Femoral nerve conduction in diabetes and chronic occlusive vascular disease

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.

Femoral nerve involvement in diabetics

BACKGROUND AND PURPOSE

In this study, the conduction of the femoral nerve has been evaluated in diabetic patients without clinical signs of femoral nerve involvement and in a group of healthy subjects.

METHODS

Forty-eight patients have been included in the study. Patients have been examined in terms of neuropathy and their neuropathy scores have been calculated. In addition to the nerve conduction studies have been performed. The findings of the diabetic patients have been compared with those of the 26 healthy volunteers.

RESULTS

There has been a statistically significant difference between diabetics and the healthy volunteers in the control group in terms of both femoral nerve motor latency and amplitude. The femoral latencies of patients have significantly been related to the total neuropathy score. A significant difference between diabetic patients without polyneuropathy and the controls was observed with respect to their femoral latencies.

CONCLUSION

In our study, femoral nerve conduction abnormalities have been determined in diabetics who clinically did not have femoral nerve involvement. It has been observed that these abnormalities become more evident as the polyneuropathy of the patients becomes more serious. Our study has shown that femoral nerve conductions may increase the sensitivity of the diagnosis of polyneuropathy.

Slower conduction velocity and motor unit discharge frequency are associated with muscle fatigue during isometric exercise in type 1 diabetes mellitus

Type 1 diabetes mellitus (T1DM) is associated with a peripheral neuropathy that reduces nerve conduction velocity. This may impair high motor-unit discharge frequencies (MUDF), decrease muscle activation, and curtail the ability to sustain repetitive contractile tasks. We examined (1) whether MUDF, the contractile properties of the knee extensors, and the conduction velocity of persons with T1DM differed from controls; (2) whether persons with T1DM can maintain adequate MUDF during a fatigue protocol; and (3) the relationship between these parameters and impaired glycemic control. We studied male and female subjects with T1DM and controls matched for age, height, weight, and gender. Single motor unit recordings were made from vastus lateralis during maximal and submaximal contractions and during a fatigue protocol. Glycemic control was assessed from blood glucose concentration and glycosylated hemoglobin (HbA1c). Control femoral conduction velocities were comparable to literature values and those of the T1DM subjects were slower. These values correlated with plasma glucose and HbA1c. T1DM subjects fatigued 45% sooner than controls, and time to fatigue and conduction velocity were correlated (r = 0.54, P < 0.05). Discharge frequencies tended to be slower during 50% maximal voluntary contractile force in the T1DM subjects at task failure. Persons with T1DM had slower conduction velocities and lower MUDF than their controls, which apparently leads to impaired activation of muscle and decreased endurance during isometric fatigue.

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.

Lumbosacral Magnetic Root Stimulation in Lumbar Plexopathy

We report a 76-yr-old man with left femoral nerve distribution weakness resulting from a nontraumatic retroperitoneal hematoma associated with coumadin anticoagulation. Although electric root stimulation was relatively contraindicated, magnetic lumbosacral root stimulation identified a proximal conduction block allowing more extensive assessment of the nerve damage. To our knowledge, this is the first report of magnetic root stimulation in assessment of lumbosacral plexus dysfunction in retroperitoneal hematoma.

Proximal and distal motor nerve conduction in obturator and femoral nerves

OBJECTIVE

To study the proximal and distal motor conduction properties of obturator and femoral nerves.

DESIGN

For evaluation of distal motor conduction properties, obturator and femoral nerves were stimulated at the inguinal ligament, and M responses were recorded with needle electrodes from gracilis and rectus femoris muscles. Upper lumbar roots were stimulated with needle electrodes inserted between L1-L2 vertebral laminae.

PARTICIPANTS

Sixteen healthy adults, eight of each gender, age 22 to 52 years (mean 37.5).

MAIN OUTCOME MEASURES

Description of a method for assessing motor conduction along the obturator nerve and evaluating proximal motor conduction measurements obtained with stimulation of obturator and femoral nerves.

RESULTS

Distal motor conduction latencies were 3.9 +/- 0.7 msec for gracilis and 4.6 +/- 0.5msec for rectus femoris after stimulation of obturator and femoral nerves, respectively. Proximal conduction times from lumbar vertebral level were 10.4 +/- 0.3msec for the obturator nerve and 10.8 +/- 0.4msec for the femoral nerve. Conduction velocities of proximal segments of both nerves were similar, 62m/sec for the obturator nerve and 65m/sec for the femoral nerve. Submaximal stimulation of both nerves evoked H-reflex responses from their associated muscles.

CONCLUSIONS

Motor conduction properties of the obturator nerve can be assessed by the method described, particularly to differentiate between peripheral, plexus, or radicular lesions that involve the obturator nerve.

Femoral and obturator neuropathies

Femoral, saphenous, and obturator neuropathies have diverse causes, many of which are iatrogenic. They have overlapping, but distinct, clinical features. Electrodiagnostic testing can distinguish between these disorders and others in the differential diagnosis. Imaging studies may demonstrate the origin of the neuropathy in some cases. Conservative treatment is usually sufficient, but occasionally surgical exploration of the affected nerve is indicated.

Epineurial microvasculitis in proximal diabetic neuropathy

Amongst the focal and multifocal neuropathies that are associated with diabetes mellitus one of the most common is a proximal predominantly motor lower limb neuropathy. Recent evidence has indicated that, at least in a proportion of cases, this may have an inflammatory basis. We have examined a consecutive series of 15 cases of proximal diabetic neuropathy (diabetic amyotrophy). These were characterized by proximal pain and asymmetric proximal or generalized lower limb muscle weakness, associated in some cases with radicular sensory involvement. Two-thirds of the patients had an accompanying distal symmetric sensory polyneuropathy. Biopsy of the intermediate cutaneous nerve of the thigh, a sensory branch of the femoral nerve, showed epineurial microvasculitis in 3 patients and nonvasculitic epineurial inflammatory infiltrates in another case. In a further case, microvasculitis was found in both in the sural nerve and a quadriceps muscle biopsy specimen. The detection of inflammatory changes appeared to be correlated with the occurrence of sensory radicular involvement. Whether similar changes are present in muscle nerves in this predominantly motor syndrome requires further study. Nevertheless, the present observations confirm the view that secondary vasculitic or other inflammatory reactions may contribute to some forms of diabetic neuropathy.

Peripheral nerve conduction abnormalities in lower extremity ischemia: the effects of revascularization

Peripheral nerve conduction studies were performed on 32 limbs in 25 patients to determine the incidence of peripheral nerve conduction defects and prospectively evaluate the influence of revascularization in patients with lower extremity ischemia. Ankle pressure indices improved from a mean preoperative value of 0.43 +/- 0.12 to 0.81 +/- 0.26 in patients with aortoiliac disease and 0.40 +/- 0.13 +/- 0.84 +/- 0.19 in the limbs of patients with femoropopliteal disease, P less than 0.001. When compared to controls, there were significant nerve conduction abnormalities detected in the common peroneal and posterior tibial nerves of patients with aortoiliac and femoropopliteal disease preoperatively, P less than 0.02. Postoperatively, there was no improvement in nerve conduction, amplitudes, or velocities in the common peroneal or posterior tibial nerves when compared to preoperative values. However, distal latency in the sural nerve in patients with aortoiliac disease was prolonged indicating deterioration in function. Nerve conduction abnormalities in patients with aortoiliac and femoropopliteal occlusive diseases are often present in patients with lower extremity ischemia and are not significantly improved by revascularization. These observations may indicate nonreversible changes as a result of chronic ischemia.

Femoral neuropathy: a case report and topic review

Pain in the lower extremity is a complaint frequently evaluated by the orthopedist. When this is localized to the anterior and medial aspect of the thigh and inner side of the leg and foot, peripheral lesions involving the femoral nerve must be included in the differential diagnosis. A case of a femoral neuropathy secondary to a retroperitoneal mass is presented. The anatomy and underlying etiologies of femoral neuropathies are reviewed.

Skin blood flow during histamine flare using the clearance of epicutaneous applied Xenon-133 in diabetic and non-diabetic subjects

The increase in skin blood flow produced by both reactive hyperemia and histamine was examined in 8 normal, 8 diabetic and 3 cancer patients using the epicutaneous Xenon-133 clearance method. The histamine flare response in both diabetic and cancer groups was reduced compared to that in the normal group. There was no significant difference in the reactive hyperemia responses. It is concluded that the reduction in the histamine flare response is due to a defect in the sensory nerves mediating the axon reflex and not due to a change in the vascular response.

Diabetic proximal neuropathy. Clinical and electromyographic studies

Clinical and electromyographic findings in 27 diabetics with proximal lower extremity weakness were analyzed. Two groups could be distinguished: patients in whom electromyographic findings were restricted to the clinically involved parts of the lower extremity (group A) and those in whom an associated distal symmetric, peripheral neuropathy could be proved on clinical and electromyographic grounds (group B). Patients in group B had significantly greater incidence of the following features: gradual onset of symptoms, bilateral proximal lower extremity weakness, insulin dependency, recent weight loss, EMG evidence of bilateral disease and paraspinal fibrillations. These findings concur with recent reports describing heterogeneity in the syndrome of "diabetic proximal neuropathy".

Wasted leg syndrome: a clinical, electrophysiological and histopathological study

Forty cases of 'wasted leg syndrome' were studied clinically and electrophysiologically. Muscle biopsy was examined in nine cases, majority of patients were adults engaged in heavy manual work. The illness was noticed incidently with a strictly unilateral wasting of the whole lower limb (in 65% of cases), of all muscles below the knee (in 22.5% of cases) or of quadriceps muscles only (in 12.5% of cases). The nerve conduction studies and the electromyographic pattern suggested anterior horn cell disorder. Neurogenic atrophy was seen in 7 out of 9 muscle biopsies. A follow up in 12 patients (2-6 years) revealed no progression of the disease. It is suggested that possibly these cases represent an entity, clinically different from other anterior horn cell disorders.

Normal sensory conduction in the saphenous nerve in man

Measurements of the sensory conduction velocity and the parameters of nerve action potentials in the saphenous nerve offer many advantages, compared with measurements in other nerves of the leg, regarding accuracy and the time required to complete the investigations. Therefore, the electroneurographical examination of the saphenous nerve is recommended in the early diagnosis of polyneuropathies and is indispensable in the exact diagnosis of proximal neuropathies and lesions of the femoral nerve. In the present study we indicate the proximal and distal segments of the saphenous nerve and illustrate the nerve action potentials from 70 normal subjects.

The syndrome of diabetic amyotrophy

Changes in the electromyograms and motor nerve conduction velocities in 12 patients with diabetic amyotrophy suggested mild distal and moderate proximal neuropathy in the lower limbs. Histological and histochemical findings in the vastus medialis muscles were consistent with denervation. Electron microscopical examination of the vastus medialis muscles in 6 patients revealed myofibrillar degeneration. One patient had abnormal mitochondria and tubular aggregates. The basement membranes of the intramuscular capillaries were thickened in all but 1 patient. Histochemical staining of the myoneural junctions showed changes consistent with degeneration and regeneration. We conclude that diabetic amyotrophy is a distinct clinical entity and is secondary to metabolic derangement rather than diabetic microangiopathy.

Pathology and time relationship of peripheral nerve changes in experimental diabetes

Structural changes have been studied in peripheral nerves in streptozotocin-induced diabetic monkeys. Teased single nerve fibre preparations were most informative. Abnormalities were present in 32 of 58 nerves examined from 15 diabetic monkeys with varying degree of hyperglycaemia. The earliest change was an increase in the gap at nodes of Ranvier, seen 12 weeks after the diabetic state had been established. Well marked segmental demyelination was seen in distal nerves at 14-16 weeks. Later similar changes were seen in proximal, larger nerves. Evidence of remyelination was present at a later date. Wallerian degneration was seen in only 4 nerves. Changes in the myelin sheath were more prominant than axonal abnormalities at all times. There was no abnormality in the vasa nervorum and only a mild increase in endoneurial and perineurial fibrous tissue. A direct correlation was present between the extent and degree of pathology and both severity as well as duration of hyperglycaemia.

Electrophysiological studies in diabetic neuropathy

In 30 patients with diabetic neuropathy sensory potentials in the median nerve, motor conduction in the lateral popliteal and median nerves, and electromyographic findings in distal and proximal muscles were compared with the severity of symptoms and signs. All patients had abnormalities in at least one of the electrophysiological parameters. The sensory potentials were the most sensitive indicator of subclinical involvement; abnormalities were found in 24 patients, 12 of whom had no sensory symptoms or signs and five of whom had no other clinical or electrophysiological evidence of neuropathy in the upper extremities. This indicates that sensory nerve fibres may be affected before motor. The next most sensitive parameter was the presence of fibrillation potentials, found in more than half the distal muscles examined. Slowing in motor conduction in the lateral popliteal nerve was the only electrophysiological change correlated to the severity of the neuropathy, and no other electrophysiological parameter was correlated to the duration or the severity of the neuropathy or the diabetes. An onset of neuropathy before or simultaneously with the manifestations of the diabetes, as well as the frequent occurrence of asymptomatic changes in sensory conduction, support the evidence at hand that the neuropathy develops concomitantly with and as an integral part of the metabolic disturbance rather than as a consequence of the vascular complications of diabetes. Of three patients with clinical signs or symptoms of a diabetic amyotrophy, two had asymptomatic electrophysiological abnormalities in distal nerves and muscles, consistent with widespread involvement of the peripheral nerves. The third patient had electromyographic changes in the medial vastus muscles suggestive of a myopathy. Motor and sensory conduction in distal and proximal nerves were normal.