Chapter IX: Injuries to the Peripheral Nerve Trunks (1)

The occurrence of these injuries has undoubtedly increased in frequency with the employment of bullets of small calibre, and no other class of case more strikingly illustrates the localised nature of the lesions produced by small projectiles of high velocity. Again, no other series of injuries affords such obvious indications of the firm and resistent nature of the cicatricial tissue formed in the process of repair of small-calibre wounds, and in none is the advantage of a conservative and expectant attitude so forcibly impressed upon the surgeon. Implication of the nerves may be primary, or secondary to an injury which left them originally unscathed.

_Nature of the anatomical lesions._--In degree these vary in mathematical progression, but the extent of the lesion is not always readily differentiated by the early clinical manifestations, and again the actual damage is not to be estimated by the gross apparent anatomical lesion alone; but, in addition, consists in part in changes of a less easily demonstrable nature, varying with the velocity with which the bullet was travelling and the consequent comparative degree of vibratory force to which the nerve has been subjected. In these injuries, as in those of every part of the nervous system, the degree of velocity appears to gain especial importance both in regard to the general symptoms and the local effect on the functional capacity of the nerve.

This is perhaps a fitting place for the introduction of a few further remarks as to the significance of the term 'concussion' in connection with the injuries produced by bullets of small calibre, since the most striking exemplification of the results following the transmission of the vibratory force of the projectile is afforded by the behaviour of the comparatively densely ensheathed and supported peripheral nerves.

As already pointed out in Chapters VII. and VIII. the chief concussion effects on the nervous tissue of the brain and spinal cord are of a destructive nature, far exceeding those accompanying the injuries designated by the same term seen in the ordinary accidents met with in civil practice, and this damage is comparatively localised in extent.

In the case of the peripheral nerves I have still employed the terms 'concussion' and 'contusion' to designate certain groups of symptoms and clinical phenomena, but any sharp distinction between the two conditions on a morbid anatomical basis is impossible. The results of severe vibratory concussion may, in fact, be more generally destructive than those of contusion, and the subsequent effects more prolonged. A certain length of the affected nerve is apparently completely destroyed as a conductor of impulses, the connective-tissue element alone remaining intact. Under these circumstances a nerve, the subject of the most serious degree of vibratory concussion, which, if cut down upon, may exhibit no macroscopic change, may take a longer period to recover than one in which the presence of considerable local thickening points to direct contact with the bullet, with resulting hæmorrhage into the nerve sheath and perhaps partial gross rupture of nerve fibres.

The therapeutic and prognostic importance of the above remarks, if correct, is obvious. The course of the nerve is preserved by its intact connective-tissue framework, and ultimate recovery by a regeneration of the nerve fibres is more likely to be complete, and will be just as rapid, if nature be relied on and the nerve be left untouched by the hand of the surgeon.

It is, I think, undeniable that nerve trunks may escape severe or irrecoverable injury by lateral displacement. The mere fact that the trunk itself may be perforated by a slit in its long axis would suggest the possibility of displacement of the whole structure, and this no doubt occurred with some frequency. Displacement would naturally be most frequent in the case of nerves, such as those of the arm, which run long courses in comparatively loose tissue. In a remarkable case already narrated, an exploratory operation showed the musculo-spiral nerve in the upper part of the arm to have been driven into a loop which projected into, and provisionally closed, an opening in the brachial artery.

I. _Simple concussion._--Anatomically, or histologically, no information exists as to the changes which give rise to the often transitory symptoms dependent on this condition. We are reduced to the same theories of molecular disturbance and change which have been invoked to account for similar affections of the central nervous system. The causation of concussion is, however, materially influenced in its degree by the velocity of flight of the bullet and consequent severity of the vibratory force exerted. Hence actual contact of the bullet with the nerves is not necessary for its production, as is seen in the temporary complete loss of functional capacity in the limbs in many cases of fracture, where the vibrations are rendered still more far-reaching and effective as the result of their wider distribution from the larger solid resistance afforded by the bone. The relative density and resistance offered by the different parts of the bone acquire great significance in this relation, since local shock due to nerve concussion is far more profound when the shafts are struck than when the cancellous ends furnish the point of impact.

The form of concussion which most nearly interests us in this chapter is that affecting single nerve trunks in wounds of the soft parts alone, and here the passage of the bullet is, as a rule, so contiguous to the nerve that there is difficulty in drawing a strict line of demarcation between such cases and those dealt with in the next paragraph.

II. _Contusion._--Clinically this was the form of nerve injury both of greatest comparative frequency and of interest from the points of view both of diagnosis and prognosis.

The seriousness of a contusion depends on two factors: first, the relative degree of violence exerted upon the nerve, which is dependent on the force still retained by the travelling bullet; and, secondly, on the extent of tissue actually implicated. The range of fire at which the injury was received determines the importance of the first factor; the second varies with the degree of exactness with which the nerve is struck, and on the direction taken by the bullet. Naturally transverse wounds affect a small area; while an oblique or longitudinal direction of the track may indefinitely increase the extent of injury to the nerve trunk, and hence acquire prognostic significance in direct ratio to the amount of tissue which needs to be regenerated.

As to the actual anatomical lesion resulting in the cases which we designated clinically as contusion I can give no information. On many occasions when the symptoms were considered of such a nature as to render an exploration advisable, no macroscopic evidence of gross injury was obtained. It was therefore impossible to draw a definite line of demarcation between such cases and those which we considered merely concussion. It could only be assumed that the vibration transmitted to the nerve had occasioned such changes as to destroy its capacity as a conductor of impressions.

In some cases the presence of a certain amount of interstitial blood extravasation was suggested clinically by early hyperæsthesia and signs of irritation; in others the paralysis was of such a degree as to lead to the inference that a complete regeneration of the existing nerve would be necessary prior to the restitution of functional capacity.

In a certain proportion of the injuries the development of a distinct fusiform swelling in the course of the nerve pointed to the existence of considerable tissue damage, while in others this was evidenced clinically by early signs of neuritis.

III. _Division or laceration._--The varying mechanical conditions affecting the last class of injury play a similar rôle here. Thus the degree of laceration depends on the direction of the wound track, and as all lacerations are accompanied by contusion, the relative velocity retained by the travelling bullet assumes the same importance.

I saw every degree of injury to the trunks, from notching to complete solution of continuity, and in some cases destruction and disappearance of pieces from one to two or more inches in length. Such lesions as the latter were most common in the forearm. In this segment of the limbs tracks of varying degrees of longitudinal obliquity are readily produced, whether the patient be in the upright or prone position, since the upper extremities are commonly in forward action whichever position is assumed.

The most peculiar form of injury consisted in perforation of the trunk without gross destruction of its fibres, and without in many cases prolonged or permanent loss of functional capacity. I cannot speak with any confidence as to the comparative frequency of occurrence of this form of injury, but judging by the analogous perforations of the vessels, it is probably not uncommon in trunks large enough to allow of its production. The trunk nerves of the arm, and the great sciatic nerve, were probably the most frequent seats of such wounds. As, however, a very short experience of the futility of early interference in the case of nerve lesions warned me against exploration before a date at which observations of this nature were unsatisfactory, I gained less experience on this point than I could have wished.

In the case of completely divided nerves the development of a bulbous enlargement on the proximal end was constant, and very marked in degree. I saw few cases in which primary effects could be certainly referred to pressure or laceration by bone spicules, excepting in some fractures of the humerus, and perhaps some injuries of the seventh nerve accompanying perforating wounds of the mastoid process.

IV. _Secondary implication of the nerves._--This was a striking characteristic in many at first apparently simple wounds of the soft parts. In such cases it was due to implication of the contiguous trunk in the process of cicatrisation, and its importance varied with the size of the nerve in question. In the smaller sensory trunks it was often evidenced by the occurrence of neuralgic pain, especially liable to be influenced by climatic changes; in the larger, by signs of more or less severe motor, sensory, and trophic disturbance. Musculo-spiral paralysis from implication in, or pressure from, callus in cases of fracture of the humerus was very frequent. This would naturally be expected from the extreme degree the comminution of the bone often reached, and the consequently large amount of callus developed.

The effect of cicatrisation of the tissues surrounding the nerves varied somewhat according to the degree of fixation of the individual nerve implicated. Thus if a nerve lay in a fixed bed some form of circular constriction resulted; if, on the other hand, the nerve was readily displaceable, the cicatrix often drew it considerably out of its course; in either case symptoms corresponding with those of pressure resulted.

_Symptoms of nerve lesion_.--These differed little in character from those common to such injuries in civil practice, except in the relative frequency with which they assumed a serious aspect. After all in civil practice nerve concussion is most familiar to us in the degree common after knocking the elbow against a hard object, and the same may be said in regard to the allied injury of contusion. It is in small-calibre bullet wounds alone that the occurrence of such severe and sharply localised injury to deep parts as was observed is possible.

_Concussion_.--Temporary loss of function was often observed in the limbs, corresponding to the distribution of one or more nerve trunks when wound tracks had passed in their vicinity. Interference with function sometimes amounted to loss of sensation alone: in others to loss of both sensation and motor power. Such symptoms were of a transitory character, lasting for a few days or a week; if both sensation and motion were impaired, sensation was usually the first to be regained. In these cases secondary trouble was not uncommon, since the near proximity of the track to the originally affected nerve offered every chance for implication of the latter in the resulting cicatrix. This sequence was often observed, and its symptoms are described under the heading of secondary implication below. Equally striking were the instances of concussion in the case of the nerves of special sense and their end organs, temporary loss of smell, vision, or hearing being not uncommon, often passing off in the course of a few days with no apparent ulterior ill-effect.

One of the most interesting illustrations of the occurrence of concussion was furnished by cases in which complete paralysis of a limb rapidly cleared up with the exception of that corresponding to a single individual nerve of the complex apparently originally implicated. Instances of severe contusion or division of one nerve of the arm, for instance, accompanied by transient signs of concussion of varying degrees of severity in all the others, were by no means uncommon.

_Contusion_.--The symptoms of contusion were somewhat less simple, since, in addition to lowering or loss of function, signs of irritation were often observed. In the slighter cases irritation was often a marked feature, as was evidenced by hyperæsthesia and pain combined with loss of power. In cases in which pain and hyperæsthesia were primary symptoms, these were often transitory. I will quote an illustrative case which, though affecting the nerve roots, is characteristic of the effects of slight contusion in the case of the nerve trunks in any part of their course:--

(107) _Contusion of cervical nerve roots_.--Range probably
about 1,000 yards. Wounded at Belmont. Aperture of _entry_
(Lee-Metford), immediately posterior to the right fifth
cervical transverse process; _exit_, immediately anterior to
the space between the third and fourth left cervical transverse
processes. The movements of the neck were perfect, there was
neither pain nor difficulty in swallowing. Extreme
hyperæsthesia was present in both palms and down the front of
the forearms. The grip in either hand was weak, this being
possibly explained in part by the hyperæsthesia of the palms,
as all movements of the upper extremities could be made,
although not with full power. On the fourth day the condition
was much improved on the left side, and at the end of a week
the left upper extremity was normal; the right (side of entry,
and therefore exposed to greater force from the bullet)
improved more slowly, becoming normal only at the end of three
weeks.

I observed an identical case of injury to the cervical roots, and many similar instances in injuries of the nerve trunks of the limbs in which the course was exactly parallel. In the more severe, pain was often added to hyperæsthesia.

In the most severe cases the signs corresponded in all particulars, except in the early entire loss of reaction of the muscles to electricity, with those of complete section. Loss of sensation and motion was immediate, complete, and prolonged, the limbs being lowered in temperature, flaccid, and powerless. General systemic shock was also severe. In the case either of plexus or multiple contusions, or where the injury was more local, correspondingly complete signs were present in the area supplied by the affected nerves.

In the cases in which the contusion was not of extreme degree, hyperæsthesia often developed as a later sign, and was probably due to the irritation of hæmorrhage, when the sensory portion of the nerve began to regain functional capacity. The date of appearance of the hyperæsthesia varied from a few days to a week or later. It might then persist for weeks or many months.

In a few instances large blebs rose on the back of the hand, or patches of vesicles appeared over the terminal distribution of the nerve, pointing to early trophic changes.

The period of recovery varied greatly; in some instances of very complete paralysis, function was regained and became apparently normal at the end of three or four weeks; in others, even after severe wasting of muscles for weeks, rapid improvement occurred often suddenly, while in some there was no apparent recovery at the end of months. In cases of long-deferred improvement, wasting of the muscles became a very prominent feature; but this without complete loss of reaction of the muscles to electrical stimulation.

Recovery of sensation usually preceded by some time that of motion, the former often reappearing in some degree at an early date, and, even if very modified in character, it formed a most useful and valuable aid both in diagnosis and prognosis.

When in a position allowing of direct examination, the contused portion of the nerve sometimes developed a palpable fusiform thickening, manipulation of which might give rise to formication in the area of distribution--a favourable prognostic sign.

Many of the cases bore a very marked resemblance in character to those in which paralysis results from tight constriction of the limb, as in the arm after the application of an Esmarch's tourniquet.

_Laceration._--If incomplete, the signs corresponded very nearly to those of severe contusion, since partial section is impossible without the occurrence of the latter. The condition indeed was only to be distinguished by the partial nature of the recovery, and even this latter might be only more prolonged.

The same remarks hold good with regard to perforation of the nerve trunks; but, as regards function, these injuries are not so serious in prognosis as very much more limited transverse divisions or mere notching, and in some cases the disturbance of function was by no means profound or prolonged.

Absolute loss of reaction to electrical stimulus from above was the only pathognomonic sign of actual section, unless the position of the nerve was such as to allow of palpation, when the presence of a bulbous end at once settled the difficulty. In many cases of superficial tracks with division of such nerves as the long or short saphenous, the early development of bulbs in the course of the trunks gave positive information, and these were often observed.

_Traumatic neuritis._--This was a common sequence of contusion of the nerve itself, or of its subsequent inclusion in a cicatrix or callus. It was evidenced by hyperæsthesia both superficial and deep, pain, contracture, wasting of the muscles, local sweating, and the development of glossy skin.

Examples of this condition were seen in the case of nearly every nerve in the body. In frequency of occurrence, degree of severity, and in its selection of individual nerves considerable variation was met with. With regard to the two former points, personal idiosyncrasy, and degree of or peculiarity in the nature of the injury, are the only explanations I can suggest. Perhaps in some instances exposure to wet or cold in the early stages of the injury was of some import. Thus, I saw several severe cases of musculo-spiral neuritis in men who were wounded during the trying and wet march on Bloemfontein. I did not observe that suppuration or wound complications seemed important explanatory moments, as most of the cases occurred in wounds that healed rapidly.

With regard to the question of selection; the same nerves that appear particularly liable to suffer from idiopathic inflammations, toxic influences, or to be the seat of ascending changes (e.g. ulnar, musculo-spiral, and external popliteal), were those most often affected by secondary neuritis. Many of the most severe cases I saw were in the musculo-spiral nerve.

_Scar implication._--The signs of this most commonly commenced with neuralgia, or painful sensations when such movements were made as to put the cicatrix on the stretch. Although such neuralgia might not be constant, it was often observed to be troublesome when the patients were exposed to cold in sleeping out at night, or to extra fatigue, as in long marches. The results in many cases stopped at this point, but the size and wide distribution of certain nerves rendered even such slight symptoms of importance; while in others well-marked signs of neuritis declared themselves, such as glossy skin, pain, muscular wasting, and paralysis.

_Ascending neuritis._--In a few cases I observed very remarkable instances of ascending neuritis, after comparatively slight wounds. I will quote three of these as illustrations and make no further remarks as to the symptoms. It will be observed that one is a case of ulnar, both the others of external popliteal, neuritis:--

(108) _Ulnar nerve: secondary ascending neuritis._--Boer
wounded at Elandslaagte. Wound of hand, implicating anterior
two-thirds of third metacarpal bone. This bone, together with
the middle finger, was removed, and healing took place by
granulation slowly.

The resulting gap allowed considerable overlapping of the
fingers, and shortening of the corresponding digit; the index
finger also became flexed as a result of destruction of the
extensor tendons. Three months later the man was still in
hospital in consequence of the tardiness with which the wound
had healed: at this time pain was noted, which became very
severe in the whole course of the ulnar nerve; superficial
hyperæsthesia and deep muscular tenderness developed, but no
wasting. Several crops of herpetic vesicles also developed over
the distribution of the radial nerve in the hand. This pain was
followed by spastic contracture, first of the ulnar fingers and
later of the wrist and elbow, which could only be straightened
by the application of considerable force. The limb was,
therefore, kept straight by the application of a splint; and
warm baths, and a blister applied over the course of the ulnar
nerve, were resorted to: under this treatment the condition
improved until the patient was well enough to be transferred as
a prisoner, and I saw him no more.

(109) _Peroneal nerve branches._--Wounded at Colenso. _Entry_,
at the anterior margin of the fibula 5 inches above the
external malleolus; the track crossed the anterior aspect of
the leg obliquely, to its _exit_ 1 inch above the centre of the
ankle joint. Incomplete paralysis of the peronei muscles
followed, combined with progressive wasting of the whole limb,
which at the end of a month was marked, and then commenced to
improve.

(110) In a second case the wound took a similar course in the
centre of the leg, crossing the line of the branches of the
musculo-cutaneous nerve. Motor paralysis of the peronei
followed, together with general lowering of tactile sensation
in the musculo-cutaneous area.

_Traumatic neurosis._--In connection with the cases just quoted, mention must be made of the fact that the functional element was often somewhat prominent. The influence of this factor was not to be neglected in case 108; again, its presence was a feature in cases 132 and 134, of injury to the sciatic nerve and of peripheral injury to the seventh nerve (p. 355). A remark has been made as to the occurrence of functional paraplegia on p. 337. Again, in the case of the organs of special sense. Case 66, of injury to the occipital lobes, showed that a mixture of organic and functional phenomena might be a source of error, even in the determination of the visual field in the subject of an undoubted destructive lesion. On more than one occasion an injury was accompanied by loss of the power of speech; thus a patient who received a slight wound of the neck did not speak again until the application of a battery by my colleague, Mr. H. B. Robinson. A patient was also for a short time an inmate of No. 1 General Hospital, Wynberg, who had become deaf and dumb as a result of the explosion of a shrapnel shell over his head. This patient also did not recover his powers until he returned to the mother-country.

In many other cases of nerve concussion or contusion, the recovery of power and sensation, or the disappearance of neuralgia or contractures, was so sudden and rapid after prolonged continuance of the symptoms, as to suggest a very strong functional element in their origin. The influence of the general shock to the nervous system received by the patients had an important bearing on these phenomena, and their interest from a prognostic point of view was very great.

INJURIES TO SPECIAL NERVES

_Cranial nerves._--It will be convenient first to make a few remarks concerning the nerves of special sense.

_Olfactory._--I observed temporary loss of smell on three occasions. In two instances this accompanied transverse wounds of the bones of the face in which the upper third of the nasal cavities was crossed; in the third a track passing obliquely downwards from the frontal region passed through the inner wall of the orbit, and crossed the nose at a lower level. In view of the small area of the olfactory distribution which was directly implicated, I was at first inclined to regard the loss of smell as dependent on the presence of dried blood on the surface of the mucous membrane, or on obstruction of the cavities from the same cause. Further observation, however, appeared to show that it was due to concussion of the branches of the olfactory nerve, since the loss of function persisted when the cavities were manifestly clear.

In all these cases we were confronted with the same difficulty which was experienced both in lesions of sight and hearing, the determination as to whether the concussion was of the branches or of the olfactory bulb. When the symptom was the accompaniment of a fracture of the roof of the orbit, the possibility of concussion of the olfactory lobe was manifest. In all, again, it was difficult to say what part the accompanying concussion of the branches of the fifth nerve took in the production of the symptom. In all three cases mentioned the return of function was gradual, but apparently fairly complete at the end of three weeks. In one it was noted that at first the patient was conscious of an odour before he was able to discriminate its actual nature; later he could determine the latter readily.

_Optic._--Some remarks concerning lesions of the optic nerve have already been made under the heading of wounds of the orbit. Concussion and contusion of the nerve both occurred, but I was unable to differentiate between the effects of these on the nerve itself, apart from the effects on the globe of the eye, which usually accompanied wounds of the orbit.

In some cases the nerve was directly divided in orbital wounds, and either pressure on or division of the nerve in the intra-cranial portion of its course, or as it traversed the optic foramen, was not uncommon.

_Auditory._--Loss of hearing was also not infrequent; thus it accompanied all three wounds of the mastoid process quoted under the heading of the seventh nerve, also two cases of fracture of the occipital bone near the ear quoted on p. 278. In all these instances it was impossible to attribute the deafness to lesion of the nerve alone, as the causative injury equally affected the internal ear, and in at least two the bullet implicated the tympanum as well in its course. The deafness was absolute in each case, and in none had any improvement occurred at the end of nine months. Deafness was a symptom in a certain number of the more severe cerebral injuries in which the course of the bullet was not so near to the internal ear: probably some of these were central in origin.

I only once observed any interference with the sense of taste.

_Remaining cranial nerves._--I have little to say regarding the _third_, _fourth_, and _sixth_ nerves. In the case of the third nerve, ptosis was occasionally seen in wounds of the skull involving the roof of the orbit, but the relative parts taken by injury to nerve and laceration or fixation of muscle respectively, were usually hard to determine. Again, the fourth and sixth nerves may have been damaged in some of the more extensive orbital wounds, especially those in which the globe suffered injury, but the signs under such circumstances were difficult to discriminate, and the injury was of slight practical importance, in view of the major injury to the globe itself.

_Fifth nerve._--Concussion, contusion, or laceration of the different branches of the three divisions of the fifth nerve were common in wounds of the head, but most frequent in fractures of the upper or lower jaws. Localised anæsthesia was common from one or other of these causes, but for the most part transitory in the cases of contusion or concussion. I saw no case of entire loss of function in any one division, symptoms being mostly confined to certain branches, as the supra-orbital, the temporo-malar, the dental branches of the second division, the auriculo-temporal nerve, and the lingual, dental, and mental branches of the third division. I did not observe any cases in which modification of the special senses accompanied these injuries beyond those mentioned in the remarks already made on the subject of anosmia, and one case in which some modification of the sense of taste accompanied an injury to the floor of the mouth. It was a matter of surprise, considering the frequency with which subsequent neuritis was met with in the nerves generally, that trifacial neuralgia in some form was not more often met with. I never observed any serious case. Perhaps this is one of the fields in which a longer after-period may increase our knowledge. Lastly, I never observed motor paralysis in the case of the third division, although sensory symptoms in some of the branches were common, evident proof that injuries to the trunk were rare.

_Seventh nerve._--Facial paralysis was most commonly observed in cases of wound of the mastoid process, apart from central cortical facial paralyses, of which several are quoted in the chapter on injuries of the head. All the wounds of the mastoid process were, in addition, accompanied by absolute deafness. I am sorry to be unable to give any details as to the electrical condition of the muscles in these cases, but I believe that in the great majority the paralysis was mainly the result of nerve concussion, since the perforations were clean in character and not obviously accompanied by comminution. Pressure from hæmorrhage into the Fallopian canal may, of course, have been present, and in some instances, particularly those in which the bullet traversed the tympanic cavity, spicules of bone may have caused laceration. In every case, however, all the branches were equally affected; the paralysis was absolute, and in none did any improvement occur while the cases were under my observation.

The following are a few illustrative examples:--

(111) Boer wounded at Belmont. _Entry_, immediately above
zygoma; the bullet passed through the temporal fossa, fractured
the neck of the mandible, traversed the mastoid process, and
emerged at the lower margin of the hairy scalp, 1 inch from the
median line. Facial paralysis was complete, and there was no
improvement at the end of ten weeks.

(112) Wounded at Magersfontein. _Entry_, at the posterior
border of the left mastoid process, 1/2 an inch above the tip;
_exit_, through the right upper lip at the junction of the
middle and outer thirds. There was considerable hæmorrhage from
the left ear. The injury was followed by complete deafness, and
facial paralysis, which showed no sign of improvement.

There was complete anæsthesia over the area of distribution of
the third division of the fifth nerve; this improved rapidly,
and at the end of five weeks was hardly to be detected; neither
at that time could any impairment of power on the part of the
muscles of mastication be detected. No impairment of the sense
of taste was noted.

(113) _Entry_, above the anterior extremity of the zygoma,
bullet retained. Primary hæmorrhage from ear. Complete facial
paralysis and deafness. Anæsthesia over distribution of
temporal branch of temporo-malar nerve, part of supra-orbital
area, auriculo-temporal nerve, and small occipital cervical
nerve. The muscles of mastication acted well. Ecchymosis below
the right mastoid process.

(114) Wounded at Paardeberg. 300 yards. _Entry_, at the
posterior border of the right mastoid process, 3/4 of an inch
above the tip; _exit_, the inner third of the left upper
eyelid. (Eye destroyed.) Complete right facial paralysis; deaf,
on right side cannot hear tick of watch either held close or in
contact. Purulent otitis media.

In this place I might mention two other cases of lesion of the seventh nerve secondary to wound of peripheral branches. In one a patient was struck by several fragments of lead from a bullet which broke up against a neighbouring stone. These for the most part lodged in the skin over the left orbicularis muscle, but one also lodged in the conjunctiva and was removed. Some ten days later the patient complained that he could not lift the upper lid. The levator palpebræ was normal, but spasm of the orbicularis held the eye firmly closed. The condition did not improve, and the patient was invalided home. He recovered later.

In another patient a bullet entered above the right zygoma and traversed the orbits, without wounding the globes. At the time no want of power of the muscles of the face was noted, but a year later there was evident weakness of the whole of the muscles of the right side of the face, with loss of symmetry.

In the former case the functional element was strong, but in both an ascending neuritis was probably present.

_Tenth nerve._--The pneumogastric was implicated in many wounds of the neck. I never observed an uncomplicated case, but laryngeal paralysis was temporarily present in two of the cases of cervical aneurism in which the wound crossed above the level of origin of the recurrent laryngeal branch, while in two others the recurrent branch itself was in close contact with the wall of the aneurism (p. 135). In all such cases signs of concussion or contusion of the nerve would be expected, judging from the similar results observed in the brachial nerves when the neighbouring artery was implicated. The only obvious symptoms occurring, however, were laryngeal paralysis and acceleration of the pulse. As the latter symptom was often observed in the cases of arterio-venous communication, wherever situated, and as the sympathetic nerve also lay in close contiguity to the wound track, it was difficult to ascribe it with certainty solely to the vagus lesion. In the two cases of high vagus injury the laryngeal paralysis steadily improved, and at the end of six months was apparently well; in the two others it persisted at the end of three months and a year respectively.

The nerve must have been very frequently damaged in wounds of the neck; it is possible that this injury may have been an important factor in the death of some of the patients with cervical wounds upon the field.

_Eleventh nerve._--I append the only case of localised spinal accessory paralysis I observed. This was one of my earliest experiences, and when I examined the neck, in the Field hospital, I assumed from the completeness of the sterno-mastoid and trapezius paralysis that the nerve was severed. The patient, however, made such a rapid recovery that it became evident that the nerve had been contused only, and that the recovery of function was not due, as is so often the case, to vicarious compensation by the cervical supply to the muscles.

(115) _Entry_, immediately to the right of the fourth cervical
spinous process; _exit_, at the anterior border of the left
sterno-mastoid opposite the angle of the mandible. The left
shoulder was depressed, the head inclined to the injured side.
There was evident spinal accessory paralysis, and marked
hyperæsthesia of the whole left upper extremity, most severe in
the circumflex area. The hyperæsthesia gradually disappeared in
a few days, and was clearly due to concussion and possibly
slight contusion of the cervical nerve roots. The spinal
accessory paralysis improved, so that the patient returned to
the front at the end of a month: when I saw him some four
months later the shoulders were held quite symmetrically.

The _twelfth nerve_ was occasionally damaged in wounds of the floor of the mouth. I saw no case of permanent paralysis.

_Injury to the systemic nerves._ _Cervical plexus._--Evidence of injury to the superficial branches of the cervical plexus was not rare; thus I saw cases of small occipital anæsthesia, and great occipital neuralgia, but none of motor paralysis from injury to the deeper muscular branches. I take it that the smallness of the branches, and the multiple supply possessed by many of the muscles of the neck, would both take part in rendering certain evidence of the injury of an individual motor nerve rare.

_Brachial plexus._--Injury to this plexus in the neck was common; the main peculiarity observed was the partial nature of the damage inflicted.

Thus injury to a single nerve, or to a complex of two or more, was far more common than one implicating the whole plexus. Again, while complete paralysis might affect one set of nerves, another might simply exhibit signs of irritation in the form of hyperæsthesia or pain.

The wounds producing these injuries varied much in direction; thus some crossed the neck transversely, some were obliquely transverse, while others took a more or less vertical course.

These same remarks hold good in the case of the nerves of the arm. In the upper half, especially, complex injury was not rare, while in the lower third affection of individual nerves was more common. Another important difference must be mentioned in regard to the upper and lower segments of the course of the brachial nerves; they are not only more widely distributed below, but also more fixed in position, a fact antagonistic to the escape of the nerve by displacement and liable to expose it to more severe contusion.

The latter point holds good in the forearm also; here, individual injuries often occurred.

While at work in the Field hospital alone I gained the impression that the musculo-spiral nerve would not retain the unenviable character of being the most vulnerable nerve of the upper extremity, since the chances of each individual nerve seemed about equal, putting the question of the long course of the musculo-spiral nerve against the humerus out of question. This expectation was, however, not confirmed, since the musculo-spiral itself, if not primarily affected, was so often the seat of secondary mischief in fractures of the humerus. The posterior interosseous branch seemed to exhibit a similar vulnerability to slight injuries, to be referred to later under the external popliteal of the lower extremity. Again, in complex injuries of the brachial plexus, or nerve trunks, the musculo-spiral branch rarely escaped being a member, if not individually singled out.

Of the _thoracic nerves_ I have little to say. They must have been often injured in the thoracic wounds, yet, as far as my experience went, intercostal neuralgia was uncommon, or at any rate not a special feature. One observation of interest, however, does exist; in the cases in which the ribs were fractured by bullets travelling across them within the thorax, pain was distinctly a prominent feature. This was no doubt referable to the facts that in such instances the intercostal nerves were especially liable to direct injury, and that this was often multiple. On one occasion a crop of herpetic vesicles developed along the course of a dorsal nerve in an injury implicating a single intercostal space posteriorly.

_Lumbar plexus._--Although not quite so well arranged to escape bullet wounds as the thoracic nerves, the lumbar, by reason of their deep position and the comparatively wide area they cover, together with the rarity of wounds taking a sufficiently longitudinal direction to cross the course of more than one or two branches, were also comparatively rarely damaged. I never saw an uncomplicated case of anterior crural paralysis, and rarely cruralgia. I think this is to be explained in two ways: first, that the trunk course of the nerve is short; secondly, that it lies in the inguinal fossa. The second fact is of importance, since wounds in this region were in my experience responsible for a considerable percentage of the deaths on the field or shortly afterwards. Such deaths probably occurred from internal hæmorrhage from the iliac arteries, and it was in such cases that the anterior crural nerve stood in greatest danger of injury. I also never saw a case of localised obturator paralysis. On the other hand, anæsthesia or hyperæsthesia in the area of distribution of the lumbar nerves in the groin, the external cutaneous and the long saphenous in the thigh, were not uncommon. Hyperæsthesia developed in more than one case in which injury to the psoas had led to hæmorrhage into the muscle sheath.

_Sacral plexus._--The sacral plexus is far more liable to extensive direct injury than either of the two preceding. Its cords are larger, gathered up into a much smaller space, and more liable to injury, from the fact that the slope in which they lie is more readily followed by a bullet track. Again, the cords rest for a considerable portion of their course on a bony bed, a particularly dangerous position in gunshot wounds, since the nerves are not only exposed to the danger of direct wound, or pressure from bony spicules, but also readily receive transmitted vibrations secondary to impact of the bullet with the bone.

None the less I had few occasions to observe extensive injuries of the plexus. In one instance damage particularly affecting the lumbo-sacral cord occurred, but this was complicated by signs of irritation of the anterior crural and obturator nerves, as the result of retro-peritoneal hæmorrhage and injury to the psoas muscle. Two cases in which the sacro-coccygeal plexus suffered isolated injury on account of their characteristic nature as gunshot injuries will be shortly quoted:

(116) _Sacro-coccygeal plexus._--_Entry_, at the junction of
the middle and posterior thirds of the left iliac crest; the
bullet passed obliquely downwards through the pelvis to lodge 3
inches below the right trochanter major. Incontinence of soft
fæces persisted for five weeks, and retention of urine during
three weeks.

This patient subsequently died on the homeward voyage, but I am
unable to say from what cause.

(117) _Entry_, over third sacral vertebra; _exit_, 2 inches
from the median line, and 1-1/2 inch above Poupart's ligament
on the anterior abdominal wall. Incontinence, with involuntary
passage of fæces, persisted during the first twenty-four hours,
and for two days the urine had to be withdrawn with a catheter.
No further signs of nerve injury were noted.

The same explanation of the comparative rarity of injuries to the sacral plexus that has been already given in the case of the anterior crural nerve holds good--viz. that in a great many of the pelvic wounds involving the plexus early death followed from the severity of the concurrent injuries.

Injuries to the great sciatic nerve outside the pelvis, or to one of its constituent elements, on the other hand, formed one of the most familiar of the nerve lesions. The wounds giving rise to these were of the most diverse character; some crossed the buttock in a vertical, transverse, or oblique direction; others travelled through the thigh in corresponding directions, while a third series involved both buttock and thigh.

The size of the great sciatic nerve renders complete laceration by a bullet of small calibre a matter almost of impossibility; hence complete division may almost be left out of consideration in the case of this nerve. On the other hand, partial division, perforation, and severe contusion are each and all favoured by the same factor.

With an extended thigh the nerve is in a state of comparatively slight tension, and this may be still lessened if the knee be flexed. This factor, together with the density of the sheath of the nerve, favours the possibility of displacement, and this occurrence is more likely in the lower segment than in the upper, which is comparatively fixed in position.

Clinical experience appeared to illustrate the importance of these anatomical factors, as the worst cases of sciatic injury that I saw were in connection with wounds of the buttock or the junction of that segment of the trunk with the thigh.

The most striking observation with regard to the injuries of the great sciatic nerve was the comparatively frequent escape of the popliteal element and the severe lesion of the peroneal. This was so pronounced as to amount to as high a proportion of peroneal symptoms as 90 per cent., and often when the whole nerve was implicated the popliteal signs were of the irritative, the peroneal of the paralytic type. When bullets crossed the popliteal space, given wounds of equal severity in corresponding degrees of contiguity to the respective nerves, the peroneal element always suffered in greater degree. Again, the peroneal nerve symptoms were more obstinate and prolonged, and instances of ascending neuritis were more common than in the case of any other nerve of the lower extremity, and the trophic wasting of muscles was more marked.

The peroneal nerve, therefore, acquires the same unenviable degree of importance in the lower extremity enjoyed by the musculo-spiral in the upper. Here, again, we are confronted with the fact that the peroneal element of the great sciatic nerve is the more prone to idiopathic inflammations or toxic influences, and hence we can only assume it to possess a special vulnerability. The peroneal element is of course somewhat the more exposed, as lying posterior; but it seems unreasonable to assume that so large a proportion of the injuries can implicate the posterior segment of the nerve as to make the startling difference in the incidence of degeneration explicable. In this relation we may bear in mind that the muscles supplied by this nerve suffer most in the degeneration subsequent to anterior polio-myelitis, and again that in cerebral hemiplegia or spinal-cord injuries they are the last to recover. Unfortunately no explanation of these remarkable facts, so forcibly impressed by the large series of cases with peroneal symptoms seen in a short time, is forthcoming.

I may dismiss the other branches of the sacral plexus in a few words. The small sciatic was occasionally injured in its course in the buttock, and the small saphenous in the leg. When either element of the latter was injured, it was surprising how sharply the imperfections in the anæsthesia corresponded with the composite character of the nerve.

CASES OF NERVE INJURY

The following cases are added mainly to give some idea of the comparative frequency with which the individual nerves were injured, and also to exemplify the more common forms of complex injury met with. Circumstances, unfortunately, did not always allow of extended observation at the time, and I have not been very fortunate in my attempts to obtain subsequent information on this series since my return. A certain amount of prognostic information is, however, furnished by some of the records, and I am very much indebted to my colleague, Dr. Turney, for help in this matter.

(118) _Brachial plexus._--_Entry_, 2 inches above the clavicle
at the anterior margin of the trapezius; _exit_, first
intercostal space, 1 inch from the sternal margin. Heavy dull
pain developed at once, extending down the upper extremity. A
fortnight later this pain still persisted; there was lowered
sensation in the ulnar area with formication, also lowered
sensation in the internal cutaneous area of distribution;
sensation in the lesser internal cutaneous area was normal. The
patient went home with the nerve symptoms well at the end of a
month.

(119) _Brachial plexus injury._--Wounded at Magersfontein.
_Entry_, at the anterior border of the sterno-mastoid opposite
the pomum Adami; _exit_, through the ninth rib below and 1/2 an
inch external to the scapular angle. Emphysema and considerable
blood extravasation developed in the posterior triangle of the
neck, also loss of power in the musculo-spiral distribution,
but no anæsthesia. At the end of the first fortnight there was
evident wasting of the muscles, but some power was returning in
the triceps. At the end of a month the man left for England,
with fair power in the triceps, but well-marked wrist-drop. A
year later the wrist-drop still persisted.

(120) _Plexus injury._--Wound of _entry_, over pomum Adami;
_exit_, below scapular spine, about centre. Complete median and
musculo-spiral paralysis.

(121) _Median, musculo-cutaneous, and musculo-spiral
nerves._--The wound traversed the axilla from just beneath the
anterior fold; three weeks later a firm mass in the axilla
corresponded to the wound track. Hyperæsthesia developed in the
area of median distribution, with deep pain in the muscles.
There was rigidity of the biceps cubiti and slight wasting in
the radial extensors. The patient improved slowly, and
eventually was discharged and passed out of sight.

(122) _Brachial nerves._--Wounded at Paardeberg. Range 500
yards. _Entry_, at the front of the arm, 2 inches below the
junction of the anterior axillary fold; _exit_, a little lower,
at the back of the arm, in the line of junction of the
posterior axillary fold.

Considerable shock attended the primary injury; when reaction
had taken place, complete motor and sensory paralysis was noted
of the whole upper extremity, with the exception of some power
of movement of the posterior interosseous group of muscles.
Three weeks later the patient could extend the wrist, but
sensation was imperfect in the arm, and completely absent in
the forearm and hand. The track was now hard and palpable, but
there was no hyperæsthesia in any area; when the track was
manipulated slight formication in the hand was experienced. The
biceps and triceps were equally paralysed. There was no wasting
in any of the muscles.

(123) _Brachial nerves._--Wounded at Modder River. _Entry_,
through the anterior axillary fold at its junction with the
arm; _exit_, on the posterior wall of the thorax, 1/2 an inch
from the median line at a level with the angle of the scapula.
Complete musculo-spiral paralysis; hæmothorax. Three weeks
later, radial sensation returned; but the triceps was very
weak, and wrist-drop was complete. There was some wasting of
the muscles supplied by the median and ulnar nerves, and
complete obliteration of the radial pulse. A year later the
musculo-spiral paralysis still persisted.

(124) _Musculo-spiral and median._--Wounded at Magersfontein.
_Entry_, 3 inches below the anterior axillary fold, on the
inner aspect of the arm; track passed obliquely downwards
behind the humerus to a point on the outer aspect of the arm
1-1/2 inch below the level of the entry. The humerus escaped
injury. Musculo-spiral paralysis was complete; hyperæsthesia in
the distribution of the median followed some days later. One
month subsequently radial sensation had returned, and a feeling
of numbness had taken the place of the median hyperæsthesia.
The triceps and marginal muscles were much wasted, and only
interosseous extension was possible in the fingers.

(125) _Brachial nerves._--Wounded at Magersfontein. _Entry_ and
_exit_, in the upper third of the arm internal to the humerus.
Complete median paralysis, anæsthesia in the ulnar area, and in
the radial supply to the dorsum of the middle and ring fingers.
Could flex, extend, and adduct and abduct the wrist; some power
of flexion in index finger, in others none. The flexion of the
wrist was dependent on the ulnar supply to the muscles of the
forearm. No wasting of the interossei, skin normal except for a
large trophic blister on the dorsum of the hand. Little
improvement had taken place in this patient at the end of a
year.

(126) _Brachial nerves._--Wounded at Magersfontein. The wound
traversed the lower part of the upper third of the arm,
fracturing the humerus. Immediate complete loss of power in the
arm was experienced, together with loss of all sensation. Three
weeks later the humerus was united; the fracture was evidently
the result of passing contact, and not of direct impact. The
paralysis was still complete in the distribution of the median,
ulnar, and musculo-spiral nerves. There was considerable
wasting of the hand and forearm, and a good deal of thickening
in the lower third of the arm.

Four months after the original injury, the nerves were explored
by Mr. Eve, who kindly gives me the following information. All
the nerves and vessels of the arm were united into one firm
bundle by cicatricial tissue. When dissected clear, the median
nerve was found to be thickened and enlarged for about 1-1/2
inch of its length; the ulnar was not completely freed, but was
found to be continuous and indurated; the musculo-spiral was
also intact, but at its entrance into the humeral groove a mass
of callus was felt. A sclerosed and thickened portion of the
median nerve 3-1/2 inches in length was resected, also 1 inch
of sclerosed ulnar nerve, and both were sutured. The
musculo-spiral nerve was left for future exploration. A small
traumatic aneurism was found on the brachial artery, and the
vessel was ligatured above it.

Ten months later no improvement in the median or ulnar nerves.
Electrical reaction present in musculo-spiral group of
muscles.

(127) _Musculo-spiral._--Transverse wound through arm posterior
to humerus. Slight suppuration. Triceps weakened only, complete
paralysis of radial extensors and posterior interosseous group.
Radial sensation lowered only.

(128) _Musculo-spiral._--_Entry_, 2 inches above and 1/2 an
inch behind the external humeral condyle; _exit_, at the inner
edge of the biceps, 1/2 an inch lower in the arm than the
entry. It is doubtful whether the paralysis was noted at first,
but a few days later complete posterior interosseous paralysis
and lowered radial sensation were remarked. No change except a
deepening of the anæsthesia, and the development of formication
on manipulation of the wound occurred, and at the end of three
weeks the nerve was exposed (Mr. Watson), and it was found that
a notch had been cut in its outer border, which had opened out
into a V shape. The margins of this notch were refreshed and
the gap closed. Ten days later radial sensation was fairly
good, but the motor symptoms remained unchanged. Nine months
later steady but very slow improvement was reported.