Apraxia of speech due to the left postcentral gyrus lesion

Apraxia of speech (AOS) due to a postcentral infarction differs from conventional precentral AOS with respect to phonemic errors (phoneme substitution) which are more common than phonetic errors (phoneme distortion) and preserved accent and intonation.

Clinical features of apraxia of speech caused by lesions in the postcentral gyrus have not yet been elucidated. Here, we report a patient with this lesion and show how postcentral apraxia of speech differs from the hitherto known precentral apraxia of speech. A 54-year-old man developed Broca's aphasia with apraxia of speech that resolved into pure apraxia of speech within 3 weeks following infarction of the postcentral gyrus. The diagnosis of apraxia of speech was based on the patient's effortful, slow speech and inconsistent phonetic distortions with phonemic paraphasia. The Western Aphasia Battery was used to examine the patient's speech samples. Speech was recorded using a digital voice recorder and transcribed into a narrow transcription of the International Phonetic Alphabet. The error types were categorized phonologically. The results revealed that (a) phonemic errors (vowel and consonant substitutions, also known as phonemic paraphasia) were more common than phonetic errors (vowel and consonant distortions). Similar to conduction aphasia, phonemic errors were more pronounced in confrontation naming than in repetition, accompanied by self-correction, and (b) word accent and sentence intonation were preserved, although the speech was slow. These two features are characteristic of postcentral apraxia of speech, which can be differentiated from conventional precentral apraxia of speech.