Pseudocortical and dissociate discriminative sensory dysfunction in a thalamic stroke.

In thalamic lesions a pseudocortical syndrome has been occasionally described but the effect of the lesion on the cortical network of tactile recognition has never been studied. We report a patient who developed tactile agnosia in the left hand after right thalamic stroke, configuring a pseudocortical sensory syndrome. The discriminative sensory dysfunction was dissociate because only tactile agnosia and mild pseudoathetosis were present. A functional magnetic resonance imaging (fMRI) study showed that tactile recognition with the unaffected hand recruited a bilateral fronto-parietal network. During recognition with the left hand the activation was restricted and lateralized to the ipsilateral hemisphere. In this patient with pseudocortical discriminative sensory dysfunction the lack of activation of the whole cortical network, implicated in tactile recognition, demonstrates that pseudocortical is functionally equivalent to cortical tactile agnosia.