Agraphia caused by left thalamic hemorrhage

Abstract

A 71-year-old right-handed man was admitted to our hospital with right hemiparesis and sensory impairment associated with mild aphasia. Although aphasia gradually resolved within 2 weeks after stroke onset, his writing ability remained disturbed. A computed tomography (CT) scan at stroke onset revealed a hematoma in the left thalamus, but no cortical lesions were observed. Further, a single-photon emission CT (SPECT) scan showed decreased blood flow in the left thalamus, in the cortical region extending from the left superior temporal gyrus to the parietal lobe, and in the frontal lobe. It is possible that agraphia may have directly resulted from the thalamic lesion, but SPECT findings strongly suggested that a general decrease in left cortical function concomitant with a disruption of the thalamocortical and cortico-thalamocortical projection fibers produced these cognitive deficits.

Keywords: Agraphia; Aphasia; Cerebral hemorrhage; Stroke.

Fig. 1

Formal language assessment was undertaken using the SLTA.

Fig. 2

a A head CT scan at stroke onset revealed a hematoma expanding from inside the posterior left thalamus. b SPECT performed around the same time showed decreased blood flow in the left thalamus, in the left cortex extending from the superior temporal gyrus to the parietal lobe, and in the frontal lobe.

Fig. 3

Most errors were incorrect responses to word dictation, termed paragraphia. The patient could transcribe characters and generally wrote the characters in the correct stroke order, but he often substituted one character for another with a similar shape or sound, perseverated, and wrote characters with 180° rotation (mirror script).