918
SECTION III
NEUROSURGERY
CHAPTER IX
ENSORY
DISTURBANCES IN PERIPHERAL NERVE LESIONS a
For
many years it has been noted that total loss of sensation after
complete division of a
peripheral nerve is limited to a much smaller area than one would
expect from its anatomic
distribution. Likewise, it has been observed that following injury of a
peripheral nerve sensory
symptoms may rapidly diminish and at times loss of sensation to pin
prick be entirely absent.
That severe, widespread anesthesia results only from trauma of several
nerve trunks of a plexus,
has generally been accepted. Lesions of single nerves result in partial
anesthesia, or, if a severe
anesthesia be present, the area of complete loss of sensation rapidly
shrinks.
Many
attempts have been made to explain these phenomena. Some of the older
theories
were to the effect: (1) That nerve fibers grow from healthy
surroundings into the insensitive
parts; 1 (2) that after section of a nerve, stimulation of the severed
part may pass through an
accessory branch into an adjacent nerve and reach the major branch of
the injured nerve above
the lesion, through a second lateral branch (collateral innervation); 2 (3) that numerous
anastomoses connect the peripheral ramifications of sensory nerves,
many cutaneous areas
receiving their innervation from different nerves.3 All
these opinions have undergone
important changes since the investigations of Head and his coworkers.
The results of their
studies led Head and Sherren 3 to conclude that the sensory
mechanism in the peripheral nerves
consists of the following three systems:
(1) Deep sensibility, capable of answering to
pressure and to movement of parts and even capable of
producing pain under the influence of excessive pressure, or when the
joint is injured. The fibers, subserving this
form of sensation, run mainly with the motor nerves, and are not
destroyed by division of all the sensory nerves to
the skin. (2) Protopathic sensibility, capable of responding to painful
cutaneous stimuli, and to extremes of heat and
cold. This is the great reflex system, producing a rapid, widely
diffused response, unaccompanied by any definite
appreciation of the locality of the spot stimulated. (3) Epicritic
sensibility, by which we gain the power of cutaneous
localization, of discrimination of two points, and of the finer grades
of temperature, called cool and warm.
Head
and Sherren 4 state that in complete division of a mixed
nerve, as the median or
ulnar, the area it supplied does not become uniformly insensitive.
Whereas previous observers
have stated that sensation is diminished over the full area usually
assigned to the injured nerve
and lost completely over a small portion only, they have shown that
this diminution of sensation
is
a The statements of fact appearing herein are
based on "Overlap of So-Called Protopathic Sensibility as Seen in
Peripheral Nerve Lesions." by Maj. Lewis J. Pollock, M. C., Archives of
Neurology and Psychiatry, 1919, ii, No. 6,
667.
919
in reality a total loss
of sensibility to stimulation with cotton wool, to the compass test, to
the
painless interrupted current, and to temperatures between 22? C. and 40? C. In this area are felt
only the stimuli affecting the protopathic sensibility, such as the
prick of a pin and temperatures
below 20? C. and above 40? C. The area rendered
insensitive to light touch by division of the
median or of the ulnar nerve varies little in extent. In sharp contrast
to this slight variation is the
extreme difference in surface extent of the loss of sensation to a pin
prick which follows division
of either of these nerves. " The consequence of both division and
irritation of these nerves shows
that as far as protopathic sensibility is concerned they overlap to an
enormous extent."'
It
is evident, therefore, that the complete sensory distribution of a
peripheral nerve
consists of its exclusive supply, or that area in which loss of
sensation is produced by its
division, and in addition its overlap or the are a determined by the
limits of. skin sensitive to
stimuli when all the adjacent nerves have been severed. Head and
Sherren, employing the
method of residual sensibility, were able to determine the complete
sensory distribution of some
of the nerves. These areas were part of the distribution of the median,
the internal saphenous,
part of the external popliteal, the external saphenous and part of the
posterior tibial nerves.
The
purpose of the present chapter is: First, to record the smallest area
of loss to prick
pain which follows interruption of the various peripheral nerves;
second, to point out the relative
smallness of this area as compared to the area of loss to touch; third,
to show that the
preservation or early return of prick pain as compared to tactile sense
is due to the assumption of
function of adjacent nerves, and not to nerve regeneration, as
interpreted by Head; and, fourth, to
outline the total sensory distribution of some of the peripheral nerves
by residual sensibility.
MATERIAL
Observations
were made on 500 patients with peripheral-nerve lesions seen early in
base
hospitals in France, and 520 patients with peripheral-nerve lesions
studied later at United States
Army General Hospital No. 28, Fort Sheridan, Ill.
The
observations of early peripheral-nerve lesions were in most instances
uncontrolled
by operative procedures. The major portion of the lesions were partial
and frequently
complicated by injuries to adjacent small sensory branches. But these
observations served a
useful purpose. They showed:(1) That in many cases for the first two or
three weeks only a very
small area within the border of the part insensitive to cotton wool was
sensitive to pinprick; (2)
that in a few a larger zone sensitive to pin prick appeared within15
days; and (3) that the return
of sensitiveness to pin prick in a larger zone, corresponding to the
area which was later
determined as overlap, usually was found, at times variable from 30 to
100 days. The cases
showing return to pinprick over a large area in less than 30 days were
predominantly cases of
radial and musculospiral lesions.
The
material of peripheral-nerve lesions studied later may be divided into
two groups:
The first, a group of 391 cases uncontrolled by operation, and in
920
the majority of
instances recovering spontaneously: the second, a group of 129cases
controlled
by operation, which many be tabulated as follows:
CHART
General
impressions relative to the sensory changes in peripheral-nerve lesions
were
derived from the whole material. The areas of total nerve supply and of
overlap were obtained
only from cases certified by operation. The cases which have been used
in the study of
regeneration of nerves likewise were certified by operation. Therefore,
although the whole 1,020
cases contributed to the general conclusions concerning these problems,
only one group,
consisting of the cases coming to operation, was employed in obtaining
the data which serve as
the basis for the special conclusions contained herein.
METHODS OF
INVESTIGATION
The problems under investigation were not
studied from a
psychological standpoint. The
areas of overlap were found in the course of clinical examinations of a
large group of cases. The
methods of examination, therefore, were those ordinarily used
clinically. The sense of touch was
tested by a wisp of cotton. The sensation of pain in response to the
prick of a pin was ascertained
By using a weighed needle sliding within a bit of glass tubing so that
with different weighed
needles a pressure of from 5 to 35 grains could be applied.
Although
in this chapter temperature sense will not be referred to because of
the
difficulty of standardizing methods and the impossibility of employing
the finer methods
clinically, it may be stated that for the rough examination of sense of
cold, a pledget of cotton
twisted to a point and saturated with ether was used. This method
permits a less diffuse type of
stimulation and has the advantage of case and simplicity. For
physiologic research this method
is, of course, inapplicable. Light touch with a wisp of cotton to
determine sense of touch may be
accepted if the exact threshold of sensation is not under
investigation, and if exact borders of loss
of sense of touch be not insisted on. For the purposes of this
investigation, the exact borders of
loss of sense of touch need not be insisted on. Only one factor must be
considered in this method
of examination, namely, return of so-called hair sensibility must not
be confused with touch;
hence, in testing for touch where an accurate border was to be
determined, the parts were closely
shaven.
The
degree of pressure which it is permissible to employ in determining
prick pain
without jeopardizing the results by confusion with pressure pain
921
remains to be discussed.
Although, as pointed out by Head and Sherren, 6 deep
sensibility may
be evoked when testing for touch with a stiff roll of wool, this
objection is not valid for
determining prick pain within certain limits. A sharp needle was used
by Head and Sherren in
their early clinical investigation, care being taken to differentiate
between sense of deep pressure
and true pain. Boring 7 says: “In determining the pain
threshold it was especially necessary not to
exceed pressures of 6 gm. Although at high intensities of stimulus the
introspective difficulty of
abstracting from pressure was less with pain than with cutaneous
pressure, the greater intensities
frequently drew blood and therefore were abandoned." As in Boring's
work it was necessary to
examine a small area of skin repeatedly and at very short intervals
for all forms of sensation,
his objection is valid. On the other hand, with the World War cases
under consideration, it was
necessary only to examine sense of prick pain in areas of overlap and
not to confuse this pain
with pressure pain. In these cases pain was never found to result from
35 gin. of pressure with a
blunt object, and since care was taken to obtain from the patient
responses only to pain from
prick of a sharp point, it is believed that pressure of even 35 gm. is
permissible to map out the
overlap of sense of prick pain. No exact measurements of threshold to
prick pain were made and
in the majority of cases pressure did not exceed 30 gm.
EXCLUSIVE NERVE SUPPLY
Recognizing
that, following section of a mixed nerve, the loss to prick pain
occupies an
area much smaller than the loss to touch, it first was necessary to
ascertain the smallest area
which is insensitive to pin prick following section of various nerves.
This would indicate the
limits of any possible overlap.
Although
only a small portion of the area insensitive to touch is quite
insensitive to pin
prick, diminution of pain sense is present in a large part of the area
insensitive to touch, and if
graduated degrees of pressure be employed, concentric rings of
analgesia are demonstrated.
However, we are concerned not with the question of whether any
hypalgesia is present, but
whether any portion of the skin is at all sensitive to pain, provided
this pain be due to superficial
sensibility. If a part of the skin is sensitive to pain, when a nerve
is divided, this sensation must
be derived from some source other than this nerve.
To
delineate the area exclusively supplied with pain sense by a given
nerve one of two
conditions must be present: First, the presence of pain sense having
been demonstrated within
the area of a nerve's supposed anastomic supply, that nerve is found at
operation to be divided,
and the ends separated. Second, the nerve having been seen to be
divided, presence of pain sense
is demonstrated in its distribution within the length of time given for
the return of protopathic
sensibility (Head, Rivers, and Sherren, 43 days). In the cases under
the second condition 28 days
was the limit, with the exception of the radial nerve, in which the
limit was 37 days.
The
relatively small number of cases studied does not warrant an attempt to
outline the
exclusive supply of peripheral nerves to both epicritic and protopathic
sensibilities. Suffice it to
say that the results as to the nerves in the
922
hand are in general accord with Stopford,8 who found in the ulnar nerve some variation from the accepted area of
epicritic sense in 20 per cent of the cases and in the median nerve in
38 percent. In three eases of median nerve section anesthesia was
present
over the dorsal surface of the
distal phalanx of the thumb.
FIG. 127.- Sensory changes
in ulnar nerve
lesions: Diagonal lines, anesthetic to touch; black lines, loss of
prick
pain
and touch sense; continuous line, borders of loss of temperature sense.
The same scheme of charting is followed in
all of the diagrams. Where duplication of letters occurs, the first is
preoperative and the second postoperative
sensory chart
In
ulnar-nerve lesions superimposing the outlines of complete analgesia,
in the cases
shown in Figure 127, the smallest area of analgesia was found to occupy
the palmar and dorsal
surfaces of the little finger, extending over the dorsal surface of the
hand in a triangular area over
the fifth metacarpal boneto one-third of its length (fig. 128). The
area included between the
borders
923
of the accepted supply of the ulnar nerve and
the borders of this analgesia represents the possibly
supply of overlapping nerves to pain sense.
The
inner border of the smallest area of exclusive supply to pain of the
median nerve was
obtained in the same way from cases in which the median nerve was
subsequently found to be
divided (fig. 129, g, h, i, j).
The outer border was obtained from
these cases and in addition from
cases of combined ulnar and median lesions which at operation were
likewise found to be
anatomic divisions, with the ends separated (fig. 129, a, b, c, d, e,
f, k). The exclusive supply of
the median nerve to pain sense was found to occupy the dorsal and
palmar surfaces of the distal
phalanges of the index and middle fingers, the ulnar half of the palmar
surface of the second
phalanx of the index finger, part of the ulnar portion of the distal
half of the second phalanx of
the middle finger and the dorsal surface of less than half of the
second phalanges of the index
and middle fingers. Despite the fact that this small area of total
analgesia in median
FIG.
128.- Smallest
composite area of
analgesia in ulnar nerve lesions nerve lesions
nerve lesions has been
recognized, 9 it is necessary at this point to call special
attention
to this observation as from the
study of this nerve much evidencerelative to overlap was obtained (fig.
130).
The
cases of radial nerve lesions, certified at operation or examined
lessthan 37 davs
after resection and suture, showed a wide variety of areas of analgesia
and in one case no
analgesia at all. (Fig. 131, a to m.)
Although
not infrequently recorded, no case of radial nerve lesion wasobserved
which
did not show loss of sensation to touch. Of all the peripheralnerves,
the radial shows the greatest
variation in the areas of loss of sensationto both epicritic and
protopathic sensation. This is due
to the fact that sixnerves are concerned with the sensory supply of the
dorsum of the hand;
themedian, radial, antibrachii, posterior branch of the musculospiral.
musculo-cutaneous, and
ulnar.
Stopford 8 emphasizes, as do Head
and Sherren,4 the importance of theinusculocutaneous nerve
in the supply of the dorsum of the hand, and states
924
FIG. 129. – Sensory
changes in median
nerve lesions: G, H J, radial and mediain; I, ulnar and
median: B. E. ulnar, median, and internal cutaneous; A,
C, D, E, ulnar median, and
musculocutaneous, K
FIG. 130.- Smallest composite area of
analgesia in median nerve lesions
925
that its terminal branches may extend oil to
the dorsum of the metacapus, and “it appears that the
extent of its distribution varies inversely with that of the radial."'
Although this may be true, it
must not be forgotten that the median nerve must be considered in the
supply of sensation to the
dorsal area over the distal portion of thethumb
FIG. 131.- Sensory
changes in radial
nerve lesions
One
of the reasons for vary ing reports relative to the sensory loss in
radial nerve lesions
is the hairy nature of the area of skin under investigation. The return
of hair sensibility
frequently is confused with the presence of settseof touch. The skin
must be closely shaved in all
cases where examination of touch is contemplated. No area of skin is
exclusively supplied by
the radial nerve for prick pain.
926
FIG.
132.- Sensory changes
in external
popliteal lesions
The
area of exclusive supply of pain of the external popliteal nerve was
obtained from
certified cases of division and cases examined less than 37 days
following resection and suture
(fig. 132, a to h). The area consists of a narrowband
extending from a point a little above the
junction of the lower and middle one-third of the outer surface of the
leg, diagonally across the
dorsum of the foot to a point over the middle of the metatarsal bone of
the great toe. It is
interrupted at the junction of its lower and middle one-third by an
area which is sensitive to pin
prick. The area is due to the overlap on one side of the internal
saphenous nerve and, on the other
side, the internal popliteal nerve. Although a number of cases showing
such an interruption in
the band of analgesia have been observed, they have not fulfilled the
requirements demanded in
estimating exclusive supply. One case, Figure 132, e, showed
this type of interruption of the
band of analgesia 27 days after resection and suture.
FIG. 133.- Smallest
composite area of
analgesia in external popliteal lesions
927
Another case which was examined 53 days after
resection and suture is shown in Figure 132, d,
but was not used in estimating the isolated supply. The external
popliteal nerve has a
surprisingly small exclusive area of pain sense(fig. 133).
The
area of the sciatic nerve was obtained from cases certified to be
anatomic divisions,
Figure 134, a to f. This area is illustrated in Figure
135 and need not be described.
Inasmuch
as the results above illustrated represent the smallest area of
exclusive supply
of various nerves for pain, it is necessary to define to what
FIG. 134.- Sensory
changes in sciatic
nerve lesions
extent they may be used in formulating our
ideas relative to nerve overlap. It is recognized that
in some instances such small areas may be present only when we are
dealing with the group of
25 percent of cases showing unusual distribution of sensory nerves.
These areas are used,
therefore, only in establishing a certain limit beyond which it is not
permitted to go in
interpreting return of sensation to pain as a sign of nerve
regeneration. Any return of sense of
pain in regions without these borders may be due to unusual nerve
distribution or sensory
overlap, and represents possible areas of overlap. It will be found
that the areas of overlap,
described below, are not as extensive as these areas would permit us to
assume were we to use
exclusive pain sensibility as an indication of the borders of overlap.
928
NERVE OVERLAP
The
return of sensibility to pin prick, which takes place before the return
of sensibility to
touch, occurs in regions which occupy the areas of nerve overlap, and
this return of sensibility to
pin prick can not be interpreted as a sign of nerve regeneration.
This
view is supported by the facts that no return of sensibility to pain
was found when
sensibility to touch had not returned, except in an area of overlap;
that when a nerve is divided
and at the same time one or more adjacent nerves are divided sensation
to pin prick does not
return in the area of the overlap of these nerves even many months
following the injury; that when a nerve adjacent to one which is
severed and which supplies an area of overlap to that
nerve is sectioned, the preexisting sensibility to pin prick in the
overlap area is lost; that when sensibility to pin prick is present
within the anatomic sensory distribution of a severed nerve
resection and sature has no effect on the general outline of this area
of sensibility.
Within
two weeks after the occurrence of a peripheral-nerve lesion the area of
analgesia
usually nearly coincides with the area of anesthesia. Some cases showed
an intermediate zone or a shrinkage of the analgesic area within 15
days. In from 30 to 100 days the majority of
cases showed the presence of a shrinkage to an extent which was later
identified with overlap. It is probable that the cases would have shown
the same
FIG. 135.- Smallest
composite area
of analgesia in sciatic nerve lesions
extent of shrinkage in less than 100 lesions
days, but conditions were such that in these cases the
first record available was obtained 100 days after the injury.
Certainly the majority of cases
showed the shrinkage to be well established under 50 days. Some months
after the injury had
been received the shrinkage was present and the remaining area of
analgesia has been described
above as the exclusive sensory supply for pain sense in various
peripheral nerves.
The
shrinkage of the analgesic area can be due to but two conditions: Nerve
regeneration,
or the assumption of function by adjacent nerves. If any overlapping of
peripheral nerves is
possible, it becomes necessary to define the extent of this overlap
before any return of sensation
can be interpreted as a sign of nerve regeneration. So far as it can be
ascertained, no evidence
has ever been adduced to show that overlapping nerves functionate
929
immediately following the injury of an
adjacent nerve. Neither have the laws of dual innervation
been clearly defined. Until this is accomplished, it is illogical to
infer that return of sensation in
the area of an overlapping nerve is a sign of nerve regeneration and is
not caused by the
functioning of this over-lapping nerve. If the shrinkage of the area
insensitive to pin prick
responsible for the increase in size of the intermediate zone be a sign
of nerve regeneration and
not a result of overlap, it should occur whether the adjacent nerves be
intact or not. This,
however, is not the case, as will be shown. In other words, if certain
areas of skin become
sensitive to pain or are found sensitive to pain following section of a
given nerve, and the
condition is due to nerve regeneration, then section of the adjacent
nerve would have no effect
on the appearance of this sensibility.
FIG. 136.- Sensory changes
in combined lesions
of the ulnar, median, and internal cutaneous nerves
SECTION OF NERVES
SECTION OF
ADJACENT NERVES
Although
in isolated lesions of the ulnar nerve sensibility to pain is
frequently seen on the
ulnar half of the ring finger, this is never observed when the median
nerve is divided at the same
time (fig. 136, a, f). Although isolated lesions of the
ulnar and of the internal cutaneous nerves
always show that the distal end of the analgesia resulting from a
lesion of the internal cutaneous
and the proximal end of the analgesia resulting from a lesion of the
ulnar, do not
930
meet, no instance is found in combined
lesions of the ulnar, median, and internal cutaneous
nerves where an area between the borders of the analgesia of the
internal cutaneous and ulnar
nerves is sensitive to pain (fig. 136, b, c, d, e, h, i, j).
When
the ulnar, radial, and median nerves are divided, a year may follow
their division
and no shrinkage of analgesia be found on the palmar or dorsal surface
of the hand except on the
proximal portion of the analgesia where the musculocutaneous and the
antibrachii posterior areas
adjoin the analgesic area (fig. 137, a, b, d).
When a radial lesion is combined with a median,
analgesia is always present on the radial part of the palm. When a
median lesion or a radial
lesion alone is present, this part of the palm is usually sensitive to
pin prick (fig. 137, d, e, f, g).
FIG. 137.- Sensory
changes in combined lesions
of the ulnar,
radial, and median nerves, A, B, C, and of the median and radial, D, E,
F, G
Isolated
lesions of the external popliteal nerve (which corresponds closely to
the fifth
lumbar root) may show only a small area of analgesia, but when the
internal popliteal as well as
the external popliteal is severed, there is never found any shrinkage
of analgesia or reappearance
of sensibility to prick pain in the zone where the supply of the
external popliteal meets that of the
internal popliteal (fig. 138, a to g).
It
can be definitely stated that when nerves supplying adjoining areas are
severed,
sensation to pain is at no time present in the border areas where it is
uniformly observed when
either nerve is divided alone. Inasmuch as a large number of the cases
observed had resections
and sutures performed at least three months prior to the last
examination, it may be stated
likewise that no
931
sensation to pain returns in such areas in
the time given for the beginning of regeneration of
protopathic sensibility.
EFFECT OF SECTION OF AN OVERLAPPING NERVE
When
return to sensibility to pain or presence of sensibility to pain is
found in the area of
overlap of an adjacent nerve, analgesia will result if this nerve is
severed. This is well illustrated
in the case shown in Figure 129, g, page 924. This patient had
a partial ulnar lesion combined
with a complete section of the median. Prick pain was preserved in the
radial portion of the
FIG. 138.- Sensory changes
in combined lesions
of internal and external popliteal portions of sciatic nerve palm and
the index finger. When at operation the superficial radial nerve was
resected for use as a cable transplant, this part of
the palm became analgesic (fig. 137, e).
EFFECTS OF RESECTION AND SUTURE ON EXISTING
OVERLAP
Following
resection and suture when sensibility to pain is present in an area of
overlap,
although some change in the outline of this area occurs, in general the
area remains the same. At
times the borders show some increase in analgesia; much more frequently
they show a shrinkage
of the analgesia. Slight changes in the borders of an area of analgesia
can not be used in arriving
932
at a hard and fast conclusion. Frequentlv
these borders chance in an astonishing manner for pain
produced by higher degrees of pressure by a sharp point not sufficient
to produce pressure pain.
The laws
governing dual innervation have not been clearly ascertained. What
effect, if
any, the handling of nerves or freshening of their ends may have on
inhibition is unknown.
Another fact in support of the statement that return of sensation in an
area of possible overlap
can not be ascribed to the regeneration of a nerve is that this area is
not generally changed by
resection and suture of a severed nerve.
FIG. 139.- Sensory changes
before and after
resection and suture or the ulnar, and median nerve
The
conditions necessary to study profitably the effect of resection and
suture of nerves
on return of sensibility to pain are: First, that the nerve ends be
separated, and, second, that the
examination subsequent to the operation be made within the period of
time ascribed to the return
of protopathic sense. Some difficulty is encountered in meeting the
second condition inasmuch
as frequently the wide separation of the ends of the nerves makes it
necessary to place the
extremity in a position which will permit approximation, and to fix it
in such a position by
means of a case. This often prevents an examination before six weeks
have elapsed. None of the
cases under consideration were examined later than 50 days after
operation, one in less than 1a
days. Although some objection may be made to the cases examined over 45
days after operation
on the grounds of beginning return of protopathic sense due to
regeneration,
933
the similarity of the areas unaffected by
operation in cases examined under 45 days and those
between 45 and 50, coupled with the facts that the ends of the nerves
were separated in all of
these cases, makes it reasonable to admit them into the group.
To
describe again the areas sensitive to pin prick in the lesions
examined. or to attempt
by description to show the sensory changes following operation, is
needless. They are clearly
indicated by Figures 139 and 140. It is sufficient to state that the
following nerves were studied:
Ulnar, examined 42 days after operation (fig. 139 a); median, 8
days after operation (fig. 139 f);
ulnar and median, 45, 36, 40, 46, 48, and 14 days after operation (fig.
139, b, c, d, e, q, h);
external popliteal, 48, 36, 20, and 26 days after operation (fig. 140 a, b, c, d); sciatic, 50and 36
days after operation (fig. 140 f, h).
FIG. 140.- Sensory changes
before and after
resection of external popliteal and sciatic nerves
RESIDUAL SENSIBILITY
If
we assume the relatively early return of sensibility to pin prick to be
due to overlap it
becomes possible by the method of residual sensibility to outline the
borders of overlap of the
various peripheral nerves.
The
method of residual sensibility is based on the assumption that
following section of a
given nerve, the area of skin, in its anatomic distribution in which
sensation remains, is
subserved by the intact adjoining nerves distributed to that area. For
example, four nerves supply
the palmar surface of the hand: The ulnar, median, musculocutaneous,
and radial. If two--the
ulnar and
934
median-are severed, what sensibility remains
is subserved by the musculocutaneous and radial. If then the
borders of the musculocutaneous be determined, that which remains is
radial.
In
employing this method certain precautions must be observed. For
example, we can
not take the outer border of the analgesia on the dorsal surface of the
hand in an ulnar section to
be any part of the border of the overlap of the median unless we may
observe the effect of a
combined ulnar and musculospiral so that the overlap of the latter
nerve be not included.
Similarly, we can not outline the border of the overlap of the median
on to the radial unless
FIG. 141.- Sensory changes
in lesions of median, internal cutaneous,
combined median and radial nerves, B, G, M, from which the residual
sensibility of the ulnar nerve was obtained and of the ulnar and
internal cutaneous radial, combined radial and median nerves, H, J, M,
from which the residual
sensibility of the median nerve was obtained
we have had a combined lesion of the ulnar and radial to indicate the
distribution of the ulnar; or
the overlap of the radial to the median on the palm unless we have had
a combined median and
musculocutaneous lesion, or the overlap of the internal popliteal to
the external popliteal unless
we have had a combined lesion of the external popliteal with the
internal saphenous. The
necessity for these combinations reduces the number of cases available
for conclusions to a very
few. As a result the areas of overlap as outlined probably were smaller
than the real overlap.
However, the extent of overlap was sufficiently large to prove that it
is within such an area that
return of sensibility to pin prick occurs soon after injury of
peripheral nerves.
935
It
is hardly necessary to state that the cases studied must have nerves
recently resected or
he examined prior to an operation which reveals the ends of the nerves
separated.
In
illustrating the areas of overlap the space between the borders of the
overlapping to
adjacent nerves has been blocked out with black. The black area
therefore represents the total
supply to pain of the various nerves studied. The area of actual
overlap would be that part of the
total sensory supply to pain which extends beyond the accepted sensory
limit of the adjacent
nerves. The restrictions of the methods necessary to obtain these areas
are responsible for an
indicated area of total supply, which in some instances is smaller than
is actually present, as may
be seen in the case of the outer border of the ulnar on the dorsal
surface of the hand and the inner
border of the external popliteal on the back of the leg (figs. 143, p.
9,36, and 147, p. 938).
FIG. 142.- Residual
sensibility to prick pain
of the ulnar nerve
The
area of total supply to pain of the ulnar nerve was obtained by the
method of residual
sensibility from a median lesion, an internal cutaneous lesion, and a
combined median and radial
(fig. 141, b, g, m). It occupies the ulnar
portion of the palm to a line which is a continuation of
the ulnar border of the abducted index finger, the palmar surface of
the fingers except the terminal phalanx and one-third of the ulnar part
of the second phalanx of
the middle finger. On the
dorsal surface it occupies the ring, little, and more than the ulnar
half of the proximal, one and a
half phalanges of the middle finger, and the dorsum of the hand to the
radial border of the fourth
metacarpal bone, ending proximally 1 inch above the wrist (fig. 142).
The
area of the median nerve was obtained from an ulnar and internal
cutaneous lesion, a
radial, a combined radial and median lesion, and cases of combined
radial and ulnar lesions (fig.
141, h, j, m). The inner border on the palmar
surface was obtained by the method of residual
sensibility from an ulnar and internal cutaneous lesion. As to the
dorsal surface it was necessary
to employ another method, as the cases of combined ulnar and radial
lesions were too recent to
have had return of prick pain due to overlap. The border
936
of overlap of the musculocutaneous to the
radial was obtained by means of residual sensibility in
a ease of combined radial and median lesion. Inasmuch as the radial has
no isolated supply to
prick pain, this border separates the musculocutaneous from the median
overlap. Therefore, this
border was used as the proximal border of the median overlap to the
radial nerve, especially in
such cases as showed an area of analgesia between the areas of overlap
of the median and
musculocutaneous nerves (fig. 141). Part of the inner border of the
over-lap on the dorsum of the
hand is hypothetical and shown as a rough border (fig. 143).
The
total supply of the musculospiral nerve was obtained from cases of
combined ulnar
and median nerve lesions, a ease of combined ulnar, median, and
musculocutaneous lesions and
a ease of combined ulnar and internal cutaneous lesions (fig. 141, a, d, e, f, h, i, k, 1, m, n). An
overlap onto the palm was found to an extent heretofore undescribed. In
median nerve lesions
the sensibility
FIG. 143.- Residual
sensibility to prick pain
of the median nerve
to pain in the palm has frequently been
ascribed to ulnar overlap. But. Athanassio-Bénisty 9recognized the importance of the
musculospiral and the musculocutaneous nerves in this
condition.
The
area of overlap on the palm of the musculospiral nerve extends over the
radial part of
one and a half phalanges of the index finger, the radial part of the
proximal phalanx of the
middle finger, and the web between the middle and ring fingers, all of
that part of the hand
external to a line continuous with the radial border of the middle
finger. Internally, it extends
from the middle of this line to the middle of the base of the first
phalanx of the ring finger and
proximally to the middle of the outer surface of the wrist, from which
point the border extends in
a line to a point 1 inch proximal to the base of the metacarpal bone of
the thumb on the radial
border of the wrist. This area occupies the entire dorsal surface of
the hand with the exception of
a strip one-half the width of the little finger on the ulnar border,
the little finger, the distal two
phalanges of the ring finger, most of the distal two phalanges of the
middle
937
finger and a little more than the distal
phalanx of the index finger. The area on the forearm need
not be described (fig. 144).
The
inner border of the pain area of the musculoeutaneous nerve on the
anterior surface
of the forearm was obtained from the residual sensibility following
section of the internal
cutaneous nerve; the inner border on the dorsal surface of the forearm,
from a musculospiral
division. The distal border on the palm was obtained from radial
lesions, a combined radial and
median lesion, and from lines obtained in combined ulnar and median
lesions where an area of
analgesia existed between the areas of overlap of the musculospiral and
the musculocutaneous
(fig. 141, e, f, k ). On the dorsal surface of
the hand combined sections of ulnar, radial, and
median and a case of combined radial and median
FIG. 144.- Residual
sensibility to prick pain
of the musculospiral nerve
FIG. 145.- Residual
sensibility to prick pain
of the musculocutaneous nerve
were employed (fig. 137, a, b, e, f; fig. 141, m, h, j). The
area of total sensory supply to pain of
this nerve can be better appreciated by viewing the illustration than
by description (fig. 145). The
proximal limits of both the musculocutaneous and musculospiral nerves
are hypothetical.
Fortunately
two cases were obtained from which the overlap of the internal and
external
popliteal nerves could be observed according to the method of residual
sensation. One was the
case in which the internal saphenous and internal popliteal nerves were
injected with alcohol for
causalgia, producing anesthesia, the residual sensibility about which
permitted the outlining of
the total supply for pain of the external popliteal nerve (fig. 146, f). The upper border of this area
is hypothetical and merges on the outer surface with the external
cutaneous, on the posterior
surface with the small sciatic, and on the inner side with the
obturator nerve.
938
The
overlap on the sole seen in Figure 147, b, is probably smaller
than that which actually exists, as may be seen from the presence of
sensibility to pain in the blank area of the
sole in a ease of complete interruption of the internal
FIG.
146.- Sensory
changes of combined
lesions of internal saphenous and internal popliteal
nerves, F; small sciatic, external popliteal and internal saphenous and
sciatic nerve lesions from
which the residual sensibility of the external and internal popliteal
nerves was obtained
FIG. 147.- Residual
sensibility to prick pain
of external poplitoal nerve, B; sensory changes in an uncertified
case of complete interruption of the internal popliteal, A
popliteal nerve, a case which, because it was
not certified by operation, is not included in the
present series (fig. 147, a).
939
The
area of total supply for pain of the internal popliteal nerve was
obtained from the
residual sensibility in a case of a combined lesion of the small
sciatic, the internal saphenous,
and the external popliteal nerves, and a case of
FIG. 148.- Residual
sensibility to prick pain
of the internal popliteal nerve
external popliteal section (fig. 146, d, e).
The upper border of this area is hypothetical and
merges with the borders of the small sciatic and obturator nerves (fig.
148).
FIG. 149.- Residual
sensibility to prick pain
of internal saphenous nerve
The
area of total pain supply of the internal saphenous nerve was obtained
from the
residual sensibility of a combined lesion of the small and great
sciatica and eases of sciatic
section (fig. 146, a, b, d). The upper border
here is likewise hypothetical, merging with the
borders of the anterior crural, the external cutaneous, and the
obturator nerves (fig. 149).
940
CONCLUSIONS
1.
The area of prick pain supplied exclusively by an individual nerve is
far less than the
accepted sensory distribution of that nerve.
2.
The area between the border of exclusive supply of prick pain of an
individual nerve
and the border of its accepted sensory supply constitutes the area of
algesic nerve overlap.
3.
When nerves serving adjacent areas are severed, sensibility to prick
pain between these
areas is not present after injury, nor does it return before the sense
of touch.
4.
When a region in the area of sensory distribution of a severed
peripheral nerve is
sensitive to prick pain, and this region is adjacent to another nerve
area, if this second nerve be
severed, complete analgesia results in the previous sensitive region.
5.
When sensibility to prick pain is present or returns in the area of
possible overlap on to
the sensory distribution of a severed nerve, subsequent resection and
suture of this nerve does
not change the general extent of this sensitive area. although the
borders may at times be slightly
enlarged or diminished; that is, the pain sense returned or present
before the operation was not
due to partial regeneration.
6.
The laws governing the assumption of function by nerves adjacent to a
severed nerve
are unknown.
7.
Handling and resection and suture of previously divided nerves changes
the condition
governing the function of overlapping nerves, often initiating greater
function.
8.
Evidence of the assumption of function by nerves adjacent to a severed
nerve is not
present immediately following the nerve injury, but gradually shows
itself at a later date.
9.
The early return of sense of prick pain before the return of sense of
touch is not due to
temporal dissociation of epicritic and protopathic sensibilities, but
is due to the assumption of
function by adjacent overlapping nerves.
10.
The areas of overlap may be determined with fair accuracy and the early
return of
sense of prick pain in those areas can not be interpreted as a sign of
regeneration of the divided
nerve.
11.
The changes in prick pain following division of a single nerve are not
a safe basis for
conclusions regarding regeneration of that nerve.
12.
Only when a group of nerves is divided at the same time can the studies
of sensation
be used in the interpretation of regeneration of these nerves. Under
these conditions only that
part of the analgesic area may profitably be studied which is removed
from the effect of overlap
from adjacent nerves. On the other hand, if return to sensibility to
prick pain occurs on the
border of an uninjured adjacent nerve, this return to sensibility does
not indicate regeneration of
a nerve.
13.
Return of sensibility to prick pain can be used clinically for the
determination of
nerve regeneration only when it is accompanied by return of tactile
sense or when it occurs
outside the area of possible overlap of adjacent nerves.
941
REFERENCES
(1) Oppenheim, Hermann: Text-book of Nervous
Diseases. Translated by Alexander Bruce. Edinburgh, Otto Schulze
and Company, 1911, i, 5th Edition, 408.
(2) Létiévant, E.: Traité des sections
nerveuses. J. B. Baillière et fils, Paris, 1873, 41.
(3) Head, Henry, Rivers, W. H. It., and
Sherren, James: The Afferent Nervous System from a New Aspect. Brain,
London, 1905, xxviii, part 2, 99.
(4) Head, Henry, and Sherren, James: The
Consequences of Injury to the Peripheral Nerves in Man. Brain,
London,
1905, xxviii, part 2, 117.
(5) Ibid., 295.
(6) Ibid., 120.
(7) Boring, Edwin G.: Cutaneous Sensation
after Nerve-Division. Quarterly Journal of Experimental
Physiology,
London, 1916, x, No. 1, 1.
(8) Stopford, John S. B.: The Variation in
Distribution of the Cutaneous Nerves of the Hands and Digits. Journal of
Anatomy, Cambridge, October, 1918, liii, part 1, 14.
(9) Athanassio-Bénisty, Mme.: Treatment and
Repair of Nerve Lesions. University of London Press, Ltd.,
London, 1918, 32: 117.
Also: Head and Sherren, Brain,
London, 1905, xxviii, 135.
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