What is the most common site for tumor infiltration of the brachial plexus?
The type of tumor will determine where infiltration is likely to occur, but most commonly the lower brachial plexus is involved, leading to pain and hand weakness in a C7 to T1 distribution. This is typically caused by a tumor located in the superior sulcus (Pancoast tumor) or at the thoracic inlet adjacent to the eighth cervical nerve roots, the first and second thoracic trunk distribution, the sympathetic chain, and the stellate ganglion. Horner syndrome may also be present.
