Exploring Parakinesia Brachialis Oscitans: An Intriguing Post-Stroke Phenomenon

Parakinesia Brachialis Oscitans (PBO) is a rare post-stroke phenomenon characterized by abnormal, involuntary movement in a paralyzed limb triggered by yawning. We present the case of a male patient, age 57 years, who was admitted with right hemiparesis, dysarthria, and facial weakness. Brain magnetic resonance imaging revealed an infarction in the left pons. One week following the stroke, the patient began to experience involuntary elevation of his paretic arm and, to a lesser extent, his leg, triggered specifically by yawning. Based on these observations, he was diagnosed with PBO. The characteristic movement pattern of elevation of the upper limb during yawning was consistent with the typical presentation of PBO. The patient was reassured about the benign nature of his condition and continued his rehabilitation program. This phenomenon occurs due to a dissociation between autonomic and voluntary motor control, reflecting a disruption of cortical inhibition of the cerebellum, while sparing functional spinocerebellar pathways. Given the potential for confusion with focal seizure activity, especially during the acute phase of a stroke, a high index of suspicion is necessary to distinguish PBO from other neurologic disorders. Correctly identifying PBO can guide accurate diagnosis and appropriate management preventing unnecessary investigations and facilitating better outcomes in post-stroke care.