In spite of their frequency among those who are addicted to tic, echolalia and echokinesis cannot be enumerated with the tics, seeing that their exhibition is dependent on the actions of others, whereas once a tic is established it requires no stimulus from without for its manifestation. Of course their affinity to the tics is very close: they spring from the same soil; they represent in the adult the persistence and amplification of the child's propensity for imitation, and therefore in their own way postulate a degree of mental infantilism.
Echolalia in the blind has been made the subject of an interesting study by Noir.
The echolalic repeats abruptly and rapidly what is said by others in his presence. That he does not stop to reflect is attested by his mimicry of bizarre words, technical terms, even of idioms in a foreign language.
It is an interesting fact that of twelve cases of echolalia that have come under our observation, fifty per cent. occurred among the blind. The coincidence is a rational one; blindness and echolalia are united as cause and effect. In the case of the person born blind the auditory memory is in such an advanced state of development that, if he be not very intelligent, he will seek to fix the sound of an auditory impression in his defectively organised mind as soon as he hears it, and being unable to whisper it mentally, he stimulates his auditory centres by a less delicate process, and forthwith repeats aloud the word he has just heard. This is why we meet with instances of the echolalic blind repeating a sentence before replying to it. It is instructive to note in this connection that the choicest example of echokinesis we have seen was in a deaf mute, in whom no doubt the visual phenomena were analogous to the auditory phenomena of the echolalic.
Noir is inclined to apply this mechanism to the case of echolalics who are not actually blind. He quotes instances which go to show that their visual memory is awanting, that as far as it is concerned they are "blind."
The hypothesis is attractive. It may be further remarked that the echolalia is a "motor," in the same way as the patient afflicted with hallucinations of sight or hearing is an "auditory" or a "visual."
Echolalia is amenable to treatment, and is even capable of cure. Noir gives an interesting example of the evolution of the process.
If I say to an echolalic, "Are you hungry?" he will instantly answer, "Are you hungry?" Under the influence of re-education the reply will eventually change to "Are you hungry? are you ...? Yes, sir, I'm hungry," then to "Yes, sir, I'm hungry," and finally to "Yes, sir."
Echolalia, however, is not an exclusive appurtenance of those who tic. We can remember a case of general paralysis in the clinique of Brissaud at the Hôtel Dieu, who had the regular habit of repeating the question that was addressed to him; if it were a little long, only the last ten or fifteen words were echoed. A case is quoted by Cantilena of a woman with right hemiplegia and partial epilepsy who invariably reiterated the closing phrase of anything said to her. Several cerebral tumours were discovered at the autopsy.
It is conceivable of course that an actual lesion, as well as a congenital developmental defect, may interfere with the will's inhibitory powers, in which case auditory or visual stimuli are transmitted to motor centres unmodified, the result being the production of sounds or of other movements.