M. van Kleef

Clinical course of non-specific low back pain: A systematic review of prospective cohort studies set in primary care

Non‐specific low back pain is a relatively common and recurrent condition for which at present there is no effective cure. In current guidelines, the prognosis of acute non‐specific back pain is assumed to be favourable, but this assumption is mainly based on return to function. This systematic review investigates the clinical course of pain in patients with non‐specific acute low back pain who seek treatment in primary care.

Effects and side effects of a percutaneous thermal lesion of the dorsal root ganglion in patients with cervical pain syndrome

&NA; Twenty consecutive patients with intractable chronic pain in the cervical region were treated with a radiofrequency lesion of the dorsal root ganglion on level C4, C5 or C6. Electromyography (EMG) and sensory evoked potentials (SEP) were recorded before and 3 weeks after the radiofrequency lesion. Side effects were studied 3 weeks, 6 weeks and 3 months after the procedure. Pain scores were evaluated on Numeric Rating Scales (NRS) before and 6 weeks after treatment. The patient was interviewed 3, 6 and 9 months after the radiofrequency lesion. The most common side effect was burning pain in the dermatome of the treated nerve root. Hyposensibility in the dermatome was noticed in 35% of patients. Except in 1 patient, these side effects had disappeared 6 weeks after treatment. The EMG showed no signs of denervation. One SEP recording remained abnormal after treatment. There was initial pain relief in 75% of patients after 3 months and in 50% of the patients after 6 months. In conclusion, this study did not reveal any signs of motor denervation after a percutaneous partial rhizotomy. There were no long‐term signs of deafferentation. Initial pain relief was found in 75% of patients, but there was a marked tendency for pain to recur in a period from 3 to 9 months after treatment.

Percutaneous pulsed radiofrequency treatment of the cervical dorsal root ganglion in the treatment of chronic cervical pain syndromes: a clinical audit.

Cervicogenic headache and cervicobrachialgia are frequent diagnoses of chronic cervical pain. After failure of conservative treatment, an interventional approach may be indicated in the absence of any indication for causal surgical treatment. The pulsed radiofrequency (PRF) technique exposes the nerve to a high‐frequency electric field while the temperature of the electrode tip does not exceed 42°C. This method is thought to be nondestructive and almost free of neurologic side effects and complications. Our extended pilot study was performed to confirm the perceived efficacy of PRF for short‐ and long‐term relief of chronic cervical pain. We carried out a clinical audit of the first 18 patients treated with PRF at the cervical dorsal root ganglion. An independent evaluator reviewed the medical records. Patients with good clinical results at 8 weeks were evaluated for long‐term effect (> 6 months), based on a 7‐point Likert scale. Thirteen patients (72%) showed short‐term clinical success (≥ 50% pain relief). Mean follow‐up was 19.4 months (SD 8.9 months), maximum 2.5 years. The duration of satisfactory pain relief (6 or 7 on the Likert scale) varied between 2 and over 30 months, with a mean duration of 9.2 months (SD 11.2 months). Kaplan‐Meier analysis illustrated that 50% of patients experienced success 3 months after treatment. We could not identify predictive variables for clinical outcome. None of the patients reported post‐treatment neuritis or other adverse events. To our knowledge, this is the first documented series of chronic cervical pain syndromes treated with PRF. Satisfactory pain relief of at least 50% was achieved in 13 of 18 (72%) patients at 8 weeks. More than one year after treatment, six patients (33%) continue to rate treatment outcome as good or very good. No side effects were reported. j

Predictors of physical and emotional recovery 6 and 12 months after surgery

A proportion of patients do not recover fully from surgery or they develop chronic postsurgical pain. The aim of this study was to examine the incidence and predictors of unfavourable long‐term outcome after surgery using a prospective cohort design.

Experimental Spinal Cord Stimulation and Neuropathic Pain: Mechanism of Action, Technical Aspects, and Effectiveness

Abstract:  Spinal cord stimulation (SCS) is a valuable treatment for chronic intractable neuropathic pain. Although SCS has gone through a technological revolution over the last four decades, the neurophysiologic and biochemical mechanisms of action have only been partly elucidated. Animal experimental work has provided some evidence for spinal as well as supraspinal mechanisms of neuropathic pain relief of SCS. A SCS computer model of the electrical properties of the human spinal cord revealed many basic neurophysiologic principles that were clinically validated later on. The main question in clinical SCS is how to further improve the effectiveness of SCS as there is still a significant failure rate of 30%. In this context, experimental studies are needed to elucidate which target pain neuron(s) are involved, as well as with what exact electrical stimulation this target neuron can be influenced to produce an optimal supapression of neuropathic pain. This article reviews the basic clinical and experimental technical aspects in relation to the effectiveness of SCS in view of recent understanding of the dorsal horn pain circuit involved. These data may then result in experiments needed for an improved understanding of the mechanisms underlying SCS and consequently lead to improvement and increased effectiveness of SCS in neuropathic pain as a clinical therapy.

Application of radiofrequency treatment in practical pain management: state of the art.

Abstract: Many therapeutic interventions for chronic pain are available, and decisions about optimal management are not easy to make. Radiofrequency (RF) treatment is classified as a percutaneous minimal invasive procedure for patients who do not respond to appropriate medical and physical therapy. Although RF treatment is widely used differences in current practice exist due to ongoing controversies.

Differential GABAergic disinhibition during the development of painful peripheral neuropathy

An impaired spinal GABAergic inhibitory function is known to be pivotal in neuropathic pain (NPP). At present, data concerning time-dependent alterations within the GABAergic system itself and post-synaptic GABA(A) receptor-mediated inhibitory transmission are highly controversial, likely related to the experimental NPP model used. Furthermore, it is unknown whether the severity of NPP is determined by the degree of these GABAergic disturbances. In the present study we therefore examined in one experimental animal model whether anatomical changes within the spinal GABAergic system and its GABA(A) receptor-mediated inhibitory function are gradually aggravated during the development of partial sciatic nerve injury (PSNL)-induced NPP and are related to the severity of PSNL-induced hypersensitivity. Three and 16 days after a unilateral PSNL (early and late NPP, respectively), GABA-immunoreactivity (GABA-IR) and the number of GABA-IR neuronal profiles were determined in Rexed laminae 1-3 of lumbar spinal cord cryosections. Additionally, the efficiency of dorsal horn GABA(A) receptor-induced inhibition was examined by cation chloride cotransporter 2 (KCC2) immunoblotting. NPP-induced hypersensitivity was only observed at the ipsilateral side, both at early and late time points. During early NPP, a decrease in ipsilateral dorsal horn GABA-IR was observed without alterations in the number of GABA-IR neuronal profiles or KCC2 protein levels. In contrast, bilateral increases in spinal GABA-IR accompanied by an unchanged number of GABA-IR interneurons were observed during late NPP. This was furthermore attended with decreased ipsilateral KCC2 levels. Moreover, the degree of hypersensitivity was not related to disturbances within the spinal GABAergic system at all time points examined. In conclusion, our anatomical data suggest that a dysfunctional GABA production is likely to be involved in early NPP whereas late NPP is characterized by a combined dysfunctional GABA release and decreased KCC2 levels, the latter suggesting an impaired GABA(A) receptor-mediated inhibition.

Pain prevalence and its determinants after spinal cord injury: a systematic review.

Pain prevalence studies are important as they illustrate the magnitude of pain problems in a certain patient population, such as patients living with a spinal cord injury (SCI). Strikingly, reported pain prevalence rates in SCI patients are found to vary greatly, while determinants for the differences between pain prevalence reports remain unclear. We here aim to identify determinants for the differences (heterogeneity) in pain prevalence reports through a systematic review of all SCI pain prevalence reporting studies. Literature search was done using Medline, Cumulative Index to Nursing and Allied Health Literature, ISI Web of Knowledge and Embase. Data abstraction was performed while blinded and was followed by meta‐(regression)‐analyses. We identified 82 studies. Study design‐related determinants of SCI pain prevalence reports were pain definition strictness (mild, moderate or high), primary study goal (pain study or not), data source (retrospective or not), and in a limited number of cases response/attrition rates. While correcting for these items, population characteristics correlating with pain prevalence rates were both proportion of patients with a depression and average time after injury (positive correlations). Between‐study heterogeneity may remain even after the identification/correction of above‐mentioned causes of heterogeneity.Pain after SCI does seem to relate to the duration of the injury and depression, yet major causes of bias in reported pain prevalence are found to be related to the primary study goal (pain study or not), choice of pain definition and the use of retrospective data.

Spinal Cord Stimulation and Pain Relief in Painful Diabetic Peripheral Neuropathy: A Prospective Two-Center Randomized Controlled Trial

OBJECTIVE Painful diabetic peripheral neuropathy (PDPN) is a common complication of diabetes mellitus. Unfortunately, pharmacological treatment is often partially effective or accompanied by unacceptable side effects, and new treatments are urgently needed. Small observational studies suggested that spinal cord stimulation (SCS) may have positive effects. RESEARCH DESIGN AND METHODS We performed a multicenter randomized clinical trial in 36 PDPN patients with severe lower limb pain not responding to conventional therapy. Twenty-two patients were randomly assigned to SCS in combination with the best medical treatment (BMT) (SCS group) and 14 to BMT only (BMT group). The SCS system was implanted only if trial stimulation was successful. Treatment success was defined as ≥50% pain relief during daytime or nighttime or “(very) much improved” for pain and sleep on the patient global impression of change (PGIC) scale at 6 months. RESULTS Trial stimulation was successful in 77% of the SCS patients. Treatment success was observed in 59% of the SCS and in 7% of the BMT patients (P < 0.01). Pain relief during daytime and during nighttime was reported by 41 and 36% in the SCS group and 0 and 7% in the BMT group, respectively (P < 0.05). Pain and sleep were “(very) much improved” in 55 and 36% in the SCS group, whereas no changes were seen in the BMT group, respectively (P < 0.001 and P < 0.05). One SCS patient died because of a subdural hematoma. CONCLUSIONS Treatment success was shown in 59% of patients with PDPN who were treated with SCS over a 6-month period, although this treatment is not without risks.

Spinal cord stimulation of dorsal columns in a rat model of neuropathic pain: evidence for a segmental spinal mechanism of pain relief.

Summary Spinal cord stimulation of the dorsal columns in treatment of experimental neuropathic pain acts through a segmental spinal site of action. ABSTRACT Although spinal cord stimulation (SCS) of the dorsal columns is an established method for treating chronic neuropathic pain, patients still suffer from a substantial level of pain. From a clinical perspective it is known that the location of the SCS is of pivotal importance, thereby suggesting a segmental spinal mode of action. However, experimental studies suggest that SCS acts also through the modulation of supraspinal mechanisms, which might suggest that the location is unimportant. Here we investigated the effect of the rostrocaudal location of SCS stimulation and the effectiveness of pain relief in a rat model of chronic neuropathic pain. Adult male rats (n = 45) were submitted to a partial ligation of the sciatic nerve. The majority of animals developed tactile hypersensitivity in the nerve lesioned paw. All allodynic rats were submitted to SCS (n = 33) for 30 minutes (f = 50 Hz; pulse width 0.2 ms). In one group (n = 16) the electrodes were located at the level where the injured sciatic nerve afferents enter the spinal cord (T13), and in a second group (n = 17) the electrodes were positioned at more rostral levels (T11) as verified by X‐ray. A repositioning experiment of electrodes from T12 to T13 was performed in 2 animals. Our data demonstrate that SCS of the dorsal columns at the level where the injured fibers enter the spinal cord dorsal horn result in a much better pain‐relieving effect than SCS at more rostral levels. From this we conclude that SCS in treatment of neuropathic pain acts through a segmental spinal site of action.