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Chapter XII NEUROSURGICAL IMPLICATIONS Barnes Woodhall, Frank E. Nulsen, James C. White, and Loyal Davis A. INTRODUCTION A great mass of pertinent data has been presented in the body of this study of peripheral nerve regeneration. It is now necessary to attempt an interpretation of these data in terms of practical surgical management. A firm realization exists that the concept of treatment by hospital echelon, so clearly seen in World War II, has now become largely obsolete, or at least modified to a great extent by more rapid evacuation of patients. No possible fresh approach to this subject, however, can alter the lessons of the past. These have shown in a most convincing fashion that: (1) no ex- pectant attitude in the treatment of peripheral nerve injury can be main- tained unless supported by objective and accurate longitudinal observations; (2) there exists a demonstrable relationship between time of iajury and onset of appropriate therapy on the one hand and the extent of nerve regeneration on the other; and (3) men with peripheral nerve injuries can be rehabilitated adequately only through the means of specialized neuro- surgical treatment. In the absence of some fundamental contribution to the control of the reaction of connective tissue to injury, which constitutes the essential barrier to peripheral nerve regeneration, the following analysis of management of war injuries to peripheral nerves can be considered as valid as can be fashioned from the observed facts. B. MANAGEMENT IN FORWARD AREAS 1. Recognition of Peripheral Nerve Involvement The surgical task in a forward area is not conducive to the recognition and early management of peripheral nerve injury and rightly so. Here the primary surgical design has to do with the preservation of life, and this demand upon the surgeon is often a great one (14). When possible, how- ever, the forward surgeon should look upon himself as the first agent in a potential series of surgical enterprises and, in this function, seek evidence of peripheral nerve injury in all extremity wounds. Simple tests are avail- able for the recognition of nerve involvement for both upper and lower extremity, even if the limb be immobilized in a cast. The testing pro- cedures may be listed as follows for the major peripheral nerves. 569

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Ulnar nerve. Loss of sensitivity to painful stimuli over the distal phalanx of the little or fifth finger. Median nerve. Loss of sensitivity to painful stimuli over the distal phalanx of the index or second finger. Radial nerve. Loss of ability to extend the wrist (wrist-drop), inability to extend the thumb and abduct the thumb in the "thumbs up" position. Sensory loss is variable. Wrist and lower forearm wounds may involve tendons directly and make such testing invalid. Brachial plexus. Recognized by the position of the wound and the in- volvement of component nerves of the upper extremity. Peroneal nerve. Inability to dorsiflex the ankle and the big toe (foot-drop). The sensory loss is inconstant. Tibial nerve. Loss of plantar flexion of ankle and big toe. Sensory loss over the sole of the foot is constant and may be the only indication of tibial involvement in wounds below the middle third of the calf. Sciatic nerve. The high location of the wound with either peroneal or tibial or combined nerve involvement. Characteristic hand postures may be observed immediately after wound- ing but they are not as well defined as they may be when muscle atrophy and shortening have occurred. 2. Immediate or Emergency Treatment of Peripheral Nerve Wounds These data have shown that 92 percent of the nerve injuries whose re- generation has been studied were caused by battle wounds. The remainder were due to accidental or civilian type injuries. In battle wounds caused by high velocity missiles, immediate or emergency peripheral nerve sur- gery is contraindicated, with but a single exception. This exception is found in the rare case of an expanding hematoma, the precursor of a false aneurysm, with progressive peripheral nerve dysfunction caused by pressure. These data have shown conclusively that, even in the best hands, the emergency suture of war wounds of peripheral nerves is followed by a failure to regenerate in over 50 percent of cases. If the nerve injury is visible without further nerve dissection at the time of wound debridement, its appearance should be described as accu- rately as possible in terms of complete nerve division, of partial nerve division with an estimate of the cross section involved or of continuity of nerve segments. Even if the examinations noted have indicated the presence of a major nerve segment injury, undue exploration for the lesion at the time of debridement is contraindicated and it is likewise not indicated at the time of secondary wound closure. In cases of complete nerve divi- sion, approximation or coaptation sutures may prevent some retraction of divided nerve ends. This is usually not an important issue since so much nerve tissue is customarily lost in war wounds. If such a suture is used, care must be taken not to damage normal nerve trunk and it is mandatory 570

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that the word "suture" be not loosely used in the medical record without its qualifying terms. Packs in contact with peripheral nerve tissue may be harmful. Of primary importance in the initial time period following injury are: (1) identification and recording of the clinical characteristics of the nerve injury; and (2) description of the findings at debridement if the injured nerve is visualized. 3. Early Splinting of Paralyzed Muscles Continuous splinting should never be carried out as a form of treatment of a peripheral nerve injury. Such splinting or casting is indicated only by fracture or extensive soft tissue wounds near working joint surfaces. When continuously splinted, nerve injuries will show severe joint fixation, particularly of wrist, finger, and thumb articulations. When such casting must be done, the distal half of the hand and fingers should be left free. Intermittent splinting of peripheral nerve injury is indicated in two specific injuries. The first is the complete wrist-drop of radial nerve paralysis which should be supported by a light cast, splint, or brace which holds only the wrist in dorsiflexion. The patient will feel more comfortable and will use the fingers and thumb for useful function with such support. Support of the proximal phalanges may lead to ankylosis of the metacarpophalangeal joints in partial extension, a severe and often permanent disability. Pa- tients will discard more elaborate braces because of their inability to use the hand for grasping. The end results of regeneration have been good in patients with only the wrist supported. The wrist-drop support should be worn at night but removed intermittently during the day and a full range of wrist movement carried out passively by the patient. The second spe- cific injury requiring intermittent splinting is one involving the sciatic nerve or the peroneal nerve with foot-drop, for which the foot should be splinted in a position of dorsiflexion. The posterior splint should be light so that the patient may be ambulatory with crutches, until such time as he can bear weight and use the ordinary spring brace. The splint must be removed intermittently during the day, both to permit full passive ankle movement and to check for early signs of pressure sores on the heel or sole. Such pressure lesions may develop with posterior tibial nerve involvement alone. Ischemic paralysis of the median nerve with a tight cast, for instance, and peroneal nerve palsy from local cast pressure are common sequelae of poorly designed or unwatched continuous casting. The corollary to the proper early splinting of nerve injuries is the contin- uous effort directed toward mobilization of joints by physiotherapy, whether by the physiotherapist or, of greater importance, by the patient himself. C. EVALUATION AND DEFINITIVE MANAGEMENT 1. Introduction As already pointed out, evidence gathered from personnel of the auxiliary surgical teams of World War II or the MASH units of the Korean campaign 371

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suggests that the forward surgeon cannot be oriented in detail to the problem of peripheral nerve injury. This statement is not to be construed as a measure of their reluctance to be so oriented. It seems clear that, unless survival of an extremity is threatened, the actual demands of neck, chest, and abdomi- nal wounds upon their time and energies are very pressing. Even the simple tests that have been outlined are usually omitted and the demonstration of nerve disruption at the time of debridement is, of course, purely fortuitous. Such inevitable circumstances emphasize sharply the need for the study and exact recording of neurological changes in the wounded extremity when the casualty reaches a fixed installation. Here, for the first time, in the presence of complete clinical paralysis, the surgeon encounters the task of answering the fundamental question, whether this apparent complete nerve paralysis will go on to spontaneous resolution or some degree of return of function better than that which can be gained by suture, or whether an incapaci- tating paralysis will continue as a result of actual nerve segment disruption. No conservative or expectant attitude can be tolerated toward the return of peripheral nerve function in war injuries, unless main- tained by objective evidence studied in terms of time after injury. Only a laborious dissection of the factors that have been presented in preceding chapters can even approximate an answer to this issue. The statistical evidence concerned with the number of complete anatom- ical disruptions of nerve tissue as a result of war injury as compared to par- tial injury or axonal injury with their better prognosis is conflicting. This conflict is in all probability dependent upon the variable pathological forms, perhaps unequally recognized, and upon when after injury the observations were noted. Perhaps the most succinct statement in this regard has been made by Seddon (68), a statement particularly appealing to surgeons who tend to judge an issue in "black and white"terms, since they must inevitably func- tion in such terms. "A more difficult question is what to do in the case where a degenerative lesion is present and where the anatomical state of the nerve has not been disclosed during treatment of the wound. Are we justified, as in the case of nerve injuries due to closed fractures, in waiting in the hope that spon- taneous recovery will occur?" and "One of the most curious inconsistencies in the whole story of the surgery of peripheral nerve injuries is that it has been generally accepted that primary suture is the ideal form of nerve repair. It has, at the same time, been widely held that in dealing with nerve injuries due to war wounds repair of the nerve is not a matter of urgency, and that in a good proportion of cases an expectant attitude may properly be adopted. If, as we all agree, primary suture is the theoretical ideal, then it follows that in cases requiring secondary suture repair should be undertaken at the earliest convenient time." Such a policy demands an exploratory operation of every case of complete paralysis due to an open or gunshot wound in which the anatomical status of the nerve segment is not known. What evidence is available in terms 571

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of gross tissue injury to indicate that such an exploration is indicated? The Oxford group, in support of this thesis, found complete or virtually complete loss of nerve segment continuity in 50 percent of their cases. Spurling and Woodhall (75) studied operative findings in 2,873 cases of complete paralysis and found nerve segment division in 54 percent of cases; the remainder represented neuromas or nerve contusions in contin- uity. The observations made were recorded at an average time period of 39 days after wounding. Studying the same matter under somewhat similar circumstances in a specialized center, Foerster (24) found complete nerve division in 44 percent of his cases. "Thus it may be argued," states Seddon, "as the Americans and the writer have done, that with an equal chance of finding a divided nerve the surgeon is justified in subjecting his patient to an operation which may be unnecessary." There is considerable evidence to the contrary and this evidence needs careful scrutiny since it is well documented. Sunderland (77), studying 339 cases of nerve injury rather carefully segregated in purely Australian hands, found that 68 percent of these cases recovered spontaneously, and the statement is made that this regeneration was better than that to be expected from suture. Sunderland's roster was apparently under recorded contact from the time of wounding and included both partial and complete nerve paralyses and also included some types of accidental wounding. Sunderland states that these findings are supported by Foerster, and by Tinel and Benisty. Tinel (79) stated "* * * according to our personal statistics, we may estimate at between 60 and 70 percent, approximately, the number of spontaneous regenerations without surgical intervention; at the same time, there are a certain number of these, between 10 and 20 percent, which in our opinion would have gained by such an intervention." Livingston (44) studied 132 patients in World War II at a time period of 3 months postinjury. Their records were uniformly well documented, they had been injured by high velocity missiles, and they had been operated upon by trained per- sonnel as elective procedures. Of these 132 patients, 3 had irreparable injuries, 20 proved to have complete nerve division at operation, and 4 partially divided nerves that required suture. The remainder, roughly 80 percent, appeared at this very early time period at least to be recovering spontaneously. Strange as it may seem, definitive information on the incidence of peripheral nerve injury in World War II is lacking. Men are injured in myriad ways, and injuries to specific structures are also extremely variable. Unfortunately, the extent of injury to a peripheral nerve cannot be determined by gross inspection unless it be divided; nor can one reliably infer the extent of injury from the functional deficit. Sampling is con- ducted in various ways, ordinarily in more or less close association with therapy, and bias easily enters. To obtain a representative sample of peripheral nerve injuries, one must start with a sample of all WIA involving the extremities. If one samples at any point along the echelons of treatment one will encounter more or less opportunity for distortion. Depending on 573

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how the sampling is done, disagreements will inevitably arise. On the basis of accredited sampling, there were 30,000 to 40,000 nerve injuries; at least 17 percent were treated by suture or graft and possibly as many as 26 percent (4). These varied and good expressions would indicate that the observed degrees of tissue injury are predicated upon the time at which the observa- tions are made after the inflicting trauma, the availability of longitudinal data, and the ability to recognize total or subtotal injury at the time of operation. There must be a substantial percentage of nerve injuries that are incomplete in terms of functional loss if seen shortly after the shock of injury. These present a problem of longitudinal observation that is in turn a weighing of the degree of spontaneous regeneration against what may be obtained, for instance, by resection and suture. Of more immediate concern is the adequate recognition of complete versus incomplete nerve paralysis, without regard to its pathological source, since among these cases will be found some percentage, as noted in the observations above, that may require operative intervention. They may be recognized by the following techniques of study. The same techniques are applicable to the complete, the incomplete, or the regenerating nerve injury. There appear to be two prerequisites for the proper diagnosis and treat- ment of peripheral nerve injury. These may be combined in the statement "careful repeated examinations carried out in a standardized fashion." In this way, data collected over any period of time by various observers may be readily and effectively compared. An outline of examination includes history taking, operative observations, pathological records, and tests of motor, sensory, autonomic and electrical properties of nerves and muscles which reduce descriptions to a minimum and convert results into numbers as far as possible. When such examinations must be formulated for practical use, their exposition should be restricted to a single page. Workable examination sheets may be constructed as follows: Form 1—History. The nerve casualty may now be considered placed at a more permanent installation than the MASH unit or any other forward resuscitation facility. This is the time for recording certain simple and basic data having to do with the date and time of injury and causative agent, the location of the wound, the immediate subjective responses of the patient to trauma, the operative procedures and observations of the forward surgeon, and the subsequent course of the patient prior to this first formal review of the alleged nerve injury. Form 2—Examination—Motor. Any examination of motor status presup- poses a knowledge of the anatomy and function of the muscles in the distri- bution of each nerve. Specifically, the examiner must know the origin and insertion of the muscle in question, its level of nerve supply, and the isolated, synergistic, and antagonistic functions it is capable of producing. Since an individual always uses a group of muscles to effectuate a functional movement, it is usually difficult to isolate any given muscle. It is also necessary to take into account the possibility that the patient can instinc- 574

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tively but falsely effect any given motor performance by substituted or trick muscle movements. Anomalous innervation, particularly of intrinsic hand muscles, must also be kept in mind. These details of examination and the usual sources of error are won and kept in mind only under the pressure of constant usage. They must be recorded and have been in such texts as these: Haymaker and Woodhall, Peripheral Nerve Injuries, Second Edition (33); British MRC War Memorandum No. 7, Aid to \the Investigation of Peripheral Nerve Injuries (51); and Kendall and Kendall, Muscles, Testing and Function (35). Such monographs are not part of the usual scene of even the base wartime installation, particularly in the presence of heavy casualty loads. Form 2, however, may be initiated with a study of certain designated muscles. A standard group of muscles has been tested repeatedly by the study centers. These include representative muscles from proximal and distal groups which by their position or by the particular motion they perform are most reliably tested. The muscles for each nerve are listed and should be written in the examination sheet for the appropriate nerve. Ulnar Nerve Flexor carpi ulnaris Flexor digitorum profundus (fourth and fifth fingers) Abductor digit! quinti First dorsal interosseous Median Nerve Flexor carpi radial is Flexor digitorum profundus (index finger) Flexor pollicis longus Abductor pollicis brevis Opponens pollicis Radial Nerve Triceps Brachioradialis Extensor carpi radialis Extensor digitorum Extensor carpi ulnaris Abductor pollicis longus Extensor pollicis longus ct brevis Sciatic Nerve Proximal—Biceps fcmoris, scmimembranosus, scmitcndinosus Distal Tibial Nerve Gastrocnemius-soleus Tibialis posticus Flexor digitorum longus Flexor hallucis longus Intrinsic foot muscle (cupping of sole of foot) Peroneal Nerve Tibialis anticus Extensor digitorum longus Extensor hallucis longus Peroneus longus

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Musculocutaneous Nerve Biceps brachii Axillary Nerve Deltoid Femoral Nerve Quadriceps femorU The choice of muscles made by the group concerned with the follow-up study is given on page 73. Further discussion of techniques of study is not necessary at this point since these matters have been covered indetail in the preceding data chapters. The purpose in hand will be served better by a survey of the problem of nerve regeneration as it was found in casualties of the Korean campaign. 2. Evaluation of Evidence For or Against Nerve Regeneration as an Indication for Resection and Suture.2" It should be clear that a real dilemma may exist in the choice of manage- ment of the early nerve lesion. If this lesion will not permit satisfactory regeneration, it is evident, from reference to the correlation between time of suture and end result, that this suture should be undertaken as early as possible. There would seem to be no arbitrary time limit—a suture at 1 month after injury does better than one at 2 months, and far better than one at 6 months where an average reduction of 30 percent in overall motor recovery may be expected. Such a reduction is clearly more critical in nerves which do badly, such as the ulnar or the peroneal, as well as in high lesions of any nerve. But regardless of individual situations, the statistics on the influence of delay can only result in a sense of urgency for every lesion, not only in order to shorten hospitalization by getting necessary treatment under way but also to achieve the best possible end results in a situation which has definite limitations. The urgency of accomplishing indicated sutures is offset by the certain limitations in regeneration which are imposed when suture is undertaken. Radical management of a nerve lesion should not be undertaken if there is any indication that a neuroma in continuity will permit greater regenera- tion than could be accomplished by its resection and suture. It must be remembered that roughly 75 percent of nerve lesions associated with initial total paralysis (in the military situation where the usual wounding agent is a high velocity missile) do not require suture and achieve an end result far better than could have been accomplished by suture. Fifty percent of this group showed no evidences of regeneration for such a long period that the nerve lesion was explored and the dissection of a contused nerve segment from surrounding scar tissue was usually referred to as neurolysis. Whether such a neurolysis constitutes a therapeutic measure which actually influences » This section is based on the Valley Forge series studied by Dr. Frank E. Nulsen, Dr. William J. Erdman, II, and Dr. Harry W. Slade. 576

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the course of regeneration or should simply be considered a nerve explora- tion to establish that resection and suture were not indicated is highly debatable. Nevertheless, it is clear that both those lesions which recover so early that no exploration is undertaken and those which are subjected to lysis for the most part develop more complete regeneration than is seen in the suture group. On the other hand, an occasional patient subjected to no more definitive treatment than lysis fails to show the level of regeneration expected of suture in this location and an occasional lesion in continuity, subjected to resec- tion, shows histologic evidence of more distal neurotization than suture can achieve. The problem is one of accomplishing all indicated sutures as early as possible but only in those cases where spontaneous regeneration will be limited. Under ideal circumstances, negative explorations should be avoided or kept at a minimum, but this is chiefly a matter of expediency since the negative exploration is an innocuous procedure which does not affect the end result. In other words, if an exploration had only a 10 percent chance of resulting in the early accomplishment of an indicated suture, it would seem justified. Postponement would seem indicated only when a short additional interval of delay might allow for evidences of regeneration that would eliminate an unnecessary operative procedure. This last consideration would justify delay of most operative procedures until 1 month after injury because of the large proportion of spontaneous recoveries that become defined within this short period of waiting. More than 30 percent of initial total paralyses from high velocity missiles will be- come resolved as situations not requiring operation as early as 1 month after injury. This is an insufficient time for regeneration of any disrupted neuroma and must be attributed to the functional recovery of intact neu- rones that have suffered axonopraxis. Such early recovery, either motor or sensory, is especially favorable for, if the nerve trunk contains some axons that did not even degenerate, a major proportion of the degenerated fibers are probably capable of spontaneous regeneration. The kind of disruption that presents a permanent block to axonal regeneration cannot exist in a nerve segment with intact axons. This month's delay for sorting-out purposes would not be indicated if divided nerve ends had actually been visualized at the time of initial injury or if the configuration of the wound was such that the nerve trunk could not possibly have escaped severance. Nor would such delay be indicated in the simple laceration where the neuro- logical deficit can be assumed to be the result of actual severance of axon rather than the possible temporary result of concussion by a missile passing close to the nerve. Whether suture is indicated will usually be settled by the gross appearance of the lesion explored at the end of 1 month, when a clean wound and flexible joints make this feasible. However, when gross anatomical continuity exists even though there is obvious damage to the nerve segment, this is not the time to elect suture. Such neuroma in continuity problems will be found in over 50 percent of those early explora- tions and only subsequent observation will determine whether spontaneous 403930—57 39 577

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regeneration is to offer a better result than can be expected from reoperation and suture. An evaluation of evidence for regeneration is therefore an important and necessary task for each nerve lesion until it defines itself as requiring no further operative procedures. In the early case sufficient evidence of regeneration is sought to preclude the necessity for operative exploration. In the neurolysed neuroma in continuity the nature of the lesion is defined, as time passes, as one which will show more or less recovery than can be provided by resection and suture. In the sutured case sufficient evidence for regeneration is compiled to remove any question that a sec- ondary suture might accomplish more. Finally, when a motor deficit can be corrected by tendon transplants or joint fusions and nerve regeneration has also a pood expectancy of correcting this motor deficit, the evaluation of regeneration must continue until it is established whether these supple- mentary procedures are or are not indicated. The following discussion on evidence for regeneration embodies a concept of examination and evaluation that must be employed at frequent intervals in every nerve injury case until the statement can be made that no further therapeutic measures are required. A knowledge of the final end result in each case is also of importance but has nothing- to do with the concept that hospitalization should be continued only until it is clear that, regardless of possible variations in the end result, further definitive procedures will not be employed. The following discussion therefore applies not just to the initial early examination but to all subsequent examinations that are necessary until the individual is finally sorted into the group that can be labeled as requiring no further definitive therapy. This discussion has been divided into three parts: certain evidence for re- generation, uncertain evidence for regeneration, and certain evidence for failure in regeneration. By satisfactory regeneration is meant regeneration as good as can be accomplish?d by the average suture of this nerve in this location at a certain time period after injury. Such a degree of regeneration may be far from satisfactory in some situations and it may be defined as a level of function which precludes the necessity for further operative pro- cedure. At this point of the discussion it should be stated that electro- physiological evidence as proof of some regeneration is of no interest unless it carries with it a strong predictive value for satisfactory regeneration. The rules which are presented for the interpretation of evidence for re- generation cannot be derived from a study of end results but must be based upon serial data obtained from early cases in the interval when decisions regarding surgical management are made. The unavailability of such pertinent data from late follow-up material was realized and a study of 300 patients with early nerve injuries at Valley Forge Army Hospital was therefore undertaken by the Philadelphia Study Center under Army con- tract in the interval from 1951 to 1954. Further longitudinal data ob- tained from 500 cases during the active hospitalization period at Gushing General Hospital (1944 to 1946) are occasionally brought to bear as well. 5/8

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a. Certain Evidence of Regeneration (7) Voluntary motor function. When there is movement against resistance which can only be the result of the voluntary contraction of the first muscle receiving its nerve supply through the nerve lesion, satisfactory regeneration is present. This involves the assumption that spotty recovery is a rarity— that the degree of recovery which develops in the most proximal muscle to receive its nerve supply foreshadows the recovery that will obtain in more distal muscles and in sensory supply to skin. Such a correlation uniformly exists in this follow-up study and it obtains again in the Valley Forge series. The extreme distal muscle will not do nearly as well as proximal ones in the high lesions that involve both proximal and distal groups but this is not of present concern since the distal function predictable with this evidence for proximal recovery is certain to be better than could be achieved by resection and suture. The assumption appears to be correct that at the level of nerve damage the axons supplying proximal muscles are so widely dispersed through the entire cross section of the nerve trunk that the recovery of a reasonable proportion of these dispersed axons as reflected in one muscle's contraction is a proper index of the regenerative capacity of the nerve trunk as a whole. The conclusion that this movement against resistance is truly a reflection of nerve regeneration must be reached with some caution. A clear under- standing is necessary of the substitutive or compensatory movements that can be learned progressively by utilizing unaffected muscles. In addition, there is the possibility, particularly in the case of the median and ulnar nerves, for overlapping or anomalous innervation so that even the definitely established contraction of an easily visualized muscle may not be evidence of recovery in the nerve presumed to supply it. Whether a movement should be properly ascribed to innervation by a particular nerve is a ques- tion which can sometimes not be settled by clinical observation but can easily be decided, as will be discussed below, by observing the motor responses on electrical stimulation of the nerve in question. The statement has been made that movement against resistance is a certain evidence of satisfactory regeneration, but obviously this degree of muscle strength can occur only after there is at first only a visible contraction in the muscle insufficient to move the part, followed by contraction sufficient to cause movement at the joint which then becomes of sufficient strength to lift the part against gravity and finally against resistance. Accordingly, when only a visible contraction of the muscle is evident at a time early enough to be consistent with progressive improvement in that muscle, there is reason to follow its performance for 4 to 6 weeks in the expectation that contraction against resistance will result. If reference to the expected result of suture in cases like this one indicates that this particular muscle could not possibly go so far as to develop contraction against resistance, satisfactory or end- point regeneration would then be assumed. If, on the other hand, good muscle strength is the usual result of suture in the case at hand, the evidence 579

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an estimate of the average magnitude of the effect of arterial injury, one finds that muscles affected by such injuries contract against resistance with only 82 percent of the frequency observed from muscles not so affected and of comparable site. In no sensory modality was the observed variation sufficient to conclude that such an associated injury had any effect upon sensory regeneration. This combined injury in an extremity manifests itself as a peripheral nerve injury in three aspects. (1) Tissue and therefore peripheral nerve ischemia. There is no simple periph- eral nerve injury more conducive to poor neural regeneration than that secondary to ischemia. With an otherwise intact peripheral nerve system, the treatment of peripheral nerve ischemia becomes a part of the treatment of extremity ischemia. Such therapy must be established at a very early time period after major vessel severance. If tissue ischemia is associated with major peripheral nerve injury, the therapy of ischemia holds prece- dence, with that of the peripheral nerve injury being carried out in the subsequent period following wounding. (2) Peripheral nerve injury may develop from compression of an expanding arterial aneurysm. Peripheral nerve tissue does not withstand prolonged pressure without axonal degeneration and without local ischemic changes. The appearance of a developing peripheral nerve paralysis in an extremity with an arterial aneurysm is a signal for immediate treatment of the vascular lesion. Among all of the late sequelae of vascular injuries, the expanding arterial aneurysm is the only vascular lesion that should command prece- dence over the therapy of peripheral nerve injury. Smaller arterial aneu- rysms may actually erode peripheral nerve tissue. (3) Major peripheral nerve injury may occur in any pathologic form with major vascular injury. The peripheral nerve injury should be evaluated as already described and a decision reached concerning operation. There is little doubt that a combined approach to peripheral nerve injury and vascular injury is preferable to separate operative interventions. Due to the com- plexity of the repair of ooth lesions, and due to the formidable nature of many arteriovenous aneurysms, it is a fact that in the past the repair of the peripheral nerve lesion has been deferred or, at best, has assumed a secondary role. This trend should be reversed. Except in the instance of expanding arterial aneurysms, the neurosurgeon must participate at all times in the repair of these combined injuries. Much further attention should be directed toward the proper care of these very crippling injuries of an extremity. Because of the anatomic contiguity of neural and vascular structures in the neck, combined vascular and neural lesions of the last cranial nerves are common. Many such patients undoubtedly succumb to immediate hemor- rhage. Treatment of the nerve lesion in those that survive needs only brief consideration. The neurological defect shows a strong tendency toward spontaneous resolution and direct repair of cranial nerve lesion is rarely indicated. More peripheral lesions of the spinal accessory and hypoglossal 628

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nerves may demand operation but such peripheral lesions are uncommon with vascular injury. Residual paralysis of the vocal cord may precipitate respiratory difficulty or aspiration of fluids. Repair of the vascular lesion does not favorably influence the cranial nerve injury, and this particular group of cranial-peripheral nerve involvements should be the responsibility of the vascular surgeon directly. c. Soft Tissue. Roughly 10 percent of these cases were complicated by soft tissue injury that needed definitive plastic repair. A plastic procedure per- formed at the site of injury prior to nerve repair was found, particularly in the peroneal, median, and ulnar nerves, to be associated with an average loss of one-fifth in the expected percentage of muscles contracting against resistance. Any delay in definitive nerve suture as a result of such a repair was of too little moment to produce this effect, which probably depends in part upon loss of muscle substance. Sensory regeneration was not altered by the presence of a major plastic procedure. World War II experience demonstrated that any adverse time influence dependent upon prolonged plastic repair could be largely obviated by combined operative approaches. Peripheral nerve injuries cannot be repaired through split thickness skin grafts. Again, the concept of placing such combined injuries under neurosurgical care during the early months following injury will prevent the occurrence of splendid skin repair and a functionally useless extremity. The first task of the plastic surgeon is to enable the neurosurgeon to repair peripheral nerve tissue; his major task may well be completed at a single procedure. If not, it should be reserved for a later period of rehabilitation surgery. d. Chronic Infection. It has been pointed out that there is a considerable delay in nerve repair in cases with chronic infection. The effect of wound infection upon peripheral nerve regeneration is then a matter of elapsed time. In lesions complicated by infection, muscles were found to contract against resistance only about two-thirds as often as muscles not so com- plicated. There was no adverse effect upon sensory regeneration. The foregoing observations appear sufficient to make well founded the statements that peripheral nerve surgery must be a part of total limb surgery, that peripheral nerve regeneration is adversely affected by time as perhaps no other tissue is in the extremity and that in the presence of associated injury, combined reparative procedures are indicated. F. INFLUENCE OF TECHNICAL FACTORS OF SURGICAL MANAGEMENT UPON ANATOMICAL REGENERA- TION There remains to be reviewed the general influence of several technical factors concerned with surgical treatment as this influence is reflected in terms of peripheral nerve regeneration in these cases. Such a discussion would be repetitious of the detailed data presented in the chapters devoted to motor and sensory regeneration, and the reader is referred to summaries 629

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on pages 191-197 and 308-309. It seems pertinent to point out that such technical factors as those concerned with suture material, cuffs, the trimming of nerve ends, and the minutiae of suture play little role in peripheral nerve regeneration, if conducted with reasonable skill and certitude, as compared to such factors as elapsed time, the management of associated injury, and the approach to peripheral nerve surgery as a part of total limb rehabili- tation. G. DISPOSITION TO DUTY Only 2.3 percent of the men with 1,890 peripheral nerve sutures studied in this representative sample returned to some form of duty status during World War II. The variations among the 7 major nerves in this respect was in the range of 0.6 to 4.2 percent and these data may be found in the last pages of chapter II. It also appears a fact that men with sutured peripheral nerve injuries were hospitalized on the average for 523 days in military hospitals as compared to 54 days for all the wounded in World War II. Some of this enormous time period devoted to hospitalization was, of course, spent on leave or on work furloughs. The number dis- charged from hospital prior to day 200 was negligible. These and other relevant data may also be found in chapter II. These studies upon anatomical and functional regeneration in this series of patients in terms of separate nerve injuries give considerable credence to the feeling that was held in World War II by experienced rehabilitation surgeons that time in hospital was, in general, excessive for these injuries. This feeling was reflected in part by the emphasis upon work furloughs by certain hospital centers where this manpower pool was used in noncombat or civilian type duties. This technique was not used widely and, in general, the convalescent hospital was developed to absorb a volume of patients quite well except for their treated nerve or other injuries. This mass of patients overwhelmed the capacities of available medical and ancillary personnel and scant progress was made in terms of exact observation of the extent, or the failure, of peripheral nerve regeneration. It appears essen- tial, therefore, to present in this survey of surgical implications the broad essentials of the results of peripheral nerve repair for separate nerves and certain suggestions concerning disposition from hospital. The latter in turn have to do only with the proposed period of active hospitalization. H. END RESULTS OF REPAIR, SUMMARY BY INDIVIDUAL NERVE The decision that the patient will not benefit from further hospitalization requires knowledge of the best that can be expected of his nerve injury and the degree to which his existing disability can be improved by orthopedic techniques. The former knowledge has been described in considerable detail in preceding chapters and is summarized below under separate nerve injuries. The latter information can only be obtained when the neuro- surgical center is associated with an orthopedic and hand center. Since 630

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the benefits of tendon transfer can be largely realized in a period of 6 weeks, such an association of special skills tends toward adequate treatment, increased therapeutic experience, and prompt disposition. Since the prob- lem of achieving rehabilitation is quite different in arm and leg injuries, they will be discussed separately. 1. Lower Extremity Injuries In these follow-up studies, the regeneration of nerve injuries has been rated in percent of anatomical regeneration, reflecting the degree to which motor strength has returned to involved muscles, and the degree to which sensory thresholds have been lowered in the involved skin. At the same time, functional recovery has been analyzed and reported in terms of a percentage of functional recovery. In the case of the lower extremity, functional recovery is measured largely by the distance the patient is able to walk in reasonable comfort. In the lower extremity, extreme discrepan- cies may be apparent between these two factors of recovery. One patient with no anatomical regeneration secondary to a high sciatic nerve division may show 60 percent functional return if he is free of foot ulceration and if he has a satisfactory padded shoe and a brace to hold the foot in dorsi- flexion. On the other hand, examples are common of injuries to the sciatic nerve involving only the tibial component where nerve suture has given adequate motor power in all muscles of the calf, including the flexors of the toes, plus a reasonable appreciation of the modalities of pain and touch over the sole of the foot. This sensory return, however, may be so disagreeable, in spite of an adequately padded shoe, that walking for a distance of 2 blocks requires considerable effort. Although anatomical regeneration may be rated high yet this patient's functional recovery is of little value. The regeneration summaries of the sciatic, peroneal, and tibial nerves appear in tables 280 through 283. Although a poor correlation exists between anatomical and functional regeneration, it is not so poor as to preclude the advisability of sciatic nerve suture. Such sutures must be done early after injury if any type of ana- tomical regeneration is to be expected. If the patient with a high sciatic nerve division has had a technically good suture by an experienced neuro- surgeon, and if he has been fitted with shoe and brace so that he can walk comfortably without foot ulceration, a subsequent failure of improvement in nerve function is not an indication for reoperation. It seems clear that when a patient with a lower extremity nerve injury has secured complete functional rehabilitation, he will derive no benefits from further hospitaliza- tion. These studies have shown that no resuture of an original peroneal suture which had been performed adequately showed improved regenera- tion, and that resuture of a low tibial nerve injury that has been done adequately may increase or precipitate painful sensory reaction over the sole of the foot and increase functional disability. In most instances of uncomplicated lower extremity peripheral nerve injuries, discharge is indicated 3 to 4 months after peripheral nerve suture. 631

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Table 280.—Regeneration Summary: Sciatic-Peroneal Motor recovery, by site in thigh tipper M Middle H Lower H All sites PI M' P" M' P1 M' P' M Tib. ant 54 37 29 49 34 31 26 21 60 43 35 57 24 20 29 25 72 59 48 68 37 28 15 35 59 43 35 55 32 23 Ext dig long Ext. hall long . . 28 27 Peron. long Sensory recovery Autonomic recovery Practical function Percent Pain threshold, 10 gm. or less . . . 24 Increased SR Absent sweati Percent 52 Median percc inal functio nt of nor- a 60 Patent Touch threshold, 5 gm . or less 19 n:f 65 1 Percentage (P) of affected muscles contracting voluntarily* and mean (M) relative power of affected muscles capable of movement against resistance. Table 281.—Regeneration Summary: Sciatk-Tibial Motor recovery, by site in thigh Upper K Middle H Lower % All sites P' Mi P' M' P' M' P1 M' Oast roc. & sol 94 56 94 53 91 62 95 85 65 67 59 64 60 37 34 34 Tib. post Flex. dig. long 17 18 36 37 33 21 27 41 41 MOO 55 Flex hall long 31 Inteross Sensory recovery Autonomic recovery Practical function Percent Pain threshold, 10 gm. or less 20 Increased SR Absent sweati Percent 55 Median perce nt of mil - i. . . 60 Perant Touch threshold, 5 gm. or less 18 aa 60 rnal funcrio 1 Percentage (P) of affected muscles contracting voluntarily, and mean (M) relative power of affected muscles capable of movement against resistance. ' Mean based on five cases.

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Table 282.—Regeneration Summary: Peroneal Motor recovery All sites P' M1 Tih. ant 75 46 Hxt. dig. long 66 32 Ext. hall. long 54 36 Peron. long 71 42 Sensory recovery Autonomic recovery Practical function Percent Pain threshold, 10 gm. or less 38 Touch threshold, 5 gm. or less 37 Percent Increased SR 32 Absent sweating 63 Percent Median percent of nor- mal function 60 1 Percentage (P) of affected muscles contracting voluntarily, and mean (M) relative power of affected muscles capable of movement against resistance. Table 283.—Regeneration Summary: Tibial Motor recovery All sites P1 M1 Gastroc. & sol 94 64 Tib. post. . . 85 60 Flex. dig. long . 65 36 Flex. hall. long * * * * , * * 67 34 Inteross 52 32 Sensory recovery Autonomic recovery Practical function Percent Pain threshold, 10 gm. or less 29 Touch threshold, 5 gm. or less 26 Percent Increased SR 36 Absent sweating 63 Percent Median percent of nor- mal function 76 1 Percentage (P) of affected muscles contracting voluntarily, and mean (M) relative power of affected muscles capable of movement against resistance.

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In summary, there is evidence that all peripheral nerve injuries of the lower extremity should not have any type of further operative intervention, even if anatomical regeneration is unsatisfactory. If an adequate early suture has been done and if functional rehabilitation has been completed, there is no need to hospitalize such patients, because evidence of neural regeneration may take 18 to 24 months to appear. This combined therapy should be completed by 4 months after suture and the patient discharged from the active neurosurgical center. 2. Upper Extremity Injuries Whereas the leg will do its job satisfactorily if it functions as a comfortable support with full movement at the knee, a hand to be useful requires active innervation of a variety of movements plus satisfactory sensation to at least the domain of the median nerve. Since one missing movement may make the difference between a useless and a relatively useful member, the re- sponsibility for terminating hospital care with an incompletely functioning hand is a heavy one. The regeneration summary of the median nerve appears in table 284. Table 284.—Regeneration Summary: Median Motor rcc by sit overy, High Low e P« M' P' M' Fl. car. rad 97 88 88 60 42 37 34 92 91 94 92 83 75 56 60 45 32 Fl dig prof #2 Opponcns . . 76 78 Abd. poll. brev 35 Sensory recovery, percent Autonomic recovery, percent Practical function, percent High Low Pain threshold, 10 gm. or less. . 39 49 49 Increased SR ... 43 Aver pe fur age (median) rcent of normal Touch threshold* 5 gm. or less. . . 48 Absent sweating 36 1 Percentage of affected muscles contracting voluntarily. 1 Mean relative power of affected muscles capable of movement against resistance. Even with the best sensory recovery after suture, the patient with a median nerve injury will still have difficulty in the organization of perceived pain and touch sensations that limit the hand's usefulness even though

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mechanical function with visual aid be good. Therefore, a median nerve injury must be followed until useful function has returned to the thumb and fingertip. If sensation does not return at the scheduled time, reopera- tion is indicated since this is the only way of establishing improved sensa- tion. Reoperation may not be indicated if the nerve injury was extensive and everything possible, including nerve grafting, was done at the original procedure. Sensory recovery is often reasonably good but the hand may be handi- capped by loss of the opponens pollicis muscle preventing opposition of thumb pad to finger pad in picking up objects. Some patients with no opponens function compensate by the ulnar-innervated short flexor to the thumb. This is, however, not the rule. If the opponens has failed to re- cover on schedule, and if the patient can pick up small objects only by grasping them between the thumb and side of the index finger, compensa- tory tendon transplant is indicated. A variety of procedures for supplying opposition of the thumb have been described. With median nerve division above the elbow, the expectancy of recovery of normal thumb opposition is low. Tendon transplant repair of thumb opposition is indicated in such cases at an early period of hospitalization. Such a procedure seems prefer- able to waiting 14 to 18 months for opponens pollicis recovery, only to find that tendon transplant is required after all. In a few cases, there may be failure of innervation of the flexor digitorum longus and flexor pollicis longus with high median nerve injuries. The loss of flexion of the terminal phalanges of the index finger and thumb may be readily supplied by tendon transfers. In summary, a patient with a median nerve injury should not be dis- charged from the hospital until he has regained useful sensation in the autonomous sensory zone of the median nerve, unless poor regeneration must be accepted because of the extent of the lesion. Such a patient should always be provided, by tendon transfer, with the ability to oppose the thumb to the tips of the index and middle finger, if this function has not returned as a result of reinnervation. In median nerve injuries above the elbow, early tendon transfer for such function is indicated. Study center records indicate that this failure to provide thumb opposition was one of the major defects in the management of peripheral nerve injuries in World War II. Some patients were found still willing to undergo operation years after injury in an effort to regain thumb opposition that would give them a useful hand. The regeneration summary of the ulnar nerve is given in table 285. The patient who is left with an irreparable ulnar nerve paralysis, even including the forearm flexors, still has a relatively good hand. Although the fourth and fifth fingers may be useless and clawed into the palm, he is able to grasp heavy objects and pick up small objects with the radial three digits. Even with a complete paralysis, function of the hand may be rated at 60 percent. If, on the other hand, the fourth and fifth fingers can be extended and used for grasping, hand usefulness is increased to an 80 percent rating. These figures are expressed in terms of disability in the average white collar 635

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Table 285.—Regeneration Summary: Ulnar Motor recovery, Hi f?h Lc Mr by site P> M' P' M> Fl rflr* jiJo -*..... . 96 66 97 72 Fl. dig. prof. 4-5 94 42 95 48 Abd. dig. quint 85 21 90 28 Add. poll . . 85 34 92 40 1 st dorsal inteross . . 78 26 87 31 Sensory recovery, percent Autonomic recovery, percent Practical function, percent High Low Pain threshold, 10 gm. or less. Touch threshold, 5 gm. or less. 29 31 Increased SR 45 Average (median) percent of normal 73 function. 39 Absent sweating 29 1 Percentage of affected muscles contracting voluntarily. 1 Mean relative power of affected muscles capable of movement against resistance. worker or laborer. The ability to set the lumbricals so that the fourth and fifth fingers may be extended is one of the last functions to return as the ulnar intrinsic muscles are reinnervated. Although the functional disability of the clawed fourth and fifth fingers is minimal as compared to loss of thumb opposition, patients should not be discharged until lumbrical action has been established by reinnervation or by tendon transfer. Ulnar regeneration is notably spotty and particularly so in high injuries. When poor regeneration must be accepted, tendon transfer is indicated early in the course of hospitaJization. When rein- nervation is proceeding normally, since the functional disability is slight, patients may be discharged to duty, to return for reexamination. Whether tendon transfer in these injuries is deferred or immediately con- templated, physiotherapy must provide relatively full motion in the inter- phalangeal articulations. Little can be done with fixed clawing and patients sometimes have not accepted amputation. The amount of exten- sion of fingers possibly by tendon work can be roughly predicted by noting the amount of passive finger extension possible when the wrist is held flexed to relax the flexor tendons. The tendon transfer technique is commonplace. Combined median-ulnar nerve injuries are extremely disabling since all the fingers become flexed into the hand and the only grasp possible is between the thumb and the side of the index finger. High injuries often 636

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also involve a vascular component. Forearm injuries are often associated with massive soft tissue and bone injury. These studies show that in com- bined high injuries, regeneration to the forearm flexors is surprisingly good but that intrinsic muscle function never recovers sufficiently to permit thumb to finger opposition. This is also usually true in low injuries. Emphasis, therefore, must be placed upon the restoration of median nerve sensory function and upon restoring opposition to the thumb using the best of the available flexors. In addition, lumbrical function must be supplied to at least the index and middle fingers, so that they will reach out to meet the opposing thumb, rather than curling past it into the palm. The regeneration summary of the radial nerve is given in table 286. These studies indicate that anatomical regeneration may be of the highest order in radial injuries and that satisfactory functional recovery can always be anticipated. In instances of poor regeneration, adequate orthopedic techniques are available for restoring wrist and finger-drop and abduction of the thumb. When good wrist extension has been established by re- innervation adequate finger extension usually follows. Abduction and extension of the thumb customarily follows in 4 to 5 months and it is a moot question whether patients need to be kept under observation for this period of time. If wrist extension fails to appear at the scheduled time, the question of tendon transfer should then be considered. Table 286.—Regeneration Summary: Radial Motor recovery All sites P' M« Triceps Brach. rad Ext. carp* rad . . Ext. dig. comm. Ext. carp* ulnar. Abel. poll. long. Ext. poll. long. . Ext. poll. brev. . 100 92 94 89 93 78 83 79 69 68 49 47 50 37 37 36 Sensory recovery Autonomic recovery Practical function Percent Pain threshold, 10 gm. or less 51 Touch threshold, 5 gm. or less 56 Percent Increased SR 10 Absent sweating 20 Percent Median percent of normal function.... 78 1 Percentage (P) of affected muscles contracting voluntarily, and mean (M) relative power of affected muscles capable of movement against resistance. 637

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It seems probable that the routine exploration of open wounds of the brachial plexus is neither profitable nor justifiable since, in the brachial plexus, a suture of elements supplying the forearm and hand seldom adds significantly to function. Proximal muscles such as the deltoid and biceps do occasionally secure useful recovery through suture. Cases must, therefore, be surveyed individually because of the complex nature of the injury. If exploration is done, in spite of evidence that it fails to add perceptibly to anatomic regeneration, postoperative emphasis must be placed upon ortho- pedic rehabilitation measures. I. FINAL NOTE The history of military neurosurgery demonstrates the fact that succeeding generations often fail to use the accumulated knowledge of the past. Much of the basic information in this report can be found in books by Foerster and by Pollock and Davis and in the Medical History of World War I, and in other monographs devoted to this subject. A large amount of data is also available in papers published during and after World War II in this par- ticular field. The concept of relatively early nerve suture carried out perhaps within 3 months following injury by an experienced team, the importance of peripheral nerve regeneration in total limb rehabilitation, the emphasis upon orthopedic hand surgery, the understanding of patho- logic changes in peripheral nerve tissue, and the trend toward exact neuro- physiological studies of peripheral nerve injury and regeneration are, however, relatively new. It is hoped that this final report of the peripheral nerve study centers will provide data in support of the surgical principles that have become accepted over the years and have been restated here. The military neurosurgeon, however, must not assume that these results cannot be improved. 638