Follow-up study of sensory-motor polyneuropathy in Type 1 (insulin-dependent) diabetic subjects after simultaneous pancreas and kidney transplantation and after graft rejection

The influence of successful simultaneous pancreas and kidney transplantation on peripheral polyneuropathy was investigated in 53 patients for a mean observation period of 40.3 months. Seventeen patients were followed-up for more than 3 years. Symptoms and signs were assessed every 6 months using a standard questionnaire, neurological examination and measurement of sensory and motor nerve conduction velocities. While symptoms of polyneuropathy improved (pain, paraesthesia, cramps, restless-legs) and nerve conduction velocity increased, there was no change of clinical signs (sensation, muscle-force, tendon-reflexes). Following kidney-graft-rejection there was a slight decrease of nerve conduction verlocity during the first year, which was not statistically significant. Following pancreas-graft rejection there was no change of nerve conduction velocity during the first year. Comparing the maximum nerve conduction velocity of the patients with pancreas-graft-rejection to the nerve conduction velocities of these patients at the end of the study, there was a statistically significant decrease of 6.5 m/s. In conclusion, we believe that strict normalization of glucose metabolism alters the progressive course of diabetic polyneuropathy. It may be stabilized or partly reversed after successful grafting even in long-term diabetic patients

Differential aging of median and ulnar sensory nerve parameters

Introduction: Nerve conduction velocity slows and amplitude declines with aging. Methods: Median and ulnar sensory nerves were tested at the annual meetings of the American Dental Association. Seven hundred four subjects had at least two observations. The rate of change in the nerve parameters was estimated while controlling for gender, age, change in hand temperature, baseline body mass index (BMI), and change in BMI. Results: Amplitudes of the median sensory nerve action potentials decreased by 0.58 μV per year, whereas conduction velocity decreased at a rate of 0.41 m/s per year. Corresponding values for the ulnar nerve were 0.89 μV and 0.29 m/s per year. The rates of change in amplitudes did not differ, but the median nerve demonstrated a more rapid loss of conduction velocity. Conclusions: The rate of change for the median conduction velocity was higher than previously reported. The rate of change of median conduction velocity was significantly greater than for the ulnar nerve. Muscle Nerve 45: 60–64, 2012Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/89485/1/22233_ftp.pd

Focal conduction block in the dorsal root ganglion in experimental allergic neuritis

Acute experimental allergic neuritis was induced in Lewis rats by inoculation with bovine intradural root myelin and adjuvants. In terminal experiments, sensory conduction was assessed in rats with hindlimb ataxia and weakness by stimulating the exposed sciatic nerve and recording directly from the exposed L-4 spinal nerve, dorsal root ganglion, dorsal root, and dorsal root entry zone. Focal conduction block was present in a high proportion of large-diameter fibers in the dorsal root ganglion. In contrast, nerve conduction in the peripheral nerve and spinal nerve was essentially normal apart from probable conduction block in some fibers in the proximal spinal nerve in a minority of rats. The afferent volley arriving at the dorsal root entry zone of the spinal cord was greatly reduced, as a consequence of the conduction block in the dorsal root ganglion and probable conduction block in the dorsal root. The M wave recorded from the fourth dorsal interosseus muscle of the hindfoot was normal in amplitude but slightly prolonged in latency and the H reflex was absent. These electrophysiological findings correlated well with the histological findings of inflammation and prominent demyelination in the dorsal root ganglia and dorsal roots with minimal involvement of the proximal spinal nerve and no involvement of the sciatic nerve. It is concluded that the hindlimb ataxia in rats with this form of acute experimental allergic neuritis is due to demyelination-induced nerve conduction block in the dorsal root ganglia and probably in the dorsal roots

Nerve Conduction Through Dendrites via Proton Hopping

Background: In our previous studies of nerve conduction conducted by proton hopping, we have considered the axon, soma, synapse and the nodes of Ranvier. The role of proton hopping described the passage of information through each of these units of a typical nerve system. The synapse projects information from the axon to the dendrite and their associated spines. Methods: We have invoked the passage of protons via a hopping mechanism to illustrate the continuum of the impulse through the system, via the soma following the dendrites. This is proposed to be a continuum invoked by the proton hopping method. Results: With the proposal of the activity through the dendrites, via proton hopping, a complete model of the nerve function is invoked. At each step to the way, a water pathway is present and is invoked in the proposed model as the carrier of the message via proton hopping. The importance of the dendrites is evident by the presence of a vast number of spines, each possessing the possibility to carry unique messages through the nervous system. Conclusion: With this model of the role of dendrites, functioning with the presence of proton hopping, a complete model of the nerve system is presented. The validity of this model will be available for further studies and models to assess it\u27s validity

Conduction block in acute motor axonal neuropathy

Guillain-Barré syndrome is divided into two major subtypes, acute inflammatory demyelinating polyneuropathy and acute motor axonal neuropathy. The characteristic electrophysiological features of acute motor axonal neuropathy are reduced amplitude or absence of distal compound muscle action potentials indicating axonal degeneration. In contrast, autopsy study results show early nodal changes in acute motor axonal neuropathy that may produce motor nerve conduction block. Because the presence of conduction block in acute motor axonal neuropathy has yet to be fully recognized, we reviewed how often conduction block occurred and how frequently it either reversed or was followed by axonal degeneration. Based on Ho's criteria, acute motor axonal neuropathy was electrodiagnosed in 18 patients, and repeated motor nerve conduction studies were carried out on their median and ulnar nerves. Forearm segments of these nerves and the across-elbow segments of the ulnar nerve were examined to evaluate conduction block based on the consensus criteria of the American Association of Electrodiagnostic Medicine. Twelve (67%) of the 18 patients with acute motor axonal neuropathy had definite (n = 7) or probable (n = 5) conduction blocks. Definite conduction block was detected for one patient (6%) in the forearm segments of both nerves and probable conduction block was detected for five patients (28%). Definite conduction block was present across the elbow segment of the ulnar nerve in seven patients (39%) and probable conduction block in two patients (11%). Conduction block was reversible in seven of 12 patients and was followed by axonal degeneration in six. All conduction blocks had disappeared or begun to resolve within three weeks with no electrophysiological evidence of remyelination. One patient showed both reversible conduction block and conduction block followed by axonal degeneration. Clinical features and anti-ganglioside antibody profiles were similar in the patients with (n = 12) and without (n = 6) conduction block as well as in those with (n = 7) and without (n = 5) reversible conduction block, indicating that both conditions form a continuum; a pathophysiological spectrum ranging from reversible conduction failure to axonal degeneration, possibly mediated by antibody attack on gangliosides at the axolemma of the nodes of Ranvier, indicating that reversible conduction block and conduction block followed by axonal degeneration and axonal degeneration without conduction block constitute continuous electrophysiological conditions in acute motor axonal neuropath

Conduction velocity in nerve exposed to a high magnetic field

Conduction velocity in nerve exposed to high magnetic fiel

Simulation of intrafascicular and extraneural nerve stimulation

A model of nerve stimulation for control of muscle contraction and ensuing isometrical muscle force has been developed and implemented in a simulation algorithm. A description of nerve fiber excitation was obtained using probability distributions of a number of excitation parameters. The volume conduction model of the stimulated nerve incorporates both inhomogeneities and anisotropy within the nerve. The nerve geometry was assumed to be cylindrically symmetric. The model of the nerve fiber excitation mechanism was based on that of D.R. McNeal (1976), using the Frankenhaeuser-Huxley equations. Simulations showed that the diameter dependence of nerve fiber recruitment is influenced by the electrode geometr

Identification of mechano-sensitive C fibre sensitization and contribution to nerve injury-induced mechanical hyperalgesia

Background: C fibre hyperexcitability is fundamental to chronic pain development in humans and rodents; therefore, peripheral sensory neuronal sensitization plays a role in the development of mechanical hyperalgesia. However, the axonal properties and underlying mechanisms that are associated to these chronic pain states still require investigation. Methods: Teased fibre electrophysiology of the saphenous nerve was used to identify C fibres in naïve and nerve-injured rats. C fibres were identified using electrical stimulation which further provided conduction velocity slowing profiles. From these nerve filaments evoked responses to mechanical stimuli were recorded. Vehicle or galanin were applied directly to the saphenous nerve trunk prior to stimulation. Results: Increased levels of mechanically evoked activity in mechano-sensitive C fibres was associated to reduced conduction failure, enhanced conduction velocity latency recovery and reduced conduction velocity slowing. Mechanical hyperalgesia developed in nerve-injured animals in which mechano-sensitive C fibres demonstrated increased mechanically evoked responses and reduced rate of adaptation. Mechano-sensitive C fibres in nerve-injured animals had reduced levels of conduction velocity slowing, enhanced rate of conduction velocity recovery and reduced firing frequency failure versus naïve animals; all hallmarks of enhanced sensory neuronal excitability. Directly applying the antinociceptive agent galanin to the saphenous nerve trunk in naive animals led to increased conduction failure, reduced latency recovery rate and increased levels of conduction velocity slowing. Discussion: Nerve injury-induced enhanced neural responses to mechanical stimulation are associated to defined parameters set out by conduction velocity slowing, mediated via axonal processing. Application of galanin inhibits axonal excitability

Foot drop of central origin: a misleading alteration of nerve conduction study

We present a case of foot drop of central origin in a 45-year-old woman who was diagnosed a malignant brain tumor in the motor area. Extensive neurophysiological assessment with nerve conduction study and electromyography (EMG) was performed during the diagnostic process and showed abnormalities which challenged us towards a comprehensive clinical and neurophysiological evaluation

Comparison of automated versus traditional nerve conduction study methods for median nerve testing in a general worker population

OBJECTIVE: To investigate the validity of automated nerve conduction studies compared to traditional electrodiagnostic studies (EDS) for testing median nerve abnormalities in a working population. DESIGN: Agreement study and sensitivity investigation from two devices SETTING: Field research testing lab PARTICIPANTS: Active workers from several industries participating in a longitudinal study of CTS. METHODS: Sixty-two subjects received bilateral median and ulnar nerve conduction testing across the wrist with a traditional device and the NC-stat automated device. We compared intermethod agreement of analogous measurements. MAIN OUTCOME MEASUREMENT: Nerve conduction study parameters RESULTS: Median motor and sensory latency comparisons showed excellent agreement (intra-class correlation 0.85 and 0.80 respectively). Areas under the receiver operator characteristic curves were 0.97 and 0.96 respectively, using the optimal thresholds of 4.4ms median motor latency (sensitivity 100%, specificity 86%) and 3.9ms median sensory latency (sensitivity 100%, specificity 87%). Ulnar nerve testing results were less favorable. CONCLUSION: The automated NC-stat device showed excellent agreement with traditional EDS for detecting median nerve conduction abnormalities in a general population of workers, suggesting that this automated nerve conduction device can be used to ascertain research case definitions of CTS in population health studies. Further study is needed to determine optimal thresholds for defining median conduction abnormalities in populations that are not seeking clinical care