unknown, though as a result of education extreme delicacy of taste, a
relative hyperæsthesia, may be produced. Paræsthesiæ are rare. In two
cases in which we have observed the symptom (one of neurasthenia, the
other of hypochondriacal melancholia) it consisted in a constant and
most distressing sweet taste. The application of the galvanic current
at the base of the brain, under the jaw, on the cheeks, and within the
mouth produces subjective tastes of an acid or metallic nature.
Anæsthesia of the gustatory nerve occurs after section of the lingual
branch of the trigeminus—an operation sometimes done for lingual
neuralgia, in which case the frontal two-thirds of the tongue on one
side loses its property of perceiving taste. As the result of central
disease next to nothing is known of this symptom. It is probable that
sweet and acid tastes are perceived in the mouth and forward part of
the tongue; bitter tastes on its caudal (posterior) third and in the
throat (glosso-pharyngeal nerve). In the insane, paræsthesiæ and
anæsthesia give rise to a great variety of delusions about the state
of the parts, the nature of their food, poison in the food, etc.
As a part of typical complete hemianæsthesia the special senses are
{42} involved. When of hysterical origin the whole retina of one eye
is generally devoid of sensibility, or it does not perceive colors.
When the hemianæsthesia is due to a lesion of the caudal part of the
internal capsule (organic anæsthesia), we should expect to find
lateral hemianopsia, with dark half-fields on the same side as the
cutaneous anæsthesia. We would not be understood as claiming that this
point of distinction is as yet positively determined, but would
advance it suggestively, subject to the result of observations on new
cases.
III. Motory Symptoms.
PARALYSIS, or AKINESIS, is a condition in which loss of voluntary or
involuntary muscular movement occurs through defective innervation.
Such a strict definition is desirable, as excluding cases in which
motion is abolished by local or general morbid states not essentially
nervous, as in acute articular rheumatism, ruptures of muscles or
tendons, fractures, extreme asthenia, etc.
Paresis is a term often employed to designate a paralysis partial in
degree; it does not mean an essential muscular paralysis.
Paralysis varies infinitely in extent and distribution, yet certain
types are recognized as having diagnostic value, and their exact
determination is of great importance in practice.
(_a_) Hemiplegia, or paralysis of many muscular groups in one lateral
half of the body.
(_α_) Common Hemiplegia.—In this, the most frequent form, we find loss
of voluntary motion in many muscles of one side of the face and body.
This condition may or may not be preceded by apoplectic or epileptic
symptoms: it may occur gradually or suddenly. Although it is customary
to say that in hemiplegia a patient is paralyzed on one side, this is
not strictly correct, as careful observation shows that (1) in the
face only the lower facial muscles are distinctly affected; the tongue
itself is rarely paralyzed, but its projecting muscular apparatus is,
so that when protruded it deviates as a whole toward the paralyzed
side; the eye-muscles and masticatory muscles are unaffected; (2) in
the extremities the loss of power is greatest in the hand and foot,
less so in the arm and thigh, very slight in the muscular groups of
the shoulders and hips; (3) the muscles of the neck and trunk, the
respiratory muscles, and in general the muscles of the vegetative life
are practically unaffected. These facts may be summarized by the
statement that in common hemiplegia the greatest paralysis is shown in
those muscular groups whose action is most independent on either side
of the body; or, in other words, in those whose functions are most
highly differentiated and whose innervation is most cortical (from the
motor centres in the cerebral cortex). Those muscular groups, on the
other hand, whose action is usually or necessarily simultaneously
bilateral or associated across the median line—or, in other words,
whose innervation is largely spinal or subcortical—are least
paralyzed; while the purely automatic or reflex muscular apparatuses,
those having a strictly spinal or sympathetic innervation, are not at
all affected.
Common hemiplegia is rarely accompanied by hemianæsthesia.
{43} It must not be forgotten that double hemiplegia may occur, in
which case the symptoms are simply duplicated.
As regards the seat of the lesion in common hemiplegia, it may here be
said, in general terms, that it is in the cerebral hemisphere opposite
to the paralysis (with excessively rare exceptions which are
susceptible of explanation), in its motor cortex, in the subjacent
associated white fasciculi, or in the knee and caudal part of the
internal capsule; the lesion may directly injure those parts or act
upon them by compression.
(_β_) Crossed Hemiplegia (hémiplégia alterne).—In this form there is
paralysis of many muscular groups on one side of the body, while the
facial nerve or some other cranial nerve (or several cranial nerves
together) show loss of innervation on the other side of the median
line. Theoretically, therefore, there may be as many varieties of
crossed hemiplegia as there are cranial nerves, but, practically, we
meet only with a few forms, of which the following are the most
common: (1) motor oculi (N. iii.) on one side, and body and face on
the other; (2) facial nerve (N. vii.) on one side, and body on the
other; (3) trigeminus nerve (N. v.) on one side (anæsthesia of face,
paralysis of masticatory muscles), and body on the other; (4) abducens
(N. vi.), facial (N. vii.), and acoustic (N. viii.) together on one
side, and the body on the other. (5) With symptoms of No. i. we may
have lateral hemianopia, dark half-fields on the same side as
paralyzed extremities.
In crossed hemiplegias anæsthesia is more common; there is a strong
tendency to bilateral extension of the paralysis, and neuro-retinitis
is seldom absent before the close of life.
As regards the location of the lesion in crossed hemiplegias, it may
be stated, in a general way, that it is in the base of the brain on
one side of the median line, so placed as to directly injure one or
more cranial nerves at their origin, and to compress or destroy the
cerebral motor tract (pyramidal tract) above its decussation-point,
and in some cases also the sensory tract in the crura, pons, and
oblongata.[4]
[Footnote 4: For a statement of the exact seat of the lesion causing
various forms of crossed hemiplegia, vide article on the LOCALIZATIONS
OF LESIONS IN THE NERVOUS SYSTEM.]
(_b_) Spinal Hemiplegia.—In this type the face and head are normal,
excepting in some cases the iris; the extremities and trunk are more
or less paralyzed on one side, the loss of power being more evenly
distributed (_i.e._ less distal) than in hemiplegia of cerebral
origin. Often there is also anæsthesia, and this is always on the
other side of the median line, involving more or less of the whole
side. The coincidence of these symptoms below the head indicates
positively that the lesion is in the spinal cord, involving one of its
lateral halves. Where there is no anæsthesia, care must be taken not
to confound the condition with that in which a cerebral lesion causes
paralysis of one arm and leg (combined brachial and crural
monoplegia).
(_c_) Paraplegia.—The loss of voluntary power involves one transverse
half of the body, usually the caudal. When only the lower extremities
are affected, the condition is designated simply a paraplegia; when
all the parts below the head are paralyzed, the term cervical
paraplegia is employed. Frequently, the bladder and rectum are
paralyzed, and in some cases the thoracic muscles also, leaving
inspiration to be performed by the diaphragm alone. Often there is
coextensive anæsthesia.
{44} Hemiparaplegia is a rare variety in which one lower extremity is
paralyzed while the other is anæsthetic.
The location of the lesion in paraplegias is in the spinal cord at
various levels and in various portions of the gray and white columns.
Theoretically, we may now again admit the old proposition that a
paraplegia may be of cerebral origin: in such a case the loss of power
should follow the laws of distal prevalence (vide (_α_)); there should
be no anæsthesia or vesical paralysis, and the lesion ought to be one
involving the paracentral lobules of both hemispheres (meso-vertex at
fissure of Rolando).
(_d_) Monoplegia, or paralysis of one extremity or of one side of the
face, is not rarely observed. It may be caused by central lesions in
the brain or spinal cord, or by an affection of the nerve-trunks of
the part. Cerebral monoplegias are of great importance in diagnosis,
and may be distinguished from others by—(1) loss of power is greatest
in the distal part of the affected member; (2) the precedence or
coincidence of spasm (usually clonic or epileptiform) in the limb; (3)
the absence of marked anæsthesia; (4) the preservation of muscular
nutrition.
(_e_) Localized Paralysis.—The extreme types of this form of paralysis
are paralysis of one external rectus and of one superior oblique.
These muscles are each supplied by one whole nerve, and may therefore
exhibit isolated paralysis. In the rest of the body, however,
localized paralysis shows itself in groups of muscles as innervated by
nerve-trunks or by certain so-called centres in the spinal cord. As
examples of the former variety may be cited common facial paralysis
(Bell's palsy) and paralysis of the extensor muscles of the hand by
injury to the musculo-spinal (radial) nerve, of the foot and leg from
lesions of the sciatic nerve. As examples of the second variety we
have the irregular paralysis of anterior poliomyelitis (infantile
spinal paralysis). In localized paralyses due to lesion of the
nerve-trunks anæsthesia is usually present, whereas it is not common
in the second variety. The determination of the seat of lesion in
neural localized paralysis is much facilitated by bearing in mind Van
der Kolk's law of the distribution of the motor and sensory fibres of
a nerve-trunk.
Pseudo-paralysis—_i.e._ conditions in which voluntary motion is lost
without defect in innervation, as from muscular disease, injuries,
inflammations, etc.—is usually localized or irregularly distributed.
(_f_) The various internal organs, the viscera, supplied with striped
or unstriped muscular fibres, may be paralyzed.
(_g_) The muscular coat of the vascular system beyond the heart may be
paralyzed in extensive or limited areas—the so-called vaso-motor
paralysis. This may assume hemiplegic or monoplegic or localized
forms.
SPASM, or HYPERKINESIS, consists in abnormal and often violent
involuntary muscular contractions, with or without loss of
consciousness.
1. A purely mechanical classification of spasms into tonic and clonic
forms is generally admitted as serviceable for clinical description,
though we have as yet no positive knowledge of their relations to
pathological conditions.
(_a_) Tonic or tetanic spasm is one in which the muscular contraction
is continuous or constant for a measurable length of time. Thus, in
some cases of petit mal there is a momentary stiffness or rigidity of
the entire {45} voluntary muscular apparatus (respiratory muscles
included): the patient sits or stands with staring eyes as if
petrified. In tetanus and local tetanoid seizures the muscles of large
regions or of a part of a limb may remain contracted for many minutes;
in the disease called tetany this condition may endure days and
weeks—in hysteria and in some paralyses dependent upon organic disease
for years or permanently. Prolonged tonic spasms occurring in chronic
diseases are designated as contractures, and the affected parts are
said to be tetanoid or spastic. A tonic spasm of long duration may
show itself in involuntary muscles, as in the arteries, causing
vaso-motor spasm and ischæmia; in the ciliary muscle, causing spasm of
accommodation; in the urethra, œsophagus, etc.
A tonic muscular contraction accompanied by intramuscular pain is
termed cramp.
Under this general head may also be classed the emotional or dramatic
expressive spasms of hysteria and hystero-epilepsy—a condition in
which the emotions or ideas occurring in the patient's mind are
involuntarily translated externally into attitudes or gestures: _e.g._
anger, fear, disgust, amorous and religious feelings, etc.
(_b_) Clonic spasms are those which consist in rapidly intermittent
muscular contractions, local or general. These may be rhythmical in
time or form, as in paralysis agitans, or wholly irregular, as in
chorea. Jerking is a quasi-popular designation of clonic spasms.
Tremor, or trembling, observed in persons during repose in any
attitude, consists in small, wholly involuntary muscular contractions
of sufficient extent to communicate to the parts a visible to-and-fro
movement which is very often rhythmical. In order to distinguish this
from any form of inco-ordination it is necessary that the observed
movement should occur independently of all volitional effort. Thus in
the senile state, in chronic alcoholism, in paralysis agitans, and in
dementia paralytica we observe trembling of the facial and lingual
muscles, of the extremities, and even of the whole body in some cases.
These are usually conditions of permanent or chronic tremor, but the
symptom is sometimes observed as a transient phenomenon, as after
violent muscular effort, after excesses of various sorts, under the
influence of emotions, etc. Occasionally, persons are met with who
have trembled from childhood or early years without actual disease of
the nervous system. It is clinically useful to divide tremor into
varieties, as rhythmical and irregular, fine and coarse, constant and
occasional. These terms define themselves sufficiently, so that no
further statement is necessary, but we would repeat that it is of much
advantage in diagnosis to determine accurately the characteristics of
tremor.
2. A much more useful classification of spasms, and to a certain
extent a physiological one, is into types according to their
distribution in the body, following exactly the classification of
paralyses. There are few topics of more utility for the physician to
study, in our opinion, than that of monoplegias and monospasms, of
hemiplegias and hemispasms in their genesis, mutual relations, and
diagnostic significance.
(_a_) Hemispasm of cerebral origin, tonic or clonic (or both forms
associated), may affect the face and limbs on one side of the body,
with or without paralysis. As in hemiplegia, the morbid phenomena are
greatest in the most distal muscular groups or in those whose
innervation is most {46} cortical. Very often hemispasm precedes,
immediately or remotely, hemiplegia in the same parts. In other cases
the relation is inverse, as when, after a severe hemiplegia, we find
the paralyzed muscles in a state of nearly constant tonic contraction
(secondary contracture), or when hemi-epilepsy follows a cerebral
lesion. In the former case the spasm, clonic or tonic, is designated
as pre-paralytic; in the second case, as post-paralytic. These terms
are useful, because they are associated with laws of diagnosis and
prognosis.
(_b_) Conjugate deviation of the eyeballs and head is an important
symptom of gross cerebral lesions, and may be considered here,
although it is probably due to paralysis. Still, the deviation itself
always strikes the observer as a spasmodic effect. The symptom
consists in a steady turning of the eyes, face, and head toward one or
the other side, and may be best described by likening it to the normal
act of looking at an object which is on one side or a little back of
us. In one form—that due to an irritative lesion of the motor cortex
of one hemisphere—the conjugate deviation forms a part of the
hemiplegic epileptiform convulsions (mixed tonic and clonic) which are
produced: the deviation is away from the lesion. In a second form,
where severe hemiplegia is produced by an acute lesion of the motor
area and the subjacent fasciculi of one hemisphere, whether the
patient be comatose or semi-conscious, the deviation, of paralytic
origin, is away from the paralyzed side of the body and toward the
injured hemisphere: the patient is said to be looking at his lesion.
In a third form, when the lesion is in one side of the base of the
brain (more particularly of the pons), the deviation, again paralytic,
is away from the lesion, as a rule. In some cases conjugate deviation
exists only as a tendency to look to either side. It is always a
valuable symptom in severe cerebral affections, more especially the
apoplectic state.
(_c_) Paraplegic spasm is also shown in tonic and clonic forms.
Partial tonic spasm of this distribution, with paresis of the legs,
causes the gait or attitude known as tetanoid or spastic. The four
extremities may be in this state of mixed paresis and contraction, as
observed in some very young children whose cerebral motor area is
probably undeveloped or ill-developed, or which has been damaged
shortly after birth by meningeal hemorrhage.
(_d_) Monospasm, spasm affecting one side of the face or one
extremity, may be of cerebral, spinal, or neural origin. Very often
monospasm of clonic form serves to indicate with wonderful precision
beginning disease (irritation stage) in limited parts of the cerebrum
(in cortical centres and in the connected fasciculi for the face and
limbs). Cerebral monospasms are sometimes combined so as to almost
constitute hemispasm—_i.e._ brachio-facial or brachio-crural
monospasm. Monospasm may precede or succeed monoplegia.
(_e_) Universal spasms, tonic, clonic, or mixed, occur in numerous
diseased states—in hysteria, epilepsy, chorea, tetanus, toxic
conditions, etc. A universal tonic spasm may last long enough
(tetanus, epilepsy) to kill by apnœa.
(_f_) Localized spasms, not monoplegic, are observed. For example, the
orbicularis palpebrarum may be the seat of clonic spasm, or the
masseters of tonic spasm for long periods of time; the œsophagus or
urethra may be temporarily closed by constriction; chorea may affect a
small muscular {47} group. A rhythmic spasm limited to a single muscle
is termed myoclonus; the use of this term should not lead one to
forget the nervous origin of the spasm. A localized tonic arterial
spasm may be so severe and prolonged as to produce great ischæmia,
even gangrene of the affected part.
(_g_) Fibrillary contractions, non-rhythmic contractions of fasciculi
in muscles, spontaneous or provoked by direct mechanical excitation,
may be considered as hyperkinesis. Subjectively, fibrillary
contractions are felt as a quivering or as if a worm moved under the
skin; objectively, they appear not unlike the rising and falling of a
cord under the cutaneous covering. They unquestionably occur
frequently in muscles which are undergoing degenerative or atrophic
changes (progressive muscular atrophy), but they are also met with in
cases of lead paralysis, neurasthenia, etc.
INCO-ORDINATION, or DYSKINESIS, is the condition in which volitional
movements are not performed with normal precision and steadiness.
Several varieties are recognized.
(_a_) Ataxic tremor is distinguished from common or spasmodic tremor
by the fact that it is developed during the performance of a
volitional act in parts which are quiet when not used. Thus, tremor
appears in speaking, putting out the fingers, using the hands, etc. in
the muscles actively employed, and occasionally also in others at the
same time. This form of tremor is well seen in dementia paralytica,
where in certain cases the patient's muscles are still until we induce
him to make voluntary movements or provoke expression movements. In
cases of disseminated sclerosis the same phenomenon is a
characteristic symptom, a coarse tremulous ataxia or oscillatory
trembling appearing whenever volitional acts are attempted. In
looking, there appears nystagmus, a rhythmic ataxic tremor of some of
the ocular muscles; in speaking, an irregular, jerky, slow, or
syllabic speech is heard; and when the hand is carried to a given
object or pointed the extremity exhibits oscillatory trembling. Common
and ataxic tremors may coincide, as in some cases of dementia
paralytica and in alcoholism.
(_b_) Ataxia is a symptom of the utmost importance, and its strict
definition should be maintained. It is that form of inco-ordination in
which there is want of harmony in the action of the various muscular
groups employed in the voluntary performance of a given act. The
simplest movement of an extremity (and more complicated ones a
fortiori) is made up of simultaneous contractions of flexor and
extensor muscles, often also of adductors and abductors in due
proportion, so as to produce a steady position and movement of the
parts. This is not accomplished by the will acting directly on the
different muscles themselves, but through the medium of a
co-ordinating mechanism which is strictly spinal (including the
intracranial expansion of the cord as far frontad as the third
ventricle), and which is educated or trained from the first days of
life. We will the action and set the co-ordinating mechanism going, so
that the movement is in a certain sense indirectly accomplished. Yet
volition does interfere directly to a certain extent by estimating
through the muscular sense, and by exerting the proper amount of force
required, and by guiding the movement in a general way. The most
striking peculiarity about ataxic movements is the defect in the
harmonious action of the various {48} (antagonistic) muscles employed,
resulting in jerky, oscillatory, but non-rhythmic movements,
constantly made worse by greater tension of the will. In simple tremor
volition may for a few moments stop the movements (as best shown in
paralysis agitans), while in ataxia the more the patient tries to
achieve the act, the greater becomes the disorder. The anatomical
fault is mostly in the spinal co-ordinating mechanism; the
long-established motor and sensori-motor associations are interrupted
or confused, and in some cases besides the muscular sense is
impaired.[5] The idea that ataxia results from faulty centripetal
impressions due to various degrees of anæsthesia is certainly
erroneous and misleading. In the first place, there are cases recorded
in which typical ataxia of the extremities occurred without the
slightest impairment of sensibility; and, secondly, neither in animals
(section of posterior roots of spinal nerves) nor in man does ataxia
appear as a result of anæsthesia. In this condition there is
inco-ordination, to be sure, but not ataxia in the strict meaning of
the term. Ataxia is nearly always a symptom of organic disease of the
spinal cord, more especially posterior spinal sclerosis and
diphtheritic myelitis. It may also occur from disease of the
oblongata, pons, and crura cerebri. In certain cases of lesion in
caudo-lateral part of the thalamus involving the caudal part of the
internal capsule (irritation or partial destruction), we observe
various forms of irregular movements which have been designated by
Weir Mitchell as post-paralytic chorea. We long ago became satisfied
that this term included quite a number of forms of inco-ordination,
some cases showing choreiform and trembling movements, others ataxic
tremor, true ataxia, and athetoid movements (also the true athetosis
of Hammond?). It seems probable that diseases of the cerebellum, by
exerting pressure on or by irritating subjacent parts, may sometimes
cause pure ataxia of the extremities on the side opposite the lesion.
That a strictly localized cortical lesion can give rise to ataxia we
are not now prepared to admit.
[Footnote 5: Ataxia is greatly aggravated by closing the eyes.]