DREZ coagulations for deafferentation pain related to spinal and peripheral nerve lesions: indication and results of 79 consecutive procedures

The Safety and Efficacy of Dorsal Root Entry Zone Lesioning for Pain Management in Patients With Brachial Plexus Avulsion: A Systematic Review and Meta-Analysis

BACKGROUND AND OBJECTIVES

Persistent neuropathic pain after brachial plexus avulsion (BPA) is common and generally nonresponsive to medical management. Dorsal root entry zone (DREZ) lesioning is the last resort for pain management in patients with BPA. This study aims to investigate and compare the outcomes and complications of DREZ procedures.

METHODS

A systematic literature search was conducted to identify all related studies. Comparisons were based on the number of patients with preoperative pain vs postoperative pain, with the effect size calculated using the risk ratio. Mean visual analog scale (VAS) scores were extracted and analyzed between interventions. A meta-regression analysis was performed to identify risk factors for final outcomes. The rates of complications were also assessed and analyzed between interventions.

RESULTS

A total of 30 studies with 917 patients (90.0% male and 10.0% female, mean age: 42.9 ± 16.6) were included in this systematic review. Of the 917 patients who underwent surgery, 655 (71.4%) patients had significant pain reduction at the last follow-up (P < .05). The weighted mean preoperative VAS score was 8.3 ± 1.3, compared with postoperative VAS scores (1.9 ± 2.2); a significant improvement was observed (P < .05). The subgroup analysis showed that microsurgical DREZotomy (MDT) is associated with better outcomes in terms of VAS score improvements compared with radiofrequency (RF)-assisted DREZ lesioning (P < .05). Meta-analysis showed that the relative risk of motor deficits was significantly lower in the MDT group, compared with the RF-assisted group (P < .05). Meta-regression showed that older age is correlated with an elevated risk of postoperative motor deficits compared with the incidence of sensory loss.

CONCLUSION

DREZ lesioning is effective for intractable pain alleviation after BPA. Compared with RF-assisted DREZ lesioning, MDT is associated with better VAS score improvements and a lower rate of postoperative motor weakness.

Dorsal Root Entry Zone Lesioning for Brachial Plexus Avulsion Injuries: Case Series and Literature Review

Introduction: Brachial plexus avulsion (BPA) injuries commonly occur secondary to motor vehicle collisions, usually in the young adult population. These injuries are associated with significant morbidity, and up to 90% of patients suffer from deafferentation pain. Neuromodulation procedures can be efficacious in the treatment of refractory neuropathic pain, although the treatment of pain due to BPA can be challenging. Dorsal root entry zone (DREZ) lesioning is a classical and effective neurosurgical technique which has become underutilized in treating refractory root avulsion pain.

Methods: A systematic review of the different technical nuances, procedural efficacy, and complication profiles regarding DREZ lesioning for BPA injuries in the literature is included. We also present an institutional case series of 7 patients with BPA injuries who underwent DREZ lesioning.

Results: In the literature, 692 patients were identified to have undergone DREZ lesioning for pain related to BPA. In 567 patients, the surgery was successful in reducing pain intensity by over 50% in comparison to baseline (81.9%). Complications included transient motor deficits (11%) and transient sensory deficits (11%). Other complications including permanent disability, cardiovascular complications, infections, or death were rare (<1.9%). In our case series, all but one patient achieved >50% reduction in pain intensity, with the mean pre-operative pain of 7.9 ± 0.63 (visual analog scale) reduced to 2.1 ± 0.99 at last follow-up (p < 0.01).

Conclusion: Both the literature and the current case series demonstrate excellent pain severity reduction following DREZ ablation for deafferentation pain secondary to BPA.

Dorsal Root Entry Zone Lesioning for Brachial Plexus Avulsion: A Comprehensive Literature Review

Dorsal root entry zone (DREZ) lesioning is a neurosurgical procedure that aims to relieve severe neuropathic pain in patients with brachial plexus avulsion by selectively destroying nociceptive neural structures in the posterior cervical spinal cord. Since the introduction of the procedure over 4 decades ago, the DREZ lesioning technique has undergone numerous modifications, with a variety of center- and surgeon-dependent technical differences and patient outcomes. We have reviewed the literature to discuss reported methods of DREZ lesioning and outcomes.

Neuropathic Pain: From Mechanisms to Treatment

Neuropathic pain caused by a lesion or disease of the somatosensory nervous system is a common chronic pain condition with major impact on quality of life. Examples include trigeminal neuralgia, painful polyneuropathy, postherpetic neuralgia, and central poststroke pain. Most patients complain of an ongoing or intermittent spontaneous pain of, for example, burning, pricking, squeezing quality, which may be accompanied by evoked pain, particular to light touch and cold. Ectopic activity in, for example, nerve-end neuroma, compressed nerves or nerve roots, dorsal root ganglia, and the thalamus may in different conditions underlie the spontaneous pain. Evoked pain may spread to neighboring areas, and the underlying pathophysiology involves peripheral and central sensitization. Maladaptive structural changes and a number of cell-cell interactions and molecular signaling underlie the sensitization of nociceptive pathways. These include alteration in ion channels, activation of immune cells, glial-derived mediators, and epigenetic regulation. The major classes of therapeutics include drugs acting on α₂δ subunits of calcium channels, sodium channels, and descending modulatory inhibitory pathways.

DREZotomy in the treatment of deafferentation pain: review of results and analysis of predictive factors for success

BACKGROUND AND OBJECTIVES

The treatment of deafferentation pain by spinal DREZotomy is a proven therapeutic option in the literature. In recent years, use of DREZotomy has been relegated to second place due to the emergence of neuromodulation therapies. The objectives of this study are to demonstrate that DREZotomy continues to be an effective and safe treatment and to analyse predictive factors for success.

PATIENTS AND METHODS

A retrospective study was conducted of all patients treated in our department with spinal DREZotomy from 1998 to 2018. Bulbar DREZotomy procedures were excluded. A visual analogue scale (VAS) and the reduction of routine medication were used as outcome variables. Demographic, clinical and operative variables were analysed as predictive factors for success.

RESULTS

A total of 27 patients (51.9% female) with a mean age of 53.7 years underwent DREZotomy. The main cause of pain was brachial plexus injury (BPI) (55.6%) followed by neoplasms (18.5%). The mean time of pain evolution was 8.4 years with a mean intensity of 8.7 according to the VAS, even though 63% of the patients had previously received neurostimulation therapy. Favourable outcome (≥50% pain reduction in the VAS) was observed in 77.8% of patients during the postoperative period and remained in 59.3% of patients after 22 months average follow-up (mean reduction of 4.9 points). This allowed for a reduction in routine analgesic treatment in 70.4% of them. DREZotomy in BPI-related pain presented a significantly higher success rate (93%) than the other pathologies (41.7%) (p=.001). No association was observed between outcome and age, gender, DREZ technique, duration of pain or previous neurostimulation therapies. There were six neurological complications, four post-operative transient neurological deficits and two permanent deficits.

CONCLUSION

Dorsal root entry zone surgery is effective and safe for treating patients with deafferentation pain, especially after brachial plexus injury. It can be considered an alternative treatment after failed neurostimulation techniques for pain control. However, its indication should be considered as the first therapeutic option after medical therapy failure due to its good long-term results.

Spinal cord injury below-level neuropathic pain relief with dorsal root entry zone microcoagulation performed caudal to level of complete spinal cord transection

OBJECTIVE

Surgically created lesions of the spinal cord dorsal root entry zone (DREZ) to relieve central pain after spinal cord injury (SCI) have historically been performed at and cephalad to, but not below, the level of SCI. This study was initiated to investigate the validity of 3 proposed concepts regarding the DREZ in SCI central pain: 1) The spinal cord DREZ caudal to the level of SCI can be a primary generator of SCI below-level central pain. 2) Neuronal transmission from a DREZ that generates SCI below-level central pain to brain pain centers can be primarily through sympathetic nervous system (SNS) pathways. 3) Perceived SCI below-level central pain follows a unique somatotopic map of DREZ pain-generators.

METHODS

Three unique patients with both intractable SCI below-level central pain and complete spinal cord transection at the level of SCI were identified. All 3 patients had previously undergone surgical intervention to their spinal cords—only cephalad to the level of spinal cord transection—with either DREZ microcoagulation or cyst shunting, in failed attempts to relieve their SCI below-level central pain. Subsequent to these surgeries, DREZ lesioning of the spinal cord solely caudal to the level of complete spinal cord transection was performed using electrical intramedullary guidance. The follow-up period ranged from 1 1/2 to 11 years.

RESULTS

All 3 patients in this study had complete or near-complete relief of all below-level neuropathic pain. The analyzed electrical data confirmed and enhanced a previously proposed somatotopic map of SCI below-level DREZ pain generators.

CONCLUSIONS

The results of this study support the following hypotheses. 1) The spinal cord DREZ caudal to the level of SCI can be a primary generator of SCI below-level central pain. 2) Neuronal transmission from a DREZ that generates SCI below-level central pain to brain pain centers can be primarily through SNS pathways. 3) Perceived SCI below-level central pain follows a unique somatotopic map of DREZ pain generators.

Efficacy and factors determining the outcome of dorsal root entry zone lesioning procedure (DREZotomy) in the treatment of intractable pain syndrome

BACKGROUND

Chronic pain is a disabling condition that adversely affects patient quality of life. The dorsal root entry zone lesioning procedure (DREZotomy) is a modality used to treat intractable pain caused by insults to neural structures. This study aimed to investigate the efficacy of and the factors that determine the outcome of microsurgical DREZotomy (MDT).

METHOD

All consecutive patients who underwent MDT for treatment of intractable pain during September 2008 to December 2016 were enrolled. Demographic data, clinical characteristics, intraoperative findings, and postoperative outcomes were analyzed.

RESULTS

The 40 included patients underwent MDT for relief of intractable pain caused by 27 brachial plexus injuries (BPIs), 6 spinal cord injuries, 3 neoplasms, and 4 other causes. A significant reduction in pain was observed post-MDT for both average (p < 0.001) and maximal pain (p < 0.001). Favorable outcome (≥50% pain reduction) was observed in 67.5% of patients, with the best outcome in BPI-related pain. In multivariate analysis, injury of the spinal nerve root (root avulsion or injury) was significantly associated with good average pain relief (OR, 5.8; 95% CI, 1.2-27.5; p = 0.026) and pain freedom (OR, 5.0; 95% CI, 1.12-22.30; p = 0.035). Electrical pain (OR, 6.49; 95% CI, 1.20-35.19; p = 0.030) and lower number of painful dermatomes (OR, 1.30; 95% CI, 1.01-1.67; p = 0.039) were significantly associated with good maximal pain relief.

CONCLUSIONS

MDT is an effective procedure for treatment of intractable pain in well-selected patients, particularly in cases with brachial plexus avulsion pain. Injury of the spinal nerve root (brachial plexus avulsion and cauda equina injury) was associated with good average pain relief and pain freedom, and electrical pain and lower number of painful dermatomes were associated with good maximal pain relief. The results are useful in the selection of candidates for DREZotomy and prediction of surgical outcome.

A review of the management of phantom limb pain: challenges and solutions

BACKGROUND

Phantom limb pain (PLP) occurs in 50% and 80% of amputees. Although it is often classified as a neuropathic pain, few of the large-scale trials of treatments for neuropathic pain included sufficient numbers of PLP sufferers to have confidence that they are effective in this condition. Many therapies have been administered to amputees with PLP over the years; however, as of yet, there appears to be no first-line treatment.

OBJECTIVES

To comprehensively review the literature on treatment modalities for PLP and to identify the challenges currently faced by clinicians dealing with this pain.

METHOD

MEDLINE, EMBASE, CINAHL, British Nursing Index, Cochrane and psycINFO databases were searched using "Phantom limb" initially as a MeSH term to identify treatments that had been tried. Then, a secondary search combining phantom limb with each treatment was performed to find papers specific to each therapy. Each paper was assessed for its research strength using the GRADE system.

RESULTS

Thirty-eight therapies were identified. Overall, the quality of evidence was low. There was one high-quality study which used repetitive transcutaneous magnetic stimulation and found a statistical reduction in pain at day 15 but no difference at day 30. Significant results from single studies of moderate level quality were available for gabapentin, ketamine and morphine; however, there was a risk of bias in these papers. Mirror therapy and associated techniques were assessed through two systematic reviews, which conclude that there is insufficient evidence to support their use.

CONCLUSION

No decisions can be made for the first-line management of PLP, as the level of evidence is too low. Robust studies on homogeneous populations, an understanding of what amputees consider a meaningful reduction in PLP and agreement of whether pain intensity is the legitimate therapeutic target are urgently required.

Dorsal root entry zone lesion, midline myelotomy and anterolateral cordotomy

This review encompasses the most common spinal cord lesioning procedures used for the treatment of pain: dorsal root entry zone lesioning, open cordotomy, percutaneous cordotomy, and midline myelotomy. A literature review and summary of each technique regarding relevant anatomy, patient selection, surgical technique, outcomes, and complications are discussed. A general review of somatic and visceral pain pathways of the spinal cord is included, as each procedure requires an understanding of the advantages and disadvantages of various approaches to lesioning the spinal cord for pain. Neurosurgical education of these rarely used procedures needs to be included in residency and fellowship training.

Cordotomy procedures for cancer pain: A discussion of surgical procedures and a review of the literature

Treating pain in patients with terminal cancer is challenging but essential part of their care. Most patients can be managed with pharmacological options but for some these pain control methods are inadequate. Ablative spinal procedures offer an alternative method of pain control for cancer patients with a terminal diagnosis that are failing to have their pain controlled sufficiently by other methods. This paper provides a review of ablative spinal procedures for control of cancer pain. Patient selection, surgical methods, outcomes and complications are discussed in detail for cordotomy, dorsal root entry zone (DREZ) lesioning and midline myelotomy. Cordotomy is primarily done by a percutaneous method and it is best suited for patients with unilateral somatic limb and trunk pain such as due to sarcoma. Possible complications include unilateral weakness possibly respiratory abnormalities. Approximately 90% of patients have significant immediate pain relief following percutaneous cordotomy but increasing portions of patients have pain recurrence as the follow-up period increases beyond one year. The DREZ lesion procedure is best suited to patients with plexus invasion due to malignancy and pain confined to one limb. Possible complications of DREZ procedures include hemiparesis and decreased proprioception. Midline myelotomy is best suited for bilateral abdominal, pelvic or lower extremity pain. Division of the commissure is necessary to address bilateral lower extremity pain. This procedure is relatively rare but published case series demonstrate satisfactory pain control for over half of the patients undergoing the procedure. Possible complications include bilateral lower extremity weakness and diminished proprioception below the lesion level. Unlike cordotomy and DREZ this procedure offers visceral pain control as opposed to only somatic pain control. Ablative spinal procedures offer pain control for terminal cancer patients that are not able to managed medically. This paper provides an in depth review of these procedures with the hope of improving education regarding these underutilized procedures.

Anatomy, physiology and neurobiology of the nociception: a focus on low back pain (part A)

INTRODUCTION

The treatment of Failed Back Surgery Syndrome (FBSS) remains a challenge for pain medicine due to the complexity in the interactions between [1] a residual mechanical pain after surgery and, [2] a progressive transition into chronic pain involving central nervous system plasticity and molecular reorganization. The aim of this paper is to provide a fundamental overview of the pain pathway supporting the nociceptive component of the back pain.

METHODS

Literature searches included an exhaustive review of 643 references and 74 book chapters updated by searching the major electronic databases from 1930 to August 2013.

RESULTS

Pain input is gathered by the peripheral fibre from the innervated tissue's environment and relayed by two contiguous central axons to the brain, via the spinal cord. At this level, it is possible to characterize physical pain and emotional pain. These are supported by two different pathways, encoding two dimensions of pain perception: In Neo-spino-thalamic pathway, the wide dynamic range neuron system is able to provide the information needed for mapping the "sensory-discriminative" dimension of pain. The second projection system (Paleo-spino-thalamic pathway) also involves the ventromedial thalamus but projects to the amygdala, the insula and the anterior cingulate cortex. These areas are associated with emotionality and affect.

CONCLUSION

The mechanical component of FBSS cannot be understood unless the functioning of the pain system is known. But ultimately, the highly variable nature of back pain expression among individuals would require a careful pathophysiological dissection of the potential generators of back pain to guide pain management strategies.

Neuropathic pain post spinal cord injury part 2: systematic review of dorsal root entry zone procedure

BACKGROUND

Pharmacotherapy may not sufficiently reduce neuropathic pain in many individuals post spinal cord injury (SCI). The use of alternative therapies such as surgery may be effective in reducing neuropathic pain in these individuals. However, because of the invasive nature of surgery, it is important to examine the evidence for use of this treatment.

OBJECTIVE

The purpose of this study was to conduct a systematic review of published literature on the surgical treatment of neuropathic pain after SCI.

METHODS

MEDLINE, CINAHL, EMBASE, and PsycINFO databases were searched for articles in which surgical treatment of pain after SCI was examined. Articles were restricted to the English language. Article selection was conducted by 2 independent reviewers with the following inclusion criteria: the subjects participated in a surgical intervention for neuropathic pain; at least 50% of the subjects had an SCI; at least 3 subjects had an SCI; and a definable intervention involving the dorsal root entry zone (DREZ) procedure was used to reduce pain. Data extracted included study design, study type, subject demographics, inclusion and exclusion criteria, sample size, outcome measures, and study results. Randomized controlled trials (RCTs) were assessed for quality using the Physiotherapy Evidence Database (PEDro) assessment scale. Levels of evidence were assigned to each intervention using a modified Sackett scale.

RESULTS

Eleven studies met the inclusion criteria. One study provided level 2 evidence, and the rest provided level 4 evidence. The DREZ procedure was shown to be more effective for segmental pain than for diffuse pain after SCI. Further, individuals with conus medullaris level injury were found to have a higher level of neuropathic pain relief than those with cervical, thoracic, or cauda equina injury.

CONCLUSIONS

The studies demonstrated that the DREZ procedure may be effective in reducing segmental pain. Hence, DREZ may be important in treatment of neuropathic pain in individuals resistant to less invasive treatments. Because the studies lacked control conditions and examination of long-term effects, there is a need for larger trials with more stringent conditions.

Peripheral nerve stimulation in treatment of intractable postherpetic neuralgia

Objective.  This case report presents an application of peripheral nerve stimulation to a patient with intractable postherpetic neuralgia that conventional treatment failed to ameliorate. Methods.  The patient underwent an uneventful peripheral nerve stimulator trial with placement of two temporal eight-electrode percutaneous leads (Octrode leads, Advanced Neuromodulation Systems, Plano, TX, USA) into the right subscapular and right paraspinal area of the upper thoracic region. Results.  Upon experiencing excellent pain relief over the next two weeks, the patient underwent implantation of permanent leads two weeks later and reported sustained pain relief. Conclusion. Peripheral nerve stimulation offers an alternative treatment option for intractable pain associated with postherpetic neuralgia, especially for elderly patients where treatment options are limited due to existing comorbidities. Further studies are warranted.

Surgical management of post-traumatic syringomyelia

STUDY DESIGN

Systematic review.

OBJECTIVE

To determine the indications for surgical intervention and optimal surgical treatment technique for patients with post-traumatic syringomyelia and spinal cord tethering.

SUMMARY OF BACKGROUND DATA

The proper management strategy for post-traumatic syringomyelia has not been established. Most modern surgical series have documented improvement in symptomatic patients who have an internal decompression of their syrinx. Several options exist and include shunting the syrinx (to the subarachnoid space or to either the pleural or peritoneal cavities) as well as spinal cord untethering (with or without expansile duraplasty).

METHODS

A systematic review of literature followed by expert panel consensus was performed. English language literature published between 1980 and 2010 was gathered to examine articles search was conducted using the search terms syringomyelia, syrinx, spinal cord injury, traumatic syringomyelia, post-traumatic syringomyelia. Case reports and articles examining syrinx due to other cause were excluded. Articles were graded for strength of evidence according to the GRADE approach. The evidentiary tables were reviewed and approved by all 4 authors, and disagreements were resolved by consensus.

RESULTS

The literature search yielded a total of 296 abstracts, and 22 articles were found to fulfill all the criteria specified above. All identified articles were of low or very low evidence levels. The reported incidence of post-traumatic syringomyelia is 0.5% to 4.5%; the incidence is twice as common in complete versus incomplete injuries. The literature consistently demonstrated that surgery post-traumatic syringomyelia is effective at arresting or improving motor deterioration, but not sensory dysfunction or pain syndromes. The literature does not support surgical intervention for incidental, asymptomatic syrinx. The literature does not support one surgical technique as superior for the treatment of post-traumatic syringomyelia.

CONCLUSION

The literature supports and the consensus panel recommended that there is no indication for direct decompression at the time of initial injury specifically for the purpose of limiting future risk of syringomyelia. The literature supports and the consensus panel gave a strong recommendation for surgical intervention in the setting of motor neurologic deterioration as a consequence of post-traumatic syrinx/tethered cord. The panel gave a weak recommendation against surgical intervention for patients developing sensory loss/pain syndrome or for asymptomatic but expanding syrinx. Finally, the literature does not provide strong evidence to support the superiority of one surgical technique over the others; however, the consensus panel gave a weak recommendation that spinal cord untethering with expansile duraplasty is the preferred first-line surgical technique.

Neuropathic pain in patients with upper-extremity nerve injury

PURPOSE

The purpose of this review was to present an analysis of the literature of the outcome studies reported in patients following traumatic upper-extremity (UE) nerve injuries (excluding amputation), to assess the presence of an association between neuropathic pain and outcome in patients following traumatic UE nerve injuries, and to provide recommendations for inclusion of more comprehensive outcome measures by clinicians who treat these patients.

SUMMARY OF KEY POINTS

A Medline and CINAHL literature search retrieved 48 articles. This review identified very few studies of patients with peripheral nerve injury that reported neuropathic pain. When pain was reported, visual analogue or numeric rating scales were most frequently used; standardized questionnaires measuring pain or psychosocial function were rarely administered. Recent evidence shows substantial long-term disability and pain in patients following peripheral nerve injury.

RECOMMENDATION

To better understand neuropathic pain in patients following peripheral nerve injury, future outcome studies should include valid, reliable measures of physical impairment, pain, disability, health-related quality of life, and psychosocial functioning.

Subpopulation triage: how to allocate conservation effort among populations

Threatened species often exist in a small number of isolated subpopulations. Given limitations on conservation spending, managers must choose from strategies that range from managing just one subpopulation and risking all other subpopulations to managing all subpopulations equally and poorly, thereby risking the loss of all subpopulations. We took an economic approach to this problem in an effort to discover a simple rule of thumb for optimally allocating conservation effort among subpopulations. This rule was derived by maximizing the expected number of extant subpopulations remaining given n subpopulations are actually managed. We also derived a spatiotemporally optimized strategy through stochastic dynamic programming. The rule of thumb suggested that more subpopulations should be managed if the budget increases or if the cost of reducing local extinction probabilities decreases. The rule performed well against the exact optimal strategy that was the result of the stochastic dynamic program and much better than other simple strategies (e.g., always manage one extant subpopulation or half of the remaining subpopulation). We applied our approach to the allocation of funds in 2 contrasting case studies: reduction of poaching of Sumatran tigers (Panthera tigris sumatrae) and habitat acquisition for San Joaquin kit foxes (Vulpes macrotis mutica). For our estimated annual budget for Sumatran tiger management, the mean time to extinction was about 32 years. For our estimated annual management budget for kit foxes in the San Joaquin Valley, the mean time to extinction was approximately 24 years. Our framework allows managers to deal with the important question of how to allocate scarce conservation resources among subpopulations of any threatened species.

Pain syndromes after missile-caused peripheral nerve lesions: part 2--treatment

OBJECTIVE

To analyze treatment procedures and treatment outcomes of painful missile-caused nerve injuries and factors influencing the outcome.

METHODS

The study included 326 patients with clinically significant pain syndromes, including complex regional pain syndrome Type II, deafferentation pain, reinnervation pain, and neuralgic pain. Treatment modalities included drug therapy, nerve surgery, sympatholysis, and dorsal root entry zone operation. Pain intensity was assessed before and after the treatment using a visual analog scale, and treatment outcome was defined as successful (pain relief >70%), fair (pain relief between 50 and 69%), or poor (pain relief <50%). The outcome was compared between different pain syndromes and different treatment modalities.

RESULTS

A successful outcome was achieved in 28.6% of patients with deafferentation pain, in 76.9% of patients with complex regional pain syndrome Type II, and in 87.9 to 100% of patients with other pain syndromes (P = 0.002). Each type of pain syndrome required a specific treatment algorithm, but average pain relief was similar for all definitive treatment modalities (range, 81-88%; P > 0.05). Ten factors were found to significantly influence the treatment outcome, but only three factors were independent predictors of a successful outcome: type of pain syndrome (P < 0.001), severity of nerve injury (P < 0.001), and absence of pain paroxysms (P = 0.03).

CONCLUSION

The treatment outcome of painful nerve injury depends on several factors, including the type of pain syndrome, severance of nerve injury, and absence of pain paroxysms. Drug therapy (carbamazepine, amitriptyline, or gabapentin) should be recommended, at least as a part of treatment, for patients with reinnervation pain, deafferentation pain, and complex regional pain syndrome Type II. Nerve surgery should be recommended for patients with posttraumatic neuralgia, either as the first treatment choice (acute nerve compression or intraneural foreign particles) or after unsuccessful pharmacological treatment (other causes of neuralgic pain).

Microsurgical lesioning in the dorsal root entry zone for pain due to brachial plexus avulsion: a prospective series of 55 patients

OBJECT

Most patients with preganglionic lesions after brachial plexus injuries suffer pain that is hard to control through medication or neuromodulation. Lesioning in the dorsal root entry zone (DREZ) is undeniably effective. Fifty-five patients who had undergone the so-called microsurgical DREZotomy (MDT) procedure were studied with the two following objectives: 1) to describe the anatomical lesions observed during MDT in correlation with sensory deficits and pain features; and 2) to analyze the results in the 44 patients who were followed for more than 1 year (mean 6 years).

METHODS

The observed lesions were severe: 79.6% of ventral and 78.2% of dorsal roots from C5-T1 were impaired. Damage extended to all five roots in 42% of patients. Strong arachnoiditis was present in 38.2%, pseudomeningoceles in 31%, spinal cord distortion and/or atrophy in 49%, and abundant gliotic tissue and/or microcavitations within the dorsal horn at the avulsed segments in 36.4% of cases. Sensory deficit corresponded to the entire territory of the dorsal root lesions in 52% of patients, but was larger in 30% most certainly due to the associated extrarachidian lesions. At the last evaluation after MDT, 66% of patients showed excellent (total relief without medication) or good (total relief with medication) pain relief and 71% experienced an improvement in activity level.

CONCLUSIONS

Apart from other indications not addressed in this article, MDT can be performed to treat refractory pain due to brachial plexus avulsions. The long-term efficacy of this procedure strongly indicates that pain after brachial plexus avulsion originates from the deafferented (and gliotic) dorsal horn.

Current management of postherpetic neuralgia

BACKGROUND

The herpes zoster rash occurs when a dormant varicella zoster virus reactivates in dorsal root and cranial nerve ganglia. Pain that persists in the region where this rash occurred after the cutaneous lesions have healed is termed postherpetic neuralgia (PHN). A wide variety of therapies has been used with varying degrees of success to prevent the occurrence of PHN and to reduce pain with established PHN.

REVIEW SUMMARY

In this review, we discuss the clinical presentation of PHN, current strategies for the prevention and management of this disease, and observations that have increased our understanding of the neural mechanisms involved in PHN.

CONCLUSIONS

Several classes of drugs are effective in attenuating the pain and hyperalgesia caused by PHN, but no single drug leads to the complete relief of symptoms. Additional research is needed to improve treatment strategies and define the role of invasive pain management techniques in cases where PHN is associated with intractable pain.

Dorsal root entry zone microcoagulation for spinal cord injury-related central pain: operative intramedullary electrophysiological guidance and clinical outcome

OBJECT

Surgically created lesions of the spinal cord dorsal root entry zone (DREZ) to relieve central pain after spinal cord injury (SCI) have historically resulted in modest outcomes. A review of the literature indicates that fair to good relief of pain is achieved in approximately 50% of patients when an empirical procedure is performed. This study was undertaken to determine if intramedullary electrical guidance in DREZ lesioning could improve outcomes in patients with SCI-induced central pain. Additionally, electrical data were used to determine if the spinal cord could be somatotopically mapped with regard to this pain of central origin.

METHODS

Forty-one patients with traumatic SCI and intractable central pain underwent DREZ lesioning in which intramedullary electrical guidance was conducted. In nine patients, recording of DREZ-related spontaneous electrical hyperactivity guided the lesioning process. In 32 patients, recording of DREZ-induced evoked electrical hyperactivity during transcutaneous C-fiber stimulation (TCS) additionally guided lesioning. The follow-up period ranged from 1 to 7 years. The analyzed electrical data allowed for somatotopic mapping of the spinal cord.

CONCLUSIONS

Intramedullary electrical guidance of DREZ lesioning substantially improves pain outcomes in patients with traumatic SCI-induced central pain, compared with an empiric technique. The best outcome occurs when DREZ-related spontaneous electrical hyperactivity and evoked hyperactivity during TCS are both used to guide the DREZ lesioning procedure. With such guidance, 100% relief of pain was achieved in 84% of patients and 50 to 100% relief of pain in 88%. Somatotopic mapping of the electrical data led to a proposed pain mechanism for below-level pain, implicating the sympathetic nervous system.

Dorsal root entry zone lesioning used to treat central neuropathic pain in patients with traumatic spinal cord injury: a systematic review

STUDY DESIGN

A systematic review was conducted for studies of any design.

OBJECTIVES

To evaluate the effectiveness and safety of dorsal root entry zone lesioning in treating central neuropathic pain of patients with traumatic spinal cord injury.

SUMMARY OF BACKGROUND DATA

Central neuropathic pain has a great impact on the quality of life of many patients with traumatic spinal cord injury. Dorsal root entry zone lesioning has become one of several treatment options. No previous systematic reviews were found that address this indication for the procedure.

METHODS

Several computerized databases were searched along with reference lists of eligible articles and personal files of advisory panel members. Only primary studies of patients older than 13 years with both traumatic spinal cord injury and central neuropathic pain receiving dorsal root entry zone lesioning were included. Two assessors independently performed data extraction and quality assessment for all the studies.

RESULTS

The selection criteria were met by 11 studies. All were case series of 5 to 54 patients. As reported by 10 of the studies, at least 50% of the patients attained more than 50% pain relief or experienced no pain limitation of activity and no need for narcotics. However, all the studies had poorly defined eligibility criteria or none at all, no control groups, and inadequate reporting of adverse effects. Only one study provided adequate patient description. None of the studies reported the validity, reliability, or responsiveness of outcome measures.

CONCLUSIONS

Reviewed studies indicate promising results from dorsal root entry zone lesioning for the treatment of central neuropathic pain in selected patients with traumatic spinal cord injury. However, the strength of the evidence provided by the studies was poor in terms of study design, outcome measures, reports on the severity of adverse effects, patient selection criteria, and patient description. For these reasons, the evidence is weak for the use of dorsal root entry zone lesioning to relieve central neuropathic pain in patients with traumatic spinal cord injury.

Pain and spasticity after spinal cord injury: mechanisms and treatment

STUDY DESIGN

A comprehensive survey of literature on the proposed mechanisms and treatment of pain and spasticity after spinal cord injury (SCI) was completed.

OBJECTIVES

To define the current understanding of these entities and to review various treatment options.

SUMMARY OF BACKGROUND DATA

The neurophysiologic basis of spasticity after SCI is well established. The mechanism of neuropathic pain after SCI remains conjectural, although considerable new data, much of it from animal models, now add to our understanding of this condition.

METHODS

A comprehensive search and review of the published literature was undertaken.

RESULTS

Treatment options for spasticity are effective and include oral medication (baclofen, tizanidine), intrathecal baclofen, and rarely, surgical rhizotomy or myelotomy. Selected patients with post-SCI pain can respond to surgical myelotomy (DREZ lesions) or intrathecal agents (e.g., morphine + clonidine), but the majority continue to suffer.

CONCLUSIONS

Medical and surgical treatments for spasticity are established and highly successful. Management of post-SCI pain remains a clinical challenge, as there is no uniformly successful medical or surgical treatment.

Nerve lesions and the generation of pain

This review addresses the issue of how axotomy of peripheral nerve fibers leads to pain and hyperalgesia. The point of axotomy (the nerve injury site), the dorsal root ganglia, and the dorsal horn of the spinal cord are candidate sites for generation of the pain signal that is likely to be critical for maintaining the neuropathic pain state. This review considers neuropathic pain from a "systems" perspective, tracing concepts of neuropathic pain from the work of Henry Head to the present. Surprisingly, the nerve injury site and the dorsal root ganglion belonging to a transected spinal nerve do not give rise to spontaneous activity in putative C-fiber nociceptors. The intact nociceptor belonging to adjacent uninjured spinal nerves, however, does acquire abnormal spontaneous activity and a chemical sensitivity to catechols. It is suggested that partially denervated tissues in the nerve, skin, and other locations may release substances that, in turn, sensitize the intact nociceptors. These abnormalities in the intact nociceptor, which arise in the context of Wallerian degeneration, probably play a role in creating or maintaining the abnormal pain state. These considerations probably also apply to the understanding of pain arising in other neuropathies. The findings relative to the "intact" nociceptor provide a rationale by which to understand how therapies distal to the nerve injury site may diminish pain.

Microsurgical junctional DREZ coagulation for treatment of deafferentation pain syndromes

BACKGROUND

In the treatment of intractable deafferentation pain, different procedures in the DREZ have proved most effective. For most of the spot-like techniques special equipment is mandatory. In this study the technique and the results of junctional DREZ coagulation for treatment of different pain syndromes with the help of bipolar forceps is presented.

METHODS

In 40 patients with intractable deafferentation pain syndromes a junctional DREZ coagulation lesion along the entire dorsolateral fissure of the involved spinal cord segments was made using bipolar forceps. Etiologies of the pain included avulsion of the brachial plexus (21 cases), postherpetic pain (4 cases), phantom pain (3 cases), peripheral nerve injury (3 cases), reflex sympathetic dystrophy (2 cases), spinal cord transsection (1 case), and syringomyelia (6 cases).

RESULTS

Of 21 patients who underwent junctional DREZ surgery for pain because of brachial plexus avulsion 10 (47.6%) had complete, 7 (33.3%) excellent, 3 (14.3%) good, and 1 (4.7%) fair pain relief (follow-up 20 to 120 months). In the group of 19 patients (follow-up 6 to 84 months) with pain syndromes other than postavulsion pain we achieved excellent results in 10 cases (52.6%), good in 8 (42.1%) and no pain relief in 1 case (5.3%). Transient sensory neurological disturbances lasting up to 8 weeks were observed in 6 (15%) cases; permanent sensory and motor deficit in 1 (2.5%) case.

CONCLUSIONS

Clinical results of junctional coagulation DREZ lesion for the treatment of deafferentation pain syndromes are promising. There is no need for special equipment for creating DREZ lesions. The lesions are precisely placed with only a bipolar electrode. Postoperative complications are rare and transient. We believe that the junctional coagulation includes the entire dorsolateral sulcus and DREZ structures important for deafferentation pain.

Treatment of Refractory Pain after Brachial Plexus Avulsion with Dorsal Root Entry Zone Lesions

OBJECTIVE

Significant numbers of patients experience intractable pain after brachial plexus root avulsions. Medications and surgical procedures such as amputation of the limb are often not successful in pain treatment.

METHODS

Forty-seven patients with intractable pain after traumatic cervical root avulsions were treated with dorsal root entry zone coagulation between 1980 and 1998. The dorsal root entry zone coagulation procedure was performed 4 months to 12 years after the trauma, and patients were monitored for up to 18 years (average follow-up period, 14 yr).

RESULTS

Immediately after surgery, 75% of patients experienced significant pain reduction; this value was reduced to 63% during long-term follow-up monitoring. Nine patients experienced major complications, including subdural hematomas (n = 2) and motor weakness of the lower limb (n = 7). Improved coagulation electrodes with thermistors that could produce smaller and more-accurate lesion sizes, which were introduced in 1989, significantly reduced the number of complications.

CONCLUSION

Central deafferentation pain that persists and becomes intractable among patients with traumatic cervical root avulsions has been difficult to treat in the past. Long-term follow-up monitoring of patients who underwent the dorsal root entry zone coagulation procedure in the cervical cord indicated that long-lasting satisfactory relief is possible for the majority of individuals, with acceptable morbidity rates.