Conduction studies of the normal sural nerve

Abstract

The sural nerve was studied orthodromically using the near-nerve technique in 273 normal subjects (155 females, 118 males) aged 5 to 90 years. The sensory action potential (SAP), evoked at the dorsum of the foot, was recorded at the lateral malleolus and midcalf, and at the midcalf when evoked at the lateral malleolus. In addition, the SAP was recorded at intermediate distal sites and at proximal sites at the popliteal fossa, the gluteal fold, and the S-1 root. The amplitude of the SAP recorded at midcalf was 32% higher in females than in males. This was probably due to volume-conduction properties, as differences between genders were less noticeable at more distal recording sites. The amplitude decreased steeply and exponentially with age. Conduction distance had a strong influence on the amplitude of the SAP, which decreased with increasing distance following a power relationship with an exponent of 1.4 to 1.7. This decrease was due to temporal dispersion with decreased summation and increased phase cancellation. The conduction velocity was slightly lower along the very distal course of the nerve than along more proximal segments.

Effects of essential hypertension on short latency human somatosensory-evoked potentials

“…Age and stimulation-to-recording distance were entered as covariates because of their known effects on peripheral nerve sensory action potentials (Bolton & Carter, 1980;Horowitz & Krarup, 1992).…”

Different indentation velocities activate different populations of mechanoreceptors in humans

“…This reduction in proximal amplitude is due to temporal dispersion causing changes in phase summation and cancellation, which is particularly pronounced in the synchronized compound nerve action potential. 15,27,29 By contrast, the distal and proximal amplitudes of CSAPs evoked by tactile stimulation were polyphasic, due to asynchronous activation of individual fibers, 6 and less influenced by temporal dispersion than by the placement of the recording electrode relative to the active sensory fibers. In the median nerve, the needle electrodes at wrist and elbow were placed close to the nerve by means of the threshold necessary to evoke a muscle response, and the distance from active sensory fibers could therefore vary.…”

“…Sensory action potentials were recorded from two sites along the nerve using insulated 0.7-mm needle electrodes with a 3-mm bared gold-covered tip, to reduce the impedance, placed close to the nerve at the lateral malleolus (LM) and ≈130 mm proximally at the midcalf (MC). 15,29 To obtain unipolar recording, the remote electrode was a needle with a 5-mm bared goldcovered tip placed transversely at a distance of 30-40 mm from the recording electrode. 8 The electrodes were placed close to the nerve by stimulating the nerve with an electrical current through the recording electrode.…”

Sensory Conduction Velocity of Dorsal Nerve of the Penis during Pharmacoerection: A More Physiological Technique?

“…Mean penis length at rest was 95 ± 12. [10] as compared to the 32.2 ± 6.7 m/s at rest which is much too slow. Using a traction device, Clawson and Cardenas [5] found a SCY of 36.2 ± 3.2 m/s which is still too slow.…”