Radial nerve palsy at the elbow.

We studied the clinical features and images along with surgical findings of 8 cases of radial nerve palsy due to a space-occupying lesion (SOL) at the elbow. Based on image findings, we examined compressing masses and their extent, we contrasted them with operative findings of the radial nerve, and we surmised the site of impairment. Compressing masses were ganglions in 6 cases, an old radial head dislocation in 1 case, and engorged radial recurrent vessels in 1 case. The extent of the SOLs was roughly 15-40 mm from the interepicondylar line and 0-30 mm from the radiohumeral joint. In operative findings, only the posterior interosseous nerve (PIN) was compressed in 5 cases, while both the PIN and superficial branch were compressed in 3 cases. No apparent correlation between operative findings and the type of palsy was found. The radial tunnel has yet to be defined clearly, but the radial nerve palsy is readily understandable in cases of SOLs via the definition of the radial tunnel as the tubular structure from the radiohumeral joint to the outlet of the supinator muscle.