Asymmetry in the emotional content of lateralised multimodal hallucinations following right thalamic stroke

Abstract

The thalamus has been described as a “relay station” for sensory information from most sensory modalities projecting to cortical areas. Therefore injury to the thalamus may result in multimodal sensory and motor deficits. In the present study, a 61-year-old woman suffered a right thalamic cerebral vascular accident (CVA; as evidenced by a computerised tomography [CT] scan). Secondary to this incident, she complained of altered sensations across multiple sensory modalities, including olfactory, visual, auditory, tactile, temperature, and pain sensation. Interestingly, during recovery from the thalamic CVA, the patient reported hallucinations in all the modalities cited above. Multimodal dysaethesias (odd sensations) and hallucinations showed reliable laterality in the affective valence across modalities with positive associations within right hemispace and negative associations within left hemispace. Overall, the results support multimodal role of the thalamus and provide evidence for lateralisation of positive and negative affect within the right and left hemispheres respectively.