Speech, Language, Swallowing, and Auditory Rehabilitation
Beth Solomon
Carmen Brewer
Martin B. Brodsky
Jeffrey B. Palmer
Jennifer Ryder
INTRODUCTION
Human communication involves the exchange of information and ideas through various processes commonly referred to as speech, language, cognition, and hearing. It is thought that the study of speech communication is one of the oldest academic disciplines with roots dating back to the time of Aristotle. Despite technological advancements, human communication has retained its value because of its practical nature in the transfer of meaningful information amongst individuals. The components of human communication are dynamic and multidimensional, which are continuously influenced by physiological, psychological, and environmental factors. Human communication occurs through a series of autonomic processes mediated by the central neurological system and monitored via a sensory feedback loop. Although complex, the components of communication can be simplified into a four-step process:
Encoding: the speaker creates the message in his or her mind
Transmittal: the speaker sends the message
Reception: the listener receives the message
Decoding: the listener breaks down the message in his or her mind
This chapter serves to improve the understanding of human communication by describing the processes of speech, language, cognition, and hearing. Additionally, oropharyngeal swallowing is reviewed due to its anatomical and physiological similarities to speech production. Descriptions of commonly recognized acquired disorders in the adult population are reviewed to facilitate understanding of the rehabilitative assessments and management.
COMMUNICATION
Human communication is often described as a well-coordinated, timed, multidimensional group of processes used to share thoughts, ideas, and emotions. The processes include speech, language, cognition, and hearing. Speech is the system that produces individual sounds, which, when placed together, develop meaningful messages. It is the verbal means of communication often thought of as the motor vehicle for message delivery. Language may be defined as an arbitrary system of signs or symbols used according to prescribed rules to convey meaning within a linguistic community (1). Language forms the set of rules shared by communicators consisting of morphology, syntax, semantics, and pragmatics. Cognition refers to the mental processes by which one recognizes, manipulates, and exchanges information to better “understand and make sense of the world” (http://www, December, 2008). Cognition gives rise to the thoughts and ideas for which one uses speech and language. Hearing is the ability to detect and assign meaning to sounds. In the case of speech, hearing serves as the system that closes the communication loop.
COMMUNICATION PATHOLOGY
A pathologic condition that affects any one of the organs involved in the process of speech or language influences the total final product. Frequently, the pathologic condition often is limited to a single speech or language component, and the dysfunction can be detected in only one specific parameter such as an isolated voice or articulation impairment. More commonly, however, the pathologic condition of a single organ influences other elements of the communication process in ways that are predictable when one considers the integrated nature of speech and language. For example, severe obstructive pulmonary disease does not just impair the respiratory support for speech but results in alterations in vocal pitch, vocal intensity, and phrasing or prosody, as the speaker compensates for an impaired ability to sustain airflow. Certain disease states, involving organs that are not directly involved in speech or language, can affect the final vocal product in a secondary manner. For example, some endocrine disorders, such as hypothyroidism, can influence voice quality as an isolated component of speech. It can also lead to language confusion and impaired memory. Because of the complexity and interactive nature of the speech and language processes, whenever one evaluates or treats a patient with a communication disorder, some considerations must be given to overall human physiology, as well as to the dynamics of speech and language systems. Many professionals including audiologists, physiatrists, and otolaryngologists contribute to the assessment and treatment of communication. Speech-language pathologists have the specialty training in the communication impairments and are
credentialed to assess, treat, and manage the communication disorders with the ultimate goal of developing and maintaining a functional communicative status for individuals.
credentialed to assess, treat, and manage the communication disorders with the ultimate goal of developing and maintaining a functional communicative status for individuals.
SPEECH PRODUCTION
Speech production requires multiple physiological systems working together to create an intelligible message. The five systems comprising speech production include respiration, phonation, resonation, articulation, and hearing. Although each system works concurrently with each other to achieve the end result of speech, it is often easier to understand the complexity of the systems by reviewing them as separate entities.
Respiration
Two forms of respiration are recognized: chemical and mechanical. Chemical respiration is concerned with the exchange of oxygen and carbon dioxide to and from the blood, whereas mechanical respiration (or ventilation) is concerned with the tidal movement of air in and out of the lungs. For speech production, mechanical ventilation will be the primary focus.
To produce sound, an energy source is needed to initiate the process. For speech, this energy source is the respiratory system, causing air pressure variations that result in airflow out of the respiratory tract and into the vocal tract. During inhalation, the diaphragm contracts and lowers allowing the thoracic cavity to expand and the lungs to fill with air. This causes a low pressure gradient, allowing the air to rush into the lungs. The pressure then equalizes as air is sustained in the lungs. Exhalation is the more passive mechanism of the inhalation/exhalation process. Exhalation causes relaxation of the diaphragm causing it to return to its normal position and shape. This in turn causes increased pressure gradient compared to outside the lungs, which ultimately results in air flow out of the lung cavity. The entire process of breathing (inspiration and expiration) is known as one respiratory cycle. At rest, this takes place 12 to 15 times a minute. Speech production occurs upon exhalation. During speech production, the time for inhalation is often reduced while the exhalation time is increased.
Phonation
The phonatory process, or voicing, occurs when air is expelled from the lungs through the glottis (space between the vocal folds). As air passes through this area, a lower pressure gradient occurs within the larynx. When this drop becomes sufficiently large, the vocal folds begin oscillating. This oscillation causes vibration, which is often referred to as the engine of the voicing mechanism. Vocal fold motion occurs in a wavelike fashion with lateral undulations as well as superior and inferior movements. The oscillation of the vocal folds serves to modulate the pressure and flow of the air through the larynx. This airflow is modulated and is the main source of voiced sounds. A normal voice is best described as the product of a controlled exhalation of air, steady maintenance of subglottic air pressures, and delicately balanced vocal folds movement. Any perturbation to this complex process can result in a perceived vocal impairment.
Resonation
The raw vocal tone is modified and amplified by resonance within the pharyngeal, oral, and nasal cavities, which are referred to collectively as the vocal tract. The innumerable configurations of the shape of the vocal tract provide the human voice with a tremendous range of variation in perceived quality.
Following transit through the larynx, the air is modulated by (a) changing the tension of the pharyngeal walls; (b) raising or depressing the larynx; (c) modifying the position of the jaw, tongue, and lips; and (d) occluding or lowering the soft palate. Valving of the velopharyngeal region requires the closure of the nasal cavity from the oral cavity for production of all sounds other than the /m/, /n/, and /ng/ sounds. This valving is achieved in a three-dimensional pattern of closure typically described as retraction and elevation of the soft palate/velum, anterior movement of the posterior pharyngeal wall, and inward movement of the lateral pharyngeal walls. Various patterns of velopharyngeal closure were initially described by Skolnick in 1973 and adopted by others to better understand the closure mechanism (2, 3).
Articulation
The final production of sound occurs as air is expelled through and manipulated within the oral cavity by the movements of the lips, teeth, and tongue. Coordinated actions of the tongue, lips, jaw, and soft palate regulate the air stream and produce the meaningful sounds of speech called phonemes. These structures, often referred to as articulators, relax, compress, or momentarily stop the air stream in varied ways to produce specific vowels or consonants. The addition or elimination of a voicing component from the larynx, during sound production, dictates whether a consonant is voiced or voiceless.
Neural Control
Motor control for respiration, phonation, resonation, and articulation requires complex neural networking, regulation, and monitoring of muscle activity of both the central nervous system and the peripheral nervous system. Many of the speech systems and musculature used for speech production are also used for oropharyngeal swallowing and mastication. It is natural that a large amount of overlap exists in the neural networking, although affecting different behaviors. The central nervous system and peripheral nervous system are the primary controls for the neural networking, though the extrapyramidal nervous system also plays a role. Although studied since the 17th century, many questions remain in determining the brain regions involved in speech production. Neuroimaging advances continue to attempt to solve this dilemma; however, inconsistencies in normal subject’s activation patterns continue to be found (4). Speech involves simultaneous activity in various regions of the brain that are largely spread over the cortical and subcortical areas. Additionally, clinical data of patients with cerebellar lesions or Parkinson’s disease suggest that the cerebellum and the brainstem are engaged in the motor control of speech (5, 6, 7).
MOTOR SPEECH DISORDERS
Dysarthria
The dysarthrias are a group of motor speech disorders characterized by slow, weak, imprecise, or uncoordinated movements of speech musculature. Rather than a single neurological disorder, the dysarthrias vary along a number of different dimensions. As stated above, the neuroanatomical site of a lesion causing dysarthria can be one or a combination of the cerebrum, cerebellum, brainstem, and cranial nerves. The prevalence and incidence of dysarthria are not precisely known. Dysarthria can be a symptom of a neurological disease process with a constellation of other symptoms, or it can stand alone with a disease. Approximately one third of individuals with traumatic brain injury (TBI) may be dysarthric with nearly double that prevalence during the acute phase of recovery (8, 9). Dysarthria is frequently seen in 50% to 90% of parkinsonian patients with the increased prevalence as the disease progresses (10). Additionally, dysarthria is often a preliminary sign of amyotrophic lateral sclerosis or can become present as the disease progresses. In larger tertiary care medical centers, dysarthria was the primary communication impairment with acquired neurological disease seen for speech-language pathology evaluations over a 4-year period (11).
The dysarthrias can be classified by time of onset, site of lesion, and etiology; however, the most widely used classification was first described by Darley et al. (12, 13, 14). This is often referred to as the Mayo Clinic Classification System with each type representing a perceived and distinguishable grouping of speech characteristics with a presumed underlying pathophysiology or locus of lesion.
TABLE 15.1 Summary of the Etiologies, Neuropathologies, and Neuromuscular Deficits Characteristic of the Common Dysarthrias | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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As a first step, differential diagnosis involves distinguishing the dysarthrias from other neurogenic communication disorders. The dysarthrias are distinct from aphasia in that language function (i.e., word retrieval, comprehension of both verbal and written language) is preserved in dysarthria but impaired in aphasia. Although both apraxia and dysarthria are considered motor speech disorders, they can be distinguished on the basis of several clinical features. In apraxia, automatic (i.e., nonspeech) movements are intact, whereas in most dysarthrias, they are not. Highly consistent articulatory errors are characteristic of dysarthria, whereas inconsistent errors are a hallmark of apraxia. Finally, in most dysarthrias, all speech systems, including respiration, phonation, resonation, and articulation, are involved; whereas in apraxia, respiratory or phonatory involvement is rare. It should be recognized that patients often can have elements of both dysarthria and apraxia, particularly those with bilateral brain damage.
Differential diagnosis among the dysarthrias seems to have received more systematic attention than any other aspect of the disorder. Table 15-1 summarizes information related to the various dysarthrias (15). In studies conducted at the Mayo Clinic, the perceptual features of the speech of seven groups of dysarthric patients were examined (12, 13). These groups consisted of patients who were unequivocally diagnosed as having one of the following conditions: pseudobulbar palsy, bulbar palsy, amyotrophic lateral sclerosis, cerebellar lesions, parkinsonism,
dystonia, and choreoathetosis. Speech samples were rated along 38 dimensions that described pitch characteristics, loudness, vocal quality, respiration, prosody, articulation, and general impression. Results of these studies indicated that each of the seven neurological disorders could be characterized by a unique set of clusters of deviant speech dimensions and that no two disorders had the same set of clusters. Thus, differential diagnosis among the dysarthrias can be made, in part, on the basis that one type of dysarthria sounds different from the others. However, single features such as imprecise consonant production or nasal emission may not be sufficient to distinguish one type of dysarthria from another. Instead, differential diagnosis is made on the basis of clusters of features reflecting underlying pathophysiology and the findings on examination of the musculature. The following summarizes the major types of dysarthrias, their primary distinguishing perceptual attribute, and their presumed underlying localization and distinguishable deficit.
dystonia, and choreoathetosis. Speech samples were rated along 38 dimensions that described pitch characteristics, loudness, vocal quality, respiration, prosody, articulation, and general impression. Results of these studies indicated that each of the seven neurological disorders could be characterized by a unique set of clusters of deviant speech dimensions and that no two disorders had the same set of clusters. Thus, differential diagnosis among the dysarthrias can be made, in part, on the basis that one type of dysarthria sounds different from the others. However, single features such as imprecise consonant production or nasal emission may not be sufficient to distinguish one type of dysarthria from another. Instead, differential diagnosis is made on the basis of clusters of features reflecting underlying pathophysiology and the findings on examination of the musculature. The following summarizes the major types of dysarthrias, their primary distinguishing perceptual attribute, and their presumed underlying localization and distinguishable deficit.
Flaccid Dysarthria
Flaccid dysarthria is due to weakness in cranial or spinal column nerve innervations to the speech systems. Its specific characteristics depend on which nerve is involved. Nerves affecting articulation include trigeminal, facial, or hypoglossal. The vagus nerve contributes to voice and resonatory dysarthria primarily seen with breathy, hoarse, and diplophonic speech. Spinal respiratory nerves can also be affected with deficits in breath patterning for speech, often causing production of short phrases. Most common speech characteristics include hypernasality, breathiness, diplophonia, nasal emission, audible inspiration (stridor), short phrases, and rapid deterioration and recovery with rest. Brainstem stroke or brain injury is a common cause of flaccid dysarthria (14).
Spastic Dysarthria
Spastic dysarthria is usually associated with bilateral lesions of upper motor neuron pathways that innervate the relevant cranial nerve and spinal nerve. Its distinguishable characteristics are attributed to spasticity, and they often include a harsh, strained vocal quality, slow speech rate, pitch breaks, and variable loudness. All speech systems are typically affected with this classification (14).
Ataxic Dysarthria
Ataxic dysarthria is associated with lesion’s disturbances of the cerebellum or its controls. As it is known for its incoordination as a characteristic, individuals are perceived with articulation and prosodic feature disturbances. Irregular articulatory breakdowns, distorted vowels, and inappropriate variations in pitch, loudness, and stress often are the classic features (14).
This type of dysarthria has been coined with the term “drunken speech.” Ataxic dysarthria is often a result of cerebellar stroke or spinocerebellar ataxia.
Hypokinetic Dysarthria
Hypokinetic dysarthria is associated with basal ganglia control of the central nervous system. Its features are mostly related to reduce range of motion and rigidity. Additionally, reduced loudness, short rushes of speech, breathy-tight dysphonia, and monoloudness and monopitch are notable characteristics. Often dysfluency and word repetition are reported. Parkinson’s disease and its syndromes are the most noted disorder for hypokinetic dysarthria (15).
Hyperkinetic Dysarthria
Hyperkinetic dysarthria is also associated with basal ganglia control; however, unlike hypokinetic dysarthrias, it is distinguished by abnormal involuntary movements that affect the intended speech movements. It is classified in many of the movement disorders and subcategorized into slow and fast hyperkinetic dysarthrias. Slow includes dystonia and athetosis, while fast includes tic and chorea. They may affect any of the speech systems and area usually distinguished by unpredictable variability in voice and articulation. Distorted vowels, excess loudness variations, sudden forced inspiration/expiration, voice stoppages/arrests, transient breathiness, intermittent hypernasality, and inappropriate vocal noises are just some of the common characteristics. Etiologies include Huntington’s chorea, Tourette’s syndrome, cerebral palsy, and side effects of neuroleptic drugs (16).
Unilateral Upper Motor Neuron Dysarthria
This dysarthria has an anatomical rather than a pathophysiological label. It typically results from stroke affecting upper neuron pathways. Damage is unilateral; severity usually is rarely worse than mild to moderate. Often its characteristics overlap with flaccid, spastic, or ataxic dysarthrias (16).
Mixed Dysarthria
Mixed dysarthria reflects combinations of two or more of the single dysarthria type. It occurs more frequently than any single dysarthria type. A common diagnosis involving mixed dysarthria is amyotrophic lateral sclerosis, which, in advanced stages, has features of both flaccid and spastic dysarthrias (15).
Assessment
Traditionally, the assessment of dysarthric speech has mainly involved the use of perceptual evaluation measures. The inadequacies of this method of assessment have resulted in the development of a range of instrumental assessment techniques to provide more objective analyses of the underlying physiological impairments of the speech mechanism. Generally, the assessment of dysarthria relies on a combination of perceptual and instrumental analysis, including acoustic analyses. Most of the perceptual scales are based on the studies by Darley et al., using a number of speech dimensions to be rated on a severity rating scale (14). Intelligibility scores has been one of the main measurement parameters to indicate communicative functional status. The interactive product of respiration, phonation, articulation, resonance, and prosody helps to define the speech impairment and requires full attention during assessments. Often, little attention is placed on connected speech intelligibility in the dysarthria population; however, it may
be a more valid indicator of functional communication than assessment at the word or simple phrase level (17).
be a more valid indicator of functional communication than assessment at the word or simple phrase level (17).
Studies have demonstrated acoustic variations in dysarthria; however, many of the studies have focused on one element in acoustic analysis rather than a broadly directed analysis of the speech output by systems, for example the articulatory, resonatory, phonatory, and respiratory components (18, 19, 20, 21, 22).
A dysarthric speech assessment must involve perceptual acoustic description of all the systems. Clinicians must understand the interrelationship of the weakness, slowness, discoordination, or abnormal tone of the speech musculature and its effect on the systems of the speech mechanism, including respiratory, phonatory, velopharyngeal, or oral articulatory subsystems (23). Both perceptual and instrumental tools are available for measuring speech performance (24, 25). The perceptual tools are those that rely on the trained eyes and ears of the clinician, whereas instrumental approaches to assessment include devices that provide information about the acoustic, aerodynamic movement, or phonatory aspects of speech.
Assessment of the respiratory subsystem begins with perceptual measures, including ratings of the number of words produced per breath, the loudness of samples of connected speech, or visual observations of the presence of clavicular breathing. Instrumental approaches to the measurement of respiratory function may include acoustic measures of vocal intensity and utterance durations. Respiratory performance may also be assessed by estimating the subglottic air pressure generated by the speaker (26, 27). Respiratory inductive plethysmography, commercially available as the Respitrace, is an instrument capable of obtaining information about the movements of the rib cage and abdomen during breathing and speech.
Phonatory (laryngeal subsystem) assessment typically begins with perceptual ratings of pitch characteristics (e.g., pitch level, pitch breaks, monopitch, and voice tremor), loudness (e.g., monoloudness, excess loudness, variation of volume), and voice quality (e.g., harsh voice, hoarseness, wet voice, breathiness, strained-strangled voice). Acoustic analysis can be performed by deriving vocal fundamental frequency and intensity (28, 29). Measures of laryngeal resistance to airflow can also be obtained (30) along with laryngeal visualization with endoscopy or stroboscopy (30).
Assessment of the velopharyngeal mechanism can be made with perceptual judgments of hypernasality or the occurrence of nasal air emission. Nasalization also can be measured acoustically. Precise inferences can be made about the timing of velopharyngeal closure by obtaining simultaneous pneumatic measures of air pressure and air flow during selected speech samples (31, 32). Movement of the velopharyngeal mechanism can be observed through cineradiographic techniques and/or endoscopic visualizations.
Assessment of oral articulation can be made by the rating of consonant and vowel precisions and coordination of articulatory movement. Although movements can be recorded using cineradiographic technique and myoelectric activity with electromyographic recordings, these techniques are not used in routine clinical practice.
Treatment Considerations
Clinical decisions regarding treatment of dysarthria should include behavioral objectives for reaching short- and long-term goals. An overall goal to improve functional communication for the patient is necessary and should be identified and described with the patient and his or her significant family members. Generally, treatment goals can vary with the severity of the speech impairment and the overall medical disorder.
For severely involved speakers, whose intelligibility is so poor that they are unable to communicate verbally in some or all situations, the general goal of treatment involves establishing an immediate functional means of communication. This may include use of augmentative approaches. The term communication augmentation refers to any device designed to augment, supplement, or replace verbal communication for someone who is not an independent verbal communicator. These augmentative or alternative communication (AAC) systems can be as low tech as writing or communication boards, or higher tech such as talk-back switches or computer-based speech synthesis. The selection of an appropriate augmentation system requires a thorough evaluation of the individual’s communication needs. To determine an individual’s needs, the clinician needs to consider the patient’s physical and cognitive capabilities, including cognition, language, memory, physical control, vision, hearing, and overall medical condition. This assessment may require additional co-evaluators, such as an occupational therapist or a rehabilitation engineer. Once the individual’s capabilities have been ascertained, augmentative system components can be selected, and appropriate system modifications can be made.
For those moderately involved speakers who are able to use speech as their primary means of communication but whose intelligibility is compromised, the general goal of treatment involves improving intelligibility. Use of compensatory strategies with speech production or augmentative systems is common. Achieving compensated intelligibility may take a variety of forms, depending on the speaker and the nature of the underlying impairment. For some with greater involvement, use of an alphabet supplementation system, in which they point to the first letter of each word as they say the word, assists in the transition to intelligible speech (9). For others, the treatment involves an attempt to decrease the impairment by exercises that will improve performance on selected aspects of speech production. For example, exercises may involve developing more adequate respiratory support for speech (33) or training to establish an appropriate speech rate (34). For the mildly involved dysarthric speaker whose speech is characterized as intelligible but less efficient and less natural than normal, treatment planning should consider the patient’s needs in communication within his or her home or job setting. For some speakers, these mild reductions in speech efficiency pose no problems. For other mildly involved speakers, however, treatment is warranted. The general goals of treatment
for dysarthric people with mild disabilities include maximizing communication efficiency while maintaining intelligibility and maximizing speech naturalness. Maximizing naturalness is accomplished by teaching appropriate phrasing, stressing patterning, and intonation (35).
for dysarthric people with mild disabilities include maximizing communication efficiency while maintaining intelligibility and maximizing speech naturalness. Maximizing naturalness is accomplished by teaching appropriate phrasing, stressing patterning, and intonation (35).
Often partnerships with other medical professionals are appropriate. For example, a maxillofacial prosthodontist may assist with managing resonant disorders such as velopharyngeal incompetence. Fabrication of a prosthetic device such as a palatal lift can assist with management of impaired velopharyngeal closure. Assessment of candidacy for the device is a coordinated effort between the speech-language pathologist and the prosthodontist. An appropriately fitted palatal lift will allow certain dysarthric speakers to better produce speech sounds that require the buildup air pressure and can maximize intelligibility by improving prosody and contextual breath support.
Treatment approaches for patients with progressive disorders such as parkinsonism, multiple sclerosis, and amyotrophic lateral sclerosis are different from those used with the dysarthric speaker who is recovering from a single medical event (36). Initially, the patients are encouraged to maximize the functional communication level by paying specific attention to the clarity and precision of their speech. At some point, the patients will need to modify their speaking patterns by controlling rate and consonant emphasis and by reducing the number of words per breath. Some patients with progressive dysarthria make the adjustments in their speech pattern without specific treatment; others may need to practice these modifications with a speech pathologist or trained family member until the changes become habitual. In severe cases, a communication augmentation system may be considered. These augmentation systems usually are chosen or designed to accommodate the lifestyle of the patient while serving his or her anticipated communication needs over the longest period of time.
Apraxia
Apraxia of speech (AOS) occurs in the absence of significant weakness and incoordination of muscles, with automatic and reflexive movements undisturbed. Lesions in the premotor cortex are a frequent finding (37). AOS is characterized by labored and dysprosodic productions, resulting in errors of omission, substitution, and repetition. There is debate as to whether AOS is a pure motor or linguistic (i.e., phonemic) disturbance (38, 39, 40). Patients have difficulty programming the positioning of the speech musculature and sequencing the movements necessary for speech. It is seen by some as a distinct condition that often coexists and complicates aphasia, whereas others regard the characteristics as part of the nonfluent Broca’s aphasia. AOS carries a negative prognosis for recovery when there is a moderate to severe aphasia in tandem. When it occurs without the concomitant language disturbance, therapy can focus on retraining the patient’s ability to program sound patterns, to shift from one sound to another, and to use preserved melodic and rhythmic patterns to facilitate speech.
Head and Neck Cancer
The diagnosis of head and neck cancer often presents with speech and/or swallowing impairments. The location of the malignancy often dictates the speech impairment being phonatory, resonance, articulatory, or a combination of the three. Treatment of the disease can be a sole modality such as surgery or radiation therapy or multiple modalities, including surgery, irradiation, and chemotherapy. Over the last 20 years, treatment has focused on organ preservation with the goal of maintaining function. This type of treatment is often recommended for tumors of the tongue, oral cavity, tonsil, base of tongue, and pharynx and larynx. Depending on tumor size, spread of disease, and nodal involvement, the treatment often involves radiation with or without chemotherapy. Speech impairments thus would typically be seen in the acute phase of treatment and in the immediate posttreatment acute phase (6 months posttreatment). Chronic effects are often seen with scarring and fibrosis greater than 6 months posttreatment.
Often surgical intervention is needed with advanced disease or recurring disease. This may involve removal of the larynx alone or with other organs. Removal of the larynx or total laryngectomy is a common procedure. With loss of the voicing component for speech production, there is an obvious need for speech rehabilitation, beginning with presurgical teaching and continuing with communication alternatives and rehabilitation postsurgery.
Several options for speaking are available to postlaryngectomy patients including artificial larynx, esophageal speech, or tracheal esophageal puncture, a voice restoration procedure. Artificial larynx use or electrolarynx offers individuals the opportunity to speak within days of surgery. Commercially available electrolarynges are designed to introduce air vibrations either directly into the oral cavity through a catheter or indirectly through the neck tissues. In each case, the tones resonate within the oral and pharyngeal cavities and are modified by articulation into audible, intelligible words. Often an intraoral electrolarynx can be used 2 or 3 days after surgery, providing the patient with an immediate means of communication. Intraoral devices can also be used a long term for patients with necks that are unsuitable for indirect transmission of vibration, usually because of pain, edema, or scar tissue. Experience suggests that good speech is slower to develop using an intraoral device than with a neck device. Therefore, care must be taken to help the patient avoid early frustration associated with not being understood immediately.
A second form of speech alternative is esophageal speech. Esophageal speech is accomplished by training the patient to move air from the oral and pharyngeal cavities into the esophagus by injection or inhalation methods. The air is then trapped within the cricopharyngeal segment and released. The vibration of the release from the segment is the phonatory sound that is then modulated with resonatory and articulatory modifications to produce speech. Accomplished esophageal speakers can speak clearly and effortlessly; however, many laryngectomy patients are unable to learn this technique. Failure to learn esophageal speech may represent insufficient or excessive
pharyngoesophageal segment tone, scarring, nerve damage, or reduced patient commitment for learning.
pharyngoesophageal segment tone, scarring, nerve damage, or reduced patient commitment for learning.
A third option for speech involves surgical intervention and placement of a one-way-valved prosthesis between the trachea and the esophagus. This is termed tracheoesophageal puncture (TEP). The procedure often is performed by head and neck surgeons as a secondary procedure; however, it can be performed with the total laryngectomy. This method of voice production uses the same anatomic vibratory site as the esophageal speech technique.
Tracheal-esophageal puncture procedures have been used since 1980 and are a relatively simple means of voice restoration (41). A small, one-way-valved voice prosthesis is inserted through the TEP tract that is surgically created to maintain patency. Air is then shunted via digital or valve occlusion of the stoma into the esophagus without having esophageal contents enter the TEP. Air then passes through the prosthesis to the cricopharyngeal segment for vibration to produce the voicing component of speech. Early speech success following TEP and voice prosthesis fitting has been reported in almost 90% of cases (42, 43). Long-term success is reported at between 93% for patients given primary TEP and 83% for those given secondary procedures (44). Success largely depends on patient selection, and in some cases, success can be enhanced by surgical techniques that can prevent pharyngoesophageal segment spasm (45) such as pharyngeal plexus neurectomy or cricopharyngeal myotomy or botulinum toxin injection. Other factors to consider in patient selection are motivation, intellect, dexterity, eyesight, stoma size and sensitivity, hand hygiene, surgical risk, and cost.
Fluency
Fluency disorders are characterized by a disruption in the ease and flow of connected speech. The most common and well-known type of fluency disorder is stuttering. Stuttering is a very complex, dynamic, and somewhat controversial disorder in that theories and opinions abound regarding etiology, diagnosis, and treatment. Theories regarding underlying cause include genetic, cognitive, psycholinguistic, neuromuscular, as well as multifactorial. It is generally accepted that primary characteristics of stuttering include blocks (absence of sound), repetitions (of sounds or words), and/or prolonged sounds. Secondary behaviors often observed include struggle (body movement, eye blinks, lip/jaw tremors) and avoidance of sounds, words, conversation partners or environments that trigger the dysfluency. The evaluating clinician must be very cautious with diagnosis for several reasons. One, stuttering resolves in 75% to 90% of small children who begin to stutter. Additionally, there is a spectrum of normal dysfluency that is reactive to environmental pressures but is not consistent with a stuttering diagnosis. Labeling one as a “stutterer” when he or she is within the normal spectrum of behavior can be quite damaging and can lead to exacerbated symptomatology.
Due to high variability of type, severity, response to treatment, and possibly cause, having a standard treatment strategy is nearly impossible. However, common approaches include environmental modifications, desensitization, fluency-shaping techniques (i.e., easy onset, continuous phonation, auditory/visual feedback), and possibly psychological intervention. One component that is quite consistently included is counseling and support by the speech-language pathologist with the goal of changing the patient’s mindset from anticipating stuttering to anticipating fluency. Goals may vary from absence of stuttering to reducing severity and eliminating avoidance behaviors so as to improve quality and effectiveness of overall communication. It is generally believed that any effective treatment program must also have transference into nonclinical functional environments and maintenance as a goal (46, 47).
LANGUAGE
As described earlier, language is an arbitrary system of signs or symbols used according to prescribed rules to convey meaning within a linguistic community (1). An understanding of the mechanisms responsible for the processing and formulation of language is critical to good rehabilitation practice. Various theories have been developed to define language. Linguistic theory of language attempts to account for the rules and structure of language stored in memory; whereas the psycholinguistic theories of language attempt to account for how language is stored and accessed to produce the various verbal forms such as sounds, words, and phrases and discourse. Additionally, the role of attention is needed and has been studied extensively in language processing (48).
Traditional study of language has focused on specified sites being responsible for specific functions. There are many lines of evidence to support the concept that the left hemisphere plays a crucial role in language processing. Goodglass, in 1993, reported that approximately 95% of cases with aphasia had focal lesions in the left hemisphere (49). The traditional approach to language views damage to the third frontal convolution, Broca’s area, as causing language production problems, whereas damage to the first temporal convolution, Wernicke’s area, is associated with language comprehension. This approach is simplistic; more recent research has proven correlation of neurologic lesion with language function to be much more complex. Contributions from the right hemisphere have been noted to give input regarding prosody and comprehension of complex syntax (50). Additionally, other subcortical structures such as the basal ganglia and thalamus have been identified as having roles in language function (51). For example, thalamic hemorrhage has been reported to affect language to varying degrees, with some individuals having almost normal language performance and others demonstrating marked paraphasias and periods of fluctuating consciousness (52, 53). These fluctuations may be related more to the role of the thalamus in arousal and selective attention as prerequisites to communication than to its role in actual deficits of language (52). Although most studies confirm the notion that the symptoms associated with subcortical disease may be transitory, individuals who evidence attention and arousal deficits
beyond the acute stage of illness have diminished ability to learn compensations for their communication failures in spite of nearly normal comprehension skills.
beyond the acute stage of illness have diminished ability to learn compensations for their communication failures in spite of nearly normal comprehension skills.
Aphasia
Aphasia is an acquired disorder of all language modalities, including verbal expression, auditory comprehension, written expression, and reading comprehension. It interferes with the ability to manipulate the meaning (i.e., semantics) or order (i.e., syntax) of words, spoken or written. Three important points to emphasize in this definition include
The term aphasia implies impairment in both receptive and expressive language modalities. Expression may be more severely involved than reception, and reception can appear grossly intact. If the testing instrument is sensitive to subtle change in language behavior, pathology can be identified in the more intact modality.
Aphasia is consistent only with focal disease, usually of the left hemisphere. Aphasic symptoms may be part of a diffuse pathologic condition. However, these patients evidence more than disruptions in their ability to manipulate linguistic symbols, such as disorientation. Prognosis and recovery for this group are markedly different from those who evidence aphasia alone.
Although it is well-known that aphasic disturbances are usually a consequence of cortical disease, the identification and classification of more atypical aphasic syndromes are also associated with subcortical infarction and hemorrhage (54).
Language Characteristics
Verbal expressive characteristics of aphasia include anomia, agrammatism, paragrammatism, or paraphasia or the production of jargon, stereotypic, or echolalic language patterns. Although most aphasics display an overall reduction in word classes available for production, they show particular deficits in the retrieval of nouns (i.e., anomia). Because nouns carry a large part of the meaning during an intended message, the language of the anomic patient is described as “empty” because sentences often lack a subject or referent.
In their attempts to retrieve words, aphasics may make “paraphasic” language errors. When the substitution for the intended word is from the same word class, such as chair for table, it is a semantic paraphasia. The substitution of like sounds or syllables, such as flair for chair, is classified as a phonemic paraphasia. A final class of paraphasic error is the neologism. Neologisms are attempts at the target that bear no phonemic or semantic relationship to that target, such as, “I want to brush my ploker.” Patients who find word retrieval difficult may also circumlocute, or talk around the intended noun, such as saying, “I wear it on my wrist” instead of watch.
Agrammatism is a form of expressive deficit characterized by reliance on nouns and verbs (i.e., content words) to the exclusion of articles, verb auxiliaries, pronouns, and prepositions (i.e., function words). Agrammatic productions often are described as telegraphic. Paragrammatic language is characterized by the misuse, rather than the omission, of grammatical elements.
Individuals who have expressive output that is largely incomprehensible, even though the utterance is well articulated and verbose, may display a form of expressive deficit called jargon. Concentrations of neologisms are called neologistic jargon and may be associated with stereotypes such as “blam, blam, blam” substituted for all attempts at verbalization. A preponderance of unrelated semantic paraphasias is semantic jargon. Finally, some individuals evidence echolalia, typified by the patient echoing back the same utterance he or she has just heard.
Written expression also is impaired in typical aphasia, characterized by letter or word substitutions, omissions, or additions (paragraphias) or errors in syntax. The ability to use gestures as a substitute form of expression can be impaired as well (38).
Table 15-2 provides a summary of the terminology used to describe expressive language deficits in aphasia.
TABLE 15.2 Summary of the Terminology Used to Describe Expressive Disorders of Aphasia | |||||||||||||||||||||||||||||||
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Auditory comprehension characteristics of aphasia include deficits of auditory perception and auditory retention. Auditory misperceptions are characterized by a tendency to confuse words that are similar in either meaning or sound. These confusions create a distorted message resulting in errors of comprehension. Most aphasics will experience more errors in comprehension as the length of the auditory input increases. In general, the speed of auditory input, combined with increased length, leads to errors in auditory retention. In addition, increased sentence length often presupposes a more difficult syntax and vocabulary, combining to make comprehension more liable to error. It has been demonstrated that some aphasics retain more information from the beginning of an utterance, whereas others retain information from the end (55). Evaluation of this aspect of the patient’s auditory capacity is especially important if rehabilitation is to succeed. Comprehension of reading material also is impaired. The severity of this impairment often is greater than that of the linguistic deficits in other modalities. However, for some, reading comprehension is a relative strength and can be used to augment or facilitate comprehension of the spoken word by pairing the spoken message with a written message.
Aphasia: The Classical Descriptions
Historically, there have been many attempts to place pathologic language symptoms into homogeneous groups, permitting reference to specific aphasic subtypes. The Boston classification system standardizes terminology by classifying disorders into those in which expressive skills are predominantly fluent and those in which they are predominantly nonfluent (56). Although such a distinction might be useful clinically, it often can be difficult to make this classification, as in the case of a conduction aphasic (a fluent aphasia) who may have long pauses and expressive struggle (nonfluency) during speech. The eight major types of aphasia in the Boston system include the more common forms of Broca’s aphasia, Wernicke’s aphasia, anomia, conduction aphasia, and global aphasia, as well as the less frequent transcortical types, transcortical motor and transcortical sensory (Table 15-3). Each of these aphasic syndromes has discrete symptoms and is correlated with a specific localized cortical lesion, some with subcortical extension.
Nonfluent Aphasias
Broca’s Aphasia
One of the classic localization theory aphasias, with site of lesion in Broca’s area (or area 44), located in the third frontal convolution anterior to the precentral gyrus. Often called “expressive aphasia,” this aphasia is characterized by expressive skills more greatly impaired than receptive skills. Agrammatic verbal output is a hallmark symptom, with word retrieval more intact than sentence formulation. Error awareness is often good, making the patient a relatively good communicator, as compared with those with other types of aphasias (57). Repetition is typically poor. Reading and writing also show a range of impairments. AOS frequently accompanies Broca’s aphasia.
TABLE 15.3 Summary of the Boston Classification System of Aphasia | |||||||||||||||||||||||||||||||
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Transcortical Motor Aphasia
Currently, this type of aphasia is believed to be of a smaller site of lesion, located in the frontal lobe, superior and anterior to Broca’s area (57). Language function is similar to those of Broca’s aphasia with the exception that repetition is relatively preserved.
Global Aphasia
Associated with a large left hemisphere lesion, typically including both Broca’s and Wernicke’s areas. It is considered the most severe aphasia with significant deficits in all language modalities. Often, automatic expressions such as counting or profanity are preserved. Also, frequently these patients can use other modalities, such as facial expression and/or gesture, to communicate basic wants, needs, or feelings (57).
Fluent Aphasias
Wernicke’s Aphasia
The other classic localization theory aphasia, Wernicke’s aphasia is associated with lesion in the Wernicke’s area (area 22), the posterior portion of the superior temporal gyrus (57). Often called “receptive aphasia,” this aphasia is characterized by receptive skills being more severe than expressive skills. Patients with this type of aphasia often produce sentences with intact grammar and rhythm of speech but frequent paraphasias of both types and/or frequent neologisms or jargon. Due to poor auditory comprehension, error awareness is also poor, usually making for a less effective communicator than one with Broca’s aphasia. Repetition is also impaired.
Transcortical Sensory Aphasia
Lesion is typically in the inferior temporo-occipital border area. It is similar to Wernicke’s aphasia, but repetition is relatively preserved.
Conduction Aphasia
Thought to be related to subcortical lesions in the arcuate fasciculus, an association tract running beneath the cortex, connecting temporal and parietal lobes and carrying impulses between Wernicke’s area and Broca’s area. In conduction aphasia, repetition is disproportionately impaired relative to auditory comprehension and verbal expression (57). Verbal output is generally grammatical and fluent but has episodes of halting speech during moments of word retrieval difficulty.
Anomic Aphasia
It is associated with lesion site of the posterior parietotemporal juncture. It typically is the mildest form of aphasia and is marked by word retrieval difficulties, with syntax and fluency generally intact. Verbal output is characterized by frequent semantic paraphasias or overgeneralizations for the intended words. Comprehension impairment is mild (57).
Differentiation from Other Disorders
Aphasia, particularly in the acute stages, may be difficult to differentiate from other disorders that compromise communication. Accurate differentiation is necessary because each communication disorder requires separate treatment and management approaches. It should be noted that aphasia may occur in conjunction with other syndromes. Below are some disorders that compromise communication but should be differentiated from aphasia.
Agnosia
Agnosia is the inability to interpret or recognize information when the end organ is intact. For example, a patient with auditory agnosia would have normal audiometric hearing thresholds but cannot interpret speech signals at the cortical level. Hence, auditory comprehension will be severely compromised. Patients with agnosia can be differentiated from those with aphasia because they will be impaired in only one modality. For example, the patient with auditory agnosia who has severe comprehension deficits can read the same words through the intact visual modality.
Dementia
Dementia is a syndrome of progressive cognitive deterioration that adversely affects the ability to communicate (58). Although specific expressive and receptive language disturbances can present as part of an underlying disease process, the aphasic patient does not show evidence of cognitive deficits in such areas as orientation, judgment, self-care, and visual-perceptual skills. The distinction between those patients with language deficits secondary to aphasia and those with diffuse disease is particularly relevant in rehabilitation because the prognosis for retraining specific skills and developing independence is more favorable for the patient with aphasia alone.
Language of Confusion
Language of confusion is characterized by reduced recognition, reduced understanding of and responsiveness to the environment, faulty memory, unclear thinking, and disorientation (58). It often is associated with head trauma. In contrast to the language disorders of dementia, the prognosis for recovery after traumatic injury is more favorable, and the course is not progressive.
Aphasia Assessments
Tests for aphasia measure the patient’s receptive and expressive language capacities by sampling different types of language skills through systematically controlled channels. For example, an examination of reception via the visual input system might begin with a concrete task such as copying or matching and then proceed to more difficult tasks such as reading sentences or paragraphs for comprehension. Tests of expression might range from simple repetition to naming to providing definitions or picture descriptions. Most test batteries currently in use provide a representative sample from which inferences can be made about performance in similar linguistic situations. Although most tests of aphasia do sample linguistic competencies, they are not equipped to measure either the least severe or the most severe disorders. Therefore, the examination will have to be supplemented by other specialized formal and informal measures in selected cases. Additionally, most isolated aphasia test batteries do not depict an individual’s functional communication performance. To determine one’s overall communicative functional status, additional testing is often required.
Some of the more commonly utilized aphasia assessments include the Western Aphasia Battery-Revised (WAB-R), Boston Diagnostic Aphasia Examination (BDAE) third edition, and the Communication Activities of Daily Living-2 (CADL-2) (56, 59, 60). Also frequently given is the Boston Naming Test (BNT), which is actually a subtest of the BDAE. To assess reading comprehension in varied contexts, portions of the Reading Comprehension Battery of Aphasia-2 (RCBA-2) are often given (61
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