We report a 60-year-old right-handed Japanese man who showed an isolated persistent typing impairment without aphasia, agraphia, apraxia or any other neuropsychological deficit. We coined the term ‘dystypia’ for this peculiar neuropsychological manifestation. The symptom was caused by an infarction in the left frontal lobe involving the foot of the second frontal convolution and the frontal operculum. The patient’s typing impairment was not attributable to a disturbance of the linguistic process, since he had no aphasia or agraphia. The impairment was not attributable to the impairment of the motor execution process either, since he had no apraxia. Thus, his typing impairment was deduced to be based on a disturbance of the intermediate process where the linguistic phonological information is converted into the corresponding performance. We hypothesized that there is a specific process for typing which branches from the motor programming process presented in neurolinguistic models. The foot of the left second frontal convolution and the operculum may play an important role in the manifestation of ‘dystypia’.
Somatotopic organization of the human medial wall of the cerebral hemispheres was studied using functional MRI conducted at high field strength (3 T) with fine spatial resolution ( approximately 2 mm). Healthy subjects performed paced, repetitive movements of the fingers and toes. Within the supplementary motor area (SMA), two regions were identified: finger movements activated a region rostral and superior to that for toe movements. Two activation foci were also identified in the cingulate motor area: toe movements activated a region rostral and ventral to that activated by finger movements. All foci were located between the anterior and posterior commissures. Our results confirm previous human and non-human primate studies regarding the rostral-caudal organization of the SMA and CMA. The dorsal-ventral organization of the CMA, however, appears to be divergent from results derived from cortical stimulation studies conducted in non-human primates.
Infarction in the anterior inferior cerebellar artery (AICA) territory is rare, and most reports on such infarction have been restricted to autopsy studies. We analyzed the clinical figures of 5 patients with AICA territory infarction diagnosed by magnetic resonance imaging (MRI). They all developed dizziness or vertigo, unilateral ataxia and homolateral hearing impairment. The MRI demonstrated ischemic lesions in the ipsilateral middle cerebellar peduncle. All patients showed excellent neurological recovery and were ambulatory at discharge. In our series, unilateral hearing impairment was the most crucial sign for diagnosis of the AICA syndrome. Results for the auditory brain stem response suggested that the hearing impairment may be partly attributable to chochlear ischemia.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.