Isolated shoulder palsy due to infarction of the cortical branch of the middle cerebral artery.

A 71-year-old man with hyperlipidemia abruptly developed left-sided isolated shoulder palsy. Cranial magnetic resonance imaging demonstrated infarction of the cortical branch of the right middle cerebral artery (MCA). In the primary motor cortex, there is broad somatotopic representation of various body parts in a particular arrangement, and the area corresponding to the shoulder is very small. Consequently, there have been only 3 reported cases of isolated shoulder palsy due to cerebral infarction, and its vascular supply remains uncertain. The present case indicates that the corresponding area to the shoulder receives its blood from the cortical branch of the MCA.