uncomplicated cases of labio-glosso-laryngeal paralysis. There are,
however, a number of cases reported in which the degenerative process
has passed from the medulla oblongata to the spinal cord, and given
rise to paralysis of the muscles of the neck, especially of the
trapezius, and to those of the shoulders, and even to those of the
upper extremities. Atrophy of the interosseus muscles of the hand,
with those of the ball of the thumb, is not unfrequently observed. In
other cases the disease has been found associated with progressive
muscular atrophy, and in others, again, with paralysis of the lower
extremities, accompanied by contractures and depending upon
amyotrophic lateral sclerosis.
Labio-glosso-laryngeal paralysis is, as before mentioned, slow but
progressive in its course, the duration of which is from one to three,
or even five, years. It always terminates in death within the limits
of this time, either from suffocation, inanition, paralysis of the
heart, or some other intercurrent disease.
PATHOLOGICAL ANATOMY.—The macroscopical and microscopical examinations
made during the last fifteen years of the cerebro-spinal axis in quite
a number of cases of progressive labio-glosso-laryngeal paralysis show
that this disease depends upon a degeneration of the nervous elements
of the nuclei or nerve-centres in the medulla oblongata, involving
also the roots of the nerves arising from the latter, and supplying
with nervous energy the muscles of the different organs paralyzed in
this disease. The exact nature of this degeneration—that is, whether
it represents the sequel of a previously existing myelitis or
originates in a so-called parenchymatous inflammation—appears to be as
yet not definitely settled, though a number of pathologists entertain
the view that it is preceded by a chronic myelitis. This view appears
to be corroborated by the fact that frequently portions of the medulla
oblongata and cervical portion of the spinal cord are found in a state
of sclerosis. The uncertainty in the determination of the exact nature
of the pathological process here concerned chiefly depends upon the
diverse conditions in which the blood-vessels of the medulla are
found. For while, in some cases, perhaps the majority, they have been
found empty and in a normal condition, they have in others been met
with congested with blood—a condition pointing to a chronic
inflammatory process. In other cases, again, their walls have been
found thickened or undergoing fatty degeneration.
At any rate, whether inflammatory or not, the now numerous
microscopical examinations have revealed that the main features of the
{1173} process are a degeneration and atrophy, not only of the
ganglion-cells of the respective nervous nuclei with their plexuses,
but also of the fibres of the roots of the peripheral nerves arising
from these centres; frequently the degeneration extends to some
distance upon the nerves themselves. The microscopical changes in the
ganglion-cells consist of an increase of yellow pigment, a gradual
disappearance of their nuclei, terminating in an atrophy of the
ganglionic bodies themselves, the pathological process leaving,
finally, nothing but irregularly-shaped masses of pigment in the
places of these bodies. The degeneration of the nerve-fibres appears
to consist, as elsewhere, in a swelling of the axis-cylinder,
accompanied by atrophy of the medullary sheath—a condition which
finally leads to the complete destruction of these elements of the
nerve-fibres, so that, at last, the whole nerve is only represented by
the connective tissue of its neurolemma. Besides these changes,
certain pathological products, such as conglomerations of fatty
granules or globules, amylaceous bodies, etc., are also found in the
degenerated nerve-centres and nerve-fibres.
Although in different cases the route which the degenerative process
pursues is not the same, a certain general order, in which the nerves
and nerve-centres are successively affected, and corresponding to the
clinical symptoms, appears, nevertheless, to exist. It is thus that
the nucleus of the hypoglossus has been observed to degenerate before
the other nerve-centres. The nuclei of the spinal accessory and
pneumogastric nerves, and also that part of the facial nucleus from
which the inferior division of the facial nerve arises, appear to be
affected next. The glosso-pharyngeal nucleus appears not to be
affected in all cases, and still less frequently the nuclei and roots
of the abducens, auditory, and trifacial nerves. The fibres forming
the anterior pyramids have frequently been found degenerated
throughout the medulla oblongata and pons; sclerosis also has been met
with in this locality. In many cases, as has been remarked before, the
pathological process descends into the spinal cord. Here, as in the
medulla oblongata, the degeneration is principally confined to the
motor centres located in the anterior horns, while the posterior
horns, together with the lateral and posterior white columns, remain
free from disease. The degree of degeneration taking place in the
fibres of the respectively paralyzed muscles also corresponds to that
of the elements of the nerve-centres from which they are supplied. The
microscopical changes observed in the muscular fibres consist in a
decrease of their diameter, accompanied by an increase in the number
of their nuclei, as well as in the quantity of the connective tissue
surrounding the primary bundles; some authors have observed amyloid
degeneration of the muscular fibres.
ETIOLOGY.—The causes which give rise to the pathological process above
described are but little known. Nevertheless, in a number of cases the
disease has been traced back to taking cold, to physical as well as
cerebral over-exertion, mental excitement, sorrow caused by
misfortunes, poverty of nutrition, excessive use of tobacco, etc. In
some cases the disease commences in the spinal cord in the form of
progressive muscular atrophy or amyotrophic lateral sclerosis, and
gradually extends to the medulla oblongata; in many other cases no
particular cause can be found. The disease is rarely if ever met with
in persons under twenty years of age, but is confined to adult life
and old age. It occurs in {1174} both high and low walks of life,
attacking more frequently men than women.
DIAGNOSIS.—The symptoms of progressive labio-glosso-laryngeal
paralysis are so characteristic in themselves as to exclude any
mistake in the formation of a diagnosis. There are, nevertheless, some
pathological conditions, such as hemorrhages in the medulla oblongata
or thrombosis and embolism of the arteries supplying the latter with
blood, which may give rise to the same or very similar phenomena, and
thus render a correct diagnosis difficult. In such cases it must be
remembered that the cause of true labio-glosso-laryngeal paralysis,
depending upon degeneration and atrophy of the nervous nuclei along
the floor of the fourth ventricle, is very gradual, while the symptoms
produced by the causes before mentioned generally make their
appearance in a more acute and sudden manner. The latter also, if not
remaining stationary for some time, have rather a tendency to
improvement, wanting, therefore, the progressive character of the
former.
Tumors at the base of the brain also, by pressing upon the roots of
the cerebral nerves or upon the medulla oblongata itself, may produce
similar symptoms, which, on account of their comparatively slow and
gradual development, may prove more difficult to distinguish from
those characterizing genuine, progressive labio-glosso-laryngeal
paralysis. Errors of diagnosis, however, may here be avoided by taking
into consideration the special symptoms which generally accompany the
presence of tumors of the brain, such as vertigo, headache, vomiting
or even hemiplegia, and local paralysis. The sensory nerves also may
become affected by the pressure of the tumor upon them. Thus, pressure
upon the trifacial nerve may give rise to neuralgic pains, feelings of
tingling and numbness, or even anæsthesia; while pressure upon the
optic nerves or their tracts, or upon the olfactory and lingual
nerves, will be followed by derangements of vision, smell, and taste.
The symptoms produced by the pressure of a tumor at the base of the
brain, moreover, are not strictly progressive, but may for some time
appear, and disappear again before becoming permanent.
Facial diplegia, in which the expression of the face somewhat
resembles that of a patient affected with labio-glosso-laryngeal
paralysis, is distinguished from the latter disease by the paralysis
affecting both divisions of the facial nerve, while the tongue remains
free and deglutition is undisturbed.
There are still other affections of the cerebro-spinal axis, such as
paralysis of the insane, disseminated sclerosis, etc., which in their
course present some or perhaps all of the symptoms characterizing
labio-glosso-laryngeal paralysis; these may be distinguished from the
latter disease by taking their own special symptoms into
consideration.
TREATMENT.—Although almost all cases of progressive
labio-glosso-laryngeal paralysis terminate fatally, some cases have
been reported by several observers in which a temporary improvement in
the symptoms of the disease, or even a total cure, had been obtained
by treatment. Of course such favorable results can only be obtained in
the initial or earlier stages of the disease. Thus, Kussmaul
recommends in the initial stage, when pains in the head and neck are
present, wet cupping of the nape of the neck in strong persons, also
the use of the shower-bath, while {1175} nitrate of silver may be
given internally. The application of galvanism in an alternate
direction he also recommends—first, through the neck, and later on
through the whole spinal column—and at the same time currents in an
alternating direction from the neck and hypoglossus nerve to the
tongue. Dowse reported a case of bulbar paralysis which he cured by
the application of the constant current upon the paralyzed parts,
subcutaneous injections of atropine and strychnine, with the internal
administration of cod-liver oil, quinine, and phosphorus. He attaches
great importance to the careful feeding of the patient through a tube
passed through the nose, and to the strict application of the galvanic
current; for excessive salivation he recommends atropine. Erb
recommends to regulate the diet and the habits of life of the patient
in such a manner as to avoid every irritation of the nervous system;
furthermore, to generally stimulate the nutrition in order to produce
a tonic effect upon the nervous system. For this purpose he
principally relies upon a cautious hydropathic treatment, to be
continued for a long time and with great regularity. The greatest
importance, however, he attaches to electricity, considering the best
method of galvanism as follows: “Galvanize with stabile application
transversely through the mastoid processes and longitudinally through
the skull, the so-called galvanism of the cervical sympathetic (anode
on the nuchus, and cathode at the angle of the lower jaw), and then
induce movements of deglutition (twelve to twenty at each sitting);
besides this, apply, according to circumstances, direct galvanic or
faradic currents to the tongue, lips, and palate.” The electric
treatment must be continued for some time, with from four to seven
sittings a week. Of the medicines taken internally, Erb recommends
nitrate of silver, iodide of potassium, iodide of iron, chloride of
gold and sodium, ergotin, belladonna, and preparation of iron and
quinine.
{1176} {1177}
DISEASES OF THE PERIPHERAL NERVES.
BY FRANCIS T. MILES, M.D.
The nervous system of the higher animals is the apparatus by which
stimuli coming from the external world or originating in the interior
of their own bodies are perceived (its sensitive functions), or cause
muscular contraction (its motor functions), or, lastly, cause
molecular changes in tissues (its trophic functions).
Besides this power which the nervous system possesses of receiving
impressions originating outside of itself and actively replying to
them, it appears also to possess the power of originating within
itself changes the result of which are sensations, movements, and
trophic alterations. In other words, it can act automatically.
The apparatus for the performance of these various functions consists
of the end-organs, the nervous centres, and the nerves.
The end-organs are peripheral mechanisms for the reception of
impressions. The structure and mode of action of some of them, as the
eye and the ear, are pretty well understood, while others, as those
connected with the sense of touch, temperature, etc., are but
imperfectly known. It is probable that there are also peripheral
mechanisms which facilitate the delivery of the impulses coming from
the nerve-centres to the organs, tissues, muscles, glands, etc.
The nervous centres are made up of nerve-cells variously connected
with each other. They are immediately concerned in receiving
impressions conveyed to them by the nerves and transforming them into
sensations, or transmitting them to other organs, causing reflex
actions, or in originating sensations and impulses.
The nerves are organs which, connected at one extremity with the
end-organs and at the other with the nervous centres, convey
peripheral impressions to the centres, and impulses and influences
from the centres to the various organs of the body.
As it is with diseases of the peripheral nerves that we are now
concerned, let us begin by looking more closely into their structure
and functions.
The nerves appear to the naked eye as white strands of variable size,
which a close inspection shows to be made up of threads or fibrils
(best seen when the cut end of a nerve is examined) bound together by
fine connective tissue and scantily supplied with blood-vessels. A
microscopic examination shows that each of the fibrils visible to the
naked eye is made up of a great number of fibres. These are the
medullated {1178} nerve-fibres, and they extend unbroken between the
nerve-centres, with the cells of which they are connected, to the
various organs and tissues, with which they also enter into organic
union.
If we examine the structure of a medullated nerve-fibre, we find it to
consist of a central thread called the central axis or axis-cylinder,
in which close microscopic investigation shows a longitudinal
striation, indicating that it is made up of fibrillæ. Surrounding the
central axis like a sheath is the white substance of Schwann, composed
of an oleo-albuminous substance, myeline, to which the nerves owe
their white appearance. According to some observers, the white
substance of Schwann is pervaded by a meshwork of fibres. Surrounding
the white substance of Schwann is the sheath of Schwann, a
structureless membrane having at intervals upon its inner surface
nuclei, around which is a small amount of protoplasm.
At intervals along the course of the nerve-fibres are seen
constrictions which involve the sheath and white substance of Schwann,
but which do not affect the central axis, which passes unbroken the
points of constriction. These are the nodes of Ranvier. Each space on
the fibre beneath the nodes of Ranvier contains one of the nuclei of
the sheath of Schwann, and probably, together with the white substance
of Schwann, represents a cellular element. Diseased conditions
sometimes respect the limits of these cellular elements.
The central axis is the true conducting part of the nerve-fibre, and
it is probable that each of the fibrillæ of which it is composed has a
separate peripheral termination and possesses the power of isolated
conduction. The white substance of Schwann and the sheath of Schwann
protect the central axis and seem to be connected with its nutrition.
The fibres in a nerve are bound together by loose connective tissue,
the endoneurium, into the primitive bundles, which are again united by
the perineurium, a membrane of laminated connective tissue, into more
definite funiculi seen by the naked eye, the secondary bundles.
The secondary bundles are tied together by connective tissue, in which
are found fat-cells and in which run the fine blood-vessels supplying
the nerves. This connective tissue has been named the epineurium, and
its condensed outer layers constitute the sheath of the nerve. It is
important to observe that the connective tissue of the nerves is
permeated by lymphatics which penetrate to the nerve-fibres, so that
these are brought in contact with, and as it were, bathed in, the
lymph.
Each nerve-fibre runs an isolated course from end to end, without
anastomosing with other fibres, and near its peripheral termination it
usually divides into two or more branches.
The fibres of the peripheral nerves depend for their integrity and
nutrition upon their connection with central organs. The large
multipolar cells of the anterior horns of gray matter of the spinal
cord preside over the nutrition of the motor fibres; the ganglia on
the posterior roots of the spinal nerves over the nutrition of the
sensitive fibres.
If a nerve be severed from its connection with these centres of
nutrition, it in a short while undergoes degenerative changes which
result in complete destruction of its fibres.
The nerve-fibres when in a state of functional activity conduct
impressions along their length to the end-organs or to the
nerve-centres with {1179} which they are in connection. This property
of the fibres we call their conductivity. Each fibre conducts
impressions in an isolated manner, not communicating them to other
fibres with which it may be in contact. The rapidity of this
conduction in human nerve-fibres is estimated at 33.9 meters (about 38
yds.) per second. This rate may be diminished by cold or by the
anelectrotonic condition which is induced in the nerve by the passage
through it of an electric current.
The nerve-fibres are irritable; that is, the application to them of
stimuli excites their functional activity, and the impression made by
the stimulus is transmitted to their extremities.[1]
[Footnote 1: The nerve-fibres in man do not appear to attain their
full irritability until the fifth or tenth month after birth
(Soltman).]
The natural or physiological stimuli of the nerves act upon their
extremities. Either they act through the peripheral mechanisms, giving
rise to impressions which are conducted centripetally to the cells of
the nerve-centres and there cause sensations or reflex actions, or
they act upon the nerve-centres, giving rise to impulses which are
conducted centrifugally and cause the various phenomena of contraction
of muscles, inhibition of contraction, secretion, etc. Besides the
physiological, there are other stimuli which excite the functional
activity of nerve-fibres when applied at any point along their course.
Mechanical stimuli, blows, concussions, pressure, traction, etc.,
excite the nerves, causing sensations when applied to sensitive
nerves, or contraction of muscles when applied to motor nerves. When
mechanical stimuli are pushed farther, the irritability of the nerves
may be destroyed. The gradual application of mechanical stimuli may
destroy the irritability of nerve-fibres without any exhibition of
excitation, as in paralysis from pressure. In nerve-stretching it is
probable that many of the results depend upon the mechanical
stimulation of the nerve-fibres by the traction. With a certain amount
of force used the irritability of the nerve may be increased; carried
farther, both the irritability and the conductivity may be diminished,
and finally destroyed. As the centripetal fibres are soonest affected
in the stretching, we can see how this proceeding is most beneficial
in neuralgias, where a potent factor, if not the cause of the disease,
is an abnormal excitability of the nerve-fibres. It is to be observed,
nevertheless, that in cases of continued pressure upon mixed nerves
the motor fibres are the first to suffer loss of their conductivity.
Sudden alterations of temperature act as stimuli to nerves. Heat
increases their irritability, but its prolonged application diminishes
it. Cold in general diminishes the nervous irritability, and may be
carried to the point of completely destroying it temporarily.[2]
[Footnote 2: But at a certain age in freezing the ulnar nerve Mitchell
found its irritability notably increased.]
Many substances of widely-different chemical constitution, as acids,
alkalies, salts, alcohol, chloroform, strychnine, etc., act as stimuli
when applied directly to the nerves, apparently by causing in them
rapid molecular changes. Also may be enumerated as chemical stimuli to
the nerves substances found naturally in the body, as bile, bile
salts, urea. The rapid withdrawal of water from nerve-tissue first
increases, and then diminishes, its irritability. The imbibition of
water decreases nervous irritability.
{1180} An electric current of less duration than the 0.0015 of a
second does not stimulate the nerve-fibres. It would appear that more
time is required for the electric current to excite in nerve-tissue
the state of electrotonus which is necessary to the exhibition of its
functional activity. The electric current stimulates a nerve most
powerfully at the moments of entrance into and exit from the nerve,
and the more abruptly this takes place the greater the stimulation.
Thus the weak interrupted currents of the faradic or induced
electricity owe their powerfully stimulating effects to the abruptness
of their generation and entrance into and exit from the nerves. At the
moment of the entrance of the electric current into the nerve—that is,
upon closing the circuit—the stimulating effect is at the negative
pole or cathode; when the current is broken—_i.e._ leaves the
nerve—the stimulating effect is at the positive pole or anode. A
current of electricity very gradually introduced into or withdrawn
from a nerve does not stimulate it. But if while a current is passing
through a nerve its density or strength be increased or diminished
with some degree of rapidity, the nerve is stimulated, and the degree
of stimulation is in proportion to the suddenness and amount of change
in the density or strength of the current. Although with moderate
currents the stimulation of the nerve takes place only upon their
entrance and exit, or upon variations of their density, nevertheless,
with a very strong current the stimulation continues during the
passage of the current through the nerve. This is shown by the pain
elicited in sensitive nerves, and the tetanic contraction of the
muscles to which motor nerves are distributed.
An important factor in electrical stimulation is the direction of the
current through the nerve. A current passed through a nerve at right
angles with its length does not stimulate it. Currents passing through
a nerve stimulate in proportion to the obliquity of their direction,
the most stimulating being those passing along the length of the
nerve. Motor nerves are more readily stimulated by the electric
current the nearer it is applied to their central connection.
Experiments on the lower animals would seem to indicate that the motor
fibres in a nerve-trunk do not all show the same degree of
irritability when stimulated by the electric current.
The irritability of the nerve-fibres may be modified or destroyed in
various ways. Separation of nerves from their nutritive centres causes
at first an increase of their irritability, which is succeeded by a
diminution and total loss, these effects taking place more rapidly in
the portions nearer the nerve-centres. It is important to observe that
an increase of irritability preceding its diminution is generally
observed in connection with the impaired nutrition of nerves, and is
the first phase of their exhaustion.