Disorders of Speech.
The classification of the disorders of speech should depend on the anatomical site of the lesions by which they are occasioned. Broadly speaking, speech disorders resolve themselves into those of the formative apparatus for ideas and symbols and those of the purely co-ordinating and conducting mechanism. Abbreviating the schedule of Potter, we may say that the disorders of speech may be included in three classes—alalia, or lack of speech; paralalia, defective speech, the stammering of most observers; and dyslalia, difficult speech or stuttering.
The anatomy of the blood-supply of the speech-centres affords some explanation of alalia. The Sylvian artery will be remembered as the feeder of the speech-centres—an artery often the source of hemorrhage, as Charcot suggests, from the angle at which it leaves the carotid. Ducrot explains the frequency of left-sided softening and hemorrhage from the manner of origin of the left carotid, its axis being more nearly that of the ascending aorta and furnishing a ready channel for cardiac clots. In regard to the relative frequency of peripheral and central hemorrhage, Andral and Durand-Fardel cite 119 cases, of which but 17 were in the anterior or posterior lobes. It is admitted that cerebral lesions are largely those of the circulatory system, and the fact that such lesions result in the suspension of the activity of restricted areas is due to the circumstance that the cerebral arteries are terminal vessels giving off no anastomosing branches and supplying restricted areas only. With blood-supply so arranged it is not difficult to understand how the different portions of the motor centres may be separately involved, and thus the motor functions of speech may become singly at fault.
Inability to remember words and inability to form the motor impulses necessary for speech or writing are the common forms of alalia or aphasia, the former being known as amnesic, the latter as ataxic, alalia. In addition, we may cite the failure of cerebral power occurring in general softening, in microcephalic brains, and the curious instances of voluntary silence from some strong belief or prejudice. Instances of the gradual resumption of cerebral function after its loss are not wanting; and, occurring where subsequent post-mortem examinations reveal a limited area of destruction of brain-tissue, they afford examples of the vicarious performance of cerebral functions by contiguous areas.
The phenomena of amnesic alalia are commonly seen in cases of recovery from cerebral hemorrhage, cerebral injury, and severe febrile affections. Numerous cases are recorded where the memory of things themselves remained, but the faculty of denoting them had been destroyed.
Kussmaul distinguishes here two conditions: 1st, where the word is entirely effaced from memory, 2d, where it still remains, but its association with that which it represents is suppressed. Cases of the second class are the most frequent, the fundamental part which the association of ideas plays in mental activity and the extent to which memory is dependent on association explaining this fact. A marked example of the failure of the denotative faculty lies in the cases of forgetfulness of one's own name, as described by Crichton in the case of an ambassador at the Russian court, who was obliged to say to his companion, when visitors asked his name, “For Heaven's sake, tell me what I call myself!” Piorry mentions the case of an aged priest who after right-sided paralysis lost entirely the use of substantives; wishing to ask for his hat, the word hat failed him utterly, and he was obliged to express himself in the remaining parts of speech: “Give me that which I place upon the ——;” but the word head, denoting the object most commonly in relation with the hat, was wanting also. When either hat or head was mentioned he spoke the word without difficulty.
Instances of failure in linguistic faculty are not uncommon. Witness a case, reported by Proust, of an Italian who after long residence in France, though understanding his native tongue, could speak only in French. Cases in which after acute disease one language is gone entirely while several others are retained are not wanting. A striking case of amnesic alalia was that of Lordat, a French physician, who thus described his malady: “I find myself deprived of the value of all words. If any words remain to me, they become useless, because I can no longer remember the manner in which I must co-ordinate them to express my thoughts. I am conscious that I recognize all ideas, but my memory does not suggest a word. In losing the memory of the meaning of spoken words I have lost that of their visible signs.”
Fortunately, these cases are among the more tractable of cerebral disorders. Bristowe has reported a case wherein elementary instruction in speech-formation was tried with marked success. The patient, aged thirty-six, after a violent cerebral disturbance without traumatism became paraplegic, speechless, and deaf. Gradual recovery ensued until, seven months after his first illness, he was admitted into St. Thomas's Hospital in the following condition: Numbness and paresis in left leg, less in left arm; special senses healthy; no incontinence; some pain about head and neck; complete loss of speech. It was found that the patient was very intelligent, wrote legibly, could make all kinds of voluntary movements with lips, tongue, and teeth, and was capable of vocal intonation; articulation alone was lacking.
The law of the evolution of language designates as primitive forms of word-signs those words affirming qualities, while those denoting relative positions are of secondary formation (Whitney.) Remembering, also, the fact that amnesia in general “is a regression from the new to the old, from the complex to the simple, from the voluntary to the automatic, from the least organized to the best organized,”1 we are able to understand the cause of amnesic alalia, and also the steps of the process of recovery, in which the inverse order is observed.
1 Ribot, Diseases of Memory.