Optimization of Surgical Outcome in Lower Extremity Nerve Decompression Surgery

Effect of Surgical Release of Entrapped Peripheral Nerves in Sensorimotor Diabetic Neuropathy on Pain and Sensory Dysfunction-Study Protocol of a Prospective, Controlled Clinical Trial

BACKGROUND

Nerve entrapment has been hypothesized to contribute to the multicausal etiology of axonopathy in sensorimotor diabetic neuropathy. Targeted surgical decompression reduces external strain on the affected nerve and, therefore, may alleviate symptoms, including pain and sensory dysfunction. However, its therapeutic value in this cohort remains unclear.

AIM

Quantifying the treatment effect of targeted lower extremity nerve decompression in patients with preexisting painful sensorimotor diabetic neuropathy and nerve entrapment on pain intensity, sensory function, motor function, and neural signal conduction.

STUDY DESIGN

This prospective, controlled trial studies 40 patients suffering from bilateral therapy-refractory, painful (n = 20, visual analogue scale, VAS ≥ 5) or painless (n = 20, VAS = 0) sensorimotor diabetic neuropathy with clinical and/or radiologic signs of focal lower extremity nerve compression who underwent unilateral surgical nerve decompression of the common peroneal and the tibial nerve. Tissue biopsies will be analyzed to explore perineural tissue remodeling in correlation with intraoperatively measured nerve compression pressure. Effect size on symptoms including pain intensity, light touch threshold, static and moving two-point discrimination, target muscle force, and nerve conduction velocity will be quantified 3, 6, and 12 months postoperatively, and compared (1) to the preoperative values and (2) to the contralateral lower extremity that continues non-operative management.

CLINICAL SIGNIFICANCE

Targeted surgical release may alleviate mechanical strain on entrapped lower extremity nerves and thereby potentially improve pain and sensory dysfunction in a subset of patients suffering from diabetic neuropathy. This trial aims to shed light on these patients that potentially benefit from screening for lower extremity nerve entrapment, as typical symptoms of entrapment might be erroneously attributed to neuropathy only, thereby preventing adequate treatment.

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.

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.

Acute Improvement in Intraoperative EMG During Common Fibular Nerve Decompression in Patients with Symptomatic Diabetic Sensorimotor Peripheral Neuropathy: EMG and Clinical Attribute Interrelations

STUDY AIMS

 Electromyographic (EMG) recordings of the fibularis longus and tibialis anterior muscles were performed intraoperatively during nerve decompression (ND) of the common fibular nerve (CFN) in patients with symptomatic diabetic sensorimotor peripheral neuropathy. Patient demographics and clinical attributes were compared against changes in EMG after ND and analyzed for possible correlations.

METHODS

 Intraoperative changes in CFN EMG were analyzed for correlations against sex, age, body mass index (BMI), hemoglobin A1c (A1c), and type and duration of diabetes.

RESULTS

 Statistically significant changes were found between EMG changes and patient attributes, but no individual correlations were established. Significant EMG improvement was observed for both men and women (p < 0.0001 and p < 0.05, respectively), age groups (4th decade: p < 0.05; 5th decade: p < 0.05; 6th decade: p < 0.01; 7th decade: p < 0.005), diabetes duration (0-9 years: p = 0.002; 10-19 years: p = 0.002; 20-29 years: p = 0.03), and for type 1 and 2 diabetes (type 1: p < 0.005; type 2: p < 0.001). EMG improvement was greater in patients with the highest BMI levels (30-34.9: p = 0.014; 35-39.9: p = 0.013; > 39.9: p = 0.043), and highest A1c levels (> 6.4%; p < 0.0001).

CONCLUSION

 Although long-term clinical studies are needed, these results provide insight into which patients might benefit most from this surgery. These results also suggest that surgical ND can produce an acute improvement in nerve function for both men and women, for people with type 1 and 2 diabetes, and across a wide range of ages, BMI, A1c levels, and disease duration.

(Cost-)effectiveness of lower extremity nerve decompression surgery in subjects with diabetes: the DeCompression (DECO) trial-study protocol for a randomised controlled trial

INTRODUCTION

The peripheral nerves of patients with diabetes are often pathologically swollen, which results in entrapment at places of anatomical narrowing. This results in nerve dysfunction. Surgical treatment of compression neuropathies in the lower extremities (lower extremity nerve decompression (LEND)) results in relief of symptoms and gain in peripheral nerve function, which may lead to less sensory loss (short term) and less associated detrimental effects including foot ulceration and amputations, and lower costs (long term). The aim of the DeCompression trial is to evaluate the effectiveness and (cost-)effectiveness of surgical decompression of compressed lower extremity nerves (LEND surgery) compared with patients treated with conventional (non-surgical) care.

METHODS AND ANALYSIS

A stratified randomised (1 to 1) controlled trial comparing LEND surgery (intervention) with conventional non-surgical care (control strategy) in subjects with diabetes with problems of neuropathy due to compression neuropathies in the lower extremity. Randomisation is stratified for participating hospital (n=11) and gender. Patients and controls have the same follow-up at 1.5, 3, 6, 9, 12, 18, 24 and 48 months. Participants (n=344) will be recruited in 12 months and enrolled in all affiliated hospitals in which they receive both the intervention or conventional non-surgical care and follow-up. Outcome assessors are blinded to group assignment.

PRIMARY OUTCOME

disease-specific quality of life (Norfolk Quality of Life Questionnaire-Diabetic Neuropathy).

SECONDARY OUTCOMES

health-related quality of life (EuroQoL 5-dimension 5-level (EQ-5D5L), 36-item Short Form (SF-36)), plantar sensation (Rotterdam Diabetic Foot Test Battery), incidence of ulcerations/amputations, resource use and productivity loss (Medical Cost Questionnaire, Productivity Cost Questionnaire) during follow-up. The incremental cost-effectiveness ratio will be estimated on the basis of the collected empirical data and a cost-utility model.

ETHICS AND DISSEMINATION

Ethics approval has been granted by the Medical Research Ethics Committee of Utrecht University Medical Center (reference: NL68312.041.19v5, protocol number: 19-335/M). Dissemination of results will be via journal articles and presentations at national and international conferences.

TRIAL REGISTRATION NUMBER

NetherlandsTrial Registry NL7664.

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.

Balance, risk of falls, risk factors and fall-related costs in individuals with diabetes

AIMS

Sensory loss and impaired balance are considered risk factors of incident falls. The aim of this study was to assess the relationship between degree of foot sensation and balance, risk of falls, incidence of fall-related injuries and costs in a cohort of patients with diabetes.

METHODS

(Non)-neuropathic subjects participating in the Rotterdam Diabetic Foot Study were followed prospectively. Subjects underwent sensory testing of the feet (39 item Rotterdam Diabetic Foot Study Test Battery (RDF-39)); balance was assessed at the second follow-up (Brief-BESTest) as were data on incident falls. Medical records and financial data were abstracted to estimate fall-related morbidity and in-hospital costs.

RESULTS

A higher RDF-39 score, cerebral artery disease, type 2 diabetes, height and age were predictors of the Brief-BESTest total score. 41/296 patients (13.9%) reported two or more falls during follow-up. Predictors for recurrent falls were a higher RDF-39 score (aOR: 1.124, p < 0.0005), male gender (aOR: 0.319, p = 0.016), age (aOR: 0.938, p = 0.003) and type 2 diabetes (aOR: 3.157, p = 0.100). Thirty-one patients used medical resources (median US$ 440.45 (IQR: 179-1162).

CONCLUSIONS

Degree of sensory loss correlates significantly with an increased imbalance and risk of falls. The RDF-39 may be used as stratification tool in medical decision-making and patient information.

Grading the loss of sensation in diabetic patients: A psychometric evaluation of the rotterdam diabetic foot study test battery

Introduction: Static‐ and moving 2‐point discrimination (S2PD, M2PD), 10‐g monofilaments‐ and tuning fork are validated outcome measures of clinical manifestations of diabetes‐related neuropathy. No modern statistical techniques have been used to investigate how well these instruments combine to measure sensory loss. Methods: To grade sensory loss at the feet, we fitted parametric forms of Item Response Theory models to the data of these instruments. Results: The fit statistics indicate that the loss of sensation is gradable, with readily available instruments. S2PD and M2PD are lost first, followed by vibration sense, the 10‐g monofilament and the ability to feel a cold stimulus. Conclusions: This test battery appears to provide sound measurement properties in a group of diabetic patients with diverse amounts of sensory loss. This approach may be used in clinical practice to grade sensory loss reliably and quickly, with instruments that are easy to use. Muscle Nerve58: 559–565, 2018