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PubMed

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Brief description/objective

Yawning is a complex behaviour of unclear
function.The face movements may be accompanied
by generalised limb extensions. This
behaviour has been observed in single cases
with arm plegia after ischaemic brain infarctions
involving the pyramidal system at different
levels, i.e. at the level of the motor
cortex, the internal capsule and the pons.
We report a recent case of a 67-year-old man
with ischaemic stroke. On neurological examination
the patient exhibited a plegic right
upper extremity.Within a few hours, we could
observe yawning associated with involuntary
movements of the plegic upper extremity.
Using video-monitoring, the abnormal behaviour
could be detailed during sleep and
wakefulness as abduction in the shoulder and
flexion in the elbow against gravity. Magnetic
resonance imaging revealed an extended infarction
involving the precentral gyrus and
caudate nucleus.We conclude that the involuntary
movements associated with yawning
in an otherwise plegic arm may show a
more complex motor pattern than originally
described and the abnormal behaviour may
be present even in the initial phase of flaccid
paresis. Referring to experiments in the cat,
some evidence indicates that the observed
behaviour is most likely generated in the
caudal medulla, since cells in the lateral reticular
nucleus of lower medulla have both
respiratory and locomotor rhythms. The associated
movements of the extremities are
probably inhibited in healthy subjects by
central motor programs.