Intermittent or remittent pains, in line of nerve without
inflammation, or other structural lesion. Diagnosis: lameness,
stiffness of particular muscles having a common nerve. Unnatural
position habitual. Pain of inflammation and of neuralgia. No
functional change. Rheumatism. Tumors. Causes: lead, rheumatism, gout,
auto-poisons, cold, anæmia, reflex. Facial neuralgia,
occipito-cervical, dorso-intercostal, lumbo-abdominal, sciatic.
Treatment: elimination, of lead, etc.; intestinal antiseptics, tonics,
hot water, anodynes, arsenic.
This is characterized by pain paroxysmal, intermittent or remittent
situated in the course of given nerves. It must be a pure neurosis and
unaccompanied by any specific structural lesion like inflammation,
degeneration, atrophy, hypertrophy, tumor or the like. It is therefore
manifested subjectively and cannot be easily identified in the lower
animals. Nevertheless, Lafosse, Zundel, Genée, and others have recorded
cases, their conclusion being deduced from symptoms which were held to
indicate nervous suffering in the absence of any structural lesion
whatever. _A priori_ one can with difficulty escape the conviction that
neuralgia must exist in the lower animals as in man, and the only
drawback to its recognition is the difficulty of diagnosis.
The first step in such diagnosis must usually be the presence of
lameness, stiffness or indisposition to free movement of some particular
muscle or group of muscles deriving their innervation from a particular
nerve. Or there may be a particular position habitually assumed such as
semi-closed eyelids, drawn back ears, laterally inclined neck which
strongly suggests nervous suffering. Next, there must be the exclusion
of any appreciable structural cause and especially of inflammation. The
three prominent features of the pain of inflammation is that it is
aggravated by pressure, it is heightened by movement, and it is
accompanied by some decided alteration of the function of the part. If
there are at the same time exudation and swelling, inflammation is all
the more certainly indicated. In a neuralgic pain on the contrary
pressure does not increase the pain: it may even alleviate it: movement
of the part may be rather satisfactory to the patient than painful; and
the disturbance of function, contractile, secretory, trophic, is not
perceptible. There is no local exudation nor swelling to account for the
nervous disorder.
The liability to confound the affection with a neuritis more centrally
situated, but the pain of which is referred to the periphery of the
nerve, is to be obviated by a tracing of the nerve along its course to
the nerve centre so as to identify any centre of tenderness, and also by
the implication of all the peripheral branches coming off ectal of that
point.
Again, rheumatism may be easily confounded with neuralgia, but here the
affected nerve and muscle and even the skin over it is liable to be very
tender to the touch or pinch, and if at all acute some hyperthermia is
present. Like rheumatism, neuralgia shows a tendency to shift from place
to place.
Pains due to pressure on the nerves by tumors, aneurisms, and other
swellings, are constant, whereas neuralgic pains are marked by
remissions and aggravations and even by intervals of complete relief.
_Causes._ The toxic neuralgias are illustrated by chronic lead
poisoning, in which, in man, there are wandering pains like those of
rheumatism, and in the lower animals muscular stiffness and contractions
which suggest a similar condition. In man, too, gout is a common factor,
and in pigs and birds in which this condition exists, stiffness and
evidence of suffering may well be at times attributed to a similar
cause. How many other forms of chronic metallic poisoning and poisoning
by morbid autochthonous products of indigestion are attended by
disorders of innervation and nutrition, it is as yet impossible to say.
The direct action of cold, an anæmic condition of the nerves, and reflex
action from distant sources of irritation are among the other invoked
causes. Inflammation in the _nervi nervorum_ is also invoked as a
factor, but in this case the symptoms would not accord with the rule
given above, since the nerve trunks would be very tender to touch or
pressure, and the suffering would be unshifting and shown permanently in
the one seat.
=Facial Neuralgia.= Lafosse and Zundel describe as cases of this kind
those in which periodically the horse’s eyes are fixed and shining, the
ears drawn back and depressed as in vice, the head at intervals bent on
the neck, with plaintive neighing, rubbing the head on the stall and
pawing. Those cases of twitching of the head or rapid jerking of the
ears in horses, when they have been driven for some distance, and which
are relieved by wearing a close net over the nostril or by section of
the trifacial nerve at the infra-orbital foramen, manifestly partake of
this character.
=Cervico-Occipital Neuralgia.= Lafosse speaks of this as often mistaken
for torticolis, the head being turned to the affected side during the
paroxysms. In man this is often a result of cold draughts on the back of
the head, and associated with tender points on the course of the nerve,
between the mastoid and the median line.
=Dorso-intercostal neuralgia= causes pain in deep inspiration, and
=lumbo-abdominal neuralgia= develops tenderness in the loins, in one
testicle, or in one lip of the vulva according to Lafosse. Diagnosis
between such cases and neuritis, spinal disease, and other obscure
nervous affections must be very problematical.
=Sciatic Neuralgia.= This is described by Zundel as causing jerking and
lameness in the affected limb, sometimes aggravated and sometimes
improved by work and associated with muscular weakness or paresis.
Sciatica in man is, however, rarely a simple neuralgia, but partakes
rather of the nature of a neuritis, and there is no good reason for
supposing that the disease of this nerve in the lower animals is other
than an inflammatory condition.
Leclainche after consideration of the testimony adduced, is of the
opinion that we still lack absolute evidence of uncomplicated neuralgia
in the domestic animals.
_Treatment._ For =toxic= cases elimination of the poison is the first
consideration. For _lead_ carefully graduated doses of iodide of
potassium to carry off the offending agent without increasing its
poisonous action must be continued as long as the metal is passed by the
urine. It may be followed by a course of strychnia, by electricity,
massage and blisters. Gouty subjects may be treated with salicylate of
soda, alkalies, or colchicum. The victims of Bright’s disease must be
treated for the kidney affection.
Where there has been =trouble of the digestive organs=, intestinal
antiseptics (salol, sodium salicylate, bismuth-salicylate,
beta-naphthol) and small doses of arsenious acid will sometimes benefit.
In =anæmic conditions= a course of tonics (cod liver oil, iron, quinine,
nux vomica) are indicated, and, to improve the local blood supply,
nitro-glycerine. A rich stimulating ration, currying, an open air life,
and sunshine (in summer a run at grass) are called for.
In man with a suspicion of =traumatic origin=, W. H. Thomson strongly
advocates a persevering use of the hot water douche to the parts first
affected, the hypodermic use of morphia and atropia, and in case of
local anæmia nitro-glycerine every three hours. Where there is a
suspicion of inflammation he successfully employs absolute rest, with
opium narcotism so as to abolish the pain, for twenty days if necessary.
Aconite, antipyrin, acetanilid, phenacetin, exaglin, and gelsemium have
their advocates, and may benefit in individual cases. A course of
arsenic is often successful, and phosphorus and ergot have each proved
of value.