HISTORICAL
We have just become acquainted with an individual who may, we believe,
be considered the type of a species, and have described all his tics.
What is a tic, then?
Its etymology has not much information to furnish. The probability is
that the word was originally onomatopOEic, and conveyed the idea of
repetition, as in tick-tack. _Zucken_, _ziehen_, _zugen_, _tucken_,
_ticken_, _tick_, in the dialects of German, _tug_, _tick_, in English,
_ticchio_ in Italian, _tico_ in Spanish, are all derivatives of the same
root. It matters little, in fact, since the term is in general use and
acceptable for its shortness and convenience. In popular language every
one knows what is meant by a tic: it is a meaningless movement of face
or limbs, "an habitual and unpleasant gesture," as the Encyclopædias
used to say. But the definition lacks precision.
A glance at the history of the word will reveal through what
vicissitudes it has passed. We need but remind the reader of its
exhaustive treatment in the Dictionaries, and refer him for an elaborate
bibliography to a recent work by R. Cruchet,[1] to which we shall have
occasion to return.
There is no justification for regarding the risus _sardonicus_ of the
ancients as a tic. All that we can say is that the phrase apparently
stood for a complex of facial "nervous movements," whether accompanied
by pains and paralyses or not. Nor can the _rictus caninus_ or the
_tortura oris_ have been other than spasms or oontractures of the face.
Previous to its introduction as a technical term, the word _tique_,
_ticq_, _tic_, was in current use in France, and applied in the first
place to animals. In 1655 Jean Jourdin described the _tique_ of horses.
In eighteenth-century literature tic appears in the sense of a
"recurring, distasteful act"--as expressed by the
_Encyclopædia_--especially in individuals revealing certain
eccentricities of mind or character. This old-time opinion is worth
remembering, particularly in view of latter-day theories.
Once adopted by the eighteenth-century physicians, the application of
the word was extended in various directions. André (1756) was the first
to mention _tic douloureux_ of the face, an affection excluded to-day by
common consent from the category of true tics. Simple, painless
convulsive tic, spreading from face to arms, and to the body as a whole,
was differentiated by Pujol in 1785-7. During the earlier half of the
nineteenth century no solid progress was achieved by the work of Graves,
François (of Louvain), Romberg, Niemeyer, Valleix, or Axenfeld. It is to
the clinical genius of Trousseau that we owe the rediscovery of tic, the
careful observation of its objective manifestations, and the recognition
of accompanying mental peculiarities.
In spite of the fact that he considered it a sort of incomplete chorea,
and classed it[2] nosologically with saltatory and rotatory choreas and
with occupation neuroses, Trousseau's original account remains a model
of clinical accuracy:
Non-dolorous tic consists of abrupt momentary muscular contractions
more or less limited as a general rule, involving preferably the
face, but affecting also neck, trunk, and limbs. Their exhibition
is a matter of everyday experience. In one case it may be a
blinking of the eyelids, a spasmodic twitch of cheek, nose, or lip;
in another, it is a toss of the head, a sudden, transient, yet
ever-recurring contortion of the neck; in a third, it is a shrug of
the shoulder, a convulsive movement of diaphragm or abdominal
muscles,--in fine, the term embodies an infinite variety of bizarre
actions that defy analysis.
These tics are not infrequently associated with a highly
characteristic cry or ejaculation--a sort of laryngeal or
diaphragmatic chorea--which may of itself constitute the condition;
or there may be a more elaborate symptom in the form of a curious
impulse to repeat the same word or the same exclamation. Sometimes
the patient is driven to utter aloud what he would fain conceal.
The advantage of this description is its applicability to every type of
tic, trifling or serious, local or general, from the simplest ocular tic
to the disease of Gilles de la Tourette. Polymorphism is one of the
tic's distinguishing features.
Apart from his studies in objective localisation, Trousseau, as we have
seen, recognised that the tic subject was mentally abnormal, but the
credit of demonstrating the pathogenic significance of the psychical
factor is Charcot's. Tic, he declared,[3] was physical only in
appearance; under another aspect it was a mental disease, a sort of
hereditary aberration.
Advance along the lines thus laid down has been the work more especially
of Magnan and his pupils, of Gilles de la Tourette, Letulle, and Guinon.
A meritorious contribution to the elucidation of the question is the
thesis of Julien Noir, written under the inspiration of Bourneville and
published in 1893. The still more recent labours of Brissaud, Pitres,
and Grasset in France, and of others elsewhere, have added materially
to our knowledge.
Confining ourselves for the present to the discussion of the latest
interpretations put on the word tic, we may be allowed the remark that
if the influence of Magnan's teaching has been instrumental in making
our idea of tic conform more to the results of observation, nevertheless
his view is not without its dangers.
In the opinion of Magnan and his pupils, Saury and Legrain[4] in
particular, the tics do not form a morbid entity; they are nought else
than episodic syndromes of what Morel called "hereditary insanity," that
is to say, of what is usually designated nowadays "mental degeneration."
Now, if by degeneration be meant a more or less pronounced hereditary
psychopathic or neuropathic tendency which betrays itself by actual
physical or psychical stigmata, then tic patients are unquestionably
degenerates. If degeneration unveils itself in multifarious psychical or
physical anomalies, the subjects of the tic are undoubtedly degenerates.
If a degenerate may suffer from one or other variety of aboulia, or
phobia, or obsession, the man with tic is a degenerate too.
Thus understood, the epithet may be applied to all individuals affected
with tic. In fact, they _must_ be degenerates, if the word is to be
employed in its most comprehensive sense. But the explanation is
insufficient, inasmuch as the converse does not hold good; all
degenerates do not tic.
We may be safe in maintaining, then, that tic is only one of the
manifold expressions of mental degeneration, but we are not much
enlightened thereby. Obsessions and manias similarly are indications of
mental deterioration, yet the fact conveys very scanty information as
to their real nature. Physical anomalies--ectrodactyly, for
instance--betoken physical degeneration, no doubt; but are inquiries to
cease with this categorical assertion? Such certainly was not the idea
of those observers whose is the praise for having demonstrated the
common parentage of the heterogeneous manifestations of degeneration.
Synthesis cannot exclude the work of analysis, and in practice there is
scarcely a case to which this doctrine is not pertinent.
Every physical and every mental anomaly is the fruit of degeneration;
every individual who is a departure from the normal is a degenerate,
superior or inferior as the case may be. As instances of the latter we
may specify the dwarf and the weak-willed; of the former, the giant and
the exuberant. This sane and comprehensive conception of the subject
must command universal acceptance as a synthetic dogma, but it cannot
supplant the description and interpretation of individual facts. However
legitimate be our representation of tic as a sign of degeneration, it is
obviously inadequate if we rest content with styling its subject a
degenerate.
Unfortunately the inclination too often is to be satisfied with the
term, and to imagine that therewith discussion terminates. Still more
unfortunately, in concentrating their attention on the mental aspect of
the disease, some have altogether lost sight of one of its fundamental
elements, viz. the motor reaction, and have conceived the possibility of
its occurrence without any _tic_ at all. Cruchet actually postulates the
existence of an exclusively psychical tic, with no external
manifestation.
To these questions, however, we shall return. The present introductory
sketch is intended merely to demonstrate the ease with which ambiguity
arises, and the desirability of its removal. We are fully conscious of
the value of the work of Magnan and his school in emphasising a phase of
the subject the exposition of which can only result in gain.
* * * * *
The investigation of the motor phenomena of tic is no less encircled
with perplexities. Not only are the troubles of motility boundless in
their diversity and correspondingly difficult to classify, but they also
bear so close a resemblance to a whole series of muscular affections
that one is tempted to describe a special symptomatology for each
individual case.
For several years there has been, more especially outside of France, a
manifest tendency to aggregate all convulsions of ill-determined type
into one great class, under the name "myoclonus"; and into this chaotic
farrago, it is to be feared, will tumble a crowd of conditions which
should be studiously differentiated: the tics, electric and fibrillary
choreas, paramyoclonus multiplex, etc., etc.
In the present state of our knowledge, according to Raymond,[5] we must
be guided by the lessons of clinical experience, which teach us, first,
that the varying modalities of myoclonus develop from the parent stock
of hereditary or acquired degeneration; and, secondly, that transitional
forms which do not fall into any of the received categories are of
common occurrence.
From a general point of view, the deductions are entirely reasonable.
There is a suggestive analogy between these conditions and the muscular
dystrophies in the persistence with which their multiplicity seems to
defy the efforts of classification. The analytic stage witnessed the
rapid evolution of such clinical types as the facial, the
facio-scapulo-humeral, the juvenile, the pseudo-hypertrophic, not to
mention others that bear the name of their observer; but it has been
succeeded by the synthetic stage, whose function it is to incorporate
all the former myopathies in the comprehensive group of "muscular
dystrophy."
Yet here, again, peril lurks in too hasty a generalisation. To give the
disease a name is not equivalent to pronouncing a diagnosis. The
denominations "myoclonus," "muscular dystrophy," "degenerate," are alike
inconvenient. Their scope is at once too inclusive and too exclusive.
They may be indispensable; they are assuredly not sufficient.
The possibilities of misapprehension do not end here.
The manifestation of each and every tic--be it a flicker of the eyelid,
a turn of the head, a cry, a cough--is through the medium of a muscular
contraction. On the very nature of this contraction opinion is divided.
To its distinctive features of abruptness and momentariness is due the
epithet "convulsive" habitually assigned it, but the qualification is
not secure. Since the time of Willis the word convulsion has been
employed in a double sense, to signify _clonic_ muscular contractions
(the "convulsion" of popular parlance) and _tonic_ muscular contractions
(a meaning attached to the term only by the scientist).
For our part, we can raise no valid objection to the specification of
tics as convulsive, provided always that the existence of clonic
convulsive tics and of tonic convulsive tics be recognised. As a matter
of fact, clinical observation supplies instances of both sorts.
Nevertheless, attention has been confined by a majority of authors to
the consideration of the former variety only, so much so that a whole
order of facts which in derivation, essence, and external
characteristics ought to be identified with the tics has been passed
over in silence. Even on the assumption that the proposal to recognise
the two classes cannot be entertained, at the least it is advisable to
predetermine the import of the word convulsion, and to speak of _clonic_
convulsive tics. This is the formula of Ferrand and Widal in their
article "Convulsion" in the _Encyclopædic Dictionary of the Medical
Sciences_. Similarly, Troisier[6] says that the convulsive tic properly
so called is characterised by clonic movements, in which opinion Erb and
most German observers concur. Tonic tic appears to have been forgotten,
and we have thought it our duty to resuscitate it.
Cruchet has quite recently approached the subject in a critical fashion:
To extend the term tic to tonic spasms such as mental torticollis,
mental trismus, or permanent blepharospasm, is singularly to
outstep the limits of its significance. We believe Erb, Troisier,
and Oppenheim are warranted in restricting convulsive tic to clonic
convulsions, and the consequent simplification and elucidation of
the question lead us to adopt the same view.
If it be solely a matter of terminology, and if universal consent
reserve tic for convulsions whose expression is clonic, we shall be the
first to withdraw the phrase "tonic tic," making the single proviso that
some other designation be found for a condition which differs from the
clonic tic only in its external features, and not in origin, pathogeny,
or treatment.
What is this other name to be? Are these tonic muscular contractions to
be regarded as synonymous with contractures? If so, do we mean
myotetanic contracture--to utilise the excellent division imagined by
Pitres--as in hysteria, or myotonic contracture, as in Parkinson's
disease? The state of muscular contraction in tonic tic does not
correspond accurately to either, though it is certainly more akin to
the myotonic form; but myotonia is a sort of _caput mortuum_ for the too
facile classification of cases in reality difficult to place, and we are
afraid the term is not calculated to ensure precision of ideas.
Should we be reproached with straining the primary meaning of the word
tic by applying it to a contraction of a certain duration, we find ample
justification ready at hand in the pages of Cruchet himself. "It was
probably in 1656," he says, "that _tique_ appeared in the French
language, in the works of Jean Jourdin." Now, in the quaint description
of the horse's _tique_ given by that writer, the signs of the disease
are said to be cocking of the ears, rolling of the eyes, clenching and
gnashing of the jaws, stiffening of the tail, nibbling at the bit, etc.
What else are these than persistent contractions or tonic tics,
alternating or co-existing with jerking movements or clonic tics?
We have no desire, of course, to over-estimate the argumentative value
of this passage, the interest of which is mainly historical; but we find
ourselves wholly in accord with Cruchet when he remarks of the
scientific distinction formulated by Willis, and again by Michael
Etmüller, between continuous, permanent tonic convulsions, and
intermittent, momentary clonic convulsions, that it is uninvolved,
practical, and of universal applicability.
In 1768 certain tics were classified among the tonic convulsions by
Boissier de Sauvages. Marshal Hall[7] gave an account of various tonic
facial convulsions to which Valleix refers as non-dolorous tics or
idiopathic convulsions of the face. Coming nearer to our own times, we
find the distinction of which we have been speaking again elaborated by
Jaccoud,[8] in 1870, and accepted also by Rosenthal.
Doubtless physiologists and pathologists are not invariably at one as
regards the proper characters of the two, and subdivisions into
continuous tonic contractions as opposed to intermittent tonic
contractions have been deemed necessary; but without burdening the
subject with a plethora of detail, we think it simple, suggestive, and
clinically satisfactory to uphold Willis's generalisations and to enlist
their help in the exposition of the tics. Hence, unless under special
circumstances, we consider recourse to the epithet "convulsive"
superfluous, and we shall employ the word tic by itself, except when
there may be occasion to indicate the form of muscular contraction. The
gain in conciseness is not likely to be neutralised by any loss of
precision.
From our rapid survey of the vicissitudes through which the tic has
passed, we may profitably gather one or two lessons.
In so far as is compatible with its nature, the schematisation of tic is
indispensable. The inevitable variability of the personal factor and the
absence of a real breach of continuity between any two essentially
differing morbid affections ought not to deter us from the attempt to
project a line of demarcation between them. Natural science is pledged
to the labour of differentiation. It is the glory of Charcot's
alternately synthetic and analytic work to have demonstrated the value
of this method in the sphere of neuropathology. At the same time, the
wisdom of attaching only a provisional importance to any scheme and of
welcoming possible modification is of course self-evident. Inexact and
undiscriminating inference may be a stumbling-block in the path of
progress and inimical to the cultivation of the faculty of observation.
Further, inaccuracy of definition not only exaggerates the liability to
misunderstanding, but has sometimes also the disadvantage of promoting
an illusory belief in the possession of the truth.