Considering dysarthria: a speech disorder 'on the fringes' The goal of this article is to describe dysarthria, a speech disorder, as a disorder that is 'on the fringes' of the speech disorder category. The argument will be that, because dysarthria shares common neurological causes with motor disorders rather than with other speech disorders, it is distinguished from other speech disorders and is evidence of the overlap of the motor modality with the linguistic modality. Speech is probably one, if not the more complex functions produced by the human brain, and which is almost transparent as to the underlying neurological structures and processes as so many things are happening at the same time that it is difficult to say what is what. What we know is that there are different areas of representation for several aspects of language. An area in the left hemisphere above the perisylvian fissure in the frontal lobe anterior to the motor cortex approximately controls speech production and fluency; another area, in the temporal lobe of the same hemisphere, roughly controls word comprehension and retrieval. Other regions next to and between these areas perform related functions, and their lesion causes changes in the symptoms caused by lesion of one of the central regions described above (1). These areas are known to us as "language areas". However, they may be completely intact in a person suffering from severe speech disorders. So are there other “linguistic areas”? Strictly speaking, no, in a broad sense, yes. Language is more than a mental function in which structures are established, words are retrieved and sound associations are created. The final execution of speech is purely a matter of complex motor control. Disruption of this complex interaction of motor signals towards speech formation is known as dysarthria (2). It is sometimes confused with damage resulting from injury to “speech areas” (1), illustrating the fact that the process of speech production is multilayered and that it is often difficult to tell what is what. Symptoms of dysarthria may be slurred speech, nasality of sound, or quiet and slow speech (3). These different disorders reflect subsections of the "motor symphony" that speech produces: the lips, tongue, teeth, and jaw form specific sounds; the soft palate conveys air into the nasal or oral cavity, producing different sound qualities; the larynx (voice box) vibrates air across the vocal cords to create the voice; and finally, the respiratory system fuels this process (3).

Topic > Considering dysarthria: a speech disorder 'on the fringes' The goal of this article is to describe dysarthria, a speech disorder, as a disorder that is 'on the fringes' of the speech disorder category. The argument will be that, because dysarthria shares common neurological causes with motor disorders rather than with other speech disorders, it is distinguished from other speech disorders and is evidence of the overlap of the motor modality with the linguistic modality. Speech is probably one, if not the more complex functions produced by the human brain, and which is almost transparent as to the underlying neurological structures and processes as so many things are happening at the same time that it is difficult to say what is what. What we know is that there are different areas of representation for several aspects of language. An area in the left hemisphere above the perisylvian fissure in the frontal lobe anterior to the motor cortex approximately controls speech production and fluency; another area, in the temporal lobe of the same hemisphere, roughly controls word comprehension and retrieval. Other regions next to and between these areas perform related functions, and their lesion causes changes in the symptoms caused by lesion of one of the central regions described above (1). These areas are known to us as "language areas". However, they may be completely intact in a person suffering from severe speech disorders. So are there other “linguistic areas”? Strictly speaking, no, in a broad sense, yes. Language is more than a mental function in which structures are established, words are retrieved and sound associations are created. The final execution of speech is purely a matter of complex motor control. Disruption of this complex interaction of motor signals towards speech formation is known as dysarthria (2). It is sometimes confused with damage resulting from injury to “speech areas” (1), illustrating the fact that the process of speech production is multilayered and that it is often difficult to tell what is what. Symptoms of dysarthria may be slurred speech, nasality of sound, or quiet and slow speech (3). These different disorders reflect subsections of the "motor symphony" that speech produces: the lips, tongue, teeth, and jaw form specific sounds; the soft palate conveys air into the nasal or oral cavity, producing different sound qualities; the larynx (voice box) vibrates air across the vocal cords to create the voice; and finally, the respiratory system fuels this process (3).