Pdf determination of the chronaxie and rheobase of denervated. Chronaxie of a tissue is a definite measure of its excitability. The pad of an electrical stimulator was applied to the vastus lateralis and vastus medialis regions to measure rheobase and chronaxie until the contractive muscle response to electrical stimulation became visible. Rheobase is measured as the threshold stimulus current for an active response with a longduration pulse and chronaxie is the pulse width at twice the rheobase threshold current 19. A less excitable tissue has a longer chronaxie, whereas a more excitable tissue has a. Determining rheobase and chronaxie from a strength. These terms are used to discuss the relationship between the strength and duration of a rectangular pulse and. Rheobase and chronaxie were significantly higher in low back pain patients with radiculopathy than apparently healthy control subjects p rheobase and chronaxie in patients with lbp and lumbar disc herniation than the control subjects. At each setting the denervated ta was palpated manually to detect the response of the muscle. When the stimulus strength is below the rheobase, stimulation is ineffective. Rheobase may not necessarily be the electric current of choice.
Selective hb pacing was seen in 99 patients 78% and obligatory nonselective hb pacing rv threshold always. Your story matters citation stern, shani, andres agudelotoro, assaf rotem, elisha moses, and andreas neef. Rheobase is measured as the threshold stimulus current for an active response with a longduration pulse and chronaxie is the pulse width at twice the rheobase threshold current19. Teacher, physiotherapy school of victoria the strength duration test was first used for clinical purposes by adrian 1916, and later developed by ritchie 1944. This is the voltage to which the strengthduration curve asymptotes. In neuroscience, rheobase is the minimal current amplitude of infinite duration in a practical sense, about 300 milliseconds that results in the depolarization threshold of the. Chronaxie is the minimum time required for an electric current to double the strength of the rheobase to stimulate a muscle or a neuron.
There have been few studies that have focused on physical therapy using rheobase and chronaxie, and whether it should be applied differently based on these. Rheobase definition and meaning collins english dictionary. Pdf influence of lumbar disk herniation on chronaxie and. Chronaxie measurements in patterned neuronal cultures from rat hippocampus the harvard community has made this article openly available.
The wilcoxon matchedpairs signedrank test was used to compare chronaxie, rheobase, zones of programmable selective hb pacing width, and mean pulse current drain. However, it can be shown that the chronaxie, especially, is an important parameterinfluenced by several factors such as electrode size, material, and stimulation. Chronaxie was that pulse duration at which the threshold intensity was twice that of the rheobase. Double point moteur et double chronaxie des extenseurs des orteils etc. Here are a couple mnemonic hints to help you remember which term is which. Result rheobase was significantly increased on the paretic side compared to that of the nonparetic side of hemiplegic stroke. Objectives was to find rheobase and chronaxie values in. Electromyography is used to diagnose neuropathies, myopathies, and neuromuscular junction diseases. Up to now, both terms have never played an important role in cardiac pacing. Chronaxie and rheobase the results of chronaxie and rheobase measurements in the whole group and in the subset of selective hb pacing and obligatory nonselective hb pacing are presented in table 2. Chronaxie is dependent on the density of voltagegated sodium channels in the cell, which affect that cells excitability. The terms chronaxie and rheobase are 100 years old. From the graph above, the rheobase is approximately 0. Rheobase is the lowest intensity with indefinite pulse duration which just stimulated muscles or nerves.
Determination of the chronaxie and rheobase of denervated limb. Chronaxie and rheobase was first defined more than one hundred years ago, and since that time, various researchers have studied these parameters in cases of peripheral nerve lesion. Pdf differences in rheobase and chronaxie between the paretic. In patients with chronic low back pain lbp and lumbar disk herniation, strengthduration curve sdc electrodiagnostic testing is one of the means of establishing whether or not radiculopathy is present. A strengthduration threshold curve along with its rheobase and chronaxie values was constructed from the threshold points. Differences in rheobase and chronaxie between the paretic. This means that with pulses of short durations, axons are more easily excited than dendrites.
P values of may 27, 2017 chronaxie is an index of excitability and is time in millisecond, necessary to induce minimal visible contraction with a stimulus of twice the strength of the rheobase. Rheobase medical definition merriamwebster medical dictionary. The chronaxie is a duration measurement, corresponding to twice the rheobase. The chronaxie time had a larger variability, with percent differences ranging from 3 to 7 percent. In a strengthduration curve for muscle stimulation, it is the voltage at which there is no further decrease in threshold when the pulse width or duration is increased. In greek, the root rhe translates to current or flow, and basi means. Rheobase is a measure of membrane potential excitability. Chronaxie measurements in patterned neuronal cultures from. Dendritic chronaxie is measured to be about 1 ms, while that of axons is on the order of 0.
The terms chronaxie and rheobase was first stated in lapicques paper in 1909 8. Chronaxie definition of chronaxie by the free dictionary. Rheobase definition of rheobase by the free dictionary. Pdf measurements of the rheobase and chronaxie can be used to define the excitability of nerves and muscles. In neuroscience, rheobase is the minimal current amplitude of infinite duration in a practical sense, about 300 milliseconds that results in the depolarization threshold of the cell membranes being reached, such as an action potential or the contraction of a muscle. Describing mathematically, the intensity duration curves of electrostimulation by hyperbolas, lapicque introduced two terms which characterized the functional relationship. Besides the rheobase, the strengthduration curve also provides another piece of information, the chronaxie. For stroke patients, however, the uses of rheobase and chronaxie in. Determination of the chronaxie and rheobase of denervated limb muscles in conscious rabbits article pdf available in artificial organs 293. At the double intensity of rheobase, the minimal pulse width required to produce the twitch is called chronaxie of muscle. Chronaxie and excitability values medical application is electromyography, a technique for evaluating and recording the electrical activity produced by skeletal muscle. Chronaxie is an index of excitability and is time in millisecond, necessary to induce minimal visible contraction with a stimulus of twice the strength of the rheobase.
A less excitable tissue has a longer chronaxie, whereas a more excitable tissue has a shorter one. Chronaxie and rheobase are presented as median and interquartile range. Strength duration curve and importance in physiotherapy. The following steps are followed in order to determine rheobase and chronaxie. The chronaxie is defined as the pulse duration required for excitation when the current amplitude is equal to twice the rheobase current. Step 3 determine chronaxie, which is the stimulus duration that yields a response when the stimulus strength is set to exactly 2. The stimulation threshold was 4 v at a pulse duration of 0. Mar 25, 2016 at the double intensity of rheobase, the minimal pulse width required to produce the twitch is called chronaxie of muscle. The chronaxie time and its practical importance irnich. They found that chronaxie, which provides a measure of the neuromuscular electrical excitation threshold, was the most sensitive parameter for use in detection. Rheobase, chronaxie, sd curve, kink, hemiplegia, lower motor neuron, strength duration curve. Previous studies have reported chronaxie values or strengthduration time constants of sensory nerves averaging 300650 ps using currentcontrolled stimulation from the skin surface 14. Rheobase was the lowest intensity with indefinite pulse duration which just stimulated muscles or nerves. Rheobasethe minimal strength of an electrical stimulus of indefinite duration that is able to cause excitation of a tissue, e.
An often used parameter to characterize the function is chronaxie, which is the pulse duration equivalent to two times the rheobase. Sd curves with the electric field aligned either parallel or perpendicular to the axons yield the chronaxie and rheobase of axons and dendrites respectively, and these differ considerably. Step 1 determine the rheobase, which is the minimum stimulus strength that will produce a response. Chronaxie is defined as the shortest duration of stimulus required to excite a tissue by a current strength equal to twice of rheobase voltage. Determination of the chronaxie and rheobase of denervated. These terms are used to discuss the relationship between the strength and duration of. Surface electrical stimulation to evoke referred sensation sensations, such a pressure, heat, tickle, can all be produced by varying the chronaxie, an electrical pulse varyin g in length of time. What is the difference between rheobase and threshold. Differences in rheobase and chronaxie between the paretic and. The explanation given here was adapted from the book cochlear implants, chapter 5 biophysics and physiology by abbas and miller, two veterans in cochlear implant electrophysiology. His bundle has a shorter chronaxie than does the adjacent. In this example, the rheobase voltage was determined to be 1 v and the chronaxie duration was 0. Chronaxie and rheobase of various tissues muscles humans. Rheobase definition of rheobase by medical dictionary.
Rabbitdenervated muscletibialis anteriorfunctional electrical stimula tionchronaxierheobase. Pdf determination of the chronaxie and rheobase of. P values of performance, and interpretation of the strength duration test1 barry c. Rheobase and chronaxie were measured noninvasively at weekly intervals by means of a laptop pc, which communicated with the stimulator via a radio. Axons and dendrites were found to have significantly different chronaxies and rheobases.