Neuroanatomic correlates of visual hallucinations in poststroke hemianopic patients
Résumé
Homonymous hemianopia (HH) is the most frequent visual-field defect after a stroke. Some of these patients also suffer from visual hallucinations which origin and frequency remain largely unknown. Objectives: (1) Determine the occurrence of visual hallucinations among post-stroke hemianopic patients in function of the location (Brodmann areas) of the brain lesion, as determined by MRI. (2) Study the neuroanatomic correlates of these hallucinations by nature, frequency and type. Methods: 116 HH patients that had suffered a stroke in the posterior region, including the occipital lobe participated in the study. We evaluated the frequency and nature of visual hallucinations with the Q3H questionnaire. The volume of each patient's brain lesion was modeled in 3D. Results: Of 116 patients with a homonymous hemianopia from a cortical infarction, 85 were excluded due to confounding factors associated with hallucinations. In the final cohort of 31 patients, matched for lesion location and etiology, 58% had experienced hallucinations. A significant inverse correlation between lesion size and the frequency of visual hallucinations emerged. The presence of visual hallucinations in post-stroke hemianopic patients requires a relatively small lesion that includes, at the very least, loss of the striate cortex, but that spares BA19, BA20 and BA37. Conclusion: Our results suggest that visual hallucinations might be due to complex interactions between damaged areas and intact areas of the visual cortex. We discuss these findings regarding models of perception and of visual recognition. Our results also have implications for clinical care of HH patients that have suffered a stroke.
Domaines
Sciences cognitives
Origine : Fichiers produits par l'(les) auteur(s)