Decompression nerve surgery for diabetic neuropathy: a structured review of published clinical trials

Objective Evidence That Nerve Decompression Surgery Reduces Neuropathic DFU Recurrence Risk to Less than 5

Significance: Despite 20 years of research and new treatment methods, diabetic foot ulcer (DFU) remains a common problem with frequent recurrences and complications. Recent Advances: There are reports that nerve decompression (ND) surgery has been observed to produce significantly fewer DFU recurrences than standard of care (SOC). The explanation of this apparent superiority has not been understood. Critical Issues: Microcirculation is understood to be involved in diabetic peripheral neuropathy (DPN) and DFU. There is an underappreciation of the participation in DPN of entrapment neuropathy (EN) due to nerve swelling and impingement in fibro-osseous tunnels. Reducing c-fiber compression in EN by ND generates recovery of subepidermal capillary flow. ND studies have found improved neuromuscular function and epidermal microcirculation phenomena, including chronic capillary ischemia (CCI) and pressure-induced vasodilatation (PIV). There is no current therapy recommended for impaired microcirculation. Clinical and animal evidence has demonstrated that release of locally compressed peripheral nerves improves the epidermal microcirculation which is under sympathetic control. Future Directions: Using epineurolysis to relieve nerve compressions is a physiology-based therapeutic intervention and provides the scientific foundation clarifying how ND reduces DFU recurrence risk. Incorporating ND with current SOC treatments could improve DFU recurrence risk, hard-to-heal ulcers, neuroischemic wounds, amputation risk, and the resulting costs to society. More studies using ND for DFU, especially evidence-based medicine Level I studies, are needed to confirm these preliminary outcomes.

State-of-the-Art Features for Early-Stage Detection of Diabetic Foot Ulcers Based on Thermograms

Diabetic foot ulcers represent the most frequently recognized and highest risk factor among patients affected by diabetes mellitus. The associated recurrent rate is high, and amputation of the foot or lower limb is often required due to infection. Analysis of infrared thermograms covering the entire plantar aspect of both feet is considered an emerging area of research focused on identifying at an early stage the underlying conditions that sustain skin and tissue damage prior to the onset of superficial wounds. The identification of foot disorders at an early stage using thermography requires establishing a subset of relevant features to reduce decision variability and data misinterpretation and provide a better overall cost-performance for classification. The lack of standardization among thermograms as well as the unbalanced datasets towards diabetic cases hinder the establishment of this suitable subset of features. To date, most studies published are mainly based on the exploitation of the publicly available INAOE dataset, which is composed of thermogram images of healthy and diabetic subjects. However, a recently released dataset, STANDUP, provided data for extending the current state of the art. In this work, an extended and more generalized dataset was employed. A comparison was performed between the more relevant and robust features, previously extracted from the INAOE dataset, with the features extracted from the extended dataset. These features were obtained through state-of-the-art methodologies, including two classical approaches, lasso and random forest, and two variational deep learning-based methods. The extracted features were used as an input to a support vector machine classifier to distinguish between diabetic and healthy subjects. The performance metrics employed confirmed the effectiveness of both the methodology and the state-of-the-art features subsequently extracted. Most importantly, their performance was also demonstrated when considering the generalization achieved through the integration of input datasets. Notably, features associated with the MCA and LPA angiosomes seemed the most relevant.

Paradoxical Changes of Cutaneous Microcirculation and Sympathetic Fibers of Rat Hind Limbs after Sciatic Nerve Compression

BACKGROUND

Recent studies show evidence that surgical nerve decompression could improve cutaneous blood flow (CBF), which might benefit ulcer healing. However, the change of CBF and sympathetic fibers after nerve compression is poorly understood. In the current study, a unilateral sciatic nerve compression model was created in Sprague-Dawley rats.

METHODS

A laser Doppler imaging system was applied to assess the CBF of the regions below the ankles. Immunohistochemistry and transmission electron microscopy were used to investigate the histopathologic changes of sympathetic fibers in sciatic nerve samples.

RESULTS

Laser Doppler imaging revealed decreased CBF of both the lesional limb and the contralesional limb, which occurred earlier in the lesional side, indicating an enhanced sympathetic tone on vasomotor function. Intraneural density of sympathetic fibers decreased on both sides and the ultrastructure of unmyelinated fibers of both sides degenerated in a nonsynchronized manner.

CONCLUSIONS

The study revealed nonsynchronized reduced CBF of bilateral hind limbs with paradoxically degenerated and diminished sympathetic fibers in bilateral sciatic nerves after unilateral sciatic nerve compression. These results may validate the importance of and broaden the indications for surgical nerve decompression in preventing or treating foot ulcers.

Feature Ranking by Variational Dropout for Classification Using Thermograms from Diabetic Foot Ulcers

Diabetes mellitus presents a high prevalence around the world. A common and long-term derived complication is diabetic foot ulcers (DFUs), which have a global prevalence of roughly 6.3%, and a lifetime incidence of up to 34%. Infrared thermograms, covering the entire plantar aspect of both feet, can be employed to monitor the risk of developing a foot ulcer, because diabetic patients exhibit an abnormal pattern that may indicate a foot disorder. In this study, the publicly available INAOE dataset composed of thermogram images of healthy and diabetic subjects was employed to extract relevant features aiming to establish a set of state-of-the-art features that efficiently classify DFU. This database was extended and balanced by fusing it with private local thermograms from healthy volunteers and generating synthetic data via synthetic minority oversampling technique (SMOTE). State-of-the-art features were extracted using two classical approaches, LASSO and random forest, as well as two variational deep learning (DL)-based ones: concrete and variational dropout. Then, the most relevant features were detected and ranked. Subsequently, the extracted features were employed to classify subjects at risk of developing an ulcer using as reference a support vector machine (SVM) classifier with a fixed hyperparameter configuration to evaluate the robustness of the selected features. The new set of features extracted considerably differed from those currently considered state-of-the-art but provided a fair performance. Among the implemented extraction approaches, the variational DL ones, particularly the concrete dropout, performed the best, reporting an F1 score of 90% using the aforementioned SVM classifier. In comparison with features previously considered as the state-of-the-art, approximately 15% better performance was achieved for classification.

Does Lower Extremity Nerve Decompression Surgery Improve Quality of Life?

BACKGROUND

Entrapment neuropathies are more prevalent in patients with diabetes than in healthy patients. The aim of this study was to assess the effects of lower extremity nerve decompression surgery on quality of life and clarify predictors of this surgical outcome and the incidence of surgical site problems.

METHODS

Patients who underwent lower extremity nerve decompression surgery between September of 2017 and March of 2019 were followed prospectively at the outpatient clinic of University Medical Center Utrecht. The common, superficial, and deep peroneal nerve and tibial nerve at the tarsal tunnel and soleal sling were decompressed if an entrapment was diagnosed. The primary study outcome was quality of life as measured by the Norfolk Quality of Life-Diabetic Neuropathy questionnaire. Secondary outcomes of interest were change in Michigan Neuropathy Screening Instrument score, predictors of the Norfolk score at follow-up, and the occurrence of complications.

RESULTS

Sixty patients underwent surgery (45 unilateral, 15 bilateral), with a median postoperative follow-up of 13.0 months (interquartile range, 7.3 to 18.0 months). Quality of life improved significantly in this period of observation [baseline median, 46.0 (34.0 to 62.0) versus follow-up median, 37.0 (20.0 to 60.0); p = 0.011], as did Michigan Neuropathy Screening Instrument scores [7.0 (5.0 to 9.0) versus 3.0 (0.0 to 6.5); p < 0.01]. Predictors of quality of life were a higher baseline quality of life score [β, 0.59 ( p = 0.001)], longer follow-up time [β, 2.34 ( p < 0.001)], and hypertension [β, 16.38 ( p = 0.03)]. A total of 26.7 percent of patients had surgical site problems, including wound infections (18.3 percent).

CONCLUSIONS

Lower extremity nerve decompression surgery significantly improves quality of life by reducing neuropathy symptoms in patients with lower extremity nerve compressions. Attention should be given to lowering the risk of wound complications.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.

Design and Implementation of a Smart Insole System to Measure Plantar Pressure and Temperature

An intelligent insole system may monitor the individual's foot pressure and temperature in real-time from the comfort of their home, which can help capture foot problems in their earliest stages. Constant monitoring for foot complications is essential to avoid potentially devastating outcomes from common diseases such as diabetes mellitus. Inspired by those goals, the authors of this work propose a full design for a wearable insole that can detect both plantar pressure and temperature using off-the-shelf sensors. The design provides details of specific temperature and pressure sensors, circuit configuration for characterizing the sensors, and design considerations for creating a small system with suitable electronics. The procedure also details how, using a low-power communication protocol, data about the individuals' foot pressure and temperatures may be sent wirelessly to a centralized device for storage. This research may aid in the creation of an affordable, practical, and portable foot monitoring system for patients. The solution can be used for continuous, at-home monitoring of foot problems through pressure patterns and temperature differences between the two feet. The generated maps can be used for early detection of diabetic foot complication with the help of artificial intelligence.

Nerve Decompression and Distal Transtibial Amputation

Approximately 20% of patients with diabetic peripheral neuropathy (DPN) endorse painful sensations such as prickling, stabbing, and burning pain that reflect small-fiber involvement. Although glycemic control is crucial to delay the onset and progression of DPN, there have been many reports on the use of decompression nerve surgery to aid in the treatment of DPN.

A Novel Machine Learning Approach for Severity Classification of Diabetic Foot Complications Using Thermogram Images

Diabetes mellitus (DM) is one of the most prevalent diseases in the world, and is correlated to a high index of mortality. One of its major complications is diabetic foot, leading to plantar ulcers, amputation, and death. Several studies report that a thermogram helps to detect changes in the plantar temperature of the foot, which may lead to a higher risk of ulceration. However, in diabetic patients, the distribution of plantar temperature does not follow a standard pattern, thereby making it difficult to quantify the changes. The abnormal temperature distribution in infrared (IR) foot thermogram images can be used for the early detection of diabetic foot before ulceration to avoid complications. There is no machine learning-based technique reported in the literature to classify these thermograms based on the severity of diabetic foot complications. This paper uses an available labeled diabetic thermogram dataset and uses the k-mean clustering technique to cluster the severity risk of diabetic foot ulcers using an unsupervised approach. Using the plantar foot temperature, the new clustered dataset is verified by expert medical doctors in terms of risk for the development of foot ulcers. The newly labeled dataset is then investigated in terms of robustness to be classified by any machine learning network. Classical machine learning algorithms with feature engineering and a convolutional neural network (CNN) with image-enhancement techniques are investigated to provide the best-performing network in classifying thermograms based on severity. It is found that the popular VGG 19 CNN model shows an accuracy, precision, sensitivity, F1-score, and specificity of 95.08%, 95.08%, 95.09%, 95.08%, and 97.2%, respectively, in the stratification of severity. A stacking classifier is proposed using extracted features of the thermogram, which is created using the trained gradient boost classifier, XGBoost classifier, and random forest classifier. This provides a comparable performance of 94.47%, 94.45%, 94.47%, 94.43%, and 93.25% for accuracy, precision, sensitivity, F1-score, and specificity, respectively.

Electrophysiological Study of the Tibial Nerve Across the Tarsal Tunnel in Distal Symmetric Diabetic Polyneuropathy

OBJECTIVE

The aim of the study was to demonstrate abnormalities of motor conduction of the tibial nerve across the tarsal tunnel in type 2 diabetes.

DESIGN

One hundred twenty-four consecutive patients (mean age = 66.6 yrs, 62.1% male) with distal symmetric diabetic polyneuropathy clinically diagnosed were prospectively enrolled. Nerve conduction studies of deep peroneal, tibial, superficial peroneal, medial plantar, and sural nerves and standard needle electromyography in the lower limbs were performed. Demographic, anthropometric, and clinical findings were collected.

RESULTS

Motor conduction velocity of the tibial nerve across tarsal tunnel was slowed in 60.5% of patients; another 4% showed conduction block across tarsal tunnel without reduction of motor conduction velocity. Overall percentage of abnormalities across tarsal tunnel (64.5%) exceeds that of the sensory conduction velocities of proximal sural and superficial peroneal nerves. Abnormal tibial motor conduction velocity across tarsal tunnel represents the most common abnormality among all motor nerve conduction study parameters and significantly correlates with hemoglobin level, diabetic neuropathic index score, and diabetic complications frequency.

CONCLUSIONS

Tibial conduction abnormalities across tarsal tunnel are the most sensitive motor parameter in distal symmetric diabetic polyneuropathy, second only to conduction abnormalities of sensory/mixed distal nerves of the feet. The use of nerve conduction studies across tarsal tunnel of the tibial nerve may be useful in the electrophysiological protocol to confirm the diagnosis of distal symmetric diabetic polyneuropathy.

Advances in Interventional Therapies for Painful Diabetic Neuropathy: A Systematic Review

BACKGROUND

Painful diabetic neuropathy (PDN) is one of the major complications of diabetes mellitus. It is often debilitating and refractory to pharmaceutical therapies. Our goal was to systematically review and evaluate the strength of evidence of interventional management options for PDN and make evidence-based recommendations for clinical practice.

METHODS

We searched PubMed, Scopus, Google Scholar, and Cochrane Llibrary and systematically reviewed all types of clinical studies on interventional management modalities for PDN.

RESULTS

We identified and analyzed 10 relevant randomized clinical trials (RCTs), 8 systematic reviews/meta-analyses, and 5 observational studies of interventional modalities for PDN using pain as primary outcome. We assessed the risk of bias in grading of evidence and found that there is moderate to strong evidence to support the use of dorsal column spinal cord stimulation (SCS) in treating PDN in the lower extremities (evidence level: 1B+), while studies investigating its efficacy in the upper extremities are lacking. Evidence exists that acupuncture and injection of botulinum toxin-A provide relief in pain or muscle cramps due to PDN with minimal side effects (2B+/1B+). Similar level of evidence supports surgical decompression of lower limb peripheral nerves in patients with intractable PDN and superimposed nerve compression (2B±/1B+). Evidence for sympathetic blocks or neurolysis and dorsal root ganglion (DRG) stimulation is limited to case series (2C+).

CONCLUSIONS

Moderate to strong evidence exists to support the use of SCS in managing lower extremity pain in patients who have failed conventional medical management for PDN. Acupuncture or injection of botulinum toxin-A can be considered as an adjunctive therapy for PDN. Surgical decompression of peripheral nerves may be considered in patients with PDN superimposed with nerve compression. High-quality studies are warranted to further evaluate the safety, efficacy, and cost-effectiveness of interventional therapies for PDN.

The Treatment of Painful Diabetic Neuropathy

Painful diabetic peripheral neuropathy (painful-DPN) is a highly prevalent and disabling condition, affecting up to one-third of patients with diabetes. This condition can have a profound impact resulting in a poor quality of life, disruption of employment, impaired sleep, and poor mental health with an excess of depression and anxiety. The management of painful-DPN poses a great challenge. Unfortunately, currently there are no Food and Drug Administration (USA) approved disease-modifying treatments for diabetic peripheral neuropathy (DPN) as trials of putative pathogenetic treatments have failed at phase 3 clinical trial stage. Therefore, the focus of managing painful- DPN other than improving glycaemic control and cardiovascular risk factor modification is treating symptoms. The recommended treatments based on expert international consensus for painful- DPN have remained essentially unchanged for the last decade. Both the serotonin re-uptake inhibitor (SNRI) duloxetine and α2δ ligand pregabalin have the most robust evidence for treating painful-DPN. The weak opioids (e.g. tapentadol and tramadol, both of which have an SNRI effect), tricyclic antidepressants such as amitriptyline and α2δ ligand gabapentin are also widely recommended and prescribed agents. Opioids (except tramadol and tapentadol), should be prescribed with caution in view of the lack of definitive data surrounding efficacy, concerns surrounding addiction and adverse events. Recently, emerging therapies have gained local licenses, including the α2δ ligand mirogabalin (Japan) and the high dose 8% capsaicin patch (FDA and Europe). The management of refractory painful-DPN is difficult; specialist pain services may offer off-label therapies (e.g. botulinum toxin, intravenous lidocaine and spinal cord stimulation), although there is limited clinical trial evidence supporting their use. Additionally, despite combination therapy being commonly used clinically, there is little evidence supporting this practise. There is a need for further clinical trials to assess novel therapeutic agents, optimal combination therapy and existing agents to determine which are the most effective for the treatment of painful-DPN. This article reviews the evidence for the treatment of painful-DPN, including emerging treatment strategies such as novel compounds and stratification of patients according to individual characteristics (e.g. pain phenotype, neuroimaging and genotype) to improve treatment responses.

Tarsal tunnel syndrome: current rationale, indications and results

Tarsal tunnel syndrome (TTS) is a neuropathy due to compression of the posterior tibial nerve and its branches. It is usually underdiagnosed and its aetiology is very diverse. In 20% of cases it is idiopathic. There is no test that diagnoses it with certainty. The diagnosis is usually made by correlating clinical history, imaging tests, nerve conduction studies (NCSs) and electromyography (EMG). A differential diagnosis should be made with plantar fasciitis, lumbosacral radiculopathy (especially S1 radiculopathy), rheumatologic diseases, metatarsal stress fractures and Morton’s neuroma. Conservative management usually gives good results. It includes activity modification, administration of pain relief drugs, physical and rehabilitation medicine, and corticosteroid injections into the tarsal tunnel (to reduce oedema). Abnormally slow nerve conduction through the posterior tibial nerve usually predicts failure of conservative treatment. Indications for surgical treatment are failure of conservative treatment and clear identification of the cause of the entrapment. In these circumstances, the results are usually satisfactory. Surgical success rates vary from 44% to 96%. Surgical treatment involves releasing the flexor retinaculum from its proximal attachment near the medial malleolus down to the sustentaculum tali. Ultrasound-guided tarsal tunnel release is possible. A positive Tinel’s sign before surgery is a strong predictor of surgical relief after decompression. Surgical treatment achieves the best results in young patients, those with a clear aetiology, a positive Tinel’s sign prior to surgery, a short history of symptoms, an early diagnosis and no previous ankle pathology.

Cite this article: EFORT Open Rev 2021;6:1140-1147. DOI: 10.1302/2058-5241.6.210031

Cost-Effectiveness of Lower Extremity Nerve Decompression Surgery in the Prevention of Ulcers and Amputations: A Markov Analysis

BACKGROUND

The costs and health effects associated with lower extremity complications in diabetes mellitus are an increasing burden to society. In selected patients, lower extremity nerve decompression is able to reduce symptoms of neuropathy and the concomitant risks of diabetic foot ulcers and amputations. To estimate the health and economic effects of this type of surgery, the cost-effectiveness of this intervention compared to current nonsurgical care was studied.

METHODS

To estimate the incremental cost-effectiveness of lower extremity nerve decompression over a 10-year period, a Markov model was developed to simulate the onset and progression of diabetic foot disease in patients with diabetes and neuropathy who underwent lower extremity nerve decompression surgery, compared to a group undergoing current nonsurgical care. Mean survival time, health-related quality of life, presence or risk of lower extremity complications, and in-hospital costs were the outcome measures assessed. Data from the Rotterdam Diabetic Foot Study were used as current care, complemented with information from international studies on the epidemiology of diabetic foot disease, resource use, and costs, to feed the model.

RESULTS

Lower extremity nerve decompression surgery resulted in improved life expectancy (88,369.5 life-years versus 86,513.6 life-years), gain of quality-adjusted life-years (67,652.5 versus 64,082.3), and reduced incidence of foot complications compared to current care (490 versus 1087). The incremental cost-effectiveness analysis was -€59,279.6 per quality-adjusted life-year gained, which is below the Dutch critical threshold of less than €80,000 per quality-adjusted life-year.

CONCLUSIONS

Decompression surgery of lower extremity nerves improves survival, reduces diabetic foot complications, and is cost saving and cost-effective compared with current care, suggesting considerable socioeconomic benefit for society.

A machine learning model for early detection of diabetic foot using thermogram images

Diabetes foot ulceration (DFU) and amputation are a cause of significant morbidity. The prevention of DFU may be achieved by the identification of patients at risk of DFU and the institution of preventative measures through education and offloading. Several studies have reported that thermogram images may help to detect an increase in plantar temperature prior to DFU. However, the distribution of plantar temperature may be heterogeneous, making it difficult to quantify and utilize to predict outcomes. We have compared a machine learning-based scoring technique with feature selection and optimization techniques and learning classifiers to several state-of-the-art Convolutional Neural Networks (CNNs) on foot thermogram images and propose a robust solution to identify the diabetic foot. A comparatively shallow CNN model, MobilenetV2 achieved an F1 score of ∼95% for a two-feet thermogram image-based classification and the AdaBoost Classifier used 10 features and achieved an F1 score of 97%. A comparison of the inference time for the best-performing networks confirmed that the proposed algorithm can be deployed as a smartphone application to allow the user to monitor the progression of the DFU in a home setting.

Health economic evaluation of different treatment strategies for peripheral entrapment mononeuropathies: a systematic review

Introduction: In this era of cost-conscious health systems, it is of utmost importance to identify and establish the most cost-effective treatment option. However, in the case of peripheral entrapment mononeuropathies there is alack of data regarding economically effective treatment strategies. Therefore, the objective was to conduct an economic evaluation including both costs and benefits of various treatment strategies applied to peripheral entrapment mononeuropathies to estimate the relative cost-effective treatment regimens.Areas covered: Over the 19 years, seven excellent-high quality economic evaluations of three types of peripheral entrapment mononeuropathies were identified in four countries. Our findings showed that surgery was the most cost-effective therapy followed by same cost efficacy of infiltrative therapy and conservative therapy for peripheral entrapment mononeuropathies. However, the fact that surgery was the most common comparator (n = 6) in our selected studies cannot be neglected.Expert opinion: Due to huge methodological variability, the finding of surgery as the cost-effective treatment strategy remains tentative and the decision about the most suitable clinical and cost-effective therapy should be individualized from case to case. Moreover, the economic evaluation of all possible treatment strategies for peripheral entrapment mononeuropathies over alonger period of analysis is required in future studies.

Neuropathic Pain in the Elderly

Neuropathic pain due to a lesion or a disease of the somatosensory system often affects older people presenting several comorbidities. Moreover, elderly patients are often poly-medicated, hospitalized and treated in a nursing home with a growing risk of drug interaction and recurrent hospitalization. Neuropathic pain in the elderly has to be managed by a multidimensional approach that involves several medical, social and psychological professionals in order to improve the quality of life of the patients and, where present, their relatives.

Comment on IWGDF ulcer prevention guidelines

The IWGDF 2019 Updated Guidelines for prevention of foot ulcers in diabetes advise that nerve decompression surgery not be considered. This nerve decompression option has similar scientific supporting evidence to other surgeries which are recommended. The sanction ignores a large body of non-Level 1 evidence demonstrating various beneficial outcomes of ND including pain relief, DFU prevention, and protection from recurrence and amputation.

The natural history of tarsal tunnel syndrome in diabetic subjects

INTRODUCTION

Tibial nerve entrapment is highly prevalent in diabetic subjects, resulting in significantly more neuropathic complaints and concomitant sensory disturbances. The study aim was to assess the impact of tarsal tunnel syndrome (TTS) and sensory loss at baseline on incident diabetic foot ulceration (DFU) in diabetic patients, since decompressing the tibial nerve might change the natural history of the disease.

METHODS

In this study, 113 subjects with TTS (69 bilateral, 23 left-sided and 21 right-sided) participating in the prospective Rotterdam Diabetic Foot Study were compared to 303 diabetic controls without TTS, regarding incident DFU. Kaplan-Meier analysis and Cox's regression analysis were used to determine the independent hazard of baseline variables for new DFU.

RESULTS

The median observation period was 836.5 days (IQR, 459-1077.8). In bilateral TTS, 17.4% (95% CI: 8.4-26.3%) of subjects experienced DFU versus 8.3% (95% CI: 5.1-11.6%) in controls (left or right) during follow-up (p = 0.0036). In left-sided TTS, no subjects versus 6.2% (95% CI: 3.4-9.0%) in controls had DFUs (p = 0.243). Incident ulceration was seen in 14.3% (95% CI: -0.7% to -29.3%) of right-sided TTS subjects versus 4.1% (95% CI: 1.5-6.3%) in controls (p = 0.034). Besides HbA1c, diminished sensation at the hallux independently increased the risk of ulceration, in patients with (HR: 4.692, p = 0.003) and without (HR: 2.307, p = 0.002) prior DFU.

DISCUSSION

Elevated sensory thresholds in TTS render diabetic patients at a higher risk for DFU. With effective surgery, TTS is likely to be an amenable factor to potentially prevent diabetic foot disease and thereby reduce amputation risk.

LEVEL OF EVIDENCE

II.

Diabetic Neuropathy Collection: Treatment of Diabetic Neuropathy

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