Under Pressure

Surgical Management of Chronic Neuropathic Burn Pain

Burn-related chronic neuropathic pain can contribute to a decreased quality of life. When medical and pharmacologic therapies prove ineffective, patients should undergo evaluation for surgical intervention, consisting of a detailed physical examination and elective diagnostic nerve block, to identify an anatomic cause of pain. Based on symptoms and physical examination findings, particularly Tinel's sign, treatments can vary, including a trial of laser therapies, fat grafting, or nerve surgeries (nerve decompression, neuroma excision, targeted muscle reinnervation, regenerative peripheral nerve interfaces, and vascularized denervated muscle targets). It is essential to counsel patients to establish appropriate expectations prior to treatment with a multidisciplinary team.

Neuropathic pain in burn patients - A common problem with little literature: A systematic review

BACKGROUND

The prevalence of neuropathic pain (NP) in burn patients is reported in the literature to be as high as 80%1. Given the complexity of NP in burn patients and the wide range of treatments available, a systematic review of the literature is warranted to summarize our current understanding of management and treatment of NP in this population.

METHODS

This systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. The following databases were queried to identify relevant articles: PubMed, Cochrane, Embase, Scopus, Ovid, and Web of Science. The main outcome measures were incidence and management of NP. Secondary outcomes included risk factors for NP.

RESULTS

Included articles presented findings from 11 different countries, capturing outcomes for 4366 patients. Risk factors for neuropathic pain in burn patients were identified, including older age, alcohol and substance abuse, current daily smoking, greater % total body surface area burns (TBSA), and longer hospitalizations. Pharmacologic treatments included gabapentin/pregabalin (n = 7), ascorbic acid (n = 1), and lidocaine (n = 1). Overall, the studies showed varied results regarding the efficacy of pharmacological treatments. While certain studies demonstrated gabapentanoids to be effective in reducing neuropathic symptoms, others found conflicting results. With regards to non-pharmacologic treatments, electroconvulsive therapy (n = 1), electropuncture (n = 1), nerve release/reconstruction (n = 2), and somatosensory feedback rehabilitation (n = 1) were used and demonstrated promise in reducing pain intensity and improving functionality.

CONCLUSIONS

Despite NP afflicting the majority of burn patients long after their injury, this systematic review demonstrates insufficient evidence on the pathophysiology, outcomes, and risk factors in NP, as well as the efficacy of various therapies. Future prospective and randomized studies evaluating the etiology of these factors can substantially improve our treatment strategies. This can allow for the development of well-delineated and evidence-based protocols in NP management in hopes of improving quality of life and both psychological and physical function in burn patients.

Chronic Nerve Pain after Burn Injury: An Anatomical Approach and the Development and Validation of a Model to Predict a Patient's Risk

BACKGROUND

A model that predicts a patient's risk of developing chronic, burn-related nerve pain may guide medical and/or surgical management. This study determined anatomy-specific variables and constructed a mathematical model to predict a patient's risk of developing burn-related nerve pain.

METHODS

A retrospective analysis was conducted from 1862 adults admitted to a burn center from 2014 to 2019. One hundred thirteen patients developed burn-related nerve pain. Comparisons were made using 11 anatomy-specific locations between patients with and without burn-related nerve pain. The modified Delphi technique was used to select 14 potential risk variables. Multivariate regression techniques, Brier scores, area under the curve, Hosmer-Lemeshow goodness-of-fit, and stratified K-fold cross-validation was used for model development. Chronic pain was defined as pain lasting 6 or more months after release from the Burn Center.

RESULTS

Prevalence rates of burn-related nerve pain were similar in the development (6.1 percent) and validation (5.4 percent) cohorts [Brier score = 0.15; stratified K-fold cross-validation (K = 10): area under the curve, 0.75; 95 percent CI, 0.68 to 0.81; Hosmer-Lemeshow goodness-of-fit, p = 0.73; n = 10 groups]. Eight variables were included in the final equation. Burn-related nerve pain risk score = -6.3 + 0.02 (age) + 1.77 (tobacco use) + 1.04 (substance abuse) + 0.67 (alcohol abuse) + 0.84 (upper arm burn) + 1.28 (thigh burn) + 0.21 (number of burn operations) + 0.01 (hospital length-of-stay). Burn-related nerve pain predicted probability = 1 - 1/[1 + exp(burn-related nerve pain risk score)] for 6-month burn-related nerve pain risk score. As the number of risk factors increased, the probability of pain increased.

CONCLUSIONS

Risk factors were identified for developing burn-related nerve pain at 11 anatomical locations. This model accurately predicts a patient's risk of developing burn-related nerve pain at 6 months. Age, tobacco use, substance abuse, alcohol abuse, upper arm burns, thigh burns, the number of burn operations, and hospital length of stay represented the strongest predictors.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Risk, III.

Nerve Pain after Burn Injury: A Proposed Etiology-Based Classification

BACKGROUND

Understanding the mechanism of nerve injury may facilitate managing burn-related nerve pain. This proposed classification, based on cause of nerve injury, was developed to enhance the understanding and management of burn-related nerve pain.

METHODS

This retrospective investigation included patients aged 15 years or older admitted to the burn center from 2014 to 2019. Burn-related nerve pain was patient-reported and clinically assessed as pain 6 months or more after burn injury, unrelated to preexisting illnesses/medications. The pain classification consisted of direct nerve injury, nerve compression, electrical injury, and nerve dysfunction secondary to systemic injury. The four categories were statistically analyzed between groups, using 52 variables.

RESULTS

Of the 1880 consecutive burn patients, 113 developed burn-related nerve pain and were eligible for validation of the classification: direct nerve injury, n = 47; nerve compression, n = 12; electrical injury, n = 7; and nerve dysfunction secondary to systemic injury, n = 47. Factors, significantly increased, that distinguished one category from another were as follows: for direct nerve injury, continuous symptoms (p < 0.001), refractory nerve release response (p < 0.001), nerve repair (p < 0.001), and pruritus (p < 0.001); for nerve compression, Tinel signs (p < 0.001), shooting pain (p < 0.001), numbness (p = 0.003), intermittent symptoms (p < 0.001), increased percentage total body surface area burned (p = 0.019), surgical procedures (p < 0.001), and nerve release (p < 0.001); and for electrical injury, Tinel sign (p < 0.001), intermittent symptoms (p = 0.002), amputations (p = 0.002), fasciotomies (p < 0.001), and nerve release (p < 0.001). Nerve dysfunction secondary to systemic injury was distinguished by significantly less Tinel signs (p < 0.001), shooting pain (p < 0.001), numbness and tingling (p < 0.001), pruritus (p < 0.001), fascial excision (p = 0.004), skin grafts (p < 0.001), amputation (p = 0.004), nerve releases (p < 0.001), and third-degree burns (p = 0.002).

CONCLUSION

A classification consisting of direct nerve injury, nerve compression, electrical injury, and nerve dysfunction secondary to systemic injury is presented that may guide patient management and research methods, with the goal of improving pain outcomes in burn-related nerve pain.

Risk Factors Associated With the Progression From Acute to Chronic Neuropathic Pain After Burn-Related Injuries

BACKGROUND

Pain, unrelated to the initial thermal trauma itself, can result after burn injury and prolong the recovery/rehabilitation phase of the patient's care. This pain, after discharge from the burn unit, may be acute and self-limiting or chronic and contribute to long-term patient morbidity. The purposes of this study were to compare burn patients who had, after discharge from the burn unit, only acute pain with burn patients who developed chronic, neuropathic pain (CNP) and to determine risks factors for progression from acute to chronic pain in the setting of a burn center.

METHODS

A single-center, retrospective chart review of patients admitted to the adult burn center was performed from January 1, 2014, to January 1, 2019. Patients included were older than 15 years, sustained a burn injury, and admitted to the burn unit. Chronic pain was defined as pain lasting greater than 6 months after discharge from the burn unit. Pain descriptors included shooting, stabbing, sharp, burning, tingling, numbness, throbbing, pruritus, intermittent, and/or continuous dysesthetic sensations after the burn. Patients were excluded if they had preexisting neuropathic pain due to an underlying medical illness or previous surgery.

RESULTS

During a 5-year period, of the 1880 admissions to the burn unit, 143 burn patients developed post-initial-onset pain as a direct result of their burn. Of the 143 patients with acute pain, pain resolved in 30 patients, whereas pain progressed to CNP in 113 patients (79%). Patient follow-up was a median (interquartile range [IQR]) of 26.5 (10-45) months. Patients whose pain progressed to CNP had significantly greater percent total body surface area burns (median [IQR], 6 [3-25] vs 3 [1-10]; P = 0.032), had more full-thickness burns (66/113 [58%] vs 8/30 [27%] patients, P = 0.004), had surgery (85/113 [75%] vs 16/30 [53%] patients, P = 0.042), had more surgical procedures (median [IQR], 2 [1-6] vs 1 [0-3], P = 0.002), and developed more complications (32/113 [28%] vs 2/30 [7%] patients, P = 0.014) compared with those with acute neuropathic pain, respectively.

CONCLUSIONS

Burn patients who progressed from having acute to CNP had significantly greater percent total body surface area burns, had more full-thickness burns, had surgery, had more surgical procedures, and developed more complications compared with burn patients with only acute pain.

Prevalence and associated predictors for patients developing chronic neuropathic pain following burns

BACKGROUND

Chronic pain, unrelated to the burn itself, can manifest as a long-term complication in patients sustaining burn injuries. The purpose of this study was to determine the prevalence of chronic neuropathic pain (CNP) and compare burn characteristics between patients who developed CNP and patients without CNP who were treated at a burn center.

METHODS

A single-center, retrospective analysis of 1880 patients admitted to the adult burn center was performed from 1 January 2014 to 1 January 2019. Patients included were over the age of 15 years, sustained a burn injury and were admitted to the burn center. CNP was diagnosed clinically following burn injury. Patients were excluded from the definition of CNP if their pain was due to an underlying illness or medication. Comparisons between patients admitted to the burn center with no pain and patients admitted to the burn center who developed CNP were performed.

RESULTS

One hundred and thirteen of the 1880 burn patients developed CNP as a direct result of burn injury over 5 years with a prevalence of 6.01%. Patients who developed CNP were a significantly older median age (54 years vs. 46 years, p = 0.002), abused alcohol (29% vs. 8%, p < 0.001),abused substances (31% vs. 9%, p < 0.001), were current daily smokers (73% vs. 33%, p < 0.001), suffered more full-thickness burns (58% vs. 43%, p < 0.001), greater median percent of total body surface area (%TBSA) burns (6 vs. 3.5, p < 0.001), were more often intubated on mechanical ventilation (33% vs. 14%, p < 0.001), greater median number of surgeries (2 vs. 0, p < 0.001) and longer median hospital length of stay (LOS) (10 days vs. 3 days, p < 0.001), compared to those who did not develop CNP, respectively. Median patient follow-up was 27 months.

CONCLUSIONS

The prevalence of CNP over 5 years was 6.01% in the burn center. Older ages, alcohol abuse, substance abuse, current daily smoking, greater percent of total body surface area (%TBSA) burns, third degree burns, being intubated on mechanical ventilation, having more surgeries and longer hospital LOS were associated with developing CNP following burn injury, compared to patients who did not develop CNP following burn injury.