LASC Errors Despite Correct Performance in Auditory Comprehension Task for a Patient with Surface Dysgraphia

Abstract

We report a patient with aphasia who showed LASC errors in writing to dictation of two-Kanji compound words. The patient had undergone a craniotomy for excision of a tumor in the left temporal lobe. LASC (legitimate alternative spelling of component) errors are generally observed in patients with surface dysgraphia and are related to semantic impairment. However, our patient showed many LASC errors despite correct performance in an auditory comprehension task, suggesting that our patient's LASC errors did not result from semantic impairment. Analysis by cognitive neuropsychological method indicated that the patient's principal impairment pertained to access to the orthographic lexicon from the semantic system within the spelling lexical route. Analysis of LASC errors revealed that an alternative spelling showed a high consistency ratio of the Kanji character, and therefore we considered that the patient utilized the intact sub-lexical route over the impaired lexical route. Surface dysgraphia is classified into two subtypes: semantic and orthographic. We deduced that our patient's surface dysgraphia was close to the orthographic subtype.