A 51-year-old man developed severe quadriparesis without sensory loss after a fall on the occiput. When he was treated with corticosteroids, the weakness worsened slightly for 2 days, but he then progressively improved and ultimately walked unassisted. Two months later, postmortem examination disclosed metastatic tumors in the superior portion of each precentral gyrus. The subjacent white matter was edematous. No spinal cord abnormalities were found. The clinical, radiologic, and neuropathologic findings suggest that the quadriplegia resulted from these bilateral cerebral lesions and not from spinal cord dysfunction. The rapid development of cerebral edema, perhaps precipitated by trauma, seemed to account for the acute onset of symptoms in this case.