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Chapter HI RECOVERY OF MOTOR FUNCTION Melvin D. Yahr and Gilbert W. Beebe A. INTRODUCTION Of all the functions subserved by the peripheral nerves, that of movement is perhaps the most strategic to adequate performance by the affected limb, and is certainly the most susceptible of reliable assessment. Although practical function involves a great deal more than the strength of discrete movements, the latter provide an excellent approach to the investigation of the basic sources of variation in the regeneration of peripheral nerves. Only from such knowledge can the surgeon hope to plan effectively for the care of the individual patient with an injury to a peripheral nerve, whether it be an injury of war or the result of an ordinary accident. The surgeon needs to know what results to expect from his efforts at repair, and from his decisions not to resect and suture, and to know this not only in terms of the probability that a particular result will fall at one point or another on some scale of relative excellence but also in terms of those characteristics of injury and alternatives in management which tend to determine end result. Strength of movement constitutes a valuable statistical device for describing variation and for ferreting out factors which play a significant part in it, and it is appropriate, therefore, that the motor chapter contain a systematic study of the factors associated with variation in regeneration. There are, of course, other interests in regeneration but in the main these require more specialized study than seems feasible on the basis of the clinical records of military hospitals and the follow-up studies provided by a large cooperative investigation. The theoretical basis for understanding peripheral nerve regeneration is naturally of great concern to the surgeon, but it is too much to expect that his clinical observations on regeneration will contribute more than indirectly to the advancement of such theoretical knowledge. In the plan of the chapter there is first a methodological part in which are described the various methods used in the assessment of motor regenera- tion. There follows an essentially descriptive treatment of the statistical data on motor recovery in representative samples of peripheral nerve injuries treated by suture or by lysis. The two remaining parts of the chapter are rather more analytical in nature, being directed at some of the factors which have been thought to influence regeneration, factors which 71

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are of such nature as to be identifiable in clinical material, e. g., length of surgical gap, and type of suture material. Since adequate reinnervation is but one determinant of satisfactory muscular movement, complete absence of movement is compatible with alternative explanations of very different implications for regeneration. Parallel electrical studies are of value in determining when absence of movement probably connotes failure of regeneration and when other factors are involved. Electrical data constitute the subject of a subsequent chapter which includes an analysis of the relation between voluntary movement and that induced by electrical stimulation. B. METHODS OF EVALUATING MOTOR FUNCTION Most of the skilled acts which are affected by peripheral nerve injury depend upon the coordinated movement of sets of muscles innervated by more than one peripheral nerve. In order to assess the regeneration of a particular peripheral nerve it is imperative that the examiner isolate the movements of those muscles which were affected by the injury. The basic motor examination, in turn, consists of evaluating the movements of such individual muscles as act alone, or of groups of cooperating muscles innervated by a single nerve. In the analysis of such motor function one may pass in review the ratings on each muscle or seek some method of combining the information about the entire set of affected muscles. Al- though both methods have been followed in the present study, chief atten- tion has been accorded to the individual muscle; methods of describing the set of affected muscles, e. g., by averaging, have seemed essentially arbitrary in principle and without any real advantage except the convenience of a smaller bulk of data. Examiners differ as to their willingness to infer the power of a specific muscle from the strength of a certain movement, and the choice of muscles for routine testing in the present study represents some compromise among the responsible investigators. An initial list of movements was agreed upon at the Hot Springs meeting discussed earlier, but as the examination forms and coding sheets were developed a number of changes seemed necessary and the final list appears in table 48. The abductor pollicis brevis was not originally accepted as a standard muscle for purposes of testing, but in two centers this muscle was routinely examined and it appears in the final analysis of individual muscles. The muscles marked for intensive study represent a further selection on the basis of representativeness, ease of examination, and accuracy of assessment. At the time of the Hot Springs meeting it was proposed that the observa- tions on each muscle extend to a tracing of the motion as a curve in space as well as to the measurement of its strength. Each aspect of the motion would then be expressed quantitatively, as a fraction of the normal, and the product of these two fractions would be taken as the final measure of performance for the individual muscle. In the end, however, agreement was reached on a much simpler plan in which attention was confined to n

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Table 48.—Standard Muscles Chosen JOT Routine Follow-up Study, by Nerve and by Proximal or Distal Location Nerve Muscle Proximal Distal Median Flexor Carpi Radial is Flexor Pollicis Longus.1 Flexor Digitorum Profundus 2.' Abductor Pollicis Brevis.1 Ulnar Flexor Carpi Ulnaris. Abductor Digiti Quinti 1 Flexor Digitorum Profundus 4 and 5.' Adductor Pollicis. 1st Dorsal Interosseus.1 Radial Triceps. Bracbioradialis. Extensor Carpi Radialis.1 Extensor Digitorum Communis.1 Extensor Carpi Ulnaris. Extensor Pollicis Longus.1 Extensor Pollicis Brevis. Tibial and Sciatic- Gastrocnemius-Soleus.1 Tibialis Posticus. Flexor Digitorum Longus.1 Flexor Hallucis Longus.1 Interossei (any intrinsic muscle). tibial. Peroneal and Sciatic- peroneal. Tibialis Anticus.1 Extensor Digitorum Longug.1 Extensor Hallucis Longus.1 Peroneus Longus.1 1 Muscles chosen for most intensive analysis; the abductor pollicis brevis did not appear in the original standard list and does not figure in either the count of affected muscles now contracting or in the average power of distal muscles. strength of movement. For each affected muscle the examiner was re- quired first to observe voluntary movement visually, and second, if move- ment against resistance was possible, to estimate its strength in quantitative terms, using the spring-scale technique of Lewey (41) or the Newman Myometer (57). The visual observations were classified in accordance with the following scheme: 1. No voluntary contraction is perceptible. 2. Perceptible contraction only. 3. Movement, but not against gravity. 4. Movement against gravity, but not against resistance. 5. Movement against resistance. This classification, it may be noted, is essentially that used by the British Medical Research Council (70) except that in the latter classification movement against resistance is subdivided into "some" and "powerful" resistance. In the present study the power of muscles capable of movement 403930—57- 73

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against resistance was scaled in a roughly quantitative fashion, as already indicated, the normal homologous muscle serving as the control. It was thus possible to express strength of movement as a percentage of normal; the muscle unable to move against resistance is rated 0 on this quantitative scale, even if it be capable of movement against gravity. Although a 100-point scale was employed by examiners in making the quantitative ratings, when the resulting data were first tabulated it was found that the ratings centered on multiples of 5 and the scale was accordingly reduced to 20-odd intervals: 00, 01 to 02, 03 to 07, etc. There are certain inherent limitations in the method of examination adopted for the present study. The examiner must be quite expert if he is to guard against substitution and trick movements and he must be well aware of the problem of anomalous innervation. The patient must be a cooperative individual who, through muscle retraining, is capable of volun- tarily activating the muscle. Every examiner has seen patients with good muscle mass and evidence of nerve regeneration, but who have not relearned use of the muscle. This is especially true in the hand where long flexors and extensors are substituted for the small intrinsic muscles of the hand. Not infrequently is the extensor digitorum substituted for the abductor digiti quinti as an abductor of the fifth digit when evidence of regeneration is cited for this muscle. The patient without retraining in the use of the latter muscle continues to substitute the movement acquired during the phase of denervation. In addition, many patients are unable to initiate an isolated movement of a muscle, such as abduction of the fifth digit utilizing the abductor digiti quinti as a prime mover, but will utilize this muscle with good power in association with other muscles when making a fist. During examination, an interval of instruction may enable a patient to contract a muscle against resistance which earlier he was unable to move at all. There are three main factors to be considered in motor recovery following peripheral nerve injury: (1) growth of nerve fibers in both length and diameter; (2) preservation of muscle mass; and (3) retraining in the use of previously denervated muscles. The longer the period of denervation the greater will be the attendant atrophy in affected muscles, and the poorer the level of physical therapy directed at muscle reeducation the more often will voluntary activation fail even in the presence of adequate reinnervation and minimal muscular atrophy. In the upper extremity, where dexterity of movement is a major goal of treatment, physical therapy is characteristically intensive. In the lower extremity weight-bearing and gross movement are the objectives and are early accomplished by the use of a brace or other supporting device. The natural consequence is a less intensive program of muscle reeducation on the part of the physical ther- apist and a lesser expenditure of effort by the patient to relearn the use of reinnervated muscles. Most patients indulge in a passive program of watchful waiting with massage and/or electrical stimulation the only ther- apeutic effort. It is not unusual to see a patient still resorting to a foot- 74

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drop brace in the presence of adequate peroneal regeneration, for example. In preparing a summary of the history for both clinical and statistical purposes, care was taken to determine precisely which muscles had been paralyzed by injury and remained so prior to such surgical intervention as was undertaken. In addition, to guard against extraneous influences on the movement of muscles the examiner was required to classify each muscle according to the following scheme: 1. Affected by injury or operation, nerve branch sacrificed. 2. Affected, working tendon transplant. 3. Affected, loss of muscle or tendon substance by direct injury. 4. Affected, with none of the above special features. Only muscles in the fourth category are studied in this chapter. Several methods have been used to combine the observations on individual muscles into various patterns representing, say, all affected muscles on a limb, or all the distal muscles. These auxiliary measures are as follows: 1. Arithmetic average of relative power of groups of affected muscles, separated into distal and proximal groups. 2. Number of affected muscles in standard list (table 48) which now contract, separated into distal and proximal groups. 3. British assessment of motor recovery, an adaptation of the scale used by the Nerve Injuries Committee of the Medical Research Council of Great Britain. In the first two indices each affected muscle has equal weight, but a dis- tinction is made between the proximal and the distal muscles. In the British assessment consideration is given to both proximal and distal muscles and to the entire range of movement and power; it is most useful in high lesions affecting both proximal and distal muscles. The categories of the British scale as used in this study differ slightly from those most recently published (70) by the British group and are as follows: 0. No contraction. 1. Return of perceptible contraction in the proximal muscles. 2. Proximal muscles acting against gravity, no return of power in intrinsic muscles. 3. Proximal muscles acting against gravity, perceptible contraction in intrinsic muscles. 4. Return of function in both proximal and distal muscles of such an extent that all important muscles are of sufficient power to act against resistance. 5. Return of function as in category 4, with the addition that some synergic and isolated movements are possible. 6. Complete recovery. The most recent British scale subdivides category 3, providing for those cases of ulnar injury in which there is recovery in all the ulnar intrinsic muscles as distinguished from those in which there is merely a nicker of action in the hypothenar muscles alone. Also, the British group employs the assessment scale in precisely this form for upper extremity cases only, whereas in this study it has been employed for all nerves without modifi- cation. In the grading of peroneal and tibial lesions the British group rarely encountered cases other than those of category 1 above, and so sub- divided this category by averaging the ratings of the individual muscles on 75

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a scale of 0 to 5, corresponding roughly to those employed here in observing the contraction and movement of individual muscles. The presentation of a single case will suffice to illustrate the similarities and differences among the several motor indices routinely utilized in the present study. Case 2080: A radial nerve suture, lower third of the arm, with seven muscles affected, the results of the motor examination at follow-up being as follows: Brachioradialis: Movement against resistance not tested. Extensor carpi radialis: Movement against resistance, measured at 50 percent of normal. Extensor digilorum: Movement against resistance, measured at 65 percent of normal. Extensor carpi ulnaris: Movement against resistance, measured at 0 percent of normal (perceptible movement was, however, present). Abductor pollicis longus: Movement against resistance, measured at 25 percent of normal. Extensor pollicis longus: Movement against resistance, measured at 27 percent of normal. Extensor pollicis brevis: Movement against resistance, measured at 25 percent of normal. The average power ratings are as follows: Proximal muscles: 30-39 percent. Distal muscles: 20-29 percent. The numbers of affected muscles in the standard list capable of contraction, similarly, are: Proximal muscles: 4. Distal muscles: 3. The British assessment is grade 4 on the scale employed here. C. DESCRIPTION OF MOTOR RECOVERY It will be recalled, from the description of the sampling plan on pages 5-13, that the entire sample of 2,720 men studied here includes many with injuries or other characteristics of special interest, and by that token, of possibly atypical prognosis. In planning the tables for this descriptive part of the chapter, therefore, it was considered desirable to restrict the selection of cases to those in the representative sample. The analysis in chapter II (pp. 31-53), showing the differences among groups of cases drawn from the three major groups of rosters, further documents the need for this distinction which was made as follows: 1. All sutured cases were taken from the Army Peripheral Nerve Registry; and 2. Cases from the Registry were excluded if they fell outside the sampling area for the center to which they had been allocated. In addition, about 25 percent of the cases had no follow-up and for any particular muscle the number of injuries available for study depends upon the site of lesion. The descriptive data will be presented in two parts, the first pertaining to the individual muscles and the second to groups of muscles, either proximal, distal, or all combined. All data on individual muscles or groups 7*

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thereof are confined to cases in which these muscles were affected by the original injury. 1. Individual Muscles Although some average value may be the most important characteristic of the detailed distribution tabulated for each muscle, such averages provide no information about the often great individual variation seen in particular muscles. Figure 10 provides a graphic summary of the variation observed in the recovery of the abductor pollicis brevis. Relative strength of movement is scaled along the abscissa, and the height of the bars denotes the relative frequency with which muscles were observed to respond with a given strength of movement. The tallest bar, for the interval 0 to 12 percent of normal strength, is divided into three components: 19.5 percent with no contraction at all, 37.5 percent with visible contraction, but not against resistance, and 6.7 percent with movement against resistance rated at 12 percent or less of normal, or 64 percent in all. The remaining 36 percent scatter widely over the range of relative power above 12 percent. The upper line provides a cumulative distribution of the relative frequencies denoted by the vertical bars. The device of the cumulative distribution has been adopted in figure 11 to conserve space and to facilitate visual comparison of the distributions obtained for the various muscles studied here; the underlying data appear in table 49 in the same form except that a distinction is made among muscles unable to contract, those with visible contraction but not against resistance, and those contracting only weakly against resistance. Several properties of cumulative distributions generally may be noted as a guide to the interpretation of figure 11: (a) a rectangular, or flat, distribution having the same relative frequency in every region of the strength scale would appear as a straight line from the origin to the upper right corner; (b) if one cumulative distribution lies everywhere above another it is because the former distribution is more concentrated at the lower end of the strength scale; (c) the cumulative curve rises over a region only to the extent that the underlying distribution contains fre- quencies there, so that a rapid rise in a region denotes some concentration of cases there and a plateau denotes an absence of cases; and (d) a very favorable curve would start near the origin, remain fairly close to the abscissa over much of the range of relative power, and increase rapidly only in the region of normal relative power. As plotted in figure 11, each distribution shows the percentage of affected muscles rated at a specified relative strength or less, the strength being indicated by the horizontal axis. The proximal muscles, in the main, are more variable in their strength of movement and are less concentrated at the lower end of the strength scale. In none of the distributions of figure 11 is the increase a very sharp one in the range of 90 to 100 percent of normal, and in most instances there is little or no increase at all in this region because very few muscles were observed to have normal power 5 years after suture. For only 5 of the 23 muscles do more than 5 percent of the measurements of strength fall in the 77

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region of 90 to 100 percent of normal: flexor pollicis longus, flexor digi- torum profundus 2, flexor digitorum profundus 4 and 5, extensor carpi radialis, and gastrocnemius and soleus. These are the most proximal muscles in their respective sets, but not every set is represented because in this series the tibialis anticus, representing peroneal and sciatic-peroneal muscles, does not recover normal power with even this small frequency. At the other end of the scale one finds that the distributions for the most distal muscles in each set usually start with 50 percent or more rated 0 in power, indicating that in 50 percent or more of the cases there is inability to move the muscle against resistance. In the muscles innervated by the peroneal and sciatic-peroneal, however, failure to move against resistance is found in over half the cases for every one of the four muscles charted in figure 11. Although the interest here is in the individual muscle, some comparison among muscles is helpful in understanding the variation in results which may be expected following suture. In the median set, for example, the flexor pollicis longus and the flexor digitorum profundus 2 have almost identical distributions, while that for the abductor pollicis brevis is much less favor- able. The disparity, it may be noted, is not simply confined to the propor- tion of cases in which movement against resistance was possible, but extends to the measured strength of those cases in which such movement was seen. Thus, it was observed that for muscles with movement against resistance, power was 80 percent or better in about 22 percent of the flexor pollicis longus muscles and in only 2 percent of the abductor pollicis brevis muscles. Another noteworthy feature of the distributions exhibited in figure 11 for sutured lesions is that they rarely climb steeply, as such curves do when cases are concentrated at a particular point along the horizontal axis, but usually rise gently and somewhat after the fashion of a rectangular distri- bution, which follows a straight line when plotted in cumulative form. That is, examiners failed to note any real concentration of cases at any point except 0 on the power scale; if movement was made against resist- ance, its measured power might fall anywhere along the scale with almost equal probability. The average power for all the sutured lesions affecting a given muscle is shown in table 50 in systematic form. All the standard muscles are rep- resented, not merely the 23 chosen for most intensive study. Average power is expressed in two forms: (a) all examined cases are included, a 0 rating being assigned to those in which there was no voluntary movement against resistance; and (b) the average pertains only to those in which there was voluntary movement against resistance. The averages are arith- meticaverages, and for descriptive purposes one might in some instances prefera median average value as somehow more representative, particu- larly in the face of a concentration of cases at 0. However, the mean or arithmetic average is an easier statistic to work with in many ways and has been used routinely in this study. Approximate medians may be read off figure 11 as the point on the horizontal axis at which the cumulative dis- 7*

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Figure 10. Strength of Movement of the Abductor Pollicis Brevis Following Com- plete Suture of Median Nerve, Strength of Movement Against Resistance, as Percentage of Normal PERCENTAGE 20 40 6O 80 STREH8TH OF MOVEMENT ABAIN3T RESISTANCE: PERCENTAGE OF NORMAL - 50 - 40 - 30 - 20 - 10 100 79

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Such special operative features as transposition and extensive mobiliza- tion have no demonstrably adverse influence upon motor recovery. Al- though lesions first treated by bulb suture recover less well than others, when differences in length of gap are taken into account it is plain that therein lies the source of the disadvantage; otherwise lesions treated by bulb suture do as well or as poorly as others. The operator's report on the gross appearance of nerve ends prior to anastomosis correlated to some extent with that of the neuropathologist and is weakly associated with eventual motor recovery. The operator's report of tension, in contrast, is of no obvious prognostic value. World War II saw extensive use of tantalum sutures, but the present series makes it plain that such sutures were followed by the same recovery as those done by silk. A special series of plasma glue sutures was also studied and after suitable allowances for differences in the selection of the cases their motor recovery at followup proved to be indistinguishable from those done by silk or tantalum. Sutured lesions on which cuffs were used seemed to recover more com- pletely than those on which the foil was not used, but perhaps only because the initial selection of cases favored those on which tantalum foil was used. The use of stay sutures seemed to exert no particular influence upon the eventual level of motor recovery. Neurolyses were done in several ways, but no evidence was found that internal and external neurolyses differed in their effect on recovery. No demonstrable effect may be attributed to the training of the operator performing the definitive suture. In most general terms, the analysis serves to identify those aspects of management which do, and those which do not, appear to exert a significant influence upon motor recovery. Of all the characteristics studied, time from injury to suture exerts the greatest influence, and yet this factor alone does not explain much of the great variation seen in the final level of recovery. Moreover, some of the apparent influence of other treatment factors is associated with that of time, so that any overall measure of the extent to which differences in management explain variation in final recovery would not greatly exceed that observed for time alone and would hardly be impressive in any event. In addition to the treatment variables, however, as already shown in the earlier sections of this chapter there are many characteristics of the nerve injury itself, including associated lesions of various kinds, which also have a marked bearing on motor recovery. The most important of these is the character of the lesion itself, insofar as it is reflected in the surgeon's choice between suture and lysis.

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F. COMBINED INFLUENCE OF ADVERSE FACTORS UPON MOTOR RECOVERY FOLLOWING SUTURE Although chief attention has been given to the influence of individual variables affecting motor recovery, there is considerable interest in com- bining this information for use in prognosis. How good will recovery be if no unfavorable factors intervene? What is the total impact of several unfavorable factors? Such questions may be approached in a variety of ways; only the simplest has been used here. At the outset a set of factors was chosen on the basis of apparent influence upon recovery when studied individually. Sutured lesions were then classified according to presence or absence of these factors taken in all possible combinations. The recovery of each subgroup, and of patterns of subgroups, could then be studied. Of course, such subdivision dissipates the material into often quite small sub- groups, and there is need to combine these in some way. The simplest, but least exact, procedure is to group together lesions with the same number of prejudicial factors, regardless of what they might be. The latter tech- nique has been followed here, except that delay in definitive suture has been scaled as either 1 or 2 units of the score, depending on whether the suture was done in the interval 90-269 days after injury or 270 or more. Only the median and ulnar nerves have been studied in the fashion out- lined above, with a separation into high and low lesions, and with recovery based on the relative power of the following muscles: Median muscles Ulnar muscles flexor pollicis longus flexor digitorum prof. 4 & 5 flexor digitorum profundus 2 abductor digiti quinti abductor pollicis brevis first dorsal interosseus Perhaps the most important conclusion which emerges from such an analysis is that even lesions characterized by none of the prejudicial factors listed above do not have very high recovery ratios if strength is used as the criterion. Table 111 gives both indices of recovery for these cases, which are, of course, unfortunately few in number. In addition, the material on one muscle is not independent of that on another innervated by the same nerve. Nevertheless, it seems clear that absence of the selected prejudicial factors will not characteristically insure a return to anything approaching normal strength of movement. Failure to contract at least perceptibly, of course, is rare in this small, selected series, but the mean power of muscles contracting against resistance seems about average, according to the values of table 51 (p. 91). Once the median cases are subdivided in the fashion described, there are only a few groups containing as many as 10 lesions, and for none of these is the mean power (of all examined muscles, whether contracting or not) remarkably out of line. However, for both high and low lesions there are small groups which suggest that recovery of the most distal muscles may be especially susceptible to the influence of the several variables selected. For example, the average power of the abductor pollicis brevis was found earlier 198

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Table 111.—Percentage of Affected Muscles Contracting and Mean Power of Muscles Contracting Against Resistance, Median and Ulnar Lesions Treated by Complete Suture With No Prejudicial Factors, by Gross Site High Low Power of muscles contracting against resistance Power of muscles contracting against resistance Muscle Perceptible contraction Perceptible contraction N ' Percent NI Mean NI Percent NI Mean Median Fl. poll. long 5 100 2 52 3 100 2 48 Fl. dig. prof. 2. . . 8 100 5 33 4 100 3 53 Abd.poU.brev... 7 100 3 47 10 100 4 26 Ulnar FLdig. prof. 4&5 Abd. dig. V 24 24 100 88 11 5 43 23 12 20 100 10 11 58 23 95 1st. dors. inteross. 19 95 5 31 16 88 6 17 1 N represents the number of cases upon which the percentage or the mean is based. to be 12 percent of normal for high lesions and 15 percent for low lesions. Among the high lesions there is one group of 18 cases with moderate delay in repair plus an associated nerve injury, for which the average power is only 5 percent. There is another group of 20 high lesions with these same prejudicial characteristics plus arterial injuries, for which mean power is 6 percent. Finally, there is a group of 11 low lesions with long delay plus associated bone injury for which mean power is 10, in comparison with the overall average of 15. Since the groups are so small, some grouping is necessary to any analysis, and in table 112 are given summary figures for median lesions grouped according to the score obtained by counting the number of prejudicial factors, except that a long delay adds two units. There may be many different ways of reaching the same score, but inspec- tion of the data does not suggest that combining cases on this basis is unwise. In each of the comparisons of table 112 the group with the highest score appears in an unfavorable light, but only for the abductor pollicis brevis is the relationship an impressive one. Here the lesions with the largest num- ber of prejudicial factors have means of only 15 to 20 percent of those computed for the lesions with the smallest number of such factors. 199

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For the ulnar nerve variation in recovery does not follow the scoring ex- cept for the first dorsal interosseus, for which the data are much like those for the abductor pollicis brevis. Table 113 contains the mean values arranged as in table 112. Table 112.—Mean Relative Power of Affected Muscles Following Complete Suture, Median Lesions by Site and Score on Presence of Prejudicial Factors Muscle Score Fl. poll. long. FL prof. ind. 2 Abd. poll. brev. N i Mean "« Mean N' Mean High lesions 1-2 20 26 29 22 19 26 3 36 35 53 25 36 12 4 29 26 44 21 26 4 5-7 12 15 18 8 14 5 Total 97 28 144 21 95 12 Low lesions 0-1 12 56 26 19 0-2 22 55 2 20 61 25 22 3-7 20 22 26 37 3 31 10 4-7 17 3 Total 42 40 58 50 99 14 1 N represents the number of cases upon which the mean is based. 200

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Table 113.—Mean Relative Power of Affected Muscles Following Complete Suture, Ulnar Lesions by Site and Score on Presence of Prejudicial Factors Score Muscle Fl. dig. prof. 4 & 5 Abd. dig. 5 1st dors. inteross. N' Mean N' Mean N' Mean High lesions 1 18 26 22 5 15 10 2 46 28 51 5 41 12 3 98 37 109 10 77 9 4 63 23 71 5 53 6 5-7 28 26 35 4 27 1 Total 253 30 288 7 213 8 Low lesions o 12 48 20 12 16 6 1 24 41 55 14 43 17 2 43 44 98 15 69 15 3 59 7 42 10 3-6 30 27 4-6 24 11 21 5 Total 109 39 256 13 191 12 1 N represents the number of cases upon which the mean is based. 403980—B7- -15 201

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