[Auditory comprehension in transcortical motor aphasia due to a medial lesions of the left frontal lobe].

We assessed the anatomical findings and auditory comprehension of six patients with transcortical motor aphasia due to medical lesions of the left frontal lobe. All patients were right-handed and were initially mute for several hours after the onset, and they exhibited mild paresis of the right lower extremity. Their spontaneous speech was sparse and not fluent, and sometimes accompanied by echolalia, but their articulation was normal and repetition was excellent. They had difficulty in recalling words. A diagnosis of transcortical motor aphasia was made on the basis of their clinical symptoms. All patients were found to have an infarct in the left medial frontal region by MRI and/or CT. We administered the Western Aphasia Battery and 50 line drawing pointing task in order to evaluate auditory comprehension. Based on the results we concluded that there is no impairment of auditory comprehension of single words when lesions are limited to the superior frontal gyrus, but that lesions extending to the middle frontal gyrus interfere with auditory comprehension of single words. Our observations indicate that the middle frontal gyrus plays an important role in auditory comprehension of single words. All of the patients displayed impaired auditory comprehension of sentences even when their lesions were strictly limited to the medial frontal lobe. This suggests that the medial frontal lobe plays some role in the auditory comprehension of sentences.