SEVERAL neurophysiological studies have highlighted the role of the midbrain periaqueductal gray matter (PAG) in the initiation of vocalization in various animal species, from frogs to primates. With regard to humans, only two cases of complete mutism following a lesion to the PAG have been reported so far. This article describes a new case of a patient (GM) who, following an ischemic lesion to the periaqueductal gray region of the midbrain, presented with complete and irreversible mutism, though her language comprehension functions and her non-verbal expression capacity were preserved. This clinical case provides evidence that in humans the PAG also acts as a link between different vocalization-eliciting external and internal stimuli (which reach the PAG from sensory and emotional structures) and the vocal–motor coordinating mechanisms in the lower brain stem.
1Service de Revalidation Neurologique, CHU Brugmann, Université Libre de Bruxelles, Brussels, Belgium
2Children's Neurological Research Hospital ‘E. Medea’, Ass. La Nostra Famiglia, Via Don L. Monza, 20, 23842 Bosisio-Parini (LC)
3Department of Physiology and Pathology, University of Trieste, Italy
4Corresponding Author and Address: Franco Fabbro, Service de Revalidation Neurologique, CHU Brugmann, Université Libre de Bruxelles, Brussels, Belgium
ACKNOWLEDGEMENTS: We are grateful to Professor Y. Lebrun, Professor M. Paradis and Dr V. Darò for improving the manuscript.
Received 2 December 1998; accepted 4 January 1999