A case of connected superior and middle trunks of the brachial plexus or with abnormal upper trunk.

During treatment of tumors of nerve sheaths, such as schwannomas and neurofibromas, neurosurgeons should be aware of variations and aberrant formations of brachial plexus. Variations of the branches of brachial plexus are common, but its variations in the level of the roots and trunks are rare. Variations regarding lower trunk were founded more frequent in previous studies. An unusual variant of the brachial plexus was found unilaterally during routine dissection of a 75-year-old male cadaver. It was observed that middle trunk was connected to superior trunk. Deep cervical artery originating from subclavian artery passed between C6 and C7 roots. Similar variations in the brachial plexus were not observed on the contralateral side. In available literature, only two similar bilateral cases were reported. The details of this variation and its clinical significance were discussed. Knowledge about these rare variations in the trunks is very useful in surgical practice and anesthesia.