[Posterior interosseous nerve paralysis caused by ganglion: a case report].

A 63-year-old man presented with a posterior interosseous nerve palsy secondary to a ganglion compressing the nerve against the arcade of Frohse. Decompression and neurolysis resulted in full functional recovery. While patients with the so-called classic "Saturday night palsy" or even patients with a radial nerve palsy secondary to a fractured humerus may be expected to recover completely without surgery, early surgery is the conservative approach in patients with a nerve palsy secondary to the mass. However it is difficult to diagnose the nerve palsy secondary to the small mass. The treatment for patients with a progressive nerve palsy of unknown origin must be given attention.