Abstract

A disinhibition syndrome affecting speech (with logorrhoea, delirium, jokes, laughs, inappropriate comments, extraordinary confabulations), was the main manifestation of a right-sided thalamic infarct involving the dorsomedian nucleus, intralaminar nuclei and medial part of the ventral lateral nucleus. Resolution of conflicting tasks was severely impaired, suggesting frontal lobe dysfunction. These abnormalities correlated with the finding on SPECT of a marked hypoperfusion in the overlying hemisphere predominating in the frontal region. We suggest that this behavioural syndrome was produced by disconnecting the dorsomedian nucleus from the frontal lobe and limbic system.