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Behavioural Neurology
Volume 3, Issue 3, Pages 143-151

Hyperlalia: A Right Cerebral Hemisphere Syndrome

Atsushi Yamadori, Yukio Osumi, Masayasu Tabuchi, Etsuro Mori, Takashi Yoshida, Shingo Ohkawa, and Yukihiro Yoneda

Neurology Service, Hyogo Brain and Heart Center at Himeji, 520 Saisho-Ko, Himeji, Hyogo-Ken, 670, Japan

Copyright © 1990 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


We describe a new right hemispheric behavioural syndrome for which we propose the name “hyperlalia”. In a typical case an apparently unconcerned and expressionless patient is easily prompted to remarkable volubility with a content which is loose and incoherent. The voice is low and monotonous. All the lesions confirmed by computed tomography of the brain overlapped in the perisylvian area in the territory of the right middle cerebral artery. Loss of a subtle balance between the left hemispheric speech area and the corresponding area in the right hemisphere caused by acute damage of the right perisylvian area may have resulted in disinhibition of the speech function. Similarities and dissimilarities with the known pathology of talkativeness are also discussed.