Definitions

A summary of the speech and language disorders described in this chapter is presented in Table 154.1.

Aphasia is an acquired, neurogenic language processing impairment that can disrupt the modalities of language, including speaking, listening, reading, and writing. Aphasia is commonly caused by stroke; it occurs in 21% to 38% of cases of acute stroke and is associated with high morbidity, mortality, and financial cost [1]. However, aphasia can result from brain injuries other than stroke, such as tumors and head trauma, and it must be differentiated from motor or sensory dysfunction, psychiatric illness, confusion, or general intellectual impairment [2]. In the United States, there are approximately 100,000 new cases of aphasia per year; the majority are women and 65 years of age or older [3]. Primary progressive aphasia is a term reserved for subtle, insidious progressive language impairments associated with frontal-temporal dementia. In primary progressive aphasia, there is relative preservation of other mental and cognitive functions for at least the first 2 years of the condition [4].

Aphasia is classified into subtypes according to the ability to produce, to understand, and to repeat language [5]. The ability to produce language is assessed in terms of fluency, defined as the rate of speech and the amount of effort in producing speech. Each subtype of aphasia is associated with a specific profile of language capabilities and disabilities (Table 154.2). For example, an individual with Wernicke aphasia produces fluent language, has impaired auditory comprehension, and has poor repetition skills. In contrast, Broca aphasia is characterized by nonfluent language, relatively intact auditory comprehension, and poor repetition skills.

Motor speech disorders, which include dysarthria and apraxia of speech, result from neurologic impairment affecting motor planning, neuromuscular control, or execution of speech [6]. Apraxia of speech results from a disruption in programming of the volitional movements for speech and is characterized by difficulty in orchestrating the movements of the lips, tongue, jaw, soft palate, vocal cords, and respiratory system for the production of speech. It can occur without muscle weakness or impairments in receptive and expressive language. Apraxia of speech is a distinct disorder, although some of its symptoms can co-occur in the presence of dysarthria and aphasia [7].

Dysarthria, a group of motor speech disorders resulting from damage to the central or the peripheral nervous system, affects 10% to 65% of individuals with acquired brain injury, depending on the type, extent, and duration of injury [8]. Dysarthria results from weakness, paralysis, or dyscoordination of the speech muscles that impairs articulation, respiration, resonance, and phonation (voice production). Dysarthria is divided into subtypes according to the speech characteristics and underlying pathophysiologic process. Neurogenic speech disorders should be differentiated from those resulting from structural problems (such as cleft palate or post-laryngectomy status) or psychogenic disorders [6]. The extreme form of dysarthria is anarthria, in which the individual is entirely incapable of producing articulated speech. Individuals with dysarthria often have dysphagia, or impaired swallowing, regardless of the etiology or duration [9]. This is readily understood, considering the overlap of structures and functions used in speaking and swallowing (see Chapter 129).

Dysphonia is faulty or abnormal phonation (voice production). Although prevalence rates are not well established, dysphonia is common in any condition causing abnormal motion of the vocal cords or dyscoordination of breathing and speaking. These include brainstem stroke, Parkinson disease, amyotrophic lateral sclerosis, Guillain-Barré syndrome, myasthenia gravis, spastic dysphonia, and multiple sclerosis, among others [6], as well as secondary processes that alter the structure or function of the vocal cords, including vocal abuse (such as excessive talking, screaming, or smoking), trauma (traumatic or prolonged intubation, arytenoid dislocation), status post–laryngeal surgery, and a variety of disorders (laryngeal cancer, reflux laryngitis) [10]. Dysphonia is distinguished from dysarthria in that dysphonia involves only the sound of the voice, whereas dysarthria involves the overall sound of speech, including resonance and articulation.

Symptoms

Individuals with aphasia often complain of difficulty in speaking, reading, writing, or understanding speech. They often report difficulty in finding the word they wish to say and can become frustrated; however, some are unaware of their deficits. Individuals who solely have a motor speech disorder (e.g., dysarthria, dysphonia, or apraxia of speech) have no difficulty in finding the words they wish to say and report no difficulties with reading, writing, or auditory comprehension but complain primarily of difficulty in producing intelligible speech. Aphasia develops most commonly after left hemisphere stroke even in people who are left handed, whereas neglect, visual-spatial impairments, and other cognitive syndromes are more common after right hemisphere strokes [11].

Physical Examination

During the initial history and physical, the physiatrist should attend to speech intelligibility, vocal quality, language content, fluency, and auditory comprehension. Deficits in these areas warrant referral to a certified speech-language pathologist for comprehensive evaluation including standardized testing. In the rehabilitation setting, the Functional Independence Measure is widely used to measure functional abilities including communication [12]. Typical findings are described here for the four main categories of speech and language disorders.

Aphasia

Findings indicative of aphasia vary according to the location and size of the brain lesion (see Table 154.2). One classic sign of aphasia is difficulty in comprehending language (spoken, gestural, or written). Significant impairment can be characterized by difficulty in following simple commands, whereas milder impairments may be obvious only during lengthy or complicated messages. Individuals who have aphasia may also have deficits in verbal expression (producing meaningful verbal output), which may be manifested as a total loss of language, with the production of only jargon (multiple whole-word substitutions) or meaningless sounds. A person with less severe aphasia may be able to express basic wants and needs but have difficulty in expressing complex ideas in conversation. Paraphasias, or naming errors, are a classic symptom of aphasia. Phonemic paraphasias involve the substitution, addition, or omission of target sounds (phonemes). For example, an individual may say “bable” for “table.” A semantic paraphasia occurs when an individual produces a word related in meaning to the target word (i.e., “fork” for “spoon”). The severity of impairment can vary for each modality of language (listening, reading, writing, recognition of numbers, and gesturing). Aphasia is not a result of decreased auditory or visual perceptual skills, disordered thought processes, impaired motor programming, or weakness or incoordination of speech musculature [1].

Apraxia of Speech

The most common sign of apraxia of speech is a struggle to speak. This struggle is a direct result of the difficulty in finding the correct position of the articulators (i.e., lips, tongue). Speech is often halting and may contain sound substitutions, distortions, omissions, additions, and repetitions [6]. The individual is aware of his or her speech errors and will attempt to correct them with varying degrees of success. Severe forms of apraxia of speech may result in the inability to produce simple words. Interestingly, most people with apraxia of speech can produce common everyday phrases or sayings (e.g., How are you? Have a nice day. Thank you.