Peripheral Nerve Regeneration A Follow-Up Study of 3,656 World War II Injuries (1957) / Chapter Skim
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Electrical Evidence of Regeneration
Electrical Evidence of Regeneration
Pages 203-240
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From page 203... ...
Discrepancies between voluntary movement and electrical responses prompted more careful study of individual muscles, and at times alerted examiners to disparities between anatomical reinnervation and functional recovery which could be turned to patients' advantage. Since the follow-up studies were made about 5 years after injury, neither early nor interim observations could be procured under the design adopted for the study.
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From page 204... ...
the electrical data are much more subject to center variation than the observations on voluntary movement. Furthermore, the chief clinical value of the electrodiagnostic tests at the point in time at which the follow-up study was done lies in the contribution they make to an understanding of the factors associated with absence of voluntary movement.
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From page 205... ...
Stimulation of the nerve rapidly delimits the functionally intact from the nonfunctional neuromuscular groups. Together with observations on voluntary movement it also provides a clear-cut differentiation between those neuromuscular groups which are not used by the patient because of anatomical defects and those which are not used because of psychic or learning factors.
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From page 206... ...
nerve stimulation was performed in each center, and the presence of bias in the selection of cases for such stimulation, are shown in table 114, which is confined to 7,863 muscles supplied by the 7 major nerves, complete nerve sutures, standard muscles affected by injury, cases with movement not affected by tendon transplant, by loss of muscle substance by direct injury, or by sacrifice of a nerve branch, and muscles in which an examination of voluntary movement was made. Only in the New York center was direct nerve stimulation routine and the selection of muscles for testing quite unbiased, and in only three centers was nerve stimulation done on any appreciable number of cases.
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From page 207... ...
and 0.12 msec. for one of the muscle fibers innervated by that nerve fiber.
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From page 208... ...
The measurements are carried out by suitable stimulation of a motor point, with the observer striving for a minimal contraction of the muscle under study. In visual observation the response is probably composed of neurally evoked activity of a number of motor units as well as of directly stimulated nonreinnervated muscle fibers.
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From page 209... ...
In the hands of an experienced observer the differences in these values, and also in the appearance of rapid twitches of the reinnervated muscle fibers and slower contraction of still denervated muscle fibers, furnish valuable information. At a single examination, such as characterized this study, chronaxiemetry has a more restricted usefulness, since it can then only reflect the current state of reinnervation or its absence.
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From page 210... ...
There were in all 5,581 chronaxie determinations on individual muscles, or about 36 percent of all the muscles involved in the study. If attention is confined to the 7 major nerves, complete sutures, standard muscles affected by injury, muscles with movement not influenced by sacrifice of a nerve branch, by direct loss of substance through injury, or by tendon transplant, and muscles in which studies of voluntary movement were made, it appears that 44 percent were tested by chronaxiemetry.
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From page 211... ...
. 100 0 99 9 100 0 Number of muscles 162 95 145 Table 116. -- Percentage of Affected Muscles Studied by Chronaxiemetry, Complete Sutures on All Seven Major Nerves, Muscles Studied for Voluntary Movement, by Center Voluntary movement Center None Any Total Total Chronaxiemetry done Total Chronaxiemetry done Total Chronaxiemetry done Number Percent Number Percent Number Percent Boston 224 259 583 728 166 25 47 228 166 26 11.2 629 747 1,733 218 170 1,349 733 520 34.7 22.8 77.8 38.6 58.0 853 243 217 1*
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From page 212... ...
For example, 18.3 percent of upper extremity muscles observed to contract voluntarily have TR readings in contrast to 12.6 percent of those with no voluntary contraction; this discrepancy has a probability of .03 in the statistical test employed here. For the lower extremity the discrepancy is smaller and by itself well within the range of chance, but both discrepancies, considered jointly, have a probability of about .025.
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From page 214... ...
Table 117 provides average values for muscles with reasonable numbers of readings, and table 118 provides a frequency distribution for the abductor digiti V which was the most extensively studied muscle. Table 117. -- Mean Tetanus Ratio Readings Following Complete Suture, for Selected Muscles, Lesions in Representative Sample Number tested Mean tetanus ratio Nerve Muscle Median Opponcns 45 3.8 Ulnar Fl.
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From page 215... ...
Methodology During voluntary activity or on electrical stimulation of a normal innervated muscle, the neural impulses arriving at the muscle set up end-plate activity and a propagated electrical response in the activated muscle fibers. A single motor nerve fiber, by virtue of its terminal branching, innervates a number of muscle fibers which generally respond together as the motor unit.
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From page 216... ...
, or to variation in the number of muscle fibers of the motor unit responding to the neural impulse, and in their relative asynchrony. The potential reco-ded by the electrodes is a reflection of the current flowing in the medium surrounding the generators of the excitable tissues.
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From page 217... ...
In the denervated muscle, the responses obtained can only be due to spontaneous or induced activity of individual muscle fibers. As described above, the response of an individual fiber in a volume conductor will be very small, and may also be briefer than that of the motor unit.
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From page 218... ...
During the process of reinnervation the response of a motor unit may undergo complex changes but these are beyond the scope of the present analysis. An important finding of this study has been that reinnervated muscles usually show extremely large electrical responses from a few motor units (90)
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From page 219... ...
Thus, some patients possess only slight motor unit activity when asked to perform with a reinnervated member. In some of these chronaxiemetry and nerve stimulation indicate good anatomic regeneration.
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From page 220... ...
ANALYSIS OF ELECTRODIAGNOSTIC DATA 1. Orientation and methodology Interest in electrodiagnostic tests done by the follow-up centers many years after injury lies in the expectation that they may provide information on some of the factors responsible for absence of voluntary movement.
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From page 221... ...
If, in the absence of voluntary movement, direct nerve stimulation produces a contraction, it may be assumed that one of the first two factors has blocked voluntary movement. In some instances, of course, this assumption would be wrong, either because the voluntary movement is possible but was improperly elicited or observed, or because of corresponding error in reporting movement following nerve stimulation.
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From page 222... ...
In other words, the assumption is made that muscles on which chronaxie determinations were not made would be distributed exactly like those on which the determinations were made, provided that the response to both voluntary and direct nerve stimulation is fixed as in the column designations of the table. Table 120. -- Voluntary Movement and Response to Direct Nerve Stimulation for All Affected Muscles Following Complete Sutures on All Seven Major Nerves, New York Center l Response to electrical stimulation of nerve Voluntary movement None Any Total None ...
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From page 223... ...
325 599 351 133 90 77 45 16 4 6 1 3 0 1 365 143 106 105 66 47 27 28 14 57 2 3 4 5 6 7 8 9 >10.. 1 Only muscles with observations on both voluntary movement and response to direct nerve stimulation are included.
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From page 224... ...
Total 392 0 3 0 3 22 19 51 38 50 35 171 147 15 18 15 22 30 16 13 11 6 1 0 539 15 21 15 25 52 35 64 49 56 36 171 39 4 2 0 0 2 7 11 7 4 2 0 1,642 742 435 165 112 95 56 20 5 7 1 4 1,681 746 437 165 112 97 63 31 12 11 3 4 431 4 1,789 757 453 180 134 125 72 33 16 13 2 4 2,220 761 458 180 137 149 98 95 61 67 39 175 0 1 5 0 3 24 26 62 45 54 37 171 2 3 4 5 6 7 8 9 £10 1 Only muscles with observations on both voluntary movement and response to direct nerve stimulation are included. Distributions of chronaxie values shown in table 121 have been inflated to those shown here by multiplying individual frequencies by the ratio of the total on the first line of that table to the number tested, shown on the third line.
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From page 225... ...
When various cuts were tried on the New York data it was found that the regions 0 to 5 and 6 or more produced the best agreement with both voluntary contraction and response Figure 19. Cumulative Percentage Distributions of Chronaxie Values by Response to Direct Nerve Stimulation and to Voluntary Stimulation, New York Data on All Muscles.
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From page 226... ...
More complex criteria might be evolved than these, as by paying attention not merely to the total number of disagreements but also to their nature, but as may be seen from table 123 it would appear Table 123. -- Estimated Distribution of Affected Muscles by Voluntary Contraction, Response to Nerve Stimulation and Chronaxie Group, New York Data l Chronaxie group, msec. Response to direct nerve stimulation None Any Total A
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From page 227... ...
b. Muscles unable to contract voluntarily, but responding to direct nerve stimulation, have no chronaxies in the region of 10 or more msec., but are much less concentrated in the 0 to 3 msec.
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From page 228... ...
It also seems clear that the great majority of muscles unable to move voluntarily, but responding to nerve stimulation, had been reinnervated; failure to move voluntarily must be attributed to psychological factors in the areas of motivation and learning. The few muscles with voluntary movement and no response to nerve stimulation present no clear-cut picture; certainly they do not look like other muscles able to move voluntarily in that their chronaxies are higher.
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From page 229... ...
Without further analysis it is plain that the Philadelphia chronaxie determinations are much less certainly discriminating than those of the New York center. Table 125 presents adjusted data for the Philadelphia center, based on table 124, the adjustment being the same as that performed on the New York data with one exception: account has been taken of the fact that examiners in the Philadelphia center selected muscles for direct nerve stimulation with some regard for their response to voluntary stimulation.
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From page 230... ...
. 4 2 2 5 6 5 7 8 13 9 22 13 9 >10 25 13 38 5 30 1 Only muscles with observations on both voluntary movement and response to direct nerve stimulation are included.
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From page 231... ...
The chief lesson of the analysis is the same for both centers, namely that the best estimate which can be made from the data on all three tests is about what may be obtained from the joint observations on voluntary Table 125. -- Voluntary Movement, Response to Direct Nerve Stimulation, and Estimated Distribution of Chronaxie Values, for All Affected Muscles Following Complete Sutures on All Seven Major Nerves, Philadelphia Datal None Voluntary movement Any Total Chronaxie, msec. Contraction following nerve stimulation Contraction following nerve stimulation Contraction following nerve srimulation None (1)
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From page 232... ...
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From page 233... ...
In the New York center about 21 percent of the muscles examined by means of voluntary and direct nerve stimulation were also studied by means of electromyography, and in the Philadelphia center about 19 percent. In both centers there was a marked tendency to avoid electromyographic study of muscles unable to contract voluntarily or on direct nerve stimulation, as may be seen in table 127, which pertains to muscles affected by complete suture and on which both voluntary and direct nerve stimulation was performed.
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From page 234... ...
0 Table 128. -- Electromyographic Interpretations and Response to Direct Nerve Stimulation for Muscles With No Voluntary Movement, New York Data Electromyographic interpretation Response to direct nerve stimulation None Contraction Total At most fibrillation 13 1 14 Motor unit potentials 4 15 19 Total 17 16 33 The analysis of electromyographic data from the New York center was carried one step farther by introducing chronaxie as a fourth variable. It is unfortunate that the data are so few (table 129)
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From page 235... ...
One of these 4 was interpreted as "few motor unit potentials with voluntary effort" and 3 as "spontaneous fibrillation potentials plus some motor unit potentials, and no complex or other potentials." Since potentials of the latter variety were noted in only about 8 percent of the 284 with motor potentials and movement on both voluntary and direct nerve stimulation, these 3 cases are not typical of those with motor unit potentials and they will hardly serve to challenge the testimony of the other 2 electrical tests. Table 129. -- Electromyographic Interpretations in Relation to Voluntary Stimulation, Direct Nerve Stimulation, and Chronaxie, New York Data Contraction Chronaxie 0 to 5 msec.
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From page 236... ...
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From page 237... ...
to Cv!
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From page 238... ...
provided there be at least 25 such cases, i. e., Median -- abductor pollicis brevis Ulnar -- 1 st dorsal interosseus Peroneal -- extensor hallucis longus Sciatic-peroneal -- extensor hallucis longus Sciatic-tibial -- flexor hallucis longus These muscles are clearly not homogeneous as to the proportion, among all incapable of voluntary movement, which contract on direct nerve stimulation: the median and ulnar muscles more often contract on electrical srimulation.
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From page 239... ...
The muscles chosen to represent the upper extremity (abductor pollicis brevis and 1st dorsal interosseus) are, of course, distal muscles while those chosen to represent the lower extremity in the first comparison (a)
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From page 240... ...
The foregoing comparison provides a test of the hypothesis that the proportion of muscles able to contract on direct nerve stimulation, among muscles unable to contract voluntarily, is constant from nerve to nerve, muscle to muscle. Perhaps an even more meaningful hypothesis to test is that the proportion of muscles unable to contract voluntarily, among all those innervated, is constant from muscle to muscle and nerve to nerve.
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