Type II complex regional pain syndrome of the hand resulting from repeated arterial punctures during transradial coronary intervention.

Coronary catheterization using a transradial approach has become a common procedure, as the risks of local complications are low and this procedure affords relatively expeditious postprocedural patient mobilization. Access site complications--such as radial artery spasm, hematoma, and compartment syndrome--have been reported in the literature; however, cases of complex regional pain syndrome (CRPS) of the hand related to the procedure are extremely rare. We describe a case of type II CRPS affecting the hand after a transradial coronary intervention that was complicated by repeated periprocedural arterial punctures. In this case, a 55-year-old woman underwent a percutaneous coronary intervention for the treatment of unstable angina. After successful completion of the procedure, the patient complained of severe pain along the median and radial nerve distributions and resulting disability of the right hand. Although subsequent duplex sonography showed no abnormalities, a nerve conduction study uncovered injury to multiple nerves on the right. A diagnosis of type II CRPS was then made and the patient was treated with a nerve block as well as multiple medical modalities. This case demonstrates a very unusual complication resulting from the transradial approach to percutaneous coronary intervention.

Atypical odontalgia: an up-to-date view.

Atypical odontalgia (AO) is a little known chronic pain condition. It usually presents as pain in a site where a tooth was endodontically treated or extracted, in the absence of clinical or radiographic evidence of tooth pathology. It is a rare clinical challenge for most clinicians, which leads to the patients being referred to several specialists and sometimes undergoing unnecessary surgical procedures. The pain mechanisms involved in AO are far from clear, and numerous potential mechanisms have been suggested. Currently, the most accredited hypothesis is that AO is a neuropathic pain condition caused by deafferentation. The differential diagnosis of AO remains difficult, because it shares symptoms with many others pathologies affecting this area. Patients have difficulties accepting the AO diagnosis and treatment. As a result, they frequently change physicians, and may potentially also receive several invasive treatments, usually resulting in an aggravation of the pain. Although some patients do get complete pain relief following treatment, for most patients the goal should be to achieve adequate pain management. Currently, most management is based on expert opinion and case reports. More research and high quality randomized controlled trials are needed in order to develop evidence-based treatments, currently based on expert opinion or carried over from other neuropathic pain conditions in the orofacial region.

[Complex regional pain syndrome--pathophysiology, clinical presentation and treatment]. / Kompleksni regionalni bolni sindrom--patofiziologija, klinicka slika i lijecenje.

In 1994, a consensus group of experts gathered by the International Association for the Study of Pain (IASP) agreed on new diagnostic criteria for the reflex sympathetic dystrophy (RSD) and causalgia, and renamed them complex regional pain syndrome (CRPS) types I and II, respectively. CRPS is a complex pathophysiological entity characterised by pain, trophic and vasomotoric changes, limited function of affected body part and relatively fast development of osteoporosis of affected region. We described possible pathophysiological mechanisms which caused the pain, clinical presentation of the disease and treatment which includes all available pharmacological modalities as well as interventional procedures.

Testing the link between sympathetic efferent and sensory afferent fibers in neuropathic pain.

The diagnosis of sympathetically maintained pain (SMP) is typically established by assessment of pain relief during local anesthetic blockade of the sympathetic ganglia that innervate the painful body part. To determine if systemic α-adrenergic blockade with phentolamine can be used to diagnose SMP, we compared the effects on pain of local anesthetic sympathetic ganglion blocks (LASB) and phentolamine blocks (PhB) in 20 patients with chronic pain and hyperalgesia that were suspected to be sympathetically maintained. The blocks were done inrandom order on separate days. Patients rated the intensity of ongoing and stimulus-evoked pain every 5 min before, during, and after the LASB and PhB. Patients and the investigator assessing pain levels were blinded to the time of intravenous administration of phentolamine (total dose 25-35 mg). The pain relief achieved by LASB and PhB correlated closely (r = 0.84), and there was no significant difference in the maximum pain relief achieved with the two blocks (t = 0.19, P > 0.8). Nine patients experienced a greater than 50% relief of pain and hyperalgesia from both LASB and PhB and were considered to have a clinically significant component of SMP. We conclude that α-adrenergic blockade with intravenous phentolamine is a sensitive alternative test to identify patients with SMP.

Self-mutilation in patients after nerve injury may not be due to deafferentation pain: a case report.

OBJECTIVE: Animals with transected nerves may develop self-mutilating behavior (autotomy) directed at the denervated body part. Autotomy is often thought to be a response to deafferentation pain produced by pathological changes in the dorsal horn, and self-mutilation after dorsal rhizotomy has consequently been used as an outcome measure for the investigation of chronic pain in animal models. A less recognized hypothesis suggests that autotomy is simply an animal's efforts to remove the useless part. We report a case of self-mutilation of the thumb and fingers in a patient with loss of all sensory modalities in the arm after brachial plexus avulsion. CONCLUSION: Asking the patient about the reasons for his self-mutilation provides insights into the cause of autotomy which cannot be established from animal studies. We suggest that autotomy may not be a result of chronic pain, and discuss the human experience and alternative underlying pathological processes.

Motor cortex stimulation for trigeminal neuropathic or deafferentation pain: an institutional case series experience.

BACKGROUND: Trigeminal neuropathy is a rare, devastating condition that can be intractable and resistant to treatment. When medical treatment fails, invasive options are limited. Motor cortex stimulation (MCS) is a relatively recent technique introduced to treat central neuropathic pain. The use of MCS to treat trigeminal neuropathic or deafferentation pain is not widespread and clinical data in the medical literature that demonstrate efficacy are limited. METHOD: We retrospectively reviewed patients with trigeminal neuropathic or trigeminal deafferentation pain who were treated at the Oregon Health & Science University between 2001 and 2008 by 1 neurosurgeon using MCS. RESULTS: Eight of 11 patients (3 male, 8 female) underwent successful permanent implantation of an MCS system. All 8 patients reported initial satisfactory pain control. Three failed to experience continued pain control (6 months of follow-up). Five continued to experience long-term pain control (mean follow-up, 33 months). Average programming sessions were 2.2/year (all 8 patients) and 1.55/year (5 patients who sustained long-term pain control). Patients with anesthesia dolorosa or trigeminal deafferentation pain who had previously undergone ablative trigeminal procedures responded poorly to MCS. We encountered no perioperative complications. CONCLUSION: MCS is a safe and potentially effective therapy in certain patients with trigeminal neuropathy.

[Small fiber sensory neuropathies: contribution of laser evoked potentials]. / Neuropathies sensitives des petites fibres : intérêt des potentiels évoqués laser.

Standard neurophysiological techniques evaluate exclusively large myelinated fibers, but are not useful to explore sensory small fibers. Quantitative sensory tests have been developed to explore the thermal nociceptive function but this exploration is only subjective. Laser evoked potentials (LEPs) represent a noninvasive and objective test to explore thermal and nociceptive pathways. The clinical interest of LEPs have been assessed recently in the diagnosis of small fibers sensory neuropathies. In routine, the determination of detection and nociceptive thresholds, the analysis of N2P2 latencies and amplitudes enable demonstration of a dysfunction of A delta nerve fibers, to quantify these lesions and to determine whether the neuropathies are length-dependent or not. The LEP amplitude is negatively correlated to deafferentation. The interest of LEPs remained to be studied compared to skin biopsy.

Treatment of neuropathic deafferentation pain using DREZ lesions; long-term results.

INTRODUCTION: Deafferentation pain secondary to spinal cord injury, brachial plexus avulsion and other peripheral nerve injuries is often refractory to conventional treatments. This study evaluates the long-term efficacy of spinal DREZ (Dorsal Root Entry Zone) lesions for the treatment of neuropathic pain syndromes caused by deafferentation. PATIENTS AND METHODS: A series of 18 patients with refractory deafferentation pain treated with radiofrequency DREZ lesions is presented. The immediate and long-term efficacy was measured with the Visual Analogue Scale (VAS) before and after treatment, the patient's subjective evaluation, the percentage of patients returning to work and the reduction in pain medication. RESULTS: Pain on the VAS significantly decreased from 8.6 preoperatively to 2.9 (p<.001) at discharge. Over the long-term, with a mean follow-up of 28 months (6-108) pain remained at 4.7 on the VAS (p<0.002). The percentage of patients with moderate to excellent pain relief was 77% at discharge and 68% at the last follow-up. Pain medication was reduced in 67% of the patients and 28% returned to work. The best results were obtained in patients with brachial plexus avulsion, with a significant long-term pain relief in all cases. CONCLUSIONS: Radiofrequency DREZ lesion is an effective and safe treatment for refractory neuropathic pain caused by deafferentation.

Complex regional pain syndrome type II associated with lumbosacral plexopathy: a case report.

INTRODUCTION: Complex regional pain syndrome (CRPS) is a well-known clinical entity, first described in the 1800s, consisting of pain, hyperalgesia, edema, and sudomotor changes either without (Type I) or with (Type II) a definable nerve injury. CRPS Type II is most commonly caused by high velocity missile injuries, mononeuropathies, and partial nerve transections. CASE REPORT: In this case, a 25-year-old soldier who sustained a blast injury causing multiple spinal compression fractures, extremity fractures, and pelvic and sacral fractures was transferred to a U.S. Army medical center for surgical management and rehabilitation. He complained of weakness, sensory changes, and pain in his left lower extremity. The patient also demonstrated swelling and hyperesthesia of the left foot and ankle. Undiagnosed soft tissue injury, fracture, and deep venous thrombosis were ruled out by imaging studies. The patient had an electromyogram/nerve conduction study (EMG/NCS) that showed widespread left sided lumbosacral plexopathy as well as possible cauda equina injury. Triple phase bone scan demonstrated findings consistent with CRPS of the left foot and ankle. He was started on a tricyclic antidepressant and an anticonvulsant. Physical and occupational therapy were quickly engaged to incorporate range of motion exercises, mirror therapy, and physical modalities. The patient continued conservative management and rehabilitation and eventually was discharged with significantly improved function and decreased pain. CONCLUSION: Although many causes of CRPS Type II have been described, this is only the second reported case of CRPS Type II secondary to lumbosacral plexopathy in the literature.

Mechanisms of Below-Level Pain Following Spinal Cord Injury (SCI).

Mechanisms of below-level pain are discoverable as neural adaptations rostral to spinal injury. Accordingly, the strategy of investigations summarized here has been to characterize behavioral and neural responses to below-level stimulation over time following selective lesions of spinal gray and/or white matter. Assessments of human pain and the pain sensitivity of humans and laboratory animals following spinal injury have revealed common disruptions of pain processing. Interruption of the spinothalamic pathway partially deafferents nocireceptive cerebral neurons, rendering them spontaneously active and hypersensitive to remaining inputs. The spontaneous activity among these neurons is disorganized and unlikely to generate pain. However, activation of these neurons by their remaining inputs can result in pain. Also, injury to spinal gray matter results in a cascade of secondary events, including excitotoxicity, with rostral propagation of excitatory influences that contribute to chronic pain. Establishment and maintenance of below-level pain results from combined influences of injured and spared axons in the spinal white matter and injured neurons in spinal gray matter on processing of nociception by hyperexcitable cerebral neurons that are partially deafferented. A model of spinal stenosis suggests that ischemic injury to the core spinal region can generate below-level pain. Additional questions are raised about demyelination, epileptic discharge, autonomic activation, prolonged activity of C nocireceptive neurons, and thalamocortical plasticity in the generation of below-level pain. PERSPECTIVE: An understanding of mechanisms can direct therapeutic approaches to prevent development of below-level pain or arrest it following spinal cord injury. Among the possibilities covered here are surgical and other means of attenuating gray matter excitotoxicity and ascending propagation of excitatory influences from spinal lesions to thalamocortical systems involved in pain encoding and arousal.

Maladaptive homeostatic plasticity in a rodent model of central pain syndrome: thalamic hyperexcitability after spinothalamic tract lesions.

Central pain syndrome (CPS) is defined as pain associated with a lesion of the CNS and is a common consequence of spinal cord injuries. We generated a rodent model of CPS by making unilateral electrolytic or demyelinating lesions centered on the spinothalamic tract in rats. Thermal hyperalgesia and mechanical allodynia occurred in both hind paws and forepaws by 7 d postlesion and were maintained >31 d. Field potentials in the ventral posterior lateral nucleus (VPL) in thalamic brain slices from lesioned animals displayed an increased probability of burst responses. Ethosuximide, a T-type calcium channel blocker, eliminated busting in lesioned thalamic slices and attenuated lesion-induced hyperalgesia and allodynia. We conclude that CPS in this model results from an increase in the excitability of thalamic nuclei that have lost normal ascending inputs as the result of a spinal cord injury and suggest that ethosuximide will relieve human CPS by restoring normal thalamic excitability.

Practical management of complex regional pain syndrome.

Complex regional pain syndrome (CRPS) describes a diversity of painful conditions following trauma, coupled with abnormal regulation of blood flow and sweating, trophic changes, and edema of skin. The excruciating pain and diverse autonomic dysfunctions in CRPS are disproportionate to any inciting and recovering event. CRPS type I is formerly identified as "reflex sympathetic dystrophy." CRPS type II is the new term for "causalgia" that always coexists with documented nerve injury. The present diagnostic criteria of CRPS I and II depend solely on meticulous history and physical examination without any confirmation by specific test procedure (or gold standard). There are only few clinical studies with large-scale randomized trials of pharmacologic agents on the treatment of CRPS. Bisphosphonates have been studied in multiple controlled trials, based on theoretical benefit of bone resorption, to offer pain relief and functional improvement in patients with CRPS. Many current rationales in treatment of CRPS (such as topical agents, antiepileptic drugs, tricyclic antidepressants, and opioids) are mainly dependent on efficacy originate in other common conditions of neuropathic pain. There are additional innovative therapies on CRPS that are still in infancy. No wonder all the treatment of individual CRPS case nowadays is pragmatic at best. Although the interventional therapies in CRPS (such as nerve blockade, sympathetic block, spinal cord and peripheral nerve stimulation, implantable spinal medication pumps, and chemical and surgical sympathectomy) may offer more rapid response, yet it is still controversial with unpredictable outcome. Nevertheless, we need to start pain management immediately with the ambition to restore function in every probable case of CRPS. An interdisciplinary setting with comprehensive approach (pharmacologic, interventional, and psychological in conjunction with rehabilitation pathway) has been proposed as protocol in the practical management of CRPS. It is crucial to have a high sensitivity value combined with a fair specificity in revising diagnostic criteria of CRPS. The validation and consensus for new rationalized diagnostic criteria of CRPS could facilitate further research to enhance clinical outcome including quality of life. These endeavors to minimize suffering from CRPS would certainly be appreciated by many patients and their loved ones.

Peripheral median nerve stimulation for the treatment of iatrogenic complex regional pain syndrome (CRPS) type II after carpal tunnel surgery.

We report on the use and follow-up of direct peripheral nerve stimulation of the median nerve for the treatment of iatrogenic complex regional pain syndrome (CRPS). A 56-year-old woman presented with CRPS type II in the right forearm and hand, which had started after multiple carpal tunnel surgeries and had lasted for 2 years. The visual analogue scale (VAS) score was 8-10 out of 10. After a successful 15-day trial of median nerve peripheral nerve stimulation via a quadripolar lead in the right carpal tunnel space, an implantable pulse generator was inserted in the right infraclavicular space. The VAS score decreased to 1-2 out of 10 and the patient regained the ability to sleep. After 36 months of follow-up, the patient was still experiencing good pain relief without other treatment. We conclude that peripheral nerve stimulation is easy to use in pain management and could offer a valid treatment option for iatrogenic CRPS type II.

Clinical Features of Pediatric Complex Regional Pain Syndrome: A 5-Year Retrospective Chart Review.

OBJECTIVES: Complex regional pain syndrome (CRPS) is a painful condition of a limb characterized by a constellation of symptoms. Little is known about the clinical features of pediatric CRPS, with fewer than a dozen studies published to date. The aim of this study was to explore the clinical course of pediatric CRPS, with emphasis on clinical features and disease outcomes. A secondary aim was to discern differences in clinical features of pediatric CRPS with and without related movement disorders, and between children who had a favorable and unfavorable outcome. MATERIALS AND METHODS: We carried out a retrospective chart review of children with CRPS who presented to a pediatric Chronic Pain Clinic in Canada over a 5-year period (2012 to 2016). RESULTS: The study identified 59 children with CRPS (mean age: 12.7±2.5; 74.6% female; 72.9% lower extremity). In total, 87% (n=48) of children experienced complete resolution or significant improvement of CRPS, with a relapse rate of 15%. Overall, 25% (n=15) had a CRPS-related movement disorder. There were no differences in the clinical features of pediatric CRPS with or without related movement disorders. Children who experienced a favorable outcome had a significantly shorter symptom duration at the initial visit in comparison with children who experienced an unfavorable outcome. DISCUSSION: In this cohort, pediatric CRPS was most common in girls around the age of 12, usually in the lower extremity, and most experienced a favorable outcome. Further research is needed to better understand the prognosis and relapse rate of pediatric CRPS.

Dorsal root entry zone coagulation for treatment of deafferentation pain syndromes.

BACKGROUND: Deafferentation pain is a kind of chronic pain syndrome and hard to manipulate. To evaluate the effectiveness and safety of junctional dorsal root entry zone (DREZ) coagulation, 23 consecutive patients with intractable deafferentation pain syndrome were studied. METHODS: Twenty-three patients underwent junctional DREZ coagulation (C5-T1 for upper extremities and L2-S1 for lower extremities) under general anesthesia. The pain severity was evaluated by the short McGill pain questionnaire (MPQ) and the visual analog scale (VAS), and the depression and anxiety of patients were assessed by Hamilton rating scale for depression (HRSD), Hamilton anxiety scale (HAMA), self-rating anxiety scale (SAS) and self-rating depression scale (SDS). RESULTS: All the patients experienced significant pain reduction immediately after surgery. The scales of short MPQ and VAS at pre-operation, 6-month and 12-month follow-up were 31.5 +/- 3.4 and 8.8 +/- 1.5, 6.5 +/- 1.9 and 2.5 +/- 2.2, 7.1 +/- 2.1 and 2.9 +/- 1.9, respectively. The postoperative scores comparing to pre-operative scores showed a statistically significant difference (P < 0.01). The depression and anxiety state was also significantly relieved. At 12-month follow-up 6 patients had complete pain relief, 11 had excellent results with more than 75% pain relief, 17 had good results with more than 50% pain relief (73.9%). The main postoperative complications were transient slight hemiplegia (8), hypesthesia and paresthesia (15), a bearing down feeling of affected extremity (6), and deep sensory disability in the lower limbs (4) on the operated side. Because of the long time and prone position of the operation, 13 cases had a transient hyperalgesia in the upper chest. CONCLUSION: DREZ coagulation is a safe and effective procedure in the treatment of deafferentation pain syndromes.

Effect of pain on deafferentation-induced modulation of somatosensory evoked potentials.

There is a large body of evidence showing substantial sensorimotor reorganizations after an amputation. These reorganizations are believed to contribute to the development of phantom limb pain, but alternatively, pain might influence the plasticity triggered by the deafferentation. The aim of this study was to test whether pain impacts on deafferentation-induced plasticity in the somatosensory pathways. Fifteen healthy subjects participated in 2 experimental sessions (Pain, No Pain) in which somatosensory evoked potentials (SSEPs) associated with electrical stimulation of the ulnar nerve were assessed before and after temporary ischemic deafferentation induced by inflation of a cuff around the wrist. In the Pain session capsaicin cream was applied on the dorsum of the hand 30 minutes prior to cuff inflation. Results show that pain decreased the amplitude of the N20 (main effect of condition, p = 0.033), with a similar trend for the P25. Temporary ischemic deafferentation had a significant effect on SSEPs (main effect of time), with an increase in the P25 (p = 0.013) and the P45 amplitude (p = 0.005), together with a reduction of the P90 amplitude (p = 0.002). Finally, a significant time x condition interaction, reflecting state-dependent plasticity, was found for the P90 only, the presence of pain decreasing the reduction of amplitude observed in response to deafferentation. In conclusion, these results show that nociceptive input can influence the plasticity induced by a deafferentation, which could be a contributing factor in the cortical somatosensory reorganization observed in chronic pain populations.

Dental deafferentation and brain damage: A review and a hypothesis.

In the last few decades, neurobiological and human brain imaging research have greatly advanced our understanding of brain mechanisms that support perception and memory, as well as their function in daily activities. Knowledge of the neurobiological mechanisms behind the deafferentation of stomatognathic systems has also expanded greatly in recent decades. In particular, current studies reveal that the peripheral deafferentations of stomatognathic systems may be projected globally into the central nervous system (CNS) and become an associated critical factor in triggering and aggravating neurodegenerative diseases. This review explores basic neurobiological mechanisms associated with the deafferentation of stomatognathic systems. Further included is a discussion on tooth loss and other dental deafferentation (DD) mechanisms, with a focus on dental and masticatory apparatuses associated with brain functions and which may underlie the changes observed in the aging brain. A new hypothesis is presented where DD and changes in the functionality of teeth and the masticatory apparatus may cause brain damage as a result of altered cerebral circulation and dysfunctional homeostasis. Furthermore, multiple recurrent reorganizations of the brain may be a triggering or contributing risk factor in the onset and progression of neurodegenerative conditions such as Alzheimer's disease (AD). A growing understanding of the association between DD and brain aging may lead to solutions in treating and preventing cognitive decline and neurodegenerative diseases.