To investigate the normal data of pain-related evoked potentials (PREP) elicited with a concentric surface electrode among normal, healthy adults and the relationship between PREP and pain intensity.
Sixty healthy volunteers (22 men and 38 women; aged 36.4±10.7 years; height, 165.4±7.8 cm) were enrolled. Routine nerve conduction study (NCS) was done to measure PREP following electrical stimulation of hands (C7 dermatome) and feet (L5 dermatome). Negative peak (N), positive peak (P) latencies, peak to peak (NP) amplitudes, conduction velocity (CV), and verbal rating scale (VRS) score were obtained. Linear regression analysis tested for significant relevance between variables of PREP and VRS score.
Normal NCS results were obtained in all subjects. N latency of hand PREP was 163.8 ±40.0 ms (right) and 161.0±39.9 ms (left). N latency of foot PREP was 178.0±43.9 ms (right), 180.4±43.4 ms (left). NP amplitude of hands was 20.6±10.6 µV (right) and 21.9±11.6 µV (left). NP amplitude of feet was 18.8±8.3 µV (right) and 19.0±8.4 µV (left). The calculated CV was 13.2±4.7 m/s and VRS score was 3.8±1.0. A highly significant positive correlation was evident between VRS score and NP amplitude (y=0.1069x+1.781, r=0.877, n=60, p<0.0001).
PREP among normal, healthy adults revealed a statistically significant correlation between PREP amplitude and VRS score.
Citations
To derive normative values for ulnar nerve conduction study of the active recording electrode on the first dorsal interosseous muscle (FDI) and the reference electrode on the proximal phalanx of the thumb.
Ulnar nerve motor conduction study with FDI and abductor digiti minimi muscle (ADM) recording was performed in 214 hands of 107 healthy subjects. Ulnar NCS was performed with 2 different recording electrode montages (ADM-base of 5th finger; FDI-thumb) and differences in latency and amplitude were compared. Using this technique, the initial positivity of ulnar compound muscle action potential (CMAP) was not observed in any response with FDI recording.
The maximal values for distal motor latency to the ADM and FDI muscle were 3.8 ms and 4.4 ms, respectively. The maximal difference of distal motor latency between the bilateral FDI recordings was 0.6 ms. The maximal ipsilateral latency difference between ADM and FDI was 1.4 ms.
Placement of the reference electrode on the thumb results in a CMAP without an initial positivity and the normative values obtained may be useful in the diagnosis of ulnar neuropathy at the wrist.
Citations
Objective: The purpose of this study was to evaluate the most effective stimulating electrode in TENS for pain relief, and to apply to the treatment of patients with neck and shoulder problems.
Method: The objects were 30 patients with neck and shoulder problems. In 10 of them, insulated needle electrodes were inserted into a trigger point and electrical stimulation given through the electrodes. In 10 of them, non-insulated needle electrodes were applied as the same method. The others were treated with lidocaine injection into a trigger point and electrical stimulation given through the surface electrode. The effects of pain relief were assessed by visual analogue scale (VAS), pain rating score (PRS), and pain algometer.
Result: In the group with insulated needle electrode, the average score was reduced 48.33⁑24.84% in VAS score and 52.00⁑17.55% in PRS, the pressure of pain algometer was increased 34.97⁑15.33%. In non-insulated needle electrode group, reduced 43.16⁑34.62% in VAS score and 43.73⁑34.85% in PRS, the pressure was increased 22.28⁑30.62%. The score reduction of surface electrode group was 20.61⁑15.73% in VAS score and 18.22⁑16.27% in PRS, the pressure-pain threshold increased as 9.05⁑12.81%.
Conclusion: The results suggest that insulated and non-insulated needle electrodes were more effective stimulating electrode in TENS for pain relief than surface electrode.
Objective: This study was designed to investigate the effect of different sites of recording electrodes on auditory evoked potentials (AEPs) in healthy adults and to analyse these potentials properly.
Method: Eleven healthy adults, 7 males and 4 females, without any history of disease or conditions causing hearing difficulties were selected. AEPs were performed on these subjects with 4 different methods, i.e. different recording sites, Cz-Ai, Cz-Fpz, Ai-Ac, and Ai-Cs7. Auditory stimulation was given by rarefaction clicks of 75dB intensity and 11.1 Hz frequency, and responses were recorded with surface electrodes.
Results: The amplitudes of peak I and V were larger with vertical recordings, that is the vertex-auricle (Cz-Ai) or vertex-7th cervical spine (Cz-Cs7) recordings, compared to horizontal recordings of both auricle (Ai-Ac) or extracephalic electrodes. The largest amplitude ratio of peak V/I was with vertex-7th cervical spine (Cz-Cs7) recording.
Conclusion: Changes in AEPs with respect to the sites of recording and reference electrodes are thought to be due to the vector of brain stem auditory nuclei and pathways. It might be helpful to consider these changes in the evaluation of brain stem lesions.
Objective: To investigate the influence of five different recording electrodes on the various parameters of sensory nerve action potentials (SNAPs).
Method: Median sensory nerve conduction study was performed in 50 normal subjects using different five types of recording electrodes-disc electrode, ring electrode, bar electrode and two kinds of felt-tip bar electrodes (type 1 and 2). The interelectrode distances between active and reference electrodes were set at 4 cm for the disc and ring electrodes. The bar electrode, felt-tip electrodes type 1 and 2 were fixed at interelectrode distances of 3 cm, 3.7 cm and 2.3 cm, respectively. Onset and peak latency, onset to peak amplitude, peak to peak amplitude and duration of negative spike of SNAPs were measured. These parameters were compared using ANOVA test.
Results: Onset and peak latencies of SNAPs recorded from five different electrodes were not different (p＞0.05). Onset to peak and peak to peak amplitudes of SNAPs recorded from felt-tip type 2 electrode were significantly reduced compared to other electrodes (p＜0.05). Onset to peak amplitude of SNAPs was also reduced when the ring electrode was used (p＜0.05). The negative spike durations of SNAPs recorded from felt-tip type 2 and bar electrodes were shorter than other electrodes recording (p＜0.05).
Conclusion: Onset and peak latencies of SNAPs were not affected by the types of electrodes used. Shortening of interelectrode distance may be a main cause of reduction of peak to peak amplitude and negative spike duration of SNAPs.
Objective: Distance between the active and reference electrodes can affect the waveform configuration and amplitude of sensory nerve action potential (SNAP). This study was purposed to determine the change of SNAP parameters with varying interelectrode distance.
Metohod: Median sensory nerve conduction study was performed in the middle finger of 40 young healthy subjects by antidromic method. To ensure firm contact with skin, strip adhesive electrode was used for recording responses. The active electrode was fixed on 1 cm distal to the proximal flexion crease of middle finger and interelectrode separation was increased from 1 to 5 cm by 1.0 cm increments. Bar electrode was fixed 14 cm proximal from active electrode for stimulation in the wrist area.
Results: As the interelectrode distance increased from 1 cm to 5 cm, onset latency remained unchanged. The peak latency increased with increasing the distance up to 3 cm but didn't change beyond 3 cm (1 cm: 2.89⁑0.89 msec, 2 cm: 2.97⁑0.89 msec, 3 cm: 3.02⁑0.19 msec, 4 cm: 3.02⁑0.19 msec, 5 cm: 3.02⁑0.20 msec). Base-to-peak amplitude significantly increased only up to 3 cm (1 cm: 30.3⁑6.7μV, 2 cm: 43.7⁑8.6μV, 3 cm: 50.8⁑10.4μV, 4 cm: 51.1⁑10.9 μV, 5c m: 51.3⁑11.4μV) but peak-to-peak amplitude sequentially increased to 5 cm (1 cm: 49.6⁑12.1μV, 2 cm: 72.8⁑14.4μv, 3 cm: 83.6⁑19.4μV, 4 cm: 91.3⁑22.5μV, 5 cm: 93.4⁑23.9μV)(p＜.05).
Conclustion: This study showed that changing interelectrode distance altered some parameters of SNAP, especially the peak-to peak amplitude.
Objective: To explore the effects of different recording electrodes on motor nerve conduction latencies.
Method: Median motor conduction study was performed in 10 healthy subjects. Motor conduction latency was determined by placing different recording electrodes (surface disc, monopolar needle and concentric needle) at the motor point of the left abductor pollicis brevis muscle, and reference electrodes on the proximal interphalangeal joint of the thumb. Motor nerve conduction recording was performed by using a surface disc, monopolar needle, and concentric needle. For the intramuscular recordings, needles were inserted both superficially and deep. The stimulus electrodes were secured 8 cm proximal to the recording electrodes, and the same intensity was applied throughout the tests.
Results: Deep intramuscular monopolar and concentric needle electrodes recorded the shorter latencies, 3.0⁑0.4 ms and 3.0⁑0.3 ms, respectively. Superficial concentric needle electrode recorded the longest latency of 3.4⁑0.3 ms. Motor nerve conduction latencies using a surface disc and superficial monopolar electrode were 3.2⁑0.3 ms and 3.2⁑0.3 ms, respectively.
Conclusion: We conclude that the distal motor nerve conduction latency is variable depending on the type of recording electrodes.
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