reducing pain scores that could no longer be achieved with conventional tonic stimulation. It appears that pain reduction with burst SCS can be sustained for a relatively long period of time.     

Neural Modulation by Stimulation

Abstract:   Spinal cord stimulation (SCS) for the treatment of neuropathic pain is supported by good-quality randomized controlled trials, prospective and retrospective case studies, and observational case series that confirm its efficacy and safety. SCS has been successfully used in various refractory neuropathic pain conditions, including failed back surgery syndrome (FBSS), neuropathic back and leg pain, and complex regional pain syndrome (CRPS) types I and II. According to the Harbour and Miller Scale (2001), the evidence for SCS in FBSS has been classified as grade B, while that for CRPS type I has been classified as grade A. Clinical evidence has shown that compared to conventional pain therapy, more than two-thirds of carefully selected patients treated with SCS achieved sustained pain relief of 50% or more, with minimal side effects. Many patients were able to reduce their analgesic consumption. Quality of life improved and the majority of patients were happy with their treatment; in some cases, patients were able to return to work. Trial stimulation, which is relatively inexpensive and completely reversible, provides predictive value for long-term efficacy and increases the cost-effectiveness of permanent implantation. Studies consistently report that over time, SCS is potentially cost saving to the healthcare system. At present, SCS is considered a "last resort" in the treatment of refractory neuropathic pain, yet evidence suggests that early intervention with SCS results in greater efficacy and, in the case of FBSS, should be considered before re-operation.     

The Specificity and Mechanisms of Hemilateral Sensory Disturbances in Complex Regional Pain Syndrome

Hyperalgesia often extends from the affected limb to the ipsilateral forehead in patients with complex regional pain syndrome (CRPS). To investigate whether this is more common in CRPS than other chronic pain conditions, pressure-pain thresholds and sharpness to a firm bristle were assessed on each side of the forehead, at the pain site, and at an equivalent site on the contralateral side in 32 patients with chronic pain other than CRPS (neuropathic or nociceptive limb pain, radicular pain with referral to a lower limb or postherpetic neuralgia), and in 34 patients with CRPS. Ipsilateral forehead hyperalgesia to pressure pain was detected in 59% of CRPS patients compared with only 13% of patients with other forms of chronic pain. Immersion of the CRPS-affected limb in painfully cold water increased forehead sensitivity to pressure, especially ipsilaterally, whereas painful stimulation of the healthy limb reduced forehead sensitivity to pressure pain (albeit less efficiently than in healthy controls). In addition, auditory discomfort and increases in pain in the CRPS-affected limb were greater after acoustic startle to the ear on the affected than unaffected side. These findings indicate that generalized and hemilateral pain control mechanisms are disrupted in CRPS, and that multisensory integrative processes may be compromised.

Perspective

The findings suggest that hemilateral hyperalgesia is specific to CRPS, which could be diagnostically important. Disruptions in pain-control mechanisms were associated with the development of hyperalgesia at sites remote from the CRPS limb. Addressing these mechanisms could potentially deter widespread hyperalgesia in CRPS.     

Patient-reported improvements of pain,disability, and health-related quality of life following chiropractic care for back pain – A national observational study in Sweden

BackgroundChiropractic care is a common but not often investigated treatment option for back pain in Sweden. The aim of this study was to explore patient-reported outcomes (PRO) for patients with back pain seeking chiropractic care in Sweden.MethodsProspective observational study. Patients 18 years and older, with non-specific back pain of any duration, seeking care at 23 chiropractic clinics throughout Sweden were invited to answer PRO questionnaires at baseline with the main follow-up after four weeks targeting the following outcomes: Numerical Rating Scale for back pain intensity (NRS), Oswestry Disability Index for back pain disability (ODI), health-related quality of life (EQ-5D index) and a visual analogue scale for self-rated health (EQ VAS).Results246 back pain patients answered baseline questionnaires and 138 (56%) completed follow-up after four weeks. Statistically significant improvements over the four weeks were reported for all PRO by acute back pain patients (n = 81), mean change scores: NRS -2.98 (p < 0.001), ODI -13.58 (p < 0.001), EQ VAS 9.63 (p < 0.001), EQ-5D index 0.22 (p < 0.001); and for three out of four PRO for patients with chronic back pain (n = 57), mean change scores: NRS -0.90 (p = 0.002), ODI -2.88 (p = 0.010), EQ VAS 3.77 (p = 0.164), EQ-5D index 0.04 (p = 0.022).ConclusionsPatients with acute and chronic back pain reported statistically significant improvements in PRO four weeks after initiated chiropractic care. Albeit the observational study design limits causal inference, the relatively rapid improvements of PRO scores warrant further clinical investigations.     

Spinal Cord Stimulation as a Novel Approach to the Treatment of Refractory Neuropathic Mediastinal Pain

Spinal cord stimulation (SCS) offers new hope for patients with neuropathic pain. SCS "neuromodulates" the transmission and response to "painful" stimuli. The efficacy of SCS has been established in the treatment of a variety of neuropathic pain conditions and more recently in refractory angina pectoris, peripheral vascular disease, and failed back surgery syndrome. Recent publications suggest that visceral pain could be successfully treated with SCS. We report the first successful use of a spinal cord stimulator in the treatment of refractory neuropathic mediastinal, esophageal, and anterior neck pain following esophagogastrectomy.     

Evaluation of the efficacy of Superior Cluneal Nerve Block in low back pain: A prospective observational study

IntroductionSuperior cluneal nerve (SCN) entrapment giving rise to low back pain (LBP) remains undiagnosed many times; in this clinical study authors have evaluated therapeutic role of lidocaine injection of SCN for low back pain relief in patients with SCN entrapment.MethodsThe present study was a prospective, observational study; 25 patients with unilateral LBP over the iliac crest and buttock for more than six months not responding to conservative measures were included in this clinical trial. SCN lidocaine injection was done under fluoroscopy guidance; patients having more than 50% reduction in numeric rating scale (NRS) score, for at least 2 h following SCN injection, were enrolled in the study and followed for 6 months. The primary outcome measure was severity of LBP, measured by NRS score. Secondary outcome measures were percentage pain relief; Oswestry Disability Index (ODI) score, reduction of analgesic usage, DSM-IV score for psychological assessment. All these assessments were done prior to the procedure and at 2 weeks, 1, 3 and 6 months after the procedure.ResultsA significant reduction in the NRS scores was observed at 2 weeks, 1, 3 and 6 months after SCN lidocaine injection as compared to the baseline (P value < 0.05); authors also observed a significant pain relief and significantly reduced ODI scores, analgesic consumption and DSM scores compared to the baseline values (P value < 0.05).ConclusionA single SCN lidocaine injection provided significant pain relief in LBP patients with SCN entrapment for a period of 6 months.     

Dysynchiria is not a common feature of neuropathic pain

Patients with chronic neuropathic pain (non‐CRPS) and brush‐evoked allodynia watched a reflected image of their corresponding but opposite skin region being brushed in a mirror. Unlike complex regional pain syndrome Type 1, this process did not evoke any sensation at the affected area (‘dysynchiria’). We conclude that central nociceptive sensitisation alone is not sufficient to cause dysynchiria in neuropathic pain. The results imply a difference in cortical pain processing between complex regional pain syndrome and other chronic neuropathic pain.     

Psychometric properties of the Neck Disability Index and Numeric Pain Rating Scale in patients with mechanical neck pain

Cleland JA, Childs JD, Whitman JM. Psychometric properties of the Neck Disability Index and numeric pain rating scale in patients with mechanical neck pain.

Objective

To examine the psychometric properties including test-retest reliability, construct validity, and minimum levels of detectable and clinically important change for the Neck Disability Index (NDI) and the numeric rating scale (NRS) for pain in a cohort of patients with neck pain.

Design

Single-group repeated-measures design.

Setting

Outpatient physical therapy (PT) clinics.

Participants

Patients (N=137) presenting to PT with a primary report of neck pain.

Interventions

Not applicable.

Main Outcome Measures

All patients completed the NDI and the NRS at the baseline examination and at a follow-up. At the time of the follow-up, all patients also completed the global rating of change, which was used to dichotomize patients as improved or stable. Baseline and follow-up scores were used to determine the test-retest reliability, construct validity, and minimal levels of detectable and clinically important change for both the NDI and NRS.

Results

Test-retest reliability was calculated using an intraclass correlation coefficient (ICC) (NDI ICC=.50; 95% confidence interval [CI], .25-.67; NRS ICC=.76; 95% CI, .51-.87). The area under the curve was .83 (95% CI, .75-.90) for the NDI score and .85 (95% CI, .78-.93) for the NRS score for determining between stable and improved patients. Thresholds for the minimum clinically important difference (MCID) for the NDI were 19-percentage points and 1.3 for the NRS.

Conclusions

Both the NDI and NRS exhibit fair to moderate test-retest reliability in patients with mechanical neck pain. Both instruments also showed adequate responsiveness in this patient population. However, the MCID required to be certain that the change in scores has surpassed a level that could be contributed to measurement error for the NDI was twice that which has previously been reported. Therefore the ongoing analyses of the properties of the NDI in a patient population with neck pain are warranted.     

Validation of the Dutch Version of the DN4 Diagnostic Questionnaire for Neuropathic Pain

Difficulties in diagnosing neuropathic pain in routine clinical practice support the need for validated and easy‐to‐use diagnostic tools. The DN4 neuropathic pain diagnostic questionnaire aims to discriminate neuropathic pain from nociceptive pain, but needs clinical validation. A total of 269 patients with chronic pain in three pain clinics were included in the study of which 248 had analyzable data. The mean duration of pain was 4.9 years. The most frequent etiologies were posttraumatic (36%), (pseudo) radicular (14%), and mechanical back pain (12%). The mean intensity of pain at visit was 5.6 on a 0–10 scale. Hundred and ninety‐six of 248 patients had an identical pain diagnosis from both physicians: 85 had neuropathic pain, 57 had nociceptive pain, and 54 had mixed pain. Among patients with identical diagnoses of neuropathic or nociceptive pain, using a receiver operating characteristic curve analysis, the area under the curve (AUC) was 0.81 for the DN4 7‐item and 0.82 for the 10‐item version. A cutoff point of 5/10 for the full questionnaire resulted in a sensitivity of 75% and a specificity of 79%, while a cutoff point of 4/7 for the partial questionnaire resulted in a sensitivity of 74% and a specificity of 79%. The items “brushing,” “painful cold,” and “numbness” were most discriminating. The DN4 is an easy‐to‐use screening tool that is reliable for discriminating between neuropathic and nociceptive pain conditions in daily practice. Item‐specific scores provide important information in addition to the total score.     

First episode of acute low back pain – an exploratory cluster analysis approach for early detection of unfavorable recovery

Purpose: To identify recovery patterns in patients with a first episode of acute low back pain (LBP) and to define risk factors for unfavorable outcome.

Methods: One hundred and eight patients (55 male, 53 female; mean age?=?40.8, SD 14.2 years) rated pain (NRS) and disability [Oswestry Disability Index (ODI)] before the first treatment and 1 week, 1, 3, 6, and 12 months later. Hierarchical cluster analysis identified recovery patterns based on NRS data. Clusters were compared for age, NRS and ODI at baseline, pain reduction in the first week, gender, radicular signs and traumatic onset using one-way ANOVA (post hoc Bonferroni) and χ² tests.

Results: The cluster analysis revealed four clusters: moderate baseline pain/fast recovery; high baseline pain/fast recovery; high baseline pain/persistent mild pain; high baseline pain/persistent high pain. These clusters differed in baseline NRS [F(3,104)?=?39.61, p?F(3,104)?=?12.17, p?F(3,104)?=?11.51, p?χ²(3)?=?9.20, p?=?0.027].

Conclusions: These results suggest that an initial and regularly repeated assessment of pain intensity and functional disability is important. Initial pain intensity does not seem to be a prognostic factor per se, as it did not negatively affect recovery provided that it decreased early in treatment.

• Implications for Rehabilitation

• Prediction of outcome is particularly important in patients with a first episode of acute LBP as one third did not completely recover.

• Pain intensity and functional disability should be initially assessed and regularly repeated in the first phase of treatment.

• High initial pain intensity and disability combined with small pain reduction during the first week might predict unfavorable outcome and require adequate treatment.

     

Experimental Low Back Pain Decreased Trunk Muscle Activity in Currently Asymptomatic Recurrent Low Back Pain Patients During Step Tasks

Low back pain (LBP) patients show reorganized trunk muscle activity but if similar changes are manifest in recurrent LBP (R-LBP) patients during asymptomatic periods remains unknown. In 26 healthy and 27 currently asymptomatic R-LBP participants electromyographic activity (EMG) was recorded from trunk and gluteal muscles during series of stepping up and down on a step bench before and during experimentally intramuscular induced unilateral and bilateral LBP. Pain intensity was assessed using numeric rating scale (NRS) scores. Root mean square EMG (RMS-EMG) normalized to maximal voluntary contraction EMG and pain-evoked differences from baseline (ΔRMS-EMG) were analyzed. Step task duration was calculated from foot sensors. R-LBP compared with controls showed higher baseline RMS-EMG and NRS scores of experimental pain (P?<?.05). In both groups, bilateral compared with unilateral experimental NRS scores were higher (P?<?.001) and patients compared with controls reported higher NRS scores during both pain conditions (P?<?.04). In patients, unilateral pain decreased ΔRMS-EMG in the Iliocostalis muscle and bilateral pain decreased ΔRMS-EMG in all back and gluteal muscles during step tasks (P?<?.05) compared with controls. In controls, bilateral versus unilateral experimental pain induced increased step task duration and trunk RMS-EMG whereas both pain conditions decreased step task duration and trunk RMS-EMG in R-LBP patients compared with controls (P?<?.05).

Can the LANSS scale be used to classify pain in chronic cancer pain trials?

Purpose

The Leeds Assessment of Neuropathic Symptoms and Signs (LANSS) scale was developed to differentiate pain of predominantly neuropathic or nociceptive origin. The aim of this study was to determine whether the LANSS scale was an appropriate tool to classify pain in a trial of patients with advanced cancer and chronic refractory pain.

Methods

Clinician assessment of pain type (neuropathic or nociceptive) was used to determine the sensitivity and specificity of LANSS scores in 112 trial participants. Those classified as "mixed" or of uncertain aetiology were excluded. We undertook several analyses in an attempt to improve the LANSS scale and better diagnose pain type for our specific dataset.

Results

There was strong association between the LANSS score and a diagnosis of neuropathic versus nociceptive pain, p?<?0.001. When the clinical assessment was compared with the LANSS scale, the overall accuracy was 94 % (79/84). The 5 false negatives and no false positives resulted in a sensitivity of 0.86 (0.70, 0.95), specificity of 1 (0.93, 1), positive predictive value of 1 (0.88, 1) and negative predictive value of 0.91 (0.80, 0.97). The negative likelihood ratio was 0.14 (0, 0.32). The scale had good discriminant and construct validity. Reliability was assessed via internal consistency with Cronbach's α?=?0.76, similar to that of the original validation study (α?=?0.74). None of the new scales developed was better at differentiating pain type.

Conclusions

The LANSS scale predicted well for pain type in a cancer population and is a useful tool for classifying pain in cancer pain trials.     

Cryoneurolysis of alveolar nerves for chronic dental pain: A new technique and a case series

Background

Chronic neuropathic dental pain has a poor prognosis with a low chance of significant spontaneous improvement. Local or oral therapies may be efficient, however short in terms of duration with potential side effects. Cryoneurolysis has been described to prevent acute postoperative pain or to treat some chronic pain conditions; however, application to dental orofacial pain has not been reported so far.

Case Series

Following a positive diagnostic block on the corresponding alveolar nerve, neuroablation was performed using a cryoprobe on three patients suffering from persistent pain after a dental extraction and 1 after multiple tooth surgeries. The effect of treatment was assessed using a Pain Numeric Rating Scale (NRS) and determined by changes in medication dosage and quality of life at day 7 and 3 months. Two patients experienced more than 50% of pain relief at 3 months, 2 by 50%. One patient was able to wean off pregabalin medication, one decreased amitriptyline by 50%, and one decreased tapentadol by 50%. No direct complications were reported. All of them mentioned improvement in sleep and quality of life.

Conclusion

Cryoneurolysis on alveolar nerves is a safe and easy-to-use technique allowing prolonged neuropathic pain relief after dental surgery.     

Efficacy of the Sustained-Release Hydromorphone in Neuropathic Pain Management: Pooled Analysis of Three Open-Label Studies

ABSTRACT

This pooled analysis was designed to determine whether the analgesic response to treatment with OROS® hydromorphone, as measured by the “pain on average” scale of the Brief Pain Inventory (BPI), was different in patients with neuropathic pain compared to those with nociceptive pain, after adjusting for differences in baseline characteristics. Three open-label studies on patients with neuropathic and nociceptive malignant and nonmalignant chronic pain were analyzed. A mixed model for repeated measures linear regression analysis was used to compare the effect of OROS® hydromorphone on patients with neuropathic and nociceptive pain, adjusting for potentially confounding factors. Data from patients with pure neuropathic pain and mixed pain were also compared. Safety and tolerability was assessed by recording the number of adverse events. The primary outcome was “pain on average” (BPI item 5) over time. Secondary outcomes were the effect of OROS® hydromorphone on other BPI items including “pain relief” and “interference with sleep.” Patients with neuropathic pain showed a similar response to treatment with OROS® hydromorphone to those patients with nociceptive pain. There was no statistically significant difference between the pain groups (difference between groups ?0.552 at visit 7; P = .060 for overall difference between groups). For some outcome variables, treatment was more effective for patients with neuropathic pain. The treatment was generally well tolerated. This pooled analysis shows that treatment with OROS® hydromorphone had similar efficacy for neuropathic and nociceptive pain.     

Topical ambroxol for the treatment of neuropathic pain

Background

Neuropathic pain is difficult to treat, and the available options are often inadequate. The expectorant ambroxol also acts as a strong local anaesthetic and blocks sodium channels about 40 times more potently than lidocaine. It preferentially inhibits the channel subtype Na_v 1.8, which is expressed especially in nociceptive C-fibres. In view of the low toxicity of ambroxol, it seemed reasonable to try using it for the treatment of neuropathic pain that failed to respond to other standard options.

Material and methods

The medical records of seven patients with severe neuropathic pain and pain reduction following topical ambroxol treatment are reported retrospectively. As standard therapies had not proved sufficient, a topical ambroxol 20?% cream was repeatedly applied by the patients in the area of neuropathic pain.

Results

The reasons for neuropathic pain were postherpetic neuralgia (2?×), mononeuropathy multiplex, phantom pain, deafferentation pain, postoperative neuralgia and foot neuropathy of unknown origin. The individual mean pain intensity reported was between 4 and 6/10 (NRS), maximum pain at 6–10/10 (NRS). The pain reduction achieved individually following ambroxol cream was 2–8 points (NRS) within 5–30 min and lasted for 3–8 h. Pain attacks were reduced in all five patients presenting with this problem. Four patients with no improvement after lidocaine 5?% and one patient with no response to capsaicin 8?% nevertheless experienced a pain reduction with topical ambroxol. No patient reported any side effects or skin changes during a treatment that has since been continued for up to 4 years.

Conclusion

Ambroxol acts as a strong local anaesthetic and preferentially inhibits the nociceptively relevant sodium channel subtype Na_v 1.8. For the first time, we report below on a relevant pain relief following topical ambroxol 20?% cream in patients with neuropathic pain. In view of the positive side effect profile, the clinical benefit in patients with pain should be investigated further.

     

Cancer Pain With a Neuropathic Component: A Cross-sectional Study of Its Clinical Characteristics,Associated Psychological Distress,Treatments, and Predictors at Referral to a Cancer Pain Clinic

Context

In patients with cancer pain, identifying a neuropathic pain component (NPC) may inform the selection of subsequent therapeutic interventions.

The effect of Spinal Cord Stimulation in mice with chronic neuropathic pain after partial ligation of the sciatic nerve

The effect of Spinal Cord Stimulation (SCS) in chronic neuropathic pain is inversely related to the severity of mechanical allodynia and the underlying mechanisms are poorly understood. To understand these mechanisms further we aimed to develop a model of SCS in a neuropathic mouse. Further, the CatWalk analysis, which is claimed to be an improved test for mechanical allodynia and therapeutic intervention, was used to analyze the effect of SCS on mechanical allodynia. Male C57BL/6 mice (N = 31) underwent partial ligation of the sciatic nerve. After 14 days an electrode was implanted and the effect of SCS (N = 22) on mechanical allodynia was tested. Unligated mice (N = 8) also received SCS. Behavioral analysis was performed using von Frey filaments and the CatWalk system. The withdrawal threshold showed a significant decrease which remained over time. Changes in CatWalk parameters were observed after 2 days, but tended to diminish during the next 14 days. Thirty minutes of SCS resulted in a 100% response and return to pre-neuropathy levels of the withdrawal threshold. The effect of SCS on the withdrawal threshold was comparable for the most severe and milder allodynic animals. SCS did not affect any of the CatWalk parameters in all mice. In conclusion, we developed a model of SCS in a chronic neuropathic pain C57BL/6 mouse. The CatWalk gait analysis does not result in the detection of behavioral changes to SCS in mice with chronic neuropathic pain and control animals. This model allows future molecular-genetic studies on the mechanisms of SCS in chronic neuropathic pain.     

Psychische Veränderungen bei Patienten mit komplexem regionalem Schmerzsyndrom (CRPS)

Question

Do comorbid psychological disorders, dysfunctional pain processing, and psychosocial pain coping occur with complex regional pain syndrome (CRPS) and is a connection between clinical and psychological manifestations apparent?

Methods

In addition to securing information on case histories and performing clinical neurological examinations of chronic CRPS patients, the structured clinical interview (SCID), pain perception scale, and the Kiel Pain Inventory were employed.

Results

The structured clinical interview revealed evidence of a depressive episode in 65% of CRPS patients. Pain perception is similar to neuropathic pain syndromes and patient history revealed a slightly increased frequency of anxiety and affective disorders. Depressive syndrome occurred significantly more often in right-sided CRPS; otherwise, there were no significant correlations between medical history, clinical examination, and frequency of psychological disorders. However, CRPS patients with allodynia manifest clinical signs of special psychological distress.

Conclusion

In chronic CRPS depressive syndrome frequently develops and psychological treatment can be recommended.