["Drop hand" resulting from cerebral infarction--case report]

A 52-year-old male was admitted with the progressive weakness of the right 3rd, 4th and 5th fingers on three days after the onset. On admission, his right hand and all of right fingers were flexed. Any extension of the right hand and any movement of right fingers were not accomplished. The sensory deficit in the right wrist joint was not observed. Initial computed tomography (CT) scan of the brain carried out on the day of admission could not detect any abnormal findings. However, the follow-up CT scans demonstrated the localized low density lesion in the left frontoparietal area. MR imaging also revealed abnormality attributable to cerebral infarction. Diagnosis of "Pseudoradial nerve palsy" was made. The mechanisms of these neurological deficits and the problems in differential diagnosis between central and peripheral nerve involvements were discussed.