Isolated serratus palsy etiology influences its long-term outcome.

Hypothesis And Background: The cause of isolated serratus palsy is multifactorial, but evaluation of the mechanism of the injury indicates that the lesion to the long thoracic nerve is mechanical in origin in most cases. What is unknown, however, is how etiology influences its long-term outcome. We believed that overuse injuries may recover sooner and better than acute traumatic, infectious, or inflammatory injuries.

Methods: We determined the presumed etiology of isolated serratus palsy in 92 patients treated by brace or observation only and compared it with its long-term outcome after a mean follow-up of 18.1 years (range, 2.1-26.9) by measuring pain, range of motion, and winging of the scapula.

Results: Trauma preceded 22 (24%) of the cases, exertion 37 (40%), infection 14 (15%), and surgery/anesthesia 10 (11%). In 9 (10%) cases, no etiologic factor was evident. Serratus palsy preceded by infection recovered better than did cases with no infection, and those with palsy preceded by surgery/anesthesia had a poorer outcome than did those with no surgery (axilla, chest, or any other areas) or anesthesia. Those palsies caused by acute trauma or acute or chronic overuse/exertion had the same recovery course.

Discussion And Conclusion: Etiology of isolated serratus palsy influenced long-term outcome less than we had expected. It seems, however, that palsies caused by infection recover better and those caused by surgery wherever in the body recover most poorly.