A Case of Parakinesia Brachialis Oscitans and Excessive Yawning from Tumefactive Demyelination
Chia-Chen Tsai1, Joshua Lee2, Tychicus Chen2
1Faculty of Medicine, 2Division of Neurology, Department of Medicine, University of British Columbia
Objective:
To report the phenomenon of parakinesia brachialis oscitans (PBO) in a case of tumefactive demyelination.
Background:
PBO is an unusual phenomenon involving transient tonic elevation of a paralyzed arm with yawning. It is usually reported in ischemic stroke with pontomedullary brainstem or internal capsule lesions. While the exact mechanism remains unknown, it is believed to involve the release of subcortically regulated automatisms from cortical inhibition. It is postulated that strong contraction of respiratory muscles during yawning produces proprioceptive signals that spread to the anterior horn cells of C4-C8 and lead to involuntary movement of the affected upper limb. Cortical release may also lead to excessive yawning as seen in patients with multiple sclerosis.
Results:
A 31-year-old male with no past medical history presented with five days of progressive left-sided ataxic-hemiparesis which occurred two weeks after an upper respiratory tract infection. He had frequent yawning with associated transient tonic elevation of his paralyzed arm. Neurological exam revealed left hemiplegia. Magnetic resonance imaging revealed a tumefactive lesion involving the deep right subcortical white matter. Lumbar puncture was performed and demonstrated lymphocytic pleocytosis (15 cells/uL) accompanied by oligoclonal banding. Stereotactic biopsy of the lesion revealed focal demyelination without histopathological indications of vasculitis or lymphoproliferation. After treatment with high-dose intravenous corticosteroids and mitoxantrone, he achieved full motor recovery that was sustained throughout the 18-month follow-up period.
Conclusions:
Only a few cases of PBO have been documented in the literature, and these instances typically occurred following a stroke. This case uniquely demonstrates the phenomenon of PBO in a patient with a biopsy-confirmed tumefactive demyelinating lesion and excessive yawning.