TIC AND PARAMYOCLONUS MULTIPLEX—TIC AND MYOCLONUS
It is not our intention here to seek to provide a differential diagnosis between tic and the various conditions usually classed as myoclonus, and that for two reasons: in the first place, we cannot admit that the latter form a distinct clinical or nosographical entity, since the term myoclonus seems simply to be an abbreviation for clonic muscular convulsion, and is a symptom rather than a clinical syndrome; secondly, the fact that the tics themselves have been incorporated with myoclonus involves the investigation of all the published cases with a view to their critical sifting. This task we have pursued for our own edification, but to enter on it here would serve no useful purpose, and we shall rest content with examining succinctly several recent cases described as myoclonus, in the hope that the prosecution of further research will introduce order into what is at present chaos.
Among the various forms of myoclonus there is one which presents a certain individuality, and which was described originally by Friedreich under the name of paramyoclonus multiplex.
This disturbance of motility supervenes, in patients with a neuropathic heredity, after some psychical accident such as a sudden fright or emotion, and consists in clonic muscular convulsions affecting the body generally, with the exception of the face. The contractions appear without obvious cause in one or in several muscles, are instantaneous, involuntary, and usually bilateral, but their most important feature is their inequality and irregularity. They may or may not effect displacement of the limbs; in any case they compose neither gesture nor gesticulation. Volition occasionally seems to have some transient inhibitory influence over them; they are exaggerated by cold and by emotion, and usually disappear in sleep.
It is obvious that this account of a typical case precludes the possibility of any confusion with tic, but the published cases are not always in conformity with it.
In 1892 Lemoine[181] reported a case where the movements of paramyoclonus multiplex were accompanied with echolalia and psychical changes. Raymond quotes an instance of the disease being preceded by facial tic, and another associated with tremor and choreic movements.
D'Allocco[182] has recorded twenty-four cases of differing forms of myoclonus, of which nineteen occurred as a family disease, in conjunction with stigmata of degeneration, epilepsy, and hysteria.
In a patient, aged twenty-six, suffering from general paralysis, Hermann[183] noted the presence of abrupt, irregular, myoclonic twitches in the sternomastoids, recti abdominis, adductors, and in some of the toes and fingers, first on one side and then on the other, also in both legs, and subsequently in both arms, the face being unaffected.
Jancowicz considers diagnosis possible only in typical cases, and expresses the opinion that paramyoclonus is a syndrome common to many affections. Further, Schupfer makes the perfectly justifiable remark that under this denomination have been included cases of chorea, tic, hysteria, and rhythmic spasm; others have been secondary to organic disease of the cerebro-spinal axis, such as rolandic lesions, spinal muscular atrophy, chronic poliomyelitis, syringomyelia. Others, again, depend on one or other of the psychoses, others on infective conditions such as malaria, diphtheria, typhoid, or on intoxications such as uræmia, mercurialism, or lead poisoning. Only a few recorded cases cannot be attributed to any of the conditions enumerated above, hence Schupfer's objection to the promiscuous classification of them all as paramyoclonus multiplex is quite warranted, in the absence of a uniform etiology and symptomatology.
Schultze[184] has suggested the term monoclonus for the tics, and he distinguishes monoclonus, polyclonus, and paraclonus. Embraced in the last of these is the paramyoclonus of Friedreich, which, according to Schultze, is usually unilateral, voluntary action diminishing the intensity of the involuntary movements, whereas the converse is the case in tic or monoclonus. Mixed forms are met with, however, and Schultze himself mentions one in which the movements were bilateral and increased with voluntary activity.
Heldenberg[185] applies the term intermittent functional myoclonus to twitches occurring from time to time in antagonistic muscles during voluntary movement, twitches exaggerated by excitement and diminished with rest. They occur in combination with well-marked vasomotor phenomena.
The myokymia of Kny and Schultze is characterised by fibrillation, pain, hyperidrosis, and changes in electrical excitability.
A case which seemed to be a combination of paramyoclonus with Thomsen's disease has been reported by Hajos[186] under the title myospasmia spinalis.
There cannot possibly be any hesitation in arriving at a diagnosis between tonic tic and Thomsen's disease, a condition consisting in slowness of relaxation of a strongly contracted muscle, and conceivably due to defective metabolism or organic change in muscular tissue.[187]
Examples such as the above, culled at random from an abundant medical literature, and variously entitled, will serve to demonstrate the protean nature of what the medical world is content to call myoclonus, and if from this collection of motor disorders we may hope to extricate the tics, there will remain still no inconsiderable labour of differentiation for the student.