Speech problems

Recently while evaluating a child with speech problems, the parents mentioned whether the child had apraxia or not. What ensued was a discussion in which neither the parents nor myself knew what we were talking about. To add to the confusion, my hippocampus had thrown out several associations to apraxia of speech, like dysarthria, phonological disorder and aphasias. Doing an internet search compounded the difficulty just as asking various people did. Everyone answered something that they were not sure about and soon my head was swimming about their differences. Luckily I found an article in Neurocase (2005) 11, 427-432 by Ogar et al.

APRAXIA OF SPEECH: Impaired ability to coordinate the sequential, articulatory movements neccessary to produce speech sounds is called apraxia. Articulatroy erros and prosodic abnormalities are hallmarks. Signs include effortful trial and error grouping with attempts at self correction, persistent dysprosody, articulatory inconistency on repeated productions of the same utterance and/or obvious difficulty initiating utterances. Vacular lesions, trauma, tumors can cause this. Apraxia of speech is also the first symptom in neurodegenerative diseases such as corticobasal degeneration or non-fluent progressive aphasia.

CONDUCTION APHASIA: Result of damage to communication between Wernicke and Broca. This communication is through extreme capsule and/or arcuate fasiculus. Speech is fluent, comprehension is good but oral reading is poor and major impairment in repitiion. Many paraphasias occur and transpositions of sounds within a word also occurs (television -> velitision).

BROCA'S APHASIA: In this the speech is understood, and the all the levels of speech planning are intact except for motor execution which is not intact.

(Apraxic speakers are believed to select the correct phonemes, only to have trouble with their motor execution; People with conduction aphasia typically speak with near normal prosody, whereas halting effortful speech with abnormal prosody. They may also lack awareness of their speech errors and therefore may not always make attempts at self correction while the opposite is true in cases of apraxia of speech)

DYSARTHRIA: Dysarthria is caused by impairment of muscle strength, tone, range of motion and/or coordination. It can be caused by UMN or LMN lesions of the cranial nerves.

(Errors heard in dysarthric speech are typically consistent and predictable, while the speech errors heard in apraxia of speech tend to be highly irregular. Sound distortions, prolonged segment durations (e.g prolonged vowels or consonants) and prolonged inter segment durations (e.g. abnormal pauses within sounds, syllables or words) are characteristic for apraxia of speech.

PATHOPHYSIOLOGY OF APRAXIA: Van der Merwe's model of speecch planning and programming says that initially, basic linguistic units or phonemes are selected. During a second motor planning phase these phonemes are organized into temperospatial codes for speech production. In the third, motor programming phase, muscle specific motor programs are selected and sequenced before moving forward to fourth phase when these sequences are carried out by the speech musculature. Apraxia of speech is caused by problem with second phase.

TREATMENTS: For mildly apraxic patients, poor prosody may be the primary speech deficit and therefore, goals designed to improve intonation and stress. For the moderately or severely apraxic patient, therapy might focus on relearning oral postures for individual speech sounds.
-PROMPT uses rate and rhythm control strategies
-Wambaugh and colleagues use remediation of misarticulated consonants through modeling repetition of minimally contrastive words, graphic cues and phonetic placement cueing.