RESUMO
Objective To investigate the clinical and radiological characteristics of parakinesia brachialis oscitans (PBD) related to yawning in stroke patient and its mechanism.Methods We reported 4 patients with involuntary raising of the paralyzed limbs when yawning in neurological unit of Hainan Branch of Chinese PLA General Hospital,and analyzed their clinical characteristics together with published cases in literatures.Results In this group of stroke patients,when they yawned,their paralyzed upper limb could lift upward involuntarily.Totally 22 patients with ischemic (n=20) and hemorrhagic (n=2) stroke were enrolled.Brain imaging showed infarcts in the middle cerebral artery (MCA) in 17 patients and in the brain stem in 5 patients.This phenomenon occurred 4 hours to 4 months (14.57 ± 31.66d) after stroke onset,and lasted from 1 week to 3 years (6.70 ± 11.66 months).Corticobulbar tract and pyramidal tract were both damaged in these 22 patients.The mechanism might be that after corticobulbar tract and pyramidal tract damaged,their dominant role in the cranial nerve nuclei of the brainstem and the anterior horn cells of the spinal cord disappeared,and the projection of oxytocinergic neurons from paraventricular nucleus functions,thus causing yawning and muscle contraction.Conclusion PBO may be a rare phenomenon of abnormal movement after stroke.This phenomenon indicates damaging of pyramidal tract,and PBO disappears gradually with the recovery of pyramidal tract function.