Parietal Dysgraphia: Characterization of Abnormal Writing Stroke Sequences, Character Formation and Character Recall

Abstract

Objective: To characterize various dysgraphic symptoms in parietal agraphia. Method: We examined the writing impairments of four dysgraphia patients from parietal lobe lesions using a special writing test with 100 character kanji (Japanese morphograms) and their kana (Japanese phonetic writing) transcriptions, and related the test performance to a lesion site. Results: Patients 1 and 2 had postcentral gyrus lesions and showed character distortion and tactile agnosia, with patient 1 also having limb apraxia. Patients 3 and 4 had superior parietal lobule lesions and features characteristic of apraxic agraphia (grapheme deformity and a writing stroke sequence disorder) and character imagery deficits (impaired character recall). Agraphia with impaired character recall and abnormal grapheme formation were more pronounced in patient 4, in whom the lesion extended to the inferior parietal, superior occipital and precuneus gyri. Conclusion: The present findings and a review of the literature suggest that: (i) a postcentral gyrus lesion can yield graphemic distortion (somesthetic dysgraphia), (ii) abnormal grapheme formation and impaired character recall are associated with lesions surrounding the intraparietal sulcus, the symptom being more severe with the involvement of the inferior parietal, superior occipital and precuneus gyri, (iii) disordered writing stroke sequences are caused by a damaged anterior intraparietal area.

Cognitive Performance Deficits and Dysgraphia in Alzheimer’s Disease Patients

“…They observed that while Kana writing-to-dictation and copying Kanji were preserved in these AD patients, writing to dictated Kanji words was impaired. The impaired writing of dictated Kanji words was associated with dysfunctional cortical activity predominantly in the left frontal, parietal and temporal brain regions [43] consistent with other Japanese dysgraphia studies [44][45][46]. The present observations of dysgraphia associated with deficits in semantic memory that were exacerbated acutely by the writing task appear to fit current notions pertaining to the progressive performance impairments of AD patients within language and cognition domains from a staging perspective [47,48].…”

Cognitive Performance Deficits and Dysgraphia in Alzheimer’s Disease Patients

“…They observed that while Kana writing-to-dictation and copying Kanji were preserved in these AD patients, writing to dictated Kanji words was impaired. The impaired writing of dictated Kanji words was associated with dysfunctional cortical activity predominantly in the left frontal, parietal and temporal brain regions [41] consistent with other Japanese dysgraphia studies [42][43][44]. The present observations of dysgraphia associated with deficits in semantic memory that were exacerbated acutely by the writing task appear to fit current notions pertaining to the progressive performance impairments of AD patients within language and cognition domains from a staging perspective [45,46].…”

Isolated thalamic agraphia with impaired grapheme formation and micrographia

“…Apraxic agraphia is defined as having the following deficits [12]: (1) illegible graphemes in writing that cannot be accounted for by sensorimotor dysfunction, (2) grapheme production improves with copying, (3) preserved oral spelling or typing, and (4) disordered writing stroke sequences [13]. Apraxic agraphia has also been reported following a lesion of the dorsomedian nucleus of the thalamus [3].…”

“…For example, we have reported patients with somesthetic dysgraphia in which deficits of combined sensations (texture recognition, two-point discrimination and graphesthesia) in the digits yielded poor character formation [12]. As the ventroposterolateral (VPL) nucleus of the thalamus receives ascending fibers from the , roll) b Deformity was evaluated only for correct responses.…”