is resorted to; when, if the sound can still be heard, the stopping of the first ear has been incomplete. The test with the tuning-fork placed on the cranium is of importance, because its sound is usually heard best in the stopped or the defective ear. But care must be taken that the hearing of higher or overtones is not confused with better hearing. The ability of some deaf persons to read the lips makes it important that voice tests shall be so conducted as to exclude this source of error. When there is doubt as to the honesty of the patient's statements, it is well to make all the tests of hearing with the eyes blindfolded, so that it will be very difficult for the person tested to give dishonest answers that would still have an appearance of consistency. Deafness of one ear may be tested by the binaural stethoscope or similar instrument. One tube is to be applied to each ear, and the test conducted from behind the patient, so that either ear can, without the patient's knowledge, be shut off from the sound by pressing on the corresponding tube. The objective examination of the ear in a medicolegal case must include, with thorough inspection of the external ear and drum membrane, the examination of the nasopharynx; and it should note the presence or absence of all evidences of possible disease. CONDITION OF THE EAR IN LIFE INSURANCE. Besides the increased risk of accident which severe deafness, even of one ear, entails, certain diseases of the ear are directly dangerous to life. Cancer or lupus would, of course, have the same significance here as elsewhere. But suppurative disease of the middle ear, so long as it exists, must be regarded as a source of grave danger, greater if there be a tendency to obstruction from polypoid growths or narrowing of the meatus or caries of any part of the bony meatus or middle ear. A permanent perforation of the drum membrane must be regarded as a predisposing cause to suppurative middle-ear disease. Symptoms of disease of the internal ear are significant as pointing toward the existence of brain lesions. Injuries of the Ear.-These, like other injuries, demand careful study as soon as possible after their reception. The appearances of a fresh rupture of the drum membrane, or recent, clots will in time give place to appearances that cannot be differentiated from those due to chronic disease. Careful examination of the ear should be included in all cases of serious head injuries. No general rules can be laid down for the determination of the gravity or permanence of the results of these injuries. Malpractice suits have not very often grown out of ear injuries or treatment, but with increased attention to the subject and the more frequent resort to numerous operations, some of which can now be regarded as only experimental, actions based upon them are liable to arise. In cases of operation for catarrhal deafness our knowledge of the subject is not such as to justify the surgeon in proceeding without a careful explanation to his patient of risks and possible results, thus placing the responsibility largely upon the patient. SPEECH DISORDERS. A CONSIDERATION of the forensic aspects of speech disorders should have as a basis a knowledge of the main facts pertaining to normal speech, a brief résumé of which will here be in order.1 FIG. 42. Scheme of receptive, intermediate, and emissive mechanisms of normal speech (language). Numbers 1, 2, 3. 4, 5 indicate situation of subcortical brain lesions destroying reception or emission by one or more paths, without impairing sensory memories, concept memories, language construction, or utterance memories. It should be clearly understood that the circles, squares, and triangles do not represent groups of neurons (cells), but more probably areas or "fields of conjunction" of neuron-processes (end-tufts) (see Fig. 43 for illustration of this). Normal Speech Processes. By common consent the term "speech as a cerebral function has come to be synonymous with "lan 1 Our knowledge of localization of speech processes in separate brain areas dates practically from 1861, when Broca first located the faculty of spoken speech in "the posterior part of the third frontal convolution of the left hemisphere. This view he established, for the time being, by two autopsies on aphasic patients at the Bicêtre Hospital. Since his time the subject has been much elaborated and brought to its present advanced, though far from complete, state through the labors of Falret, Trousseau, Charcot, and others in France; Wernicke, Kussmaul, Simon, and others in Germany; Benedikt in Austria; Hughlings Jackson, Broadbent, Gowers, and Bastian in England; while our own country is represented by the labors of Austin Flint, Bigelow, Starr, Mills, and numerous others. The most important general works on the subject in the English language are those of Bateman, On Aphasia, etc., London, 1890; and Wyllie, The Disorders of Speech, Edinburgh, 1894. guage," although the two are evidently quite distinct, language bearing the same relation to spoken speech that music does to dancing-i. e., it decides the movement by which it is expressed. It is in the sense of the reception, elaboration, and emission of language, therefore, that the term speech is here used. Normal speech, in this sense, embraces the capacity to correctly receive, understand, and convey to others ideas represented by words, which words may be spoken, written, printed, or indicated by signs. To use a familiar example, the idea of a fish (see Fig. 42), correctly received, understood, and expressed, comprises: 1. Reception of sensory impressions conveyed through organs of sight, smell, taste, hearing, touch, weight, and temperature senses to appropriate brain areas, where they become percepts. 2. Association or combination of these various sensory impressions and other percepts-i. e., water, cooking, dishes, etc.-to make the "concept" or idea "fish." Here, also, would come the association with its name, considered by some (Mills,' Broadbent, Charcot, Kussmaul) to be a distinct faculty in itself. 3. Expression, composed of two distinct factors-viz.: First, the purely "psychic" act of word-construction or planning, comparable to the planning of a house by the architect; secondly, psychomotor or executive processes, leading to emission of the word fish-spoken, written, printed, drawn in outline, or indicated by pantomime. These latter processes are analogous with the building of the house by various workmen from the plans previously made. Expression here resembles all the other known forces in that it is merely a "mode of motion." The diagram (Fig. 42) shows in concise form the general relationship of the processes just mentioned. Anatomic Basis of Speech Processes. - According to modern and generally accepted doctrines, the anatomic and physiologic units of the nervous system are structures called "neurons " (Fig. 43).2 66 These are protoplasmic structures, microscopic in size, consisting of an enlarged portion called the "body" (formerly known as a nerve "cell"), from which proceed elongated processes in various directions. These processes present near their terminations small swellings called "gemmules or contact bulbs." The view has been advanced that these "contact bulbs" possess the function of extension and retraction, by "ameboid" movement or otherwise, and that to this movement are due the "make" and "break" of contact and consequently of function observed in various states, by means of which impressions are presumed to pass from neuron to neuron throughout the nervous system. 3 A Text-book of Nervous Diseases by American Authors, p. 427. 66 37 neuron to It may be well to state that the term neuron is here used in the sense indicated by Waldeyer. Some confusion respecting the scope of the term exists by reason of the fact that Schafer and perhaps some other writers have applied the term the neuravon (one of the neuron processes). Waldeyer's nomenclature, however, is now generally accepted throughout the world. 3 Vide Dercum, Journal Nervous and Mental Disease, 1896, p. 513. It is not at all necessary, however, to assume an anatomic change of relation for this "make" and "break" mechanism. Minute changes in chemical constitution of the terminal end-tufts would be quite as effective and more conceivable to the present writer. In normal speech processes chains of such neurons, commonly composed of two or three individuals linked together, conduct sensory impressions from without to the brain cortex, where they become a part of consciousness. Here FIG. 43.-The neuron of Waldeyer: A, "pyramidal" neuron of the motor cortex, highly magnified (semidiagrammatic); B, Communications of neurons with each other by means of endbrushes (tufts or arborizations). The contact bulbs or gemmules are omitted in the small figure. neurons, parts of neurons, or other chains of neurons convert percepts into concepts (ideas), concepts into word-plans, and word-plans into motor impulses. These motor impulses are transmitted through other (outgoing) chains of neurons to the various muscles of respiration, phonation, and articulation to produce spoken words. Presumably each neuron and each chain of associated neurons possesses a separate and distinct function, though this is not, at present, susceptible of actual proof as regards speech processes. It is probable that the more numerous and complete the communications and interrelations of the neurons, the more varied will be the sources of language and the more nearly perfect its elaboration, other things being equal. Differences in the complexity of organization and interrelations of neurons therefore probably constitute the natural differences in individuals as regards range and command of language. It is probable that the subject of speech disorders will eventually be considered from the standpoint of the neuron, as nervous diseases in general now are. At present, however, for practical purposes, the areas of brain cortex which are especially concerned with speech processes are five in number, and, as shown in the accompanying diagram (Fig. 44), they are educated for speech purposes on the left half only of the brain in right N FIG. 44.-Left cerebral hemisphere, showing receptive speech areas: A, Word-hearing; V, word vision; and emissive speech areas, M, motor; G, graphic. A fifth area, N, intermediate in order of function between the receptive and emissive areas, has been described by Mills as the "naming center," and a case reported by him to favor this view. Connections (commissures) by means of associative mechanisms are believed to exist between each of these areas. These commissures are probably paired-e. g., one set passing from A to V, another from V to A, etc. Lesions of these commissures cause the various forms of paraphasia (intermediate or "conduction" aphasias) (modified from Wyllie). handed persons. In most left-handed, persons the right half contains the speech mechanisms. Presumably, the neurons concerned in the various subdivisions of the speech process are grouped, each division to a considerable extent aggregated, but connected by neuron processes of various kinds (collaterals, dendrites, etc.) with each of the other groups. According to modern views, the chief seat of nervous activities proper (sensation, motion, thought, etc.) is at the points of contact between the end-tufts (fields of conjunction), not at the neuron bodies ("nerve-cells "), as was until recently taught. The neuron bodies (formerly cells) are now believed to bear chiefly a nutritive relation to the more active neuron procThese neuron processes again are not simple homogeneous esses. 1 Vide Mills and McConnell, Journal of Nervous and Mental Disease, vol. xxii., January, 1895, p. 1. |