Classification of human peripheral nerve fibre groups by conduction velocity and nerve fibre diameter is preserved following spinal cord lesion

Schalow, Giselher; Zäch, G A; Warzok, R

doi:10.1016/0165-1838(94)00153-b

Cited by 36 publications

(40 citation statements)

References 33 publications

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“…R n is a function of the axoplasmic resistivity (ρ ax ) and the AP's conduction velocity (v c ) is influenced by ρ ax (Moore et al 1978;. Human peripheral sensory nerve fibres can be classified into groups according to conduction velocity and fibre diameter (Schalow et al 1995). Schalow et al (1995) determined v c values of about 64.0 m/s for fibres having a diameter of 15.0 µm and about 10.0 m/s for 3.0-4.0 µm diameter fibres around 37 • C. argued that although ρ ax had not been reliably measured before, their model studies suggest a value of 0.07 k cm at 37 • C and a Q 10 factor of (1.3) −1 .…”

Section: Methodsmentioning

confidence: 99%

“…Human peripheral sensory nerve fibres can be classified into groups according to conduction velocity and fibre diameter (Schalow et al 1995). Schalow et al (1995) determined v c values of about 64.0 m/s for fibres having a diameter of 15.0 µm and about 10.0 m/s for 3.0-4.0 µm diameter fibres around 37 • C. argued that although ρ ax had not been reliably measured before, their model studies suggest a value of 0.07 k cm at 37 • C and a Q 10 factor of (1.3) −1 . For the new human nerve fibre cable model a value of 0.025 k cm at 37 • C for ρ ax and a corresponding Q 10 factor of (1.35) −1 were selected to give a v c of 58.3 m/s at 37 • C for the 15.0 µm diameter axonal fibre.…”

Section: Methodsmentioning

confidence: 99%

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Modelled temperature-dependent excitability behaviour of a generalised human peripheral sensory nerve fibre

Smit

Hanekom

2009

Biol Cybern

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The objective of this study was to determine if a recently developed human Ranvier node model, which is based on a modified version of the Hodgkin-Huxley model, could predict the excitability behaviour in human peripheral sensory nerve fibres with diameters ranging from 5.0 to 15.0 microm. The Ranvier node model was extended to include a persistent sodium current and was incorporated into a generalised single cable nerve fibre model. Parameter temperature dependence was included. All calculations were performed in Matlab. Sensory nerve fibre excitability behaviour characteristics predicted by the new nerve fibre model at different temperatures and fibre diameters compared well with measured data. Absolute refractory periods deviated from measured data, while relative refractory periods were similar to measured data. Conduction velocities showed both fibre diameter and temperature dependence and were underestimated in fibres thinner than 12.5 microm. Calculated strength-duration time constants ranged from 128.5 to 183.0 micros at 37 degrees C over the studied nerve fibre diameter range, with chronaxie times about 30% shorter than strength-duration time constants. Chronaxie times exhibited temperature dependence, with values overestimated by a factor 5 at temperatures lower than body temperature. Possible explanations include the deviated absolute refractory period trend and inclusion of a nodal strangulation relationship.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Modelled temperature-dependent excitability behaviour of a generalised human peripheral sensory nerve fibre

Smit

Hanekom

2009

Biol Cybern

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“…Values are similar to those measured in [33] (25-41 m/s), [14]. Therefore delay is not only due to Ranvier nodes, but also to internodal segments.…”

Section: Discussionsupporting

confidence: 70%

Transverse magnetic waves in myelinated nerves

Villapecellin-Cid

Roa²,

Reina‐Tosina³

2001 Conference Proceedings of the 23rd Annual International Conference of the IEEE Engineering in Medicine and Biology Society

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Abstract-The structure of myelinated axons is quite similar to that of a high-loss coaxial cable. An electromagnetic analysis of TM waves shows that distributed effects cannot be neglected. The attenuation and phase constants are obtained as a function of frequency. Predicted finite wave delay in the internodal segment approaches measurements. Keywords -Nerves, models, elctromagnetism, waves, velocity, delay, attenuation, myelin I. INTRODUCTIONElectric stimulation of nervous system can restore motor functions [1]. Electrical properties of nerves are ususally described by means of a cable model [2], [10]. This model is frequently simplified, and each internodal segment is modeled by a lumped impedance. This can be a series resistor [3]- [7], but sometimes parallel capacitive impedances are added [27]. A lumped resistor is unable to model a finite conduction velocity in the internodal segment, whereas the presence of capacitors modelling the myelin sheath can explain delays [27]. Despite this fact, resistor models are more frequently used, and the delay is usually assigned only to nonlinearities in Ranvier nodes [15].The existence of travelling waves in internodal segments could linearly explain, at least partially, the measured conduction speed [14]. The objective of this paper is to determine whether under any circumstances a distributed circuit [28] covering the effects of both the capacitive and resistive effects would be more suitable than a lumped model. To answer this question we shall analyze an internodal segment through which a transverse magnetic (TM) wave is guided [20], [26]. This approach links with the spatially distributed description of electric and magnetic fields found in literature [7], [11]-[13], [18], [19].From an electromagnetic point of view, lumped element models are obtained as a quasi-static approximation [20]. Clark et al. [21] calculate the wave number k as ( )For axoplasm at 1kHz with conductivity 5 mhos/m, the resultant wave number approximates 0.198 rad/m. In 10 cm., the phase shift is less than 0.02 radian or 1.46º, so in [21] conclude the field is quasi-static. This conclussion was later adopted explicitly [22] or implicitly in lumped element models [3]- [7], [27]. We shall show that the waves are not defined by k, but rather by the propagation constant h, and that quasi-static approximations don't apply always, specially for relatively high frequencies. II. METHODOLOGYFor sake of simplicity, we shall consider an infinitely long segment, surrounded by an infinite extracellular medium. Even though the results will not be the same found in physiological situations, qualitative conclusions might be useful to gain understanding into nerve conduction. The structure is quite similar to a high-loss coaxial cable ( fig. 1). Medium 1 is the axoplasm, medium 2 is the myelin sheath, and medium 3 is the extracellular fluid. [18]. We don't assume this hypothesis [27]. All media will be generic with permitivity ε i , permeability µ 0 , and conductivity σ i , where subscript i refers to mediu...

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“…Removing the nerve roots after recording and performing morphometry, a classification scheme of peripheral nerve fibers of the human nervous system could be developed (Figure 2), in which a nerve fiber group is characterized by a group conduction velocity and a group nerve fiber diameter [22].…”

Section: Methods Coordination Dynamics Therapy (Cdt)mentioning

confidence: 99%

Coma and spinal cord injury recovery achieved via coordination dynamics therapy

Schalow¹

2018

Clin Case Rep Rev

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Based on a new development of human neurophysiology, it became possible to partly repair the human brain and spinal cord by a movement-based learning therapy called "coordination dynamics therapy" (CDT). In two short case reports it will be shown that the present medical system is out-of-date by 30 years. That a spinal cord injury patient can re-learn walking and gets the urinary bladder functions repaired, which is the biggest problem in spinal cord injury, seems for the expensive conventional rehabilitation out-of-scope. In the second case report it is shown that patient being in the permanent coma, could be brought out-of-coma via CDT six years after the accident. If it is not tried by efficient treatment to get long-term coma patients out of the coma, means modern euthanasia. That brain repair is even partly possible in extreme brain injury is due to the development of human neurophysiology and especially the electrophysiology and not due to animal research; only 0.3% of the data have consequences for human patients.

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Classification of human peripheral nerve fibre groups by conduction velocity and nerve fibre diameter is preserved following spinal cord lesion

Cited by 36 publications

References 33 publications

Modelled temperature-dependent excitability behaviour of a generalised human peripheral sensory nerve fibre

Modelled temperature-dependent excitability behaviour of a generalised human peripheral sensory nerve fibre

Transverse magnetic waves in myelinated nerves

Coma and spinal cord injury recovery achieved via coordination dynamics therapy

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