[Parakinesia brachialis oscitans]

Abstract

Introduction: In some cases of hemiplegia the onset of yawning is associated with an involuntary raising of the paralyzed arm.

Patients and method: Four observations of this movement, which is seldom described probably because it is mostly neglected, were made in the neurology unit of the University Hospital of Poitiers. The descriptions were compared with other cases that have been published in the medical literature of the last 150 years. Cerebral imagery shows a lesion that is most often localized on the internal capsule. After comparison with experimental models in cats, it is proposed that the section of the cortico-neocerebellum tract of the extra-pyramidal system disinhibits the spino-archeocerebellum tract, enabling a motor stimulation of the arm by the lateral reticular nucleus, which harmonises central respiratory and locomotor rhythms.

Results and conclusion: Some subcortical structures, that are phylogenetically more ancient, thus disinhibit regained autonomy in the homeostasis process associating the massive inspiration of yawning--a form of reflex behavior that stimulates vigilance--with a motor control that is active during locomotion. For this phenomenon we coined the term "parakinesia brachialis oscitans".