Effect of preoperative gabapentin on pain intensity and development of chronic pain after carpal tunnel syndrome surgical treatment in women: randomized, double-blind, placebo-controlled study

Pharmacologic Treatments in Upper Extremity Complex Regional Pain Syndrome: A Review and Analysis of Quality of Evidence

BACKGROUND

The purpose of this study was to assess the quality of evidence informing on common pharmacologic modalities used in upper extremity complex regional pain syndrome (CRPS).

METHODS

A literature search was performed for primary prospective trials that reported on the pharmacologic treatment of CRPS type I and II specific to the upper extremity. Thirty-one trials were included and evaluated by 2 independent reviewers according to the Oxford Levels of Evidence (LOE), modified Coleman Methodology Score, and the revised Consolidated Standards of Reporting Trials (CONSORT) score. Cohen's kappa coefficient was calculated to measure interrater reliability.

RESULTS

Twenty-two Oxford LOE I and 9 level II trials met the inclusion criteria. Overall, there was high interrater reliability in the Oxford LOE (100% agreement), modified Coleman Methodology Score (87% agreement), and CONSORT score (94% agreement). The pharmacologic interventions with the highest quality of evidence supporting use in treatment of upper extremity CRPS were bisphosphonates and ketamine. Interventions that lack high-quality evidence are tricyclic antidepressants (TCAs) and topical dimethyl sulfoxide (DMSO). Pharmacologic agents that remain inconclusive are calcitonin, gabapentin, mycophenolate, probiotics, steroids, nonsteroidal anti-inflammatory drugs, vitamin C, and N-acetylcysteine. Agents with limited benefit are mannitol, isosorbide dinitrate, guanethidine, and morphine.

CONCLUSIONS

Based on the evidence evaluated in this study, bisphosphonates should be considered as a first-line medication in the treatment of CRPS. In patients presenting with chronic or refractory CRPS, strong consideration should be given for the use of ketamine. Adjunct treatment in the acute setting should include TCAs and/or topical DMSO.

Diagnostic criteria and outcome measures in randomized clinical trials on carpal tunnel syndrome: a systematic review

BACKGROUND

The diagnostic criteria for carpal tunnel syndrome (CTS) lack uniformity. Moreover, because CTS is a syndrome, there is no consensus as to which signs, symptoms, clinical and complementary tests are more reproducible and accurate for use in clinical research. This heterogeneity is reflected in clinical practice. Thus, establishing effective and comparable care protocols is difficult.

OBJECTIVE

To identify the diagnostic criteria and outcome measures used in randomized clinical trials (RCTs) on CTS.

DESING AND SETTING

Systematic review of randomized clinical trials carried out at the Federal University of São Paulo, São Paulo, Brazil.

METHODS

We searched the Cochrane Library, PubMed, and Embase databases for RCTs with surgical intervention for CTS published between 2006 and 2019. Two investigators independently extracted relevant data on diagnosis and outcomes used in these studies.

RESULTS

We identified 582 studies and 35 were systematically reviewed. The symptoms, paresthesia in the median nerve territory, nocturnal paresthesia, and special tests were the most widely used clinical diagnostic criteria. The most frequently assessed outcomes were symptoms of paresthesia in the median nerve territory and nocturnal paresthesia.

CONCLUSION

The diagnostic criteria and outcome measures used in RCTs about CTS are heterogeneous, rendering comparison of studies difficult. Most studies use unstructured clinical criteria associated with ENMG for diagnosis. The Boston Questionnaire is the most frequently used main instrument to measure outcomes.

REGISTRATION

PROSPERO (CRD42020150965- https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=150965).

Comparison of characteristics between neuropathic pain and non-neuropathic pain in patients with diabetic carpal tunnel syndrome: A cross-sectional study

Background

The aim of the study was to compare the clinical characteristics of diabetic carpal tunnel syndrome between patients with neuropathic pain (NeuP) and non-NeuP.

Methods

We enrolled 276 patients with diabetic carpal tunnel syndrome. Pain symptoms were evaluated using a visual analog scale. Douleur Neuropathique 4, the Neuropathic Pain Symptoms Inventory questionnaire, and the body map were used to assess neuropathic symptoms. Baseline information, clinical manifestations, electrophysiological test results, and psychological status were compared between the neuropathic pain (NeuP) and non-NeuP to identify the risk factor for NeuP occurrence.

Results

Results showed that the degree of pain was more severe in NeuP patients than in nociceptive pain patients (p = 0.025). The frequencies of light touch and pinprick were more pronounced in the NeuP group than in the non-NeuP group (light touch: p = 0.001; pinprick: p = 0.004). There were 48 and 27 NeuP patients with extramedian and proximal spread, respectively, whereas in the non-NeuP group, there were 11 and 9 patients, respectively (p = 0.03). Electrophysiological results showed that patients in the NeuP group exhibited greater sensory nerve conduction velocity impairment compared with the non-NeuP group (p = 0.033). Pain Catastrophizing Scale total scores of the NeuP group were significantly higher than those of the non-NeuP group (p = 0.006).

Conclusion

Of the 276 diabetic carpal tunnel syndrome patients studied, the majority had NeuP. Furthermore, light touch, electrophysiological test results, and psychological factors were found to be related to NeuP occurrence in patients with diabetic carpal tunnel syndrome.

Efficacy of Preemptive Analgesia on Tourniquet and Postoperative Pain Relief in Open Carpal Tunnel Release: A Prospective Randomized Control Trial

BACKGROUND

Preemptive analgesia has been used to reduce postsurgery pain and improve patient satisfaction. The effectiveness of multimodal preemptive analgesia in open carpal tunnel release under local anesthetic with a tourniquet is still debated. This study aimed to determine the effectiveness of preemptive analgesia on the postoperative tourniquet site and the surgical site.

METHODS

A total of 44 patients were randomly assigned to one of 2 groups. An experimental group was given 300 mg of gabapentin, 200 mg of celecoxib, and 500 mg of acetaminophen 2 hours before surgery. Placebos were given to the control group. All surgeries were done under local anesthetic by a specialist hand surgeon. A tourniquet was inflated to the recommended pressure. The outcomes included the immediate postoperative tourniquet site pain scores, surgical site pain scores (at 1, 6, 12, 18, and 24 hours after surgery), and acetaminophen consumption in the first 48 hours.

RESULT

The immediate postoperative tourniquet site pain score in the experimental group was significantly lower than in the placebo group. Although the surgical site pain score in the experimental group was significantly lower than the placebo group at 1, 6, 12, and 18 hours after surgery, these differences were not clinically significant. In addition, there was no statistically significant difference in surgical site pain score at 24 hours after surgery. The amount of acetaminophen consumed during the first 48 hours after surgery was significantly lower in the experimental group than in the placebo group.

CONCLUSION

Multimodal preemptive analgesia effectively reduced immediate postoperative pain at the tourniquet site in open carpal tunnel release. It also reduced postoperative acetaminophen consumption.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic II.

Is gabapentin a safe and effective treatment for nonneuropathic pain?

ABSTRACT

A review of the recent literature found that compared with placebo or other pain medications, gabapentin did not significantly reduce nonneuropathic pain. The drug also is associated with an increased risk of adverse reactions, including somnolence, dizziness, and nausea. Given the lack of efficacy and risk of adverse reactions, gabapentin should not be used for nonneuropathic pain.

Residual Symptoms After Carpal Tunnel Decompression and Treatment With Gabapentin: A Multicenter Study

Objectives

To identify postoperative residual symptoms of carpal tunnel syndrome (CTS) and to investigate the effectiveness of gabapentin in the treatment of residual symptoms.

Materials and methods

Of a total of 412 patients who underwent surgery for CTS in four centers over a four-year period, 14 who had residual symptoms after CTS release and did not receive gabapentin (Group A) and 14 patients with postoperative residual symptoms and received gabapentin were included in this retrospective study. Postoperative residual symptoms were defined as persistent nocturnal numbness and tingling with or without occasional daytime pain. Tinel’s and Phalen’s tests were performed for the diagnosis of residual symptoms. Functional Severity Score (FSS), Symptom Severity Score (SSS), and Visual Analog Scale (VAS) were used to evaluate functional outcomes, severity of symptoms, and numbness and sleep quality, respectively at six and 12 weeks postoperatively.

Level of Evidence: III, therapeutic study

Results

There was no statistically significant difference in the mean postoperative FSS (p=0.845) and VAS-numbness scores (p=0.367) between the groups. However, there was a statistically significant difference in the mean postoperative SSS (p=0.025) and VAS-sleep quality scores (p<0.001) between the groups.

Conclusion

Gabapentin treatment can be a treatment of choice for residual symptoms after CTS surgery and clinical improvement can be achieved owing to its relieving effect, particularly in nocturnal symptoms of patients having neuropathic pain.

Pharmacotherapy for the Prevention of Chronic Pain after Surgery in Adults: An Updated Systematic Review and Meta-analysis

BACKGROUND

Chronic postsurgical pain can severely impair patient health and quality of life. This systematic review update evaluated the effectiveness of systemic drugs to prevent chronic postsurgical pain.

METHODS

The authors included double-blind, placebo-controlled, randomized controlled trials including adults that evaluated perioperative systemic drugs. Studies that evaluated same drug(s) administered similarly were pooled. The primary outcome was the proportion reporting any pain at 3 or more months postsurgery.

RESULTS

The authors identified 70 new studies and 40 from 2013. Most evaluated ketamine, pregabalin, gabapentin, IV lidocaine, nonsteroidal anti-inflammatory drugs, and corticosteroids. Some meta-analyses showed statistically significant-but of unclear clinical relevance-reductions in chronic postsurgical pain prevalence after treatment with pregabalin, IV lidocaine, and nonsteroidal anti-inflammatory drugs. Meta-analyses with more than three studies and more than 500 participants showed no effect of ketamine on prevalence of any pain at 6 months when administered for 24 h or less (risk ratio, 0.62 [95% CI, 0.36 to 1.07]; prevalence, 0 to 88% ketamine; 0 to 94% placebo) or more than 24 h (risk ratio, 0.91 [95% CI, 0.74 to 1.12]; 6 to 71% ketamine; 5 to 78% placebo), no effect of pregabalin on prevalence of any pain at 3 months (risk ratio, 0.88 [95% CI, 0.70 to 1.10]; 4 to 88% pregabalin; 3 to 80% placebo) or 6 months (risk ratio, 0.78 [95% CI, 0.47 to 1.28]; 6 to 68% pregabalin; 4 to 69% placebo) when administered more than 24 h, and an effect of pregabalin on prevalence of moderate/severe pain at 3 months when administered more than 24 h (risk ratio, 0.47 [95% CI, 0.33 to 0.68]; 0 to 20% pregabalin; 4 to 34% placebo). However, the results should be interpreted with caution given small study sizes, variable surgical types, dosages, timing and method of outcome measurements in relation to the acute pain trajectory in question, and preoperative pain status.

CONCLUSIONS

Despite agreement that chronic postsurgical pain is an important topic, extremely little progress has been made since 2013, likely due to study designs being insufficient to address the complexities of this multifactorial problem.

EDITOR’S PERSPECTIVE

Assessment and manifestation of central sensitisation across different chronic pain conditions

Different neuroplastic processes can occur along the nociceptive pathways and may be important in the transition from acute to chronic pain and for diagnosis and development of optimal management strategies. The neuroplastic processes may result in gain (sensitisation) or loss (desensitisation) of function in relation to the incoming nociceptive signals. Such processes play important roles in chronic pain, and although the clinical manifestations differ across condition processes, they share some common mechanistic features. The fundamental understanding and quantitative assessment of particularly some of the central sensitisation mechanisms can be translated from preclinical studies into the clinic. The clinical perspectives are implementation of such novel information into diagnostics, mechanistic phenotyping, prevention, personalised treatment, and drug development. The aims of this paper are to introduce and discuss (1) some common fundamental central pain mechanisms, (2) how they may translate into the clinical signs and symptoms across different chronic pain conditions, (3) how to evaluate gain and loss of function using quantitative pain assessment tools, and (4) the implications for optimising prevention and management of pain. The chronic pain conditions selected for the paper are neuropathic pain in general, musculoskeletal pain (chronic low back pain and osteoarthritic pain in particular), and visceral pain (irritable bowel syndrome in particular). The translational mechanisms addressed are local and widespread sensitisation, central summation, and descending pain modulation.

Significance

Central sensitisation is an important manifestation involved in many different chronic pain conditions. Central sensitisation can be different to assess and evaluate as the manifestations vary from pain condition to pain condition. Understanding central sensitisation may promote better profiling and diagnosis of pain patients and development of new regimes for mechanism based therapy. Some of the mechanisms underlying central sensitisation can be translated from animals to humans providing new options in development of therapies and profiling drugs under development.