Abstract
This study investigates the mechanism of language disorder through the analysis of the aphasic symptoms and speech dysfluency in the case of a 31-year-old right handed man, who suffered from transcortical motor aphasia (TCMA) caused by a sudden left medial frontal lobe infarction. Striking struggle and hesitation were noticed in his intentional speech.
The results were as follows:
(1) TCMA was associated with left-hand unilateral apraxia and agraphia, as well as transient dysphonia. This case's speech elicited from external stimuli was well preserved, and auditory and visual comprehension were normal.
(2) The speech dysfluency was observed in the more intentional condition of speaking, and the major characteristics of the dysfluency were abnormal respiration, strained blocking, prolongation, and repetition.
(3) Changes were observed qualitatively as well as quantitatively along with the course of his recovery. That is, abnormal respiration and strained blocking in the initial stage, prolongation and prosodic disturbance in the middle stage, and repetition in the final stage were the prominent features.
(4) These symptoms may be explained as a disruption of processes which control the initiation and continuation of the flow of speech. These are consistent with the defect of the speech starting mechanism. However, the change observed in therapy lends a support to Rubens (1975) who identifies the inability to propositionalize as an underlying deficit of TCMA. That is, the volume of the case's intentional speech had not increased substantially until the therapy which focused on planning of speech was undertaken.
