Brachial plexus neuritis is reportedly caused by various factors; however, it has not been described in association with Streptococcus agalactiae. This is a case report of a patient diagnosed with brachial plexus neuritis associated with pyogenic arthritis of the shoulder. A 57-year-old man visited the hospital complaining of sudden weakness and painful swelling of the left arm. The diagnosis was pyogenic arthritis of the left shoulder, and the patient was treated with open irrigation and debridement accompanied by intravenous antibiotic therapy. S. agalactiae was isolated from a wound culture, and an electrodiagnostic study showed brachial plexopathy involving the left upper and middle trunk. Nine weeks after onset, muscle strength improved in most of the affected muscles, and an electrodiagnostic study showed signs of reinnervation. In conclusion, S. agalactiae infection can lead to various complications including brachial plexus neuritis.
Keywords: Brachial plexus neuritis; Brachial plexus neuropathies; Streptococcus agalactiae.