It is true of all forms of functional hyperkinesis, that the indefinitely prolonged repetition of the same act leads finally not merely to muscular hypertrophy, but to a ceaseless over-activity of contraction in all the muscles affected. That this hypertrophy and hyperexcitability depend on some organic central lesion is not the necessary sequel. A purely functional exasperation may entail visible augmentation of movement, the cause of which is not central, but lies in the external manifestation of muscular over-activity.
The antagonistic gesture is, in some instances, contemporaneous with the wryneck, although more usually it is not in evidence until months or years after the distortion has become inveterate.
Mental torticollis is characterised by remarkable chronicity. We have seen cases of ten or fifteen years' duration and more. Temporary remissions have been known, however, and alternations with other tics or with psychical affections. At the Congress of Limoges, the following case was reported by Briand:
As the result of a bicycle accident, a young man developed a torticollis which ordinary treatment was sufficient to cure, and it remained in abeyance until he entered a government school, when its place was taken by a tic of the shoulder, with twitching of the mouth and eye. At the approach of the annual vacation the tic disappeared, and the torticollis, for some simple reason or other, became obvious again. The latter had once more been got under control by the time the holidays were over, but on the patient's re-entering school the shoulder tic again manifested itself, and this sequence recurred several times. A permanent cure was eventually effected, but he continued as psychasthenic as ever.
In another of Briand's cases torticollis alternated with astasia-abasia, a sort of "mental paraplegia." The patient could not walk at all without crutches, or without a little minerve, which he used either to steady his gait or to keep his head straight.
No doubt facts such as these just given are rather uncommon, but there is abundant reason for considering mental torticollis one of the most tenacious and intractable of all tics.
TICS OF THE TRUNK
The rarity of isolated involvement of the thoracic muscles, and the frequency of their inclusion in tics of the neck and limbs, arise from the fact of their insertion into the bones of the extremities, and consequently conditions affecting them will be dealt with in another place. Omitting for the present all reference to the muscles of respiration, we have to consider only the vertebral and abdominal groups. These pass into activity in the rhythmical salutation and balancing movements so common among idiots, movements bearing the most intimate analogies to the tics, though their peculiarity of rhythm justifies their separate classification.
Tonic contractions that find expression in attitude tics of the body are generally associated with tonic tics of the neck and limbs, and in some cases of mental torticollis the deformation they produce is extensive.
The material part played by the abdominal muscles in the function of respiration explains their implication in respiratory tics. A curious case of this kind has been published by Pierre Janet[98]: