Right hemiparalexia vera: word blindness for the right part of words despite normal fields of vision

Abstract

A 30-year-old woman with premature hyperhomocysteinemic atherosclerosis and left subcortical occipital lobe infarction made reading errors restricted to the right end of words. For instance, when confronted with the word ‘diameter’, she would read ‘diagram’. She had no hemianopia and no problems with writing words. Calculation, color vision, and eye movements were normal. She was not aphasic. Her reading disturbance was classified as hemiparalexia. Most hemiparalexics make errors in the left part of the word. Such left hemiparalexia is caused by an interhemispheric disconnection between the right visual association area and the left angular gyrus. The condition described in this article is characterized by reading errors in the right part of the word despite fully normal visual fields. Right hemiparalexia has been described in a patient with right hemianopia, but I have been unable to find any previous report of right hemiparalexia despite normal fields of vision. Right hemiparalexia vera seems to be a suitable name for the reading disorder of this woman. Her condition was caused by a left, mainly subcortical, occipital ischemic infarct probably leading to a disruption of the intrahemispheric connections between the left visual association area and the left angular gyrus. Right hemiparalexia vera can be regarded as the next chapter in the history of word blindness, which started in 1676 when Johannes Schmid published a case report entitled ‘De oblivione lectionis ex apoplexia, salva scriptione’ (On the loss of reading with saved writing caused by apoplexia).