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Apraxia of Speech : Impairment of Motor Speech Programming

Sung Bom Pyun

Definitions

- Oral apraxia; patient cannot move the muscles of the throat, soft palate, tongue, and cheek for nonspeech purpose - Verbal apraxia; a difficulty in initiating and executing the mocment patterns necesasry to produce speech when there is no paralysis, weakness, or discoordination of speech muscles

1. Differentiation from dysarthria Dysarthria Apraxia Aphasia Slowness, weakness, incoordina-tion, or change of tone of the speech musculature Respiration, phonation, resonance, articulation, and prosody-variably involved No impairment of muscle function Continuing impairment of articulation, with prosodic alterations at times following as compensatory phenomena Have difficulty in initiating phonation at will (usually in a few days) Impaired in comprehension, formulation, and expression of language - Problem involves the proce-ssing not-meaning bearing units Problems in articulating given word, not in word-finding difficulty May be able to write it Problem lies in the processing of the meaning-bearing units of language Imprecise production of consonants, usually in the form of distortion Few simplification errors, but substitution or addition of phonemes, repetition of phon-emes, and prolongations of phonemes. Answers correctly when asked to choose from a group of words that he is trying to say. -    2. Unique features of apraxia¡¡ Contrast between voluntary and involuntary performances. 1866 Hughlings Jackson; automatic vs volitional performance of simple speech and nonspeech tasks à classical example: could not protrude his tongue on command or by imitation, but could protrude it to lick a crumb from his lips Liepmann; inability to use parts of the body in a purposeful manner, despite intact poer of movement and complete understanding of what is required à apraxia Variability of error ¡¡; errors in articulation are not evenly distributed throughout the target words, initial sounds being more formidable than final sounds and consonants causing more difficulty than vowels highly variable from patient to patient and from tiral to trial within a given patient¡¯s performance i.e., /spl/ 1st; insert schwa 2nd; unequivocally say /spl/ correctly 3rd; (a stuttering like response) 4th; a totally unrelated substitution (sukpltweeing/spleen) 5th; substitutive simplification (speen or pleen for spleen) 6th; with the precision of a normal speaker ; in apraxic patients - grossly abnormal in form; repeated utterance with great variability; vowel were prolonged and variable in length    3. Clinical features¡¡ Behavioral characteristics ¡¡Deviations from normal in apraxia of speech are primarily articulatory. The apraxic patient effortfully gropes to find the correct articulatory postures and sequences of them. Such articulatory difficulty involves consonant phonemes more often than vowel phonemes. The articulation errors are inconsistent and highly variable, not referable to specific muscle dysfunction. The articulatory errors are primarily substitutions, additions, repetitions, and prolongations-essentially complications of the act of articulation. Errors of simplification, such as distortions and omissions, are relatively much less frequent. Analysis of substitution errors by distinctive features (place, manner, voicing, and oral-nasal characteristics) indicates that the majority of errors are close approximations of the target sounds. 88%- one or two feature errors, most of the remaining 12% being three-feature errors. Place-61%, manner-53%, voicing-36% Articulatory errors appear to be at times perseverative, with recurrence of phonemes recently articulated, and at times anticipatory, with the premature introduction of a phoneme that appears in a subsequent word. In attempting to produce a difficult cluster of consonants, the patient may simplify his task by inserting a schwa between the elements, as in pronouncing ¡°stuh-rike¡± for strike. Patients with apraxia of speech can recognize their articulatory errors beyond random guess. Factors influencing apraxic speech behavior Articulatory errors increase as the complexity of motor adjustment required of the articulators increases. Vowel < Singleton consonant, fricative and affricate phonemes evoke the most errors. /puh/, /tuh/,/kuh/ vs /puh-tuh-kuh/ Initial consonant phonemes tend to be misarticulated more often than final consonant phonemes. Phonemes occurring with relatively high frequency in spoken English tend to be more accurately articulated than phonemes occurring less frequently. Apraxic patients display marked discrepancy between their relatively good performance on automatic and reactive speech productions and their relatively poor volitional-purposive speech performance. ¡°Words and phrases highly organized by practice and usage tend to sound normal¡±. Imitative responses tend to be characterized by more articulatory errors than spontaneous speech production. Articulation errors increase with increase in length of word. (thick, thicker, thickening; cat, catnip, catapult, catastrophe). Errors typically occur in the syllabel common to all of the words, not just in the added syllables. In oral reading of contextual material, articulatory errors do not occur at random. Correctness of articulation is influenced by mode of stimulus presentation. Attainment of the correct articulatory target is facilitated more by repeated trials on a word than by increase in the number of stimuli presentation. Factors not influencing apraxic speech behavior When patients perform a task under two conditions, one while observing themselves in the mirror and the other without visual monitoruing, the difference in the number of errors produced is not statistically significant. Introduction of masking noise so the patient cannot hear this own speech does not significantly alter the number of articulation errors he makes. Articulatory performance is not improved when the patient is given an opportunity to delay his imitative response. Articulatory accuracy is not influenced by the instructional set created in the patient. Associated features     1. Many patients exhibit oral apraxia.     2. Some apraxic patients demonstrate difficulty in auditory perception.     3. Some apraxic patients display impairment of oral sensation and perception as measured        by tests of oral form identification, two-point discrimination, and mandibular kinesthesia. ¡¡ ¡¡

Summary

¡¡ Apraxia of speech is a distinct motor speech disorder distinguishable from the and aphasia A disorder of motor speech programming manifested primarily by errors in articulation and secondarily by compensatory alteration of prosody High variable articulation errors embedded in a pattern of speech made slow and effortful by trial-and-error gropings for the desired articulatory postures Substitution, additions, repetitions, and prolongations, less frequently simplifications(distortion and omissions) Errors are most often on consonants occurring initially in words, predominantly on those phonemes and clusters of phonemes requiring more complex muscular adjustment. (i.e., /dr/ in drinking or /str/ in streets, for example; strategy à ¡°statir¡¦tatar..strkeg¡¦stratipy..satirigy¡¦I can¡¯t do it.¡±) Not significantly influenced by auditory, visual, or instructional set variables As patients struggle to avoid articulatory error by careful programming of muscle movements, they slow down, space their words and syllables evenly, and stress them equally. Makes many errors of articulation, recognizes errors, and makes repeated attempts to correct the errors Phonemes and words that are used more frequently are produced with greater accuracy. Speech sound of a word may be produced out of sequence. (i.e., California à ¡°lala¡¦hala¡¦uh¡¦calfa¡¦calanor¡¦calforfa¡¦halfnora¡¦calfrona..I can¡¯t get it.¡± Complex or longer words are more difficult than simpler or shorter words The person who cannot say a word can write it.

http://members.tripod.com/trainland/sensory.htm Therapy: http://www.apraxiaontario.homestead.com/therapy.html More Links: http://www.beyond-words.org/information_links.htm

 

 

 

 

 

 

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