Disproportionate Impairment in Naming and Comprehension of Nouns with Relative Sparing of Verbs in a Patient who Survived Herpes Simplex Encephalitis

Abstract: Various studies reported that patients who survived Herpes Simplex Encephalitis (HSE) may show impairments of specific semantic categories: they often show greater difficulty in naming and comprehension of stimuli belonging to “living” entities (animals, fruit and vegetables), as compared to “non-living” entities (such as handmade artifacts).We report a 26-year-old patient (RP) who suffered from HSE and developed an anomic aphasic syndrome, associated with remarkable impairment of episodic memory. Sixteen months post onset, on neuropsychological examination patient RP showed a disproportionate impairment in oral and written naming of nouns as compared to verbs. Likewise, on word-picture matching tasks she was remarkably impaired in the auditory and visual comprehension of nouns, with relative sparing of verb comprehension. Interestingly, on additional tasks of oral naming and auditory comprehension of noun stimuli belonging to either “living” or “non-living” entities, she showed remarkable difficulties in naming and comprehension of noun stimuli belonging to both categories (“living” and “non-living” entities). Single photon emission computed tomography (SPECT) showed a marked cerebral hypoperfusion in the left temporal lobe and moderate hypoperfusion in the orbital and mesial frontal regions of both cerebral hemisheres, with relative sparing of left ventro-lateral/perisylvian frontal areas, including the inferior frontal gyrus. In this patient, a damage mainly involving both semantic and lexical components critical for noun processing might be hypothesized. The relative preservation of verb production and comprehension might be explained by the relative sparing of ventro-lateral frontal areas (including the left inferior frontal gyrus) critically involved in production and comprehension of verbs.