Darley, Frederic L.

Thirty patients with apraxia of speech, 10 patients with aphasia and no apraxia of speech, and 30 normal subjects were tested by three oral sensory-perceptual measurements: oral form identification, two-point discrimination, and mandibular kinesthesia. The apraxia-of-speech group was significantly inferior to the aphasic and normal groups on all three oral sensory-perceptual tests. The normal and aphasic groups did not differ significantly from each other. Apraxia of speech and oral sensory-perceptual deficit were related in that the more severe the apraxia of speech, the more profound the oral sensory-perceptual deficit. Not all patients with apraxia of speech demonstrated impaired oral sensation and perception; however, higher cortical sensory dysfunction frequently accompanied apraxia of speech.

Studies of the effect of therapy on the course of recovery from aphasia yield inconsistent results and permit no generalization to the population of aphasic patients. Future investigations of the efficacy of therapy should specify the nature of the language disorders treated, the limits of the period of spontaneous recovery, objective measurement of relevant behavioral changes, and the nature, intensity, and quality of therapy provided. In subject selection, age, educational and social status, intelligence, health, social milieu, etiology, site and extent of lesion, time lapse since onset, type of aphasia, and nonlanguage behavior characteristics should be controlled if interpretable results are to be obtained.

To identify behaviors which might distinguish developmental apraxia of speech from “functional” articulation disorders, 30 children with moderate to severe defective articulation but with normal intelligence, hearing, and language abilities and with no apparent organic pathologic condition and a group of matched control subjects were given a battery of speech and nonspeech tests. Pediatric neurologic examinations were completed for the subjects with defective articulation. Speech data were analyzed according to type of articulation error and by a method of distinctive-feature categorization. Highly significant differences were found between control and defective articulation subjects. A rationale was established for division of the defective articulation group on the basis of their performance on isolated volitional oral movement tasks. Combinations of variables that emerged as statistically significant differentiating predictors between these two subgroups of subjects with defective articulation were neurologic ratings, two- and three-feature errors, distortions, prolongations and repetitions, additions, one-place errors, and omissions. These behavioral differences support the conclusion that an identifiable developmental apraxia of speech exists in some children with defective articulation.

In a test of auditory perception of phonemes, 10 patients with apraxia of speech were compared with 10 matched normal control subjects on a task of pointing to pictures designated by sequences of auditory word stimuli. The test items were 190 sequences of two and three words with minimal variation of initial consonant, final consonant, medial vowel, or multiple phonemes. The apraxic patients made significantly more perceptual errors as a group, but varied considerably in their level of performance. The achievement of some patients was within the range established by the control subjects; that of others was unequivocally inferior. The major deficit in the apraxic group appeared to be impairment of ability to retain the second- and third-syllable consonant elements in three-word sequences. Apraxia of speech can occur in relatively pure form in the absence of auditory perceptual impairment. It can also occur in conjunction with reduced auditory retention span, which impairs the perception of sequences of words which are minimally varied phonemically.

Less than half of a series of 168 patients with multiple sclerosis presented significant speech deviations. The most frequent speech deviations observed were impaired loudness control and harshness; less frequently occurring deviations were defective articulation, restricted use of vocal variations for emphasis, poor pitch control, hypernasality, inappropriate pitch level, and breathiness. “Scanning speech” was not a prominent characteristic. Speech deviations were not solely attributable to cerebellar involvement. Their incidence was positively related to severity of neurologic involvement, becoming more prominent as additional motor systems were implicated.

In five aphasic subjects, picture naming alone was compared with picture naming in the presence of four different auditory cues. Eighty words represented by pictures were associated with the following auditory cues: the first phoneme of the target word; an open-ended sentence designed to elicit the target word; three words, one of which was the target word; three words, all semantically related to the target word. Three conditions—the phonetic cue, the open-ended sentence, and the set of three words containing the target word—facilitated naming significantly. The condition making use of semantically related words resulted in a significant decrease in naming performance. Implications of these findings for theories of verbal recall, impairment of verbal recall in aphasia, and language therapy are discussed.

Four groups of 10 patients, each group having a different neurogenic disorder of communication, were tested for impairment in 10 language categories. Five categories—auditory comprehension, adequacy of response, arithmetic, syntax, and naming—although impaired to some degree in all groups, did not sharply differentiate them. The most strongly differentiating disabilities in the four groups were aphasia—auditory retention span and fluency; apraxia of speech—fluency; confused language—relevance, reading comprehension, and writing of words to dictation; and general intellectual impairment—reading comprehension and auditory retention span (with preservation of relevance). The groups differed also in the onset and duration of the communication difficulty, and in the nature and locus of the neurologic problem.