To investigate the effect of pulsed radiofrequency (PRF) applied proximal to the injured peripheral nerve on the expression of tumor necrosis factor-α (TNF-α) in a neuropathic pain rat model.
Nineteen male Sprague-Dawley rats were used in the study. All rats underwent chronic constriction injury (CCI) procedure. After 7 days of CCI, withdrawal frequency of affected hind paw to mechanical stimuli and withdrawal latency of affected hind paw to heat stimulus were measured. They were randomly divided into two groups: group A, CCI group (n=9) and group B, CCI treated with PRF group (n=10). Rats of group B underwent PRF procedure on the sciatic nerve. Withdrawal frequency and withdrawal latency were measured at 12 hours, and 7 days after PRF. Immunohistochemistry and Western blot analysis were performed using a TNF-α antibody.
Before PRF, withdrawal frequency and withdrawal latency were not different in both groups. After PRF, withdrawal frequency decreased and withdrawal latency prolonged over time in group B. There was significant interaction between time and group for each withdrawal frequency and withdrawal latency. Group B showed decreased TNF-α immunoreactivity of the spinal cord and sciatic nerve at 7 days.
PRF applied proximal to the peripheral nerve injury is potentially helpful for the reduction of neuropathic pain by neuromodulation of inflammatory markers.
Citations
Electrical shock can result in neurological complications, involving both peripheral and central nervous systems, which may present immediately or later on. However, delayed neurological complications caused by low-voltage electric shock are rarely reported. Here, a case of a man suffering from weakness and aphasia due to the delayed-onset of the peripheral nerve injury and ischemic stroke following an electrical shock is presented. Possible mechanisms underlying the neurological complications include thermal injury to perineural tissue, overactivity of the sympathetic nervous system, vascular injury, and histological or electrophysiological changes. Moreover, vasospasms caused by low-voltage alternating current may predispose individuals to ischemic stroke. Therefore, clinicians should consider the possibility of neurological complications, even if the onset of the symptoms is delayed, and should perform diagnostic tests, such as electrophysiology or imaging, when patients present with weakness following an electric injury.
Citations
Medial antebrachial cutaneous (MABC) nerve injury associated with iatrogenic causes has been rarely reported. Local anesthesia may be implicated in the etiology of such injury, but has not been reported. Two patients with numbness and painful paresthesia over the medial aspect of the unilateral forearm were referred for electrodiagnostic study, which revealed MABC nerve lesion in each case. The highly selective nature of the MABC nerve injuries strongly suggested that they were the result of direct nerve injury by an injection needle during previous brachial plexus block procedures. Electrodiagnostic studies can be helpful in evaluating cases of sensory disturbance after local anesthesia. To our knowledge, these are the first documented cases of isolated MABC nerve injury following ultrasound-guided axillary brachial plexus block.
Citations
Pain, numbness, and weakness in the upper extremity are the common problems among wheelchair users. The prevalence of nerve injury of the upper extremity in the wheelchair users has been reported variously by many authors in other nations. To determine the prevalence, location, and risk factors of upper extremity peripheral nerve entrapment among wheelchair users, we performed clinical and electrodiagnostic assessments on both upper extremities of wheelchair users (n=49) and able-bodied controls (n=49).
The prevalence of nerve entrapment of the upper extremity among the wheelchair users was 15.6% according to clinical criteria, and 46.9% according to electrodiagnostic criteria. Electrodiagnostically, median nerve entrapment was identified in 28.6% of tested cases, and ulnar nerve entrapment was identified in 22.4% of tested cases among wheelchair users. The carpal tunnel was the most common site of nerve entrapment. The duration of wheelchair use was found to be correlated negatively with median wrist to palm and wrist to digit sensory conduction velocity, whereas age correlated positively with distal median and ulnar motor latency.
Quantitative analysis of abnormal spontaneous activities, motor unit action potentials and interference patterns were recorded in 55 subjects with traumatic peripheral nerve injury to understand the changes of electromyographic signals.
We analyzed amplitudes of fibrillation potentials and positive sharp waves at rest, amplitude, duration, spike duration and polyphasicity of motor unit action potentials at minimal contraction, and the root mean square(RMS), and mean rectified voltage (MRV) at maximal contraction.
The amplitudes of fibrillation potentials and positive sharp waves had negative correlations with the duration of peripheral nerve injury but the amplitudes of motor unit action potentials, RMS, and MRV had positive correlations.
Therefore electromyographic evaluation could be used for the estimation of the duration of peripheral nerve injury.
The effect of electrical nerve stimulation are controversial because of the inconsistent variables of stimulating current and electrophysiologic study. The purposes of this study are to reconfirm the electrophysiolgic changes by electrical stimulation of the peripheral nerve that had been reported in 1993, and to monitor how long they will be maintained. In this study, the following conditioning stimulations were applied to 20 healthy volunteers; interferential current(frequency: 80∼100 Hz, intensity: 27∼34 mA) on the sacral paraspinal area. The H reflex, the F response, and the somatosensory evoked potential(SEP) of the tibial nerve were evaluated as the electrophysiologic study before, immediately after, 30 minutes, 60 minutes, and 120 minutes after the above conditioning stimulation. The following results were obtained;
1) Latencies of the H reflex, the F response and the SEP(P1), and the F wave conduction time, the F wave conduction velocity and the F ratio in the tibial nerve conduction study were increased by conditioning stimulation of the proximal peripheral nerves(P＞0.01).
2) Changes of the amplitude of the H reflex, the H/M ratio, and the amplitude(P1N1) of the tibial SEP were not significant in the same conditioning stimulation(P＞0.05).
3) Prolongations of the latencies of H reflex, F response and P1 SEP of the tibial nerve were the most significant immediately after conditioning stimulation and sustained for 45 minutes after conditioning on average (P＜0.01).
The above results suggest that certain conditional electrical stimulation of the peripheral nerves causes reversible changes in the conduction of the H reflex, the F response and the SEP and they may be inhibitory effect of the proximal conduction via the spinal cord.
Objective: To determine the prevalence, location, and risk factors for the peripheral nerve entrapments of upper extremity among the crutch or cane users.
Method: We performed the clinical and electrodiagnostic assessments of both upper extremities in 43 crutch or cane users and 49 able-bodied controls.
Results: The prevalence for the nerve entrapment of upper extremity among the crutch or cane users was 27.9% by the clinical criteria and 86.0% by the electrodiagnostic criteria. Electrodiagnostically, the median nerve entrapment was 76.7%, and the ulnar nerve entrapment was 72.1% among the crutch or cane users. The carpal tunnel was the most common site for the entrapment. Body weight, duration of disability, and duration of crutch or cane use were found to be significantly correlated with the emtrapments of median nerve, whereas duration of crutch or cane use alone was significantly correlated with the entrapments of ulnar nerve.
Conclusion: The peripheral nerve entrapments of upper extremity is associated with the chronic crutch or cane use and the preventive strategies need to be developed for the patients with risks.
Objective: To investigate the effect of peripheral nerve stretching on motor evoked potentials (MEP) as a method of facilitation.
Methods: Twenty three normal healthy volunteers were enrolled. Transcranial magnetic stimulation (TMS) was applied to the contralateral scalp at 7 cm lateral to Cz using 90 cm round coil. Intensity of stimulation was adjusted to 90% of maximal stimulation intensity. Recording was done on the abductor pollicis brevis muscle in three different conditions; firstly resting state, secondly voluntary contraction of abductor pollicis brevis muscle, and lastly with stretching of median nerve. The onset latency and amplitude were obtained and compared between three conditions.
Result: The amplitude of MEP was significantly increased in the condition with muscle contraction and peripheal nerve stretching compared with resting state. The latency was shortened in the condition with muscle contraction with statistical significance and with peripheral nerve stretching without significance.
Conclusion: We concluded that stretching of peripheral nerve can be used as a method of facilitation of MEP. This method is considered to be useful especially for the patients with motor paralysis or poor cooperarion for voluntary contraction.
First
Prev
