Invasive Treatments for Complex Regional Pain Syndrome in Children and Adolescents

Long-term biopsychosocial issues and health-related quality of life in young adolescents and adults treated for childhood Complex Regional Pain Syndrome, type 1

OBJECTIVES

Treatment for childhood Complex Regional Pain Syndrome (CRPS) is associated with long-term recovery. The present study aimed to investigate the long-term biopsychosocial status and quality of life in young adolescents and adults after the treatment of childhood CRPS.

METHODS

A 4 year follow-up of individuals with childhood-CRPS, type 1 (n=22; age:12 years (years) [median] at treatment and 17 years at follow-up) was completed. Biopsychosocial status and quality of life were assessed with structured interviews, using the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), the Strengths and Difficulties Questionnaire (SDQ), the Pediatric Pain Coping Inventory (PPCI), and the Pediatric Quality of Life Inventory (PedsQL). Comparisons were made with normative samples of age-matched controls.

RESULTS

CRPS at follow-up was still present in seven out of 22, and non-CRPS pain symptoms were found in 12 out of 22 individuals. Signs of mental health pain-related problems, including phobias and obsessive-compulsive disorder, were observed in ten out of 19 individuals. Mental well-being, social functioning, and quality of life (SDQ and PedsQL) were independent of pain status (p>0.05). Adaptive pain coping strategies were utilized regardless of pain status (PPCI). Social functioning (p<0.01) and the quality of life (p=0.01) were attenuated and statistically significantly poorer than healthy age-matched young adults but better than for fibromyalgia subjects.

CONCLUSIONS

A subset of individuals treated for childhood-CRPS, type 1 experiences long-term consequences of persistent pain, a decrease in quality of life indicators, and demonstrates significant psychosocial issues. Childhood-CRPS is suggested to be associated with long-term psychosocial consequences and poorer quality of life than found in age-related healthy peers. Subjects treated for childhood CRPS may need a longer clinical follow-up attempting to preclude relapse of CRPS and non-CRPS pain.

Complex Regional Pain Syndrome: A Comprehensive Review

Complex regional pain syndrome (CRPS) is a chronic pain condition often involving hyperalgesia and allodynia of the extremities. CRPS is divided into CRPS-I and CRPS-II. Type I occurs when there is no confirmed nerve injury. Type II is when there is known associated nerve injury. Female gender is a risk factor for developing CRPS. Other risk factors include fibromyalgia and rheumatoid arthritis. Unfortunately, the pathogenesis of CRPS is not yet clarified. Some studies have demonstrated different potential pathways. Neuropathic inflammation, specifically activation of peripheral nociceptors of C-fibers, has been shown to play a critical role in developing CRPS. The autonomic nervous system (ANS) is involved. Depending on whether it is acute or chronic CRPS, norepinephrine levels are either decreased or increased, respectively. Some studies have suggested the importance of genetics in developing CRPS. More consideration is being given to the role of psychological factors. Some association between a history of depression and/or post-traumatic stress disorder (PTSD) and the diagnosis of CRPS has been demonstrated. Treatment modalities available range from physical therapy, pharmacotherapy, and interventional techniques. Physical and occupational therapies include mirror therapy and graded motor imagery. Medical management with non-steroidal anti-inflammatory drugs (NSAIDs) has not shown significant improvement. There have been supporting findings in the use of short-course steroids, bisphosphonates, gabapentin, and ketamine. Antioxidant treatment has also shown some promise. Other pharmacotherapies include low-dose naltrexone and Botulinum toxin A (BTX-A). Sympathetic blocks are routinely used, even if their short- and long-term effects are not clear. Finally, spinal cord stimulation (SCS) has been used for decades. In conclusion, CRPS is a multifactorial condition that still requires further studying to better understand its pathogenesis, epidemiology, genetic involvement, psychological implications, and treatment options. Future studies are warranted to better understand this syndrome. This will provide an opportunity for better prevention, diagnosis, and treatment of CRPS.

Use of bisphosphonates in a retrospective case series of children and adolescents with complex regional pain syndrome

BACKGROUND

There is increasing evidence for the use of bisphosphonates to treat Complex Regional Pain Syndrome in adults. However, there are scarce data for their use in children with Complex Regional Pain Syndrome.

AIM

This retrospective case series aimed to analyze the effects of intravenous bisphosphonate use in children and adolescents with Complex Regional Pain Syndrome enrolled in a multidimensional pain treatment program.

METHODS

We analyzed the data of 16 patients (15 females and 1 male, mean age 14 ± 3 years) who received infusions of zoledronic acid (0.015 ± 0.0044mg/kg), pamidronate (0.72 ± 0.17mg/kg), or both depending on their initial response between October 2014 and December 2019. The primary endpoint of the study was the patient's global impression of change. Secondary outcomes included pain intensity, physical function, role function (school attendance), need for pain medications, and adverse effects.

RESULTS

Nine of 16 patients reported meaningful improvements (global impressions of change of 84% or higher) at a median follow-up time of 16 (8-21) months after their last infusion of bisphosphonates. There were also meaningful reductions in pain intensity and the need for pain medications. There was an increase in the proportion of patients with minimal or without physical disability, and almost all patients normalized their school activities. Thirteen patients (81%) reported adverse effects, mostly flu-like symptoms, for a few days after the infusion.

CONCLUSION

The use of bisphosphonate infusions may represent an effective treatment option for children with Complex Regional Pain Syndrome, not responding to multidisciplinary pain treatment programs.

Ultrasound-guided popliteal sciatic nerve block in a pediatric patient with complex regional pain syndrome: a case report

In the pediatric population, complex regional pain syndrome (CRPS) is a challenging condition that leads to chronic psychosocial dysfunction. This case is of a 12-year-old male patient, 50 kg, who, after twisting his right ankle, started to present intense pain. Without adequate diagnosis and treatment, his family sought a pain specialist. During the evaluation, a change in sensitivity and temperature was observed, besides hyperalgesia, allodynia, redness, edema, and motor dysfunction, being diagnosed with CRPS. Ultrasound-guided sciatic blocks were performed on the affected limb, increasing the interval between crises, reducing pain intensity, and promoting a return to daily activities.

Utility of Electrical Neuromodulation for Treating Chronic Pain Syndromes in the Pediatric Setting: A Systematic Review

OBJECTIVES

Chronic pain syndromes in children can carry significant threats to psychological well-being, opioid overuse, functional impairments, and severe disability. While several high-level studies, almost exclusively in adults, have demonstrated the utility of implantable electrical neuromodulation systems for treating various chronic pain syndromes, there exists a paucity of pediatric-specific evidence. Unfortunately, evidence and practice patterns established from adults may not be fully translatable to children given differences in disease manifestations and anatomical variances.

MATERIALS AND METHODS

We performed a systematic review using conventional PRISMA methodology to identify studies reporting use of implantable electrical neuromodulation systems in children. The primary outcome parameters collected were analgesic relief and functional benefits. Additionally, previous interventions attempted, neuromodulation parameters, and limitations were collected as reported.

RESULTS

A total of 11 studies was identified, which described 19 patients who were refractory to multidisciplinary pain management strategies. The cohort was mostly adolescent (18/19), suffered from CRPS (14/19), and received SCS (17/19). Nearly all patients, both those with CRPS (13/14) and non-CRPS conditions (4/4), reported significant pain relief and functional recovery following neuromodulation. There were no severe complications reported; limitations included suboptimal benefit or loss of analgesia (3/19), lead or device revision (3/19), and subcutaneous infection (1/19), all of which were congruent with adult outcomes.

CONCLUSION

There exist children with chronic pain refractory to standard of care approaches who could be considered for neuromodulation interventions. The existing data, which was limited and from a low tier of evidence, suggest that these interventions are relatively safe and provide meaningful pain reduction and functional improvements. While not previously reported, we recommend careful consideration of the pubertal growth spurt prior to device lead placement-if reasonable and appropriate-given the possibility of inferior lead migration with physiologic growth in patients with SCS devices or foraminal extrusion in patients with dorsal root ganglion stimulation devices.

Localized sympathectomy reduces peripheral nerve regeneration and pain behaviors in 2 rat neuropathic pain models

Previous studies have shown that the peripheral nerve regeneration process is linked to pain in several neuropathic pain models. Other studies show that sympathetic blockade may relieve pain in some pain models and clinical conditions. This study examined reduction in peripheral nerve regeneration as one possible mechanism for relief of neuropathic pain by sympathetic blockade. A "microsympathectomy," consisting of cutting the gray rami containing sympathetic postganglionic axons where they enter the L4 and L5 spinal nerves, reduced mechanical hypersensitivity in 2 different rat neuropathic pain models. In the spinal nerve ligation model, in which some functional regeneration and reinnervation of the ligated spinal nerve can be observed, microsympathectomy reduced functional and anatomical measures of regeneration as well as expression of growth-associated protein 43 (GAP43), a regeneration-related protein. In the spared nerve injury model, in which functional reinnervation is not possible and the futile regeneration process results in formation of a neuroma, microsympathectomy reduced neuroma formation and GAP43 expression. In both models, microsympathectomy reduced macrophage density in the sensory ganglia and peripheral nerve. This corroborates previous work showing that sympathetic nerves may locally affect immune function. The results further highlight the challenge of improving pain in neuropathic conditions without inhibiting peripheral nerve regeneration that might otherwise be possible and desired.

Median Neuropathy After Blood Draw Mimics Painful Clenched Fist Syndrome in a Child

Background: Clenched fist syndrome is a rare disorder, often attributed to a conversion disorder without anatomic basis. Here, we review the literature surrounding clenched fist syndrome and challenge the assumption it is always psychiatric in origin, via description of a case of clenched fist syndrome responsive to surgical nerve decompression. Methods: An unusual case of clenched fist syndrome is reviewed and discussed. Results: A child presenting with clenched fist syndrome failed conservative measures consisting of formal hand therapy, multidisciplinary pain management, and psychiatric treatment. On clinical examination, she had findings consistent with median nerve entrapment. After undergoing surgical decompression of the median nerve in the forearm and carpal tunnel, the clenched fist resolved immediately. Conclusions: Nerve compression may be an unrecognized factor underlying some cases of clenched fist syndrome. Evaluation by a hand surgeon or a hand therapist skilled in the detection of peripheral nerve entrapment or injury should be considered as part of the workup for this rare disorder.

Interventional procedures in children and adolescents with chronic non-cancer pain as part of a multidisciplinary pain treatment program

BACKGROUND

Interventional procedures are part of multidisciplinary pain treatment programs to treat chronic non-cancer pain conditions in children and adolescents. However, the real benefit of these interventions remains unclear.

AIMS

The aim of this study was to analyze the potential benefits of the interventional procedures in children and adolescents with chronic non-cancer pain in the setting of a multidisciplinary pain treatment program.

METHODS

We retrospectively reviewed the charts of 98 children and adolescents receiving 314 diagnostic or therapeutic interventional procedures. We applied the following definitions of efficacy Short-term positive therapeutic effect: block that produced a minimum of 50% reduction in pain intensity for at least 4 weeks. Long-term positive therapeutic effect: a patient with a minimum of 50% reduction in pain intensity for at least 6 months Full recovery: a patient free of pain, not taking analgesics with normal physical and role functioning 6 months after the last procedure.

RESULTS

Seventy-six of 112 diagnostic blocks (68%) were associated with a 50% reduction in pain intensity for at least 4 weeks after the procedure. One hundred and sixty-six of 202 therapeutics blocks (82%) were associated with a short-term benefit. Seventy-two of 98 patients (73%) referred a 50% reduction in their pain intensity (17%) or had full recovery 6 months after the procedures (56%) and a MPTP. Psychiatric comorbidity and more advanced age were factors associated with failure to respond to interventional procedures.

CONCLUSION

The use of interventional procedures may represent a valid therapeutic option, associated with positive clinical outcomes within a multidisciplinary program.

Continuous Regional Anesthesia and Inpatient Rehabilitation for Pediatric Complex Regional Pain Syndrome

BACKGROUND

Evidence supports treatment of pediatric complex regional pain syndromes (CRPS) with physical and occupational therapy and cognitive-behavioral therapy. Some patients have persistent pain and/or limb dysfunction despite these treatments. We performed a retrospective study of pediatric patients with CRPS treated by continuous epidural or peripheral perineural local anesthetic infusions along with inpatient rehabilitation at Boston Children's Hospital.

METHODS

After approval from the institutional review board, electronic medical records were reviewed for patients treated between September 2003 and September 2014. Primary outcomes were pain and functional scores. Data were collected at the first encounter, at follow-up visits between 4 months before and after admission, and daily while inpatient. Changes over time were assessed using Wilcoxon tests with Dunn corrections. Clinical significance of benefit or harm was assessed by the method of Jacobson and Truax. Response predictors were analyzed using linear mixed models and exploratory logarithmic regression analyses.

RESULTS

Pain, function, and disability scores improved during hospitalization and in follow-up over a 4-month period. Seventy percent of patients achieved clinically significant benefit (56% for pain reduction and 40% increased functionality, respectively). Univariate and adjusted predictors of favorable outcome included preadmission resting Numeric Pain Rating Scale score of less than 6 (odds ratio, 5.0; P = 0.0164 and subsequent attendance at the Pediatric Pain Rehabilitation Center at Boston Children's Hospital (odds ratio, 5.0; P = 0.0206). Mean pain scores greater than 3 during the regional anesthesia infusion predicted less favorable outcome.

CONCLUSIONS

Continuous regional anesthesia may be an option to facilitate intensive rehabilitation for selected pediatric patients with CRPS. Further research should help clarify the role of regional anesthesia in a comprehensive management program.

Trends in Medicalization of Children with Amplified Musculoskeletal Pain Syndrome

Objective

The objective of this survey was to describe trends over time in medicalization of children with Amplified Musculoskeletal Pain Syndrome (AMPS).

Design

A retrospective evaluation was conducted using self-reported data from patients presenting to the pain clinic between January 1, 2008 and December 31, 2014, who were diagnosed with AMPS.

Setting and Subjects

This was a medical record review of 899 subjects ages 3-20 presenting with Amplified Musculoskeletal Pain Syndrome. Subjects were included if they presented to a single tertiary specialized clinic and obtained a diagnosis of AMPS between January 1, 2008 and December 31, 2014.

Methods

Information collected from subjects' medical records included: past medications, current outpatient medications, procedures, aids, therapies, studies, professionals seen, hospitalizations, and surgeries. Trends in medicalization were analyzed by year of initial visit.

Results

Medication use, procedures, studies, therapies, professionals seen, hospitalizations, and surgeries in children with AMPS all increased significantly by year ( P  < 0.001). The degree of physical dysfunction, pain, and the use of aids did not significantly increase.

Conclusions

Children with amplified musculoskeletal pain syndrome are becoming increasingly medicalized. Increased medicalization introduces risk of iatrogenic injury and burdens families with unnecessary medical costs. The significant increase in medicalization of children with AMPS is not related to an increase in patient reported pain, which is evidenced by the lack of significant increase in patients' pain score, pain duration, or functional disability at the time of their initial evaluation.

Persistent postsurgical pain in children and young people: prediction, prevention, and management

Ensuring optimum preoperative and postoperative pain management should always be a priority in children.

Localized Sympathectomy Reduces Mechanical Hypersensitivity by Restoring Normal Immune Homeostasis in Rat Models of Inflammatory Pain

Some forms of chronic pain are maintained or enhanced by activity in the sympathetic nervous system (SNS), but attempts to model this have yielded conflicting findings. The SNS has both pro- and anti-inflammatory effects on immunity, confounding the interpretation of experiments using global sympathectomy methods. We performed a "microsympathectomy" by cutting the ipsilateral gray rami where they entered the spinal nerves near the L4 and L5 DRG. This led to profound sustained reductions in pain behaviors induced by local DRG inflammation (a rat model of low back pain) and by a peripheral paw inflammation model. Effects of microsympathectomy were evident within one day, making it unlikely that blocking sympathetic sprouting in the local DRGs or hindpaw was the sole mechanism. Prior microsympathectomy greatly reduced hyperexcitability of sensory neurons induced by local DRG inflammation observed 4 d later. Microsympathectomy reduced local inflammation and macrophage density in the affected tissues (as indicated by paw swelling and histochemical staining). Cytokine profiling in locally inflamed DRG showed increases in pro-inflammatory Type 1 cytokines and decreases in the Type 2 cytokines present at baseline, changes that were mitigated by microsympathectomy. Microsympathectomy was also effective in reducing established pain behaviors in the local DRG inflammation model. We conclude that the effect of sympathetic fibers in the L4/L5 gray rami in these models is pro-inflammatory. This raises the possibility that therapeutic interventions targeting gray rami might be useful in some chronic inflammatory pain conditions.

SIGNIFICANCE STATEMENT

Sympathetic blockade is used for many pain conditions, but preclinical studies show both pro- and anti-nociceptive effects. The sympathetic nervous system also has both pro- and anti-inflammatory effects on immune tissues and cells. We examined effects of a very localized sympathectomy. By cutting the gray rami to the spinal nerves near the lumbar sensory ganglia, we avoided widespread sympathetic denervation. This procedure profoundly reduced mechanical pain behaviors induced by a back pain model and a model of peripheral inflammatory pain. One possible mechanism was reduction of inflammation in the sympathetically denervated regions. This raises the possibility that therapeutic interventions targeting gray rami might be useful in some inflammatory conditions.

[Chronic primary pain disorders in children and adolescents]

AIM

Chronic and debilitating pediatric pain has a prevalence of 5% and as such constitutes a considerable health problem. The aim of this article is to provide an overview of current research activities on pediatric pain, available health care for children with chronic pain and education and training programs for health professionals.

METHOD

This overview is based on the authors' personal experience, information available from medical, research and professional associations, as well as a PubMed literature search for the time period 2012-2015 using "children";"pain" and "Germany" as search terms.

RESULTS

There are numerous research activities in Germany focusing on the epidemiology, the underlying psychobiological mechanisms and on the multimodal treatment of chronic pediatric pain. This research is internationally widely acknowledged and makes a significant contribution to current developments in pediatric pain research. By contrast, health services and basic science research is clearly lacking in Germany. Moreover, specialized health care for youth with chronic pain is far less institutionalized when compared to adults suffering from chronic pain. Indeed, primary and secondary care services have rarely been studied or even evaluated.

CONCLUSION

Similar to international trends, research on chronic pediatric pain has also grown and advanced in Germany. Indeed, not only the amount of research has increased but also its scope. Nonetheless, there is clearly a need for more research efforts with regard to the understanding of (pediatric) pain mechanisms, clinical studies and, especially, investigations on health care services. It is particularly important to focus on the implementation, improvement and systematic evaluation of specialized health care services which would be available and accessible for children and adolescents with chronic pain and not be restricted to tertiary care.

How is chronic pain related to sympathetic dysfunction and autonomic dysreflexia following spinal cord injury?

Autonomic dysreflexia (AD) and neuropathic pain occur after severe injury to higher levels of the spinal cord. Mechanisms underlying these problems have rarely been integrated in proposed models of spinal cord injury (SCI). Several parallels suggest significant overlap of these mechanisms, although the relationships between sympathetic function (dysregulated in AD) and nociceptive function (dysregulated in neuropathic pain) are complex. One general mechanism likely to be shared is central sensitization - enhanced responsiveness and synaptic reorganization of spinal circuits that mediate sympathetic reflexes or that process and relay pain-related information to the brain. Another is enhanced sensory input to spinal circuits caused by extensive alterations in primary sensory neurons. Both AD and SCI-induced neuropathic pain are associated with spinal sprouting of peptidergic nociceptors that might increase synaptic input to the circuits involved in AD and SCI pain. In addition, numerous nociceptors become hyperexcitable, hypersensitive to chemicals associated with injury and inflammation, and spontaneously active, greatly amplifying sensory input to sensitized spinal circuits. As discussed with the aid of a preliminary functional model, these effects are likely to have mutually reinforcing relationships with each other, and with consequences of SCI-induced interruption of descending excitatory and inhibitory influences on spinal circuits, with SCI-induced inflammation in the spinal cord and in DRGs, and with activity in sympathetic fibers within DRGs that promotes local inflammation and spontaneous activity in sensory neurons. This model suggests that interventions selectively targeting hyperactivity in C-nociceptors might be useful for treating chronic pain and AD after high SCI.

The Pharmacological Management of Complex Regional Pain Syndrome in Pediatric Patients

The awareness of complex regional pain syndrome (CRPS) in the pediatric population is increasing. The condition involves regional pain that is out of proportion to any initiating event (if there is one) and is associated with sensory, functional, autonomic, and inflammatory changes in the region of the pain. The signs and symptoms of CRPS can vary between patients and stage of the disease process. Like many chronic pain conditions, it is often associated with significant disability and a detrimental effect on quality of life. It has a complex pathophysiology that remains poorly understood but provides many potential targets for treatments. Management involves a biopsychosocial formulation that encompasses physical and psychological interventions alongside pharmacological strategies. We review the current evidence for the treatment of this condition in children, with particular reference to pharmacological management.

Pediatric complex regional pain syndrome: a review

Complex regional pain syndrome (CRPS) is a chronic, intensified localized pain condition that can affect children and adolescents as well as adults, but is more common among adolescent girls. Symptoms include limb pain; allodynia; hyperalgesia; swelling and/or changes in skin color of the affected limb; dry, mottled skin; hyperhidrosis and trophic changes of the nails and hair. The exact mechanism of CRPS is unknown, although several different mechanisms have been suggested. The diagnosis is clinical, with the aid of the adult criteria for CRPS. Standard care consists of a multidisciplinary approach with the implementation of intensive physical therapy in conjunction with psychological counseling. Pharmacological treatments may aid in reducing pain in order to allow the patient to participate fully in intensive physiotherapy. The prognosis in pediatric CRPS is favorable.

Progress in Sympathetically Mediated Pathological Pain

Aim of review

Many chronic pain conditions remain difficult to treat, presenting a high burden to society. Conditions such as complex regional pain syndrome may be maintained or exacerbated by sympathetic activity. Understanding the interactions between sympathetic nervous system and sensory system will help to improve the effective management of pathological pain including intractable neuropathic pain and persistent inflammatory pain.

Method

We first described the discovery of abnormal connections between sympathetic and sensory neurons. Subsequently, the functional roles of sympathetic sprouting in altered neuronal excitability and increased pain sensitivity were discussed. The mechanisms of the sympathetic sprouting were focusing on its relationship with neurotrophins, local inflammation, and abnormal spontaneous activity. Finally, we discussed clinical implications and conflicting findings in the laboratory and clinical research with respect to the interaction between sympathetic system and sensory system.

Recent findings

The findings that sprouting of sympathetic fibers into the sensory ganglia (dorsal root ganglion) after peripheral nerve injury, offers a possible explanation of the sympathetic involvement in pain. It is also suggested that releases of adenosine triphosphate (ATP), in addition to norepinephrine, from sympathetic nerve endings play important roles in sympathetic-mediated pain. New evidence indicates the importance of sympathetic innervation in local inflammatory responses.

Summary

Hopefully, this review will reinvigorate the study of sympathetic-sensory interactions in chronic pain conditions, and help to better understand how sympathetic system contributes to this serious clinical problem.