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Hand up! Yawn and raise your arm
O Walusinski1, J-P Neau, J Bogousslavsky
1walusinski@yawning.info
Summary
Yawning can cause involuntary arm movements in hemiplegia patients. This phenomenon, termed parakinesia brachialis oscitans, links yawning to motor control disruption.
Area of Science:
- Neurology
- Neuroscience
- Human physiology
Background:
- Hemiplegia, a condition causing paralysis, can present with unusual associated movements.
- The link between yawning and involuntary arm elevation in hemiplegia is rarely documented.
Observation:
- Involuntary arm raising during yawning was observed in hemiplegic patients.
- This phenomenon was studied in six patients and compared with historical cases.
Findings:
- Brain imaging revealed small vascular lesions, often in the internal capsule, in affected patients.
- Damage to the cortico-neocerebellar tract may disinhibit the spino-archeocerebellar tract, leading to arm stimulation.
- This is modulated by the lateral reticular nucleus, synchronizing respiratory and locomotor rhythms.
Implications:
- Disinhibition of primitive neural structures links yawning to locomotion-related motor control.
- This suggests a homeostatic process where vigilance behaviors (yawning) activate motor mechanisms.
- The term 'parakinesia brachialis oscitans' is proposed for this specific reflex.
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