Aphasia is an acquired disturbance of any of the modalities of language: comprehension, expression, reading and/or writing caused by injury to cerebral areas that are specialized for this function.
Apraxia of speech is a disorder of carrying out or learning complex speech movements not accountable by disturbances in strength, coordination, sensation, comprehension or attention. Verbal apraxia is manifested by limited number of consonants and vowels, articulation errors and problems sequencing movements with increasing complexity.
Dysarthria is a group of speech disorders caused by muscle paralysis, weakness or incoordination manifested by impairments in articulation, rate of speech production, respiratory coordination and/or laryngeal control, rather than language content.
Dysphagia is a disorder of swallowing that impairs the speed and/or safe delivery of food materials from the point of entry into the mouth into the upper portion of the esophagus.
Epidemiology including risk factors and primary prevention
The overall prevalence of language impairment in the United States is between 6 and 8 million.Approximately 80,000-100,000 individuals acquire aphasia annually.1,2 Incidence of aphasia varies by etiology and is most commonly associated with stroke. Dysphagia is highly prevalent in people with stroke, traumatic brain injury, Parkinson’s disease and community acquired pneumonia. However, wide variations in reported prevalence exist in the literature due to methodological differences.3
Aphasia results from injury to specific areas of the dominant cerebral hemisphere with clinical manifestations dependent on location and extent of neural damage. Non-dominant hemisphere language dysfunction may manifest as impairments in prosody and higher-level cognition including unawareness of social cues, humor and body language, as well as inappropriate utterances.
Anatomical lesions vary in cases of speech apraxia, but frequently involve the left hemisphere insula.
Dysarthrias result from either upper or lower motor neuron injury, with clinical manifestations dependent on the location and extent of neural damage.
Dysphagia results from numerous causes, including lesions of the central and peripheral nervous system, trauma and structural abnormalities affecting the anatomical substrates involved in swallowing.
Disease progression including natural history, disease phases or stages, disease trajectory (clinical features and presentation over time)
Disorders of language, speech and swallow resulting from stroke, trauma, and anoxia tend to improve over time. People with mild to moderate aphasia experience approximately 70% of maximal recovery based on validated measure within 3 months of stroke, noting recovery is most rapid during this time.4 Progression occurring from other conditions is variable and depends on disease state and progression as well as effects of treatment (e.g., radiation for neoplasms).
ESSENTIALS OF ASSESSMENT
See Etiology, above.
Aphasia: Definitive classification of aphasia is achieved through formalized assessment tools. Bedside examinations focusing on fluency, comprehension, ability to repeat sentences, reading and writing can help delineate different aphasia subtypes.
- Broca’s aphasia: Non-fluent, impaired repetition, intact comprehension;
- Transcortical motor aphasia: Non-fluent, intact repetition, intact comprehension;
- Global aphasia: Non-fluent, impaired repetition, impaired comprehension;
- Wernicke’s aphasia: Fluent, impaired repetition, impaired comprehension;
- Conduction aphasia: Fluent, impaired repetition, relatively intact comprehension;
- Transcortical sensory aphasia: Fluent, intact repetition, impaired comprehension;
- Pure word mutism: Impaired speech production with retained comprehension and ability to write;
- Pure word deafness: Loss of auditory comprehension and repetition without abnormalities of naming, reading or writing;
- Alexia without agraphia: Acquired inability to read, variable naming impairment with retained ability to write;
- Anomic: Fluent, intact repetition, impaired naming.
Non-dominant hemisphere language disorders: Bedside examination
Dysarthria: Functional assessment of the larynx, respiration, vocal articulations and the pharynx.
- Spastic: Hypertonic muscles with decreased range of motion, reduced speed of muscle excursion with strained-strangled vocal quality;
- Hyperkinetic: Altered rhythm and rate of oromotor movements with involuntary muscle actions; variability in muscle tone with altered pitch and volume control, stress, rate, phoneme duration and sudden respiratory inhalations and exhalations;
- Hypokinetic: Oromotor rigidity, decreased range of motion and force of movement with variable movement velocity manifested by decreased range of pitch and volume, reduced stress, festinating speech and a hoarse/breathy vocal quality;
- Ataxic: Articulatory and prosodic impairments manifested by imprecise articulation of vowels and consonants, articulatory breakdowns, excessive and equal stress, prolongation of phonemes and inter-word intervals, decreased rate of speech, mono-pitch and mono-loudness, and harsh vocal quality;
- Flaccid: Flaccid oromotor muscles and fasciculations. Detailed cranial nerve evaluation is essential ; often manifested by breathiness, audible inspirations, hypernasal vocal quality, decreased phrase length, consonant imprecision, vocal harshness and reduced range of pitch and volume;
- Mixed: Variable combination of above.
Apraxia of speech: Clinical features include effortful, groping or trial and error attempts at speech, dysprosody, inconsistent articulation errors and difficulty initiating speech.
Dysphagia: Bedside evaluation includes assessment of oral sensation, oral reflexes, postural abnormalities, motor assessment of face, lips, tongue, palate and larynx, level of arousal, ability to follow directions and management of saliva. Bedside screening tools useful to physicians include the 3-oz water swallow test or the Toronto Bedside Swallowing screening test (TOR-BSST)
- Modified barium swallow (MBS) or videofluoroscopic swallowing study (VFSS): evaluates swallowing by radiographically visualizing swallow using various consistencies of barium. It provides real-time viewing of oral, pharyngeal and cervical esophageal phases of swallowing.
- Fiberoptic endoscopic evaluation of swallowing (FEES) directly visualizes laryngeal and pharyngeal structures involved in swallowing. It is portable, lacks of radiation, visualizes secretions, and detects structural abnormalities of the pharynx and larynx. It does not assess the oral stage of swallowing or the cervical esophagus.
- Manometry determines the pressures and relative timing of pharyngeal contraction and relaxation of the upper esophageal sphincter during swallowing.
Supplemental assessment tools
- Boston Diagnostic Examination of Aphasia assesses severity of language impairment and classifies aphasia into subtypes. Five subtests assess conversation and expository abilities, auditory comprehension, oral expression, reading, and writing.
- Western Aphasia Battery assess the presence, degree and type of aphasia as well as both linguistic and non-linguistic skills.
- Communications Activities of Daily Living assesses functional communication skills of adults.
- Assessment of Intelligibility of Dysarthric Speech is a standardized assessment of dysarthria severity that incorporates measures of speech intelligibility, overall rate of intelligible speech and a ratio of communication efficiency.
- Frenchay Dysarthria Assessment is a standardized assessment of reflexive, respiratory, articulatory, resonatory and phonatory mechanism of speech.
- Fisher-Logemann Test of Articulation Competence is used primarily in pediatrics; testing generates an articulation profile that can be analyzed according to the nature of altered speech production within the context of developmental articulations and phonation errors.
Early predictions of outcomes
Severity of initial language impairment is predictive of neurological and functional recovery in certain central neurological disorders. Other factors affecting recovery of language post stroke include the site and extent of neurological injury, age, sex, education level and various environmental factors. 5
Dysphagia: Placement of gastrostomy tubes provides a means to deliver nutrition, hydration and enteral medications to patients with dysphagia and may reduce the risk of aspiration. Gastrostomies are often recommended following acute neurological injuries and in most cases can be removed as recovery ensues. Patients with progressive disorders often require permanent placement and may be opposed by patients or their health-care proxies, resulting in ethical and legal issues regarding implantation and potential removal. The pros and cons of alternatives to gastrostomies, such as continued unsafe oral intake, intravenous supplementation, cuffed tracheostomy or surgery (eg, laryngeal diversion) should be discussed with patients or their health-care proxies.
REHABILITATION MANAGEMENT AND TREATMENTS
Available or current treatment guidelines
Aphasia: Speech-language therapy (SLT) to maximize communication skills through verbalizations or compensatory means (eg, communication boards, augmentative communication) is standard practice. Utilization of melodic intonation may be useful. Review of literature tends to support effectiveness of SLT, noting more intensive therapy is possibly more effective than conventionally dosed treatment6. Pharmacological interventions with catecholiminergic, dopaminergic, and acetylcholinergic agonists as well as piracetam and memantine may be effective although evidence is inconclusive7. Piracetam appears to improve written language abilities rather than overall severity of aphasia.8
Dysarthria: Management focuses on maximizing strength and coordination of oromotor musculature. Behavioral approaches are used to optimize vocal cord adduction, improve posture, enhance breath support, improve strength and coordination of muscles involved in speech and improve prosody. Instrumental approaches used to improve speech include biofeedback and timers or pacers to control rate. Invasive procedures such as neurotoxins to treat spastic muscles, palatal lifts and injections to medialize paralyzed vocal cords can be used in selected cases. Augmentative communication devices are used when other strategies fail to improve intelligibility.
Dysphagia: Compensatory strategies include changing head and/or body position to reduce risk of aspiration (eg, chin tuck, head tilt, head rotated); enhancing sensory input of food materials; exercises to improve swallowing (supraglottic, super-supraglottic, effortful, Mendelsohn exercises, tongue hold, double swallow); lingual exercises; head lifting exercises; changes in food consistencies (ie, thickening liquids or changing size/consistency of solids); devices such as palatal lifts and vocal cord medialization in cases of vocal cord paralysis. Gastrostomy or jejunostomy are options in cases where aspiration risk cannot be reduced and/or nutritional/hydration needs cannot otherwise be met. Effectiveness of neuromuscular electrical stimulation remains unproven.
CUTTING EDGE/EMERGING AND UNIQUE CONCEPTS AND PRACTICE
Cutting edge concepts and practice
Aphasia: Results of small trials investigating non-invasive brain stimulation with either transcranial magnetic stimulation or transcranial direct current stimulation combined with speech language therapy are potentially promising but require more rigorous scientific investigation.6 Constraint Induced Aphasia Therapy (CIAT) combines massed practice over short periods and verbalizations with reduced attempts to use gestures or writing. Multimodal Aphasia Therapy is an intensive treatment that uses multiple modalities to facilitate spoken output.
GAPS IN THE EVIDENCE-BASED KNOWLEDGE
Gaps in the evidence-based knowledge
Limited evidence supports the effectiveness of SLT for people with post-stroke aphasia, with more intensive therapy likely more effective than conventional approaches. 6 There is a paucity of evidence supporting any one aphasia treatment technique over another. There is limited evidence supporting the effectiveness of specific SLT techniques for treatment of apraxia of speech in children9 and insufficient evidence supporting it following stroke10. There is currently insufficient knowledge regarding the superiority of electrical stimulation on dysphagia over swallow therapy alone.11
- National Institutes of Health: National Institute on Deafness and Other Communication Disorders: Statistics on voice, speech, and language. Retrieved March 12, 2020 from http://www.nidcd.nih.gov/health/ statistics/statistics-voice-speech-and-language. Accessed March 12, 2020.
- Ellis C, Dismuke C, Edwards K. Longitudinal trends in aphasia in the United States. Neurorehabilitation. 2010;27(4):327-333.
- Takizawa C, Gemmell G, Kenworthy J, Speyer R. A systematic review of the prevalence of dysphagia in stroke, Parkinson’s disease, Alzheimer’s disease, head injury, and pneumonia. Dysphagia 2016;31:434-41.
- Lazar RM, Minzer B, Antoniello D, et al. Improvement in aphasia scores after stroke is well predicted by initial severity. Stroke. 2010;41(7):1485–1488.
- Lazar RM, Speizer AE, Festa JR, et al. Variability in language recovery after first-time stroke. J Neurol Neurosurg Psychiatry. 2008;79(5):530–534.
- Brady MC, Kelly H, Godwin J, Enderby P, Campbell P. Speech and language therapy for aphasia following stroke.Cochrane Database Syst Rev. 2016 Jun 1;(6):CD000425. doi: 10.1002/14651858.CD000425.pub4.
- Saxena S, Hillis AE. An update on medications and noninvasive brain stimulation to augment language rehabilitation in post-stroke aphasia, Expert Review of Neurotherapeutics 2017;17 (11):1091-1107
- Zhang J, Wei R, Chen Z, Luo B. Piracetam for Aphasia in Post-stroke Patients: A Systematic Review and Meta-analysis of Randomized Controlled Trials. CNS Drugs. 2016 Jul;30(7):575-87. doi: 10.1007/s40263-016-0348-1.
- Morgan AT, Murray E, Liégeois FJ. Interventions for childhood apraxia of speech. Cochrane Database Syst Rev. 2018 May 30;5:CD006278. doi: 10.1002/14651858.CD006278.pub3.
- West C, Hesketh A, Vail A, Bowen A. Interventions for apraxia of speech following stroke. Cochrane Database Syst Rev. 2005;19(4):CD004298. Accessed March 25, 2020.
- Chen YW, Chang KH, Chen HC, Liang WM, Wang YH, Lin YN. The effects of surface neuromuscular electrical stimulation on post-stroke dysphagia: a systemic review and meta-analysis. Clin Rehabil. 2016;30(1):24-35. doi: 10.1177/0269215515571681. Epub 2015 Feb 19.
Original Version of Topic
Steven Flanagan, MD. Disorders of Consciousness. 11/10/2011.
Previous Revision(s) of the Topic
Steven Flanagan, MD. Disorders of Consciousness. 09/18/2015.
Steven Flanagan, MD
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Yingrong Zhu, MD
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