Axonal neuropathy in chronic peripheral arterial occlusive disease

Lower Limb Arterial Ischemia: An Independent Risk Factor of Sudomotor Dysfunction in Type 2 Diabetes

BACKGROUND

As an early manifestation of diabetic peripheral neuropathy (DPN), sudomotor dysfunction significantly increases the risk of diabetic foot ulcer. The pathogenesis of sudomotor dysfunction is still unclear. Lower limb ischemia may be related to sudomotor dysfunction, but few studies have explored it. The purpose of this study is to explore the relationship between sudomotor function and comprehensive lower limb arterial ischemia including large arteries, small arteries and microvascular in type 2 diabetes mellitus (T2DM).

PATIENTS AND METHODS

511 T2DM patients were enrolled in this cross-sectional study. Sudomotor function was assessed qualitatively and quantitatively by Neuropad. Lower limb arterial ischemia was defined as any abnormality of the ankle brachial index (ABI), toe brachial index (TBI) or transcutaneous oxygen tension (TcPO2).

RESULTS

In this study, 75.1% of patients had sudomotor dysfunction. Compared with normal sudomotor function, patients with sudomotor dysfunction had a higher incidence of lower limb arterial ischemia (51.2% vs 36.2%, p = 0.004). Similarly, compared with the non-arterial ischemia group, the proportion of sudomotor disorders was higher in the arterial ischemia group (p = 0.004). Low TBI and low TcPO2 groups also had a higher proportion of sudomotor disorders (all p < 0.05).Compare with normal groups, low ABI, low TBI, and low TcPO2 groups had lower Slop4 which quantitatively reflecting Neuropad discoloration. Arterial ischemia was an independent risk factor for sudomotor dysfunction [OR = 1.754, p = 0.024]. Low TcPO2 also independently increased the risk of sudomotor disorders [OR = 2.231, p = 0.026].

CONCLUSION

Lower limb arterial ischemia is an independent risk factor of sudomotor dysfunction. Especially below the ankle (BTA) small arteries and microvascular ischemia may also be involved in the occurrence of sudomotor disorders.

Neuropathic pain after spinal intradural benign tumor surgery: an underestimated complication?

Neuropathic pain presents a burdening and impairing condition which may occasionally occur after spinal tumor surgery. While it has been described in peripheral nerve sheath tumors, data on other intradural tumor patients is sparse. We hereby present a large cohort population undergoing different intradural spinal tumor surgery with assessment of early postoperative and follow-up outcomes, focusing on the occurrence of neuropathic pain. We performed a retrospective monocentric study including all patients treated for intradural spinal tumors between 2009 and 2020. We extracted surgical aspects as well as pre- and postoperative clinical courses from the records. Statistical analysis of potential contributing prognostic factors was performed including matched pair analysis. In total, 360 patients were included for analysis. At a median follow-up of 2 years, 26/360 patients complained of a neuropathic pain syndrome (7.2%) requiring continuous medication. Of these patients only 50% complained preoperatively of pain. Tumor entity did not significantly influence the incidence of postoperative neuropathic pain (p = 0.91). Sacrifice of the tumor carrying nerve root and tumor recurrence also did not increase the risk for this condition. Persistent neuropathic pain requiring continuous treatment occurred in 7.2% of patients undergoing intradural spinal surgery in our cohort. This frequently underestimated postoperative adverse event represents a disabling condition leading to a substantial impairment in the quality of life among the affected patients.

Parallels between the Developing Vascular and Neural Systems: Signaling Pathways and Future Perspectives for Regenerative Medicine

Neurovascular disorders, which involve the vascular and nervous systems, are common. Research on such disorders usually focuses on either vascular or nervous components, without looking at how they interact. Adopting a neurovascular perspective is essential to improve current treatments. Therefore, comparing molecular processes known to be involved in both systems separately can provide insight into promising areas of future research. Since development and regeneration share many mechanisms, comparing signaling molecules involved in both the developing vascular and nervous systems and shedding light to those that they have in common can reveal processes, which have not yet been studied from a regenerative perspective, yet hold great potential. Hence, this review discusses and compares processes involved in the development of the vascular and nervous systems, in order to provide an overview of the molecular mechanisms, which are most promising with regards to treatment for neurovascular disorders. Vascular endothelial growth factor, semaphorins, and ephrins are found to hold the most potential, while fibroblast growth factor, bone morphogenic protein, slits, and sonic hedgehog are shown to participate in both the developing vascular and nervous systems, yet have not been studied at the neurovascular level, therefore being of special interest for future research.

Leriche Syndrome Misdiagnosed as Complex Regional Pain Syndrome in a Patient with Neuropathic Pain Caused by a Chip Fracture: A Case Report

Introduction: Leriche syndrome is an aortoiliac occlusive disease caused by atherosclerotic occlusion. We report a case of Leriche syndrome with a fracture that was suspected as complex regional pain syndrome (CRPS), as the post-traumatic pain gradually worsened in the form of excruciating neuropathic pain. Case Report: A 52-year-old woman with a history of hypertension was referred to the Department of Pain Medicine from a local orthopedic clinic because of suspected CRPS for excruciating neuropathic pain for one month. She complained of gait dysfunction and severe pain in the right foot following an incident of trauma with the right first toe. The average pain intensity assessed using the visual analog scale (VAS) was 90 (0: no pain, 100: the worst pain imaginable), and the neuropathic pain was evident as a score of 6/10 on Douleur neuropathique 4. Allodynia, hyperalgesia, blue discoloration of the skin, asymmetric temperature change (1.38 °C), and edematous soft tissue changes were observed. Ultrasonography showed a chip fracture in the first distal phalanx of the right first toe. The diagnosis was most probably CRPS type I according to the Budapest research criteria for CRPS. However, multiple pain management techniques were insufficient in controlling the symptoms. A month and a half later, an ankle-brachial index score of less than 0.4 suggested severe peripheral artery disease. Computed tomography angiography showed total occlusion between the infrarenal abdominal aorta and the bilateral common iliac arteries. Therefore, she underwent aortic-bifemoral bypass surgery with a diagnosis of Leriche syndrome. Three months after the surgery, the average pain intensity was graded as 10 on the VAS (0–100), the color of the skin of the right first toe improved and no gait dysfunction was observed. Conclusion: A chip fracture in a region with insufficient blood flow could manifest as excruciating neuropathic pain in Leriche syndrome.

Gait variability is affected more by peripheral artery disease than by vascular occlusion

Background

Patients with peripheral artery disease with intermittent claudication (PAD-IC) have altered gait variability from the first step they take, well before the onset of claudication pain. The mechanisms underlying these gait alterations are poorly understood.

Aims

To determine the effect of reduced blood flow on gait variability by comparing healthy older controls and patients with PAD-IC. We also determined the diagnostic value of gait variability parameters to identify the presence of PAD.

Methods

A cross-sectional cohort design was used. Thirty healthy older controls and thirty patients with PAD-IC walked on a treadmill at their self-selected speed in pain free walking (normal walking for healthy older controls; prior to claudication onset for PAD) and reduced blood flow (post vascular occlusion with thigh tourniquet for healthy older controls; pain for PAD) conditions. Gait variability was assessed using the largest Lyapunov exponent, approximate entropy, standard deviation, and coefficient of variation of ankle, knee, and hip joints range of motion. Receiver operating characteristics curve analyses of the pain free walking condition were performed to determine the optimal cut-off values for separating individuals with PAD-IC from those without PAD-IC.

Results and discussion

Patients with PAD-IC have increased amount of variability for knee and hip ranges of motion compared with the healthy older control group. Regarding the main effect of condition, reduced blood flow demonstrated increased amount of variability compared with pain free walking. Significant interactions between group and condition at the ankle show increased values for temporal structure of variability, but a similar amount of variability in the reduced blood flow condition. This demonstrates subtle interactions in the movement patterns remain distinct between PAD-IC versus healthy older controls during the reduced blood flow condition. A combination of gait variability parameters correctly identifies PAD-IC disease 70% of the time or more.

Conclusions

Gait variability is affected both by PAD and by the mechanical induction of reduced blood flow. Gait variability parameters have potential diagnostic ability, as some measures had 90.0% probability of correctly identifying patients with PAD-IC.

Gait kinematics and kinetics are affected more by peripheral arterial disease than by age

Peripheral arterial disease (PAD) produces abnormal gait and disproportionately affects older individuals. The current study investigated PAD gait biomechanics in younger (<65 yr) and older (>/=65 yr) subjects. The study included 61 patients with PAD (31 younger, age: 57.4 +/- 5.3 yr, and 30 older, age: 71.9 +/- 5.2 yr) and 52 nondisabled age-matched control subjects. Patients with PAD were tested during pain-free walking and compared with control subjects. Joint kinematics and kinetics (torques) were compared using a 2 x 2 analysis of variance (groups: patients with PAD vs control subjects, age: younger vs older). Patients with PAD had significantly increased ankle and decreased hip range of motion during the stance phase as well as decreased ankle dorsiflexor torque compared with control subjects. Gait changes in older individuals are largely constrained to time-distance parameters. Joint kinematics and kinetics are significantly altered in patients with PAD during pain-free walking. Symptomatic PAD produces a consistent ambulatory deficit across ages definable by advanced biomechanical analysis. The most important finding of the current study is that gait, in the absence of PAD and other ambulatory comorbidities, does not decline significantly with age based on advanced biomechanical analysis. Therefore, previous studies must be examined in the context of patients with potential PAD being present in the population, and future ambulatory studies must include PAD as a confounding factor when assessing the gait function of elderly individuals.

Muscle strength and control characteristics are altered by peripheral artery disease

OBJECTIVE

Peripheral artery disease (PAD), a common manifestation of atherosclerosis, is characterized by lower leg ischemia and myopathy in association with leg dysfunction. Patients with PAD have impaired gait from the first step they take with consistent defects in the movement around the ankle joint, especially in plantar flexion. Our goal was to develop muscle strength profiles to better understand the problems in motor control responsible for the walking impairment in patients with PAD.

METHODS

Ninety-four claudicating PAD patients performed maximal isometric plantar flexion contractions lasting 10 seconds in two conditions: pain free (patient is well rested and has no claudication symptoms) and pain induced (patient has walked and has claudication symptoms). Sixteen matched healthy controls performed the pain-free condition only. Torque curves were analyzed for dependent variables of muscle strength and motor control. Independent t-tests were used to compare variables between groups, and dependent t-tests determined differences between conditions.

RESULTS

Patients with PAD had significantly reduced peak torque and area under the curve compared with controls. Measures of control differed between PAD conditions only. Load rate and linear region duration were greater in the pain condition. Time to peak torque was shorter in the pain condition.

CONCLUSIONS

This study conclusively demonstrates that the plantar flexor muscles of the PAD patient at baseline and without pain are weaker in patients with PAD compared with controls. With the onset of claudication pain, patients with PAD exhibit altered muscle control strategies and further strength deficits are manifest compared to baseline levels. The myopathy of PAD legs appears to have a central role in the functional deterioration of the calf muscles, as it is evident both before and after onset of ischemic pain.

The effect of supervised exercise therapy for intermittent claudication on lower limb lean mass

OBJECTIVE

Supervised exercise is currently recommended for the first-line treatment of intermittent claudication based on improvement in walking capacity. However, the promotion of skeletal muscle atrophy by repetitive ischemia-reperfusion caused by treadmill-based programs remains a concern. Because preservation of skeletal muscle mass (SMM) and lean mass (LM) is integral to functional capacity and longevity, this study measured the effect of standard treadmill-based supervised exercise on SMM and regional lower limb LM in patients with intermittent claudication.

METHODS

Patients with calf claudication caused by infrainguinal peripheral artery disease underwent whole-body dual-energy X-ray absorptiometry scanning before and after completion of a 12-week supervised treadmill exercise program. Total body SMM and lower limb LM were measured according to anatomical regions of the lower limb (thigh vs calf) and side of symptoms. Walking performance was assessed using pain-free walking distance and 6-minute walking distance tests.

RESULTS

Thirty-six patients with calf claudication completed exercise training and dual-energy X-ray absorptiometry scanning, allowing analysis of 55 symptomatic and 17 asymptomatic lower limbs. No difference in total body SMM (P = .41) or LM of symptomatic (P = .53) or asymptomatic calves (P = .59) was detected after the program. In contrast, a significant decrease in LM was observed in symptomatic (P = .04) and asymptomatic thighs (P = .005). Pain-free walking distance (P = .001) and the 6-minute walking distance both improved significantly (P = .004) but were not associated with changes in LM.

CONCLUSIONS

Twelve weeks of standard treadmill-training for intermittent calf claudication did not result in loss of calf LM; however, a significant decrease in bilateral thigh LM was observed, even in patients with unilateral symptoms. Further research on optimum exercise modalities and end points are required to determine the pathophysiology and effects of these changes on function and survival.

Reduced evoked motor and sensory potential amplitudes in obstructive sleep apnea patients

It is unknown to what extent chronic intermittent hypoxaemia in obstructive sleep apnea causes damage to the motor and sensory peripheral nerves. It was hypothesized that patients with obstructive sleep apnea would have bilaterally significantly impaired amplitudes of both motor and sensory peripheral nerve-evoked potentials of both lower and upper limbs. An observational study was conducted on 43 patients with obstructive sleep apnea confirmed by the whole-night polysomnography, and 40 controls to assess the relationship between obstructive sleep apnea and peripheral neuropathy. All obstructive sleep apnea subjects underwent standardized electroneurographic testing, with full assessment of amplitudes of evoked compound muscle action potentials, sensory neural action potentials, motor and sensory nerve conduction velocities, and distal motor and sensory latencies of the median, ulnar, peroneal and sural nerves, bilaterally. All nerve measurements were compared with reference values, as well as between the untreated patients with obstructive sleep apnea and control subjects. Averaged compound muscle action potential and sensory nerve action potential amplitudes were significantly reduced in the nerves of both upper and lower limbs in patients with obstructive sleep apnea compared with controls (P < 0.001). These results confirmed that patients with obstructive sleep apnea had significantly lower amplitudes of evoked action potentials of both motor and sensory peripheral nerves. Clinical/subclinical axonal damage exists in patients with obstructive sleep apnea to a greater extent than previously thought.

Lower extremity manifestations of peripheral artery disease: the pathophysiologic and functional implications of leg ischemia

Lower extremity peripheral artery disease (PAD) is frequently underdiagnosed, in part because of the wide variety of leg symptoms manifested by patients with PAD and in part because of the high prevalence of asymptomatic PAD. In primary care medical practices, 30% to 60% of patients with PAD report no exertional leg symptoms and ≈45% to 50% report exertional leg symptoms that are not consistent with classic intermittent claudication. The prevalence and extent of functional impairment and functional decline in PAD may also be underappreciated. Functional impairment and functional decline are common in PAD, even among those who are asymptomatic. Lower extremity ischemia is also associated with pathophysiologic changes in calf skeletal muscle, including smaller calf muscle area, increased calf muscle fat content, impaired leg strength, and impaired metabolic function. People with severe PAD have poorer peroneal nerve conduction velocity compared with people with mild PAD or no PAD. The degree of ischemia-related pathophysiologic changes in lower extremity muscles and peripheral nerves of people with PAD are associated with the degree of functional impairment. New interventions are needed to improve functional performance and prevent mobility loss in the large number of patients with PAD, including in those who are asymptomatic or who have exertional leg symptoms other than claudication.

[Painful ischemic neuropathy]

Chronic ischemia in patients with peripheral arterial disease (PAD) represents a common medical problem. Neuropathic changes and pain caused by chronic ischemia are often found in the lower extremities of these patients. Pain in patients with chronic critical limb ischemia fulfill the criteria of neuropathic pain. Diagnostic tools besides medical history and examination are questionnaires, quantitative sensory testing (QST) and measuring intraepidermal nerve fiber density (IENFD) when indicated. A pharmacological approach with non-opioids and opioids as well as antidepressive and anticonvulsive drugs (according to the recommendations for the therapy of neuropathic pain) seems to be indicated for treating painful ischemic neuropathy. Spinal cord stimulation (SCS) provides the best evidence for invasive procedures in treating chronic ischemic pain.

Prevalence and Risk Factors for the Peripheral Neuropathy in Patients with Peripheral Arterial Occlusive Disease

PURPOSE

Peripheral neuropathy (PN) is known as a major contributor of the worsening of ischemic symptoms and the foot ulceration in patients with peripheral arterial occlusive disease (PAOD). However, there are few studies reporting the prevalence and risk factors for PN in PAOD. This study aimed to evaluate these issues for PN and to establish the importance of screening as additional treatment target for PN in PAOD.

MATERIALS AND METHODS

A total of 52 limbs with PAOD were enrolled from January 2011 to December 2012. PN was divided into radiculopathy, ischemic PN (IPN), and diabetic PN (DPN), based on electromyographic findings. We investigated the prevalence of overall PN and subtypes of PN and then analyzed the risk factors.

RESULTS

The prevalence of overall PN in PAOD was 43 of 52 limbs (82.7%). In terms of subtypes of PN, the prevalence rate of radiculopathy and IPN was 30.8% and 23.1%, respectively. DPN showed in 22 limbs (73.3%) among 30 diabetic limbs. There was no significant correlation between each type of PN and ischemic symptoms. Our analysis showed that coronary artery disease (CAD) was a significant risk factor (P=0.01) for IPN, however, did not identify any significant risk factors for DPN.

CONCLUSION

This present study indicated that most patients with PAOD had PN and CAD was a risk factor for IPN. In particular, PAOD with diabetes represented a higher prevalence for DPN. Our study suggests that PN should be evaluated and considered as another treatment target in patients with PAOD.

Reduced intraepidermal nerve fiber density in patients with chronic ischemic pain in peripheral arterial disease

Chronic ischemic pain in peripheral arterial disease (PAD) is a leading cause of pain in the lower extremities. A neuropathic component of chronic ischemic pain has been shown independent of coexisting diabetes. We aimed to identify a morphological correlate potentially associated with pain and sensory deficits in PAD. Forty patients with symptomatic PAD (Fontaine stages II-IV), 20 with intermittent claudication (CI), and 20 with critical limb ischemia (CLI) were enrolled; 12 volunteers served as healthy controls. All patients were examined using pain scales and questionnaires. All study participants underwent quantitative sensory testing (QST) at the distal calf and skin punch biopsy at the distal leg for determination of intraepidermal nerve fiber density (IENFD). Additionally, S100 beta serum levels were measured as a potential marker for ischemic nerve damage. Neuropathic pain questionnaires revealed slightly higher scores and more pronounced pain-induced disability in CLI patients compared to CI patients. QST showed elevated thermal and mechanical detection pain thresholds as well as dynamic mechanical allodynia, particularly in patients with advanced disease. IENFD was reduced in PAD compared to controls (P<0.05), more pronounced in the CLI subgroup (CLI: 1.3 ± 0.5 fibers/mm, CI: 2.9 ± 0.5 fibers/mm, controls: 5.3 ± 0.6 fibers/mm). In particular, increased mechanical and heat pain thresholds negatively correlated with lower IENFD. Mean S100 beta levels were in the normal range but were higher in advanced disease. Patients with chronic ischemic pain had a reduced IENFD associated with impaired sensory functions. These findings support the concept of a neuropathic component in ischemic pain.

Neurological and electrophysiological parameters as outcome measurements for peripheral arterial occlusive disease

BACKGROUND

Ischemic monomelic neuropathy is not an uncommon complication of peripheral arterial occlusive disease (PAOD). However, many investigators have used revascularization, limb salvage, and complete wound healing rates instead of neurologic and electrophysiological parameters as outcome measurements of PAOD. The aim of the study is to investigate the neurologic and electrophysiological parameters associated with PAOD and to find the ideal tools for assessing PAOD.

METHODS

A total of 38 PAOD patients (68.5 ± 8.1 years old, male:female = 32:6) with a total of 76 lower limbs were enrolled in the study. Primary outcomes were neurological symptoms scores (NSSs) and neurological impairment scores (NISs) for the lower extremities. Secondary outcomes were taken from nerve conduction studies (NCSs) and included the following: sensory nerve action potential (SNAP) amplitudes of the sural, superficial peroneal, and medial plantar nerves and the compound muscle action potential (CMAP) amplitudes of the posterior tibial and common peroneal nerves.

RESULTS

Female patients with old age, hypertension, low body weights, low body mass indices (BMIs), decreased ankle-brachial indices (ABIs), and poorer Fontaine classifications exhibited worse NSSs and NISs indices. Patients with old age, diabetes mellitus, hypertension, histories of social alcohol consumption, low body weights, low BMIs, and poorer Fontaine classifications exhibited decreased SNAP and CMAP amplitudes in the sensory and motor NCSs. Decreased ABI was associated with decreased SNAP amplitudes in the sensory NCSs.

CONCLUSIONS

Neurologic and electrophysiological parameters can be good tools for the assessment of PAOD. NSSs and NISs are particularly good candidates for outcome measures of PAOD.

Vascular occlusion affects gait variability patterns of healthy younger and older individuals

Insufficient blood flow is one possible mechanism contributing to altered gait patterns in lower extremity peripheral arterial disease (PAD). Previously, our laboratory found that induced occlusion alters gait variability patterns in healthy young individuals. However the effect of age was not explored. The purpose of this study was to account for age by investigating gait variability following induced vascular occlusion in healthy older individuals and to identify amount of change from baseline to post vascular occlusion between younger and older individuals. Thirty healthy younger individuals and 30 healthy older individuals walked on a treadmill during baseline and post vascular occlusion conditions while lower extremity joint kinematics were captured. Vascular occlusion was induced by thigh cuffs inflated bilaterally on the upper thighs. Amount and temporal structure of gait variability was assessed. Older individuals exhibited significantly increased values of temporal structure of variability post vascular occlusion. Post vascular occlusion values were similar between younger and older individuals after adjusting for baseline measurements. Results show blood flow contributes to altered gait variability. However alterations were less severe than previously documented in symptomatic PAD patients, suggesting that neuromuscular problems in the lower extremities of PAD patients also contribute to gait alterations in these patients.

Impaired somatosensation in patients with isolated proximal-without-distal exercise-related lower-limb ischemia

OBJECTIVES

Isolated proximal-without-distal (buttock but not calf) exercise-related lower-limb ischemia (IPI) might develop in the presence of arterial lesions impairing the blood flow supply toward the hypogastric vascular bed. In IPI, lower-limb sensory nerve dysfunction might occur from the sacral nerve plexus becoming ischemic during exercise. The purpose of this study was to compare patients with IPI with healthy controls for the presence of sensory nerve dysfunction, as assessed using somatosensory testing (SST).

METHODS

Seventeen nondiabetic patients with IPI and 17 age-matched and sex-matched healthy controls underwent SST of both the upper and lower limbs.

RESULTS

The upper-limb SST data did not differ between groups (P>0.05). In contrast, lower-limb testing showed that patients with IPI had impaired warm (43.4±2.7 vs. 40.5±4.9°C) and vibration (5.0±2.3 vs. 6.4±1.4 arbitrary units) detection thresholds compared with healthy controls (P≤0.05). Furthermore, lower-limb mechanical detection threshold and Neuropathy Symptom and Disability Scores tended to be higher in the patients (P≤0.10).

DISCUSSION

The SST data suggest that patients with IPI have abnormal functioning of Aβ-fiber and C-fiber inputs in their affected limb(s). These sensory abnormalities might contribute to the exercise-induced ischemic symptoms experienced by these patients.

Gait variability of patients with intermittent claudication is similar before and after the onset of claudication pain

BACKGROUND

Recent research demonstrated that intermittent claudication patients have increased gait variability prior to the onset of claudication. However, it is unknown if these patients experience additional gait adaptations after the onset of claudication. Thus, we sought to determine how gait variability is affected by claudication in an effort to contribute to improved clinical management.

METHODS

Twenty-six intermittent claudication patients and 20 controls walked on a treadmill at self-selected speed; intermittent claudication patients were tested before (pain free) and after (pain) the onset of claudication. Variability of the ankle, knee, and hip joint angles was assessed using the largest Lyapunov exponent, standard deviation and coefficient of variation. Dependent t-tests were used to compare the pain free and pain conditions. Independent t-tests were used to compare intermittent claudication patients and controls.

FINDINGS

Pain free and pain conditions were not significantly different for any of the parameters evaluated except the ankle. Compared to controls, patients had significantly greater values for the largest Lyapunov exponent in both conditions for all joints.

INTERPRETATION

Gait variability was essentially the same before and after the onset of claudication at the knee and the hip, and was increased in both conditions compared to controls. This indicates altered cooperation between components of the locomotor system of intermittent claudication patients, likely due to the associated myopathy since differences were present even before the onset of claudication. This research helps provide essential biomechanical knowledge of intermittent claudication that contributes to improved clinical management.

Joint torques and powers are reduced during ambulation for both limbs in patients with unilateral claudication

OBJECTIVES

Symptomatic peripheral arterial disease (PAD) results in significant gait impairment. In an attempt to fully delineate and quantify these gait alterations, we analyzed joint kinematics, torques (rotational forces), and powers (rotational forces times angular velocity) in patients with PAD with unilateral claudication for both the affected and nonaffected legs.

METHODS

Twelve patients with unilateral PAD (age, 61.69 +/- 10.53 years, ankle-brachial index [ABI]: affected limb 0.59 +/- 0.25; nonaffected limb 0.93 +/- 0.12) and 10 healthy controls (age, 67.23 +/- 12.67 years, ABI >1.0 all subjects) walked over a force platform to acquire gait kinetics, while joint kinematics were recorded simultaneously. Data were collected for the affected and nonaffected limbs during pain free (PAD-PF) and pain induced (PAD-P) trials. Kinetics and kinematics were combined to quantify torque and powers during the stance period from the hip, knee, and ankle joints.

RESULTS

The affected limb demonstrated significantly (P <.05) reduced ankle plantar flexion torque compared to controls during late stance in both PAD-PF and PAD-P trials. There were significant reductions in ankle plantar flexion power generation during late stance for both the affected (P <.05) and nonaffected limbs (P <.05) compared to control during PAD-PF and PAD-P trials. No significant differences were noted in torque comparing the nonaffected limbs in PAD-PF and PAD-P conditions to control for knee and hip joints throughout the stance phase. Significant reductions were found in knee power absorption in early stance and knee power generation during mid stance for both limbs of the patients with PAD as compared to control (P <.05).

CONCLUSION

Patients with PAD with unilateral claudication demonstrate significant gait impairments in both limbs that are present even before they experience any claudication symptoms. Overall, our data demonstrate significantly reduced ankle plantar flexion torque and power during late stance with reduced knee power during early and mid stance for the affected limb. Further studies are needed to determine if these findings are dependent on the location and the severity of lower extremity ischemia and whether the changes in the nonaffected limb are the result of underlying PAD or compensatory changes from the affected limb dysfunction.

Gait variability is altered in patients with peripheral arterial disease

OBJECTIVE

Claudication is the most common presentation of peripheral arterial disease (PAD), producing significant ambulatory compromise. Claudicating patients, most of whom are elderly, have reduced mobility and poor health outcomes, including an increased risk of falls. The gait of elderly fallers is characterized by increased variability. Increase in the variability of the locomotor system makes the gait more noisy and unstable. The purpose of this study is to investigate gait variability in patients with PAD.

METHODS

Nineteen symptomatic PAD patients (age, 63.6 +/- 9.8 years; body mass, 82.1 +/- 18.5 kg; height, 1.71 +/- 0.06 m) walked on a treadmill in the absence of pain or claudication symptoms while joint flexion and extension kinematics were captured. Results were compared with results obtained from 17 matched healthy controls (age, 65.2 +/- 12.5 years; body mass, 82.0 +/- 25.9.5 kg; height, 1.73 +/- 0.08 m). Relative joint angles were calculated for the ankle, knee, and hip flexion/extension, and the stride-to-stride variability of joint flexion and extension was calculated from at least 30 consecutive footfalls. Variability was expressed using the largest Lyapunov exponent, standard deviation, and coefficient of variation. Independent t tests were used to compare gait variability between groups.

RESULTS

Symptomatic PAD patients had significantly higher largest Lyapunov exponent values and coefficient of variation values for all joints, and higher standard deviation values at the ankle and the hip (P < .05).

CONCLUSION

Symptomatic PAD patients have increased gait variability at the ankle, knee, and hip joints at baseline ambulation in the absence of claudication pain. Our findings indicate significant baseline deterioration in the locomotor system of symptomatic PAD patients. This deterioration results in increased noise and instability of gait and is a potential contributing factor to the falls and mobility problems experienced by symptomatic PAD patients.

[Therapy of chronic ischemic pain in peripheral arterial disease. A survey among physicians]

BACKGROUND

The intention of this study was to determine the status quo of commonly used pain therapies amongst treating physicians of different specialties and to examine their view on the problem of chronic ischemic pain.

METHODS

A total of 281 physicians treating patients with chronic ischemic pain were surveyed. The surveyed physicians were mainly specialists in the fields of surgery, pain therapy, and internal medicine.

RESULTS

Mainly a pharmacological therapy (metamizol/paracetamol, weak and strong opioids) was used in the treatment of chronic ischemic pain. We found differences between the specialties, for instance pain specialists used antidepressants and anticonvulsants more often than others. Therapeutic options were also evaluated differently by surgeons, pain therapists, and internal specialists: 57% of the surgeons considered the available symptomatic treatment options as sufficient whereas only 21% of the pain specialists agreed with that opinion.

CONCLUSION

The differences among the specialties and the fact that the majority of physicians characterized the available symptomatic treatment options as insufficient point towards a need to review the treatment of ischemic pain in an interdisciplinary approach.

Bilateral claudication results in alterations in the gait biomechanics at the hip and ankle joints

Claudication is the most common symptomatic manifestation of peripheral arterial disease (PAD), producing significant ambulatory compromise. The purpose of this study was to use advanced biomechanical gait analysis to determine the gait alterations occurring in claudicating patients both before and after onset of claudication pain in their legs. Hip, knee, and ankle joint moments were measured in claudicating patients (age: 64.46+/-8.47 years; body mass: 80.70+/-12.64kg; body height: 1.72+/-0.08m) and were compared to gender-age-body mass-height-matched healthy controls (age 66.27+/-9.22 years; body mass: 77.89+/-10.65kg; body height: 1.74+/-0.08m). The claudicating patients were evaluated both before (pain-free (PF) condition) and after (pain condition) onset of claudication pain in their legs. Thirteen symptomatic PAD patients (26 claudicating limbs) with bilateral intermittent claudication (IC) and 11 healthy controls (22 control limbs) were tested during level walking at their self-selected speed. Compared to controls, PAD hip and ankle joints demonstrated significant angular kinematics and net internal moment changes. Alterations were present both in PF and pain conditions with several of them becoming worse in the pain condition. Both PF and pain conditions resulted in significantly reduced peak hip extensor moment (5.62+/-1.40 and 5.63+/-1.33% BWxBH, respectively) during early stance as compared to controls (7.53+/-1.16% BWxBH). In the pain condition, PAD patients had a significantly reduced ankle plantar flexor moment (7.56+/-1.41% BWxBH) during late stance as compared to controls (8.65+/-1.27% BWxBH). Furthermore, when comparing PF to pain conditions, there was a decreased peak plantar flexor moment (PF condition: 8.23+/-1.37 vs. pain condition: 7.56+/-1.41% BWxBH) during late stance. The findings point to a weakness in the posterior compartment muscles of the hip and calf as being the key factor underlying the PAD gait adaptations. Our findings establish a detailed baseline description of the changes present in PAD patient's joint angles and moments during walking. Since IC is primarily a gait disability, better understanding of the abnormalities in joint and muscle function will enhance our understanding of the gait impairment and may lead to novel, gait-specific treatments.

The myopathy of peripheral arterial occlusive disease: Part 2. Oxidative stress, neuropathy, and shift in muscle fiber type

In recent years, an increasing number of studies have demonstrated that a myopathy is present, contributes, and, to a certain extent, determines the pathogenesis of peripheral arterial occlusive disease. These works provide evidence that a state of repetitive cycles of exercise-induced ischemia followed by reperfusion at rest operates in patients with peripheral arterial occlusive disease and mediates a large number of structural and metabolic changes in the muscle, resulting in reduced strength and function. The key players in this process appear to be defective mitochondria that, through multilevel failure in their roles as energy, oxygen radical species, and apoptosis regulators, produce and sustain a progressive decline in muscle performance. In this 2-part review, the currently available evidence that characterizes the nature and mechanisms responsible for this myopathy is highlighted. In part 1, the functional and histomorphological characteristics of the myopathy were reviewed, and the main focus was on the biochemistry and bioenergetics of its mitochondriopathy. In part 2, accumulating evidence that oxidative stress related to ischemia reperfusion is probably the major operating mechanism of peripheral arterial occlusive disease myopathy is reviewed. Important new findings of a possible neuropathy and a shift in muscle fiber type are also reviewed. Learning more about these mechanisms will enhance our understanding of the degree to which they are preventable and treatable.

Involvement of advanced glycation end products in the pathogenesis of diabetic complications: the protective role of regular physical activity

Advanced glycation end products (AGEs) may play an important role in the pathogenesis of chronic diabetic complications and in the natural process of biological aging. In fact, maintained hyperglycaemia favours the formation of AGEs at the tissue level in diabetic patients, which may influence the triggering of different chronic pathologies of diabetes such as retinopathy, nephropathy, neuropathy and macro- and micro-vascular diseases. Moreover, the literature has also demonstrated the involvement of AGEs in biological aging, which may explain the accelerated process of aging in diabetic patients. The practice of regular physical activity appears to positively influence glycaemic control, particularly in type 2 diabetes mellitus patients. This occurs through the diminution of fasting glycaemia, with a consequent reduction of glycation of plasmatic components suggested by the normalisation of HbA1c plasmatic levels. This exercise-induced positive effect is evident in the blood of diabetic patients and may also reach the endothelium and connective tissues of different organs, such as the kidneys and eyes, and systems, such as the cardiovascular and nervous systems, with a local reduction of AGEs production and further deceleration of organ dysfunction. The aim of this paper was to review the literature concerning this topic to coherently describe the harmful effects of AGEs in organ dysfunction induced by diabetes in advanced age as well as the mechanisms behind the apparent protection given by the practice of regular physical activity.

Peripheral arterial disease affects ground reaction forces during walking

OBJECTIVE

Claudication is the most common manifestation of peripheral arterial disease (PAD), producing significant ambulatory compromise. The gait of claudicating patients has been evaluated using primarily temporal and spatial parameters. With the present study, we used advanced biomechanical measures to further delineate the ambulatory impairment of claudicating patients. We hypothesized that the claudicating legs of PAD patients have an altered kinetic gait pattern compared with normal legs from control subjects.

METHODS

Ambulation kinetics (ground reaction forces) were evaluated in claudicating patients and compared with age-matched healthy controls. Forces were analyzed in the vertical, anterior-posterior, and medial-lateral directions. Time from heel touch-down to toe-off (stance time) and time spent in double-limb support were also evaluated.

RESULTS

The study recruited 14 PAD patients (age, 58 +/- 3.4 years; weight, 80.99 +/- 15.64 kg) with femoropopliteal occlusive disease (ankle-brachial index [ABI], 0.56 +/- 0.03) and five controls (age, 53 +/- 3.4 years; weight, 87.38 +/- 12.75 kg; ABI, >or=1.00). Vertical force curve evaluation demonstrated significant flattening in claudicating patients resulting in a lower and less fluctuant center of mass when ambulating. In the anterior-posterior direction, claudicating patients demonstrated significantly decreased propulsion forces. In the medial-lateral direction, they had significantly increased forces consistent with wider steps and an inability to swing their legs straight through. Claudicating patients demonstrated a greater stance time and time in double limb support compared with healthy controls. Most importantly, gait abnormalities were present before the onset of claudication, with gait worsening after the onset of claudication.

CONCLUSION

Claudicating patients demonstrate significant gait impairments that are present even before they experience any limb discomfort. These alterations may make them feel more stable and secure while attempting to minimize use of the affected limb. Advanced biomechanical analysis, using ambulation kinetics, permits objective and quantitative evaluation of the gaits of claudicating patients. Such evaluation may point to new rehabilitation strategies and provide objective measurement of functional outcomes after medical and surgical therapy.

Dynamic F wave study in patients suffering from peripheral arterial occlusive disease

OBJECTIVE

To prospectively detect significant transient F wave abnormalities obtained after exercise in patients with peripheral arterial disease (PAD) and to assess the potential diagnostic sensitivity of dynamic F wave study in such a context.

PATIENTS AND METHODS

A series of 40 electrical stimuli were delivered to the peroneal and the posterior tibial nerves of 25 patients with PAD in order to obtain F waves at rest and post-exercise. The following variables were estimated and the obtained pre- and post-exercise data were compared: F persistence, F wave latency, amplitude, duration and F chronodispersion. For each nerve studied, the minimum, average and maximum values were calculated. Conventional electrophysiological data were also collected pre- and post-exercise and the data obtained were also compared. Twenty-five healthy age-, gender- and height-matched individuals served as controls.

RESULTS

No evidence of conventional nerve conduction abnormalities was recorded either pre- or post-exercise in the group of patients. As regards the peroneal nerve, the significantly reduced F wave persistence (P = 0.007) and maximum F wave amplitude post- as opposed to pre-exercise (P = 0.05)- were the main findings to emerge. The average (P = 0.017) and the minimum duration (P = 0.005) of tibial F waves were also significantly increased post- compared with pre-exercise. Insignificant differences were observed between pre- and post-exercise neurophysiological and F wave values in the group of controls.

CONCLUSION

Given the observed absence of conventional neurophysiological abnormalities, the detection of dynamic F wave changes supports the view of an increased diagnostic sensitivity of this method in patients with mild PAD.

Lower extremity nerve function in patients with lower extremity ischemia

BACKGROUND

We determined whether lower extremity ischemia, as measured by the ankle brachial index (ABI), is associated with impaired lower extremity nerve function.

METHODS

Participants included 478 persons with peripheral arterial disease (PAD) identified from noninvasive vascular laboratories and 292 persons without PAD identified from a general medicine practice and noninvasive vascular laboratories. Peripheral arterial disease was defined as an ABI lower than 0.90 (mild PAD: ABI, 0.70 to <0.90; moderate PAD: ABI, 0.50 to <0.70; and severe PAD: ABI, <0.50). The ABI and electrophysiologic measures of the peroneal, sural, and ulnar nerves were obtained.

RESULTS

Among 546 participants without diabetes, PAD participants had significantly impaired peripheral nerve function in the upper and lower extremities compared with non-PAD participants. After adjusting for age, sex, race, smoking, height, body mass index, recruitment source, alcohol use, disk disease, spinal stenosis, cardiac disease, and cerebrovascular disease, these associations were not statistically significant. After adjusting for confounders among nondiabetic participants, those with severe PAD (ABI, <0.50) had poorer peroneal nerve conduction velocity (NCV) compared with participants without PAD (42.6 vs 44.8 m/s; P = .003) and poorer peroneal NCV compared with participants with mild PAD (42.6 vs 45.0 m/s; P = .001) or moderate PAD (42.6 vs 44.1 m/s; P = .03). Among 224 participants with diabetes, after adjusting for confounders, PAD was associated with poorer peroneal NCV (40.8 vs 43.5 m/s; P = .01), sural nerve amplitude (3.1 vs 4.8 muV; P = .045), and ulnar NCV (47.6 vs 50.2 m/s; P = .03) compared with those without PAD.

CONCLUSIONS

Our findings suggest that leg ischemia impairs peroneal nerve function. This association is less strong in patients with diabetes, perhaps because of the overriding influence of diabetes on peripheral nerve function. Clinicians should consider screening for PAD in patients with idiopathic peroneal nerve dysfunction. Peripheral arterial disease-associated nerve dysfunction may contribute to PAD-associated functional impairment.

Sympathetic skin response in patients with peripheral arterial occlusive disease

OBJECTIVE

The current study aimed to assess the viability of sympathetic sudomotor fibers in patients suffering from mild peripheral arterial occlusive disease (PAD).

METHODS

Sympathetic skin response (SSR) from the hand (electrical stimulation) and sole (electrical and magnetic stimulation) of 25 patients with PAD (19 males and 6 females with mean age 62.7 +/- 10.2 years) was recorded unilaterally depending on the side of the affected limb (18 right side, 7 left side). Electrophysiological data were also collected and correlated with the SSR results. Twenty-five, age- and gender-matched healthy volunteers served as controls.

RESULTS

No evidence of nerve conduction abnormalities was recorded from the group of patients. Intact SSR recordings were obtained from the upper limb of patients. Nine patients (36%) had absent SSR in the lower limb following electrical stimulation, whilst the same 9 patients had absent SSR following magnetic stimulation. Significant differences occurred between groups in the SSR latency scores recorded from the lower limb. Following electrical stimulation the mean SSR latency in patients was significantly prolonged, compared to that of controls (P = 0.000), whilst the same applied following magnetic stimulation (P = 0.000). There was no correlation between SSR abnormalities and nerve conduction measurements. The manifestation of intermittent claudication at a walking distance of 250 m was strongly correlated with absent lower limb SSR (r = 0.71, P = 0.035).

CONCLUSIONS

SSR abnormalities appeared to be an early and independent finding of neural impairment in our patients.

SIGNIFICANCE

SSR study, performed at an early stage of PAD may prove useful in differentiating PAD-induced neuropathy from other neuropathic processes.