Pectoralis Minor Syndrome: Diagnosis with Botulinum Injection and Treatment with Tenotomy - a Prospective Case Series

Background: Pectoralis minor syndrome involves pain, paraesthesia and weakness in the arm due to compression of the brachial plexus passing beneath pectoralis minor; this paper reports the results of a single centre's treatment pathway in affected patients.

Methods: During a four-year period, patients exhibiting symptoms of pectoralis minor syndrome without significant improvement following physiotherapy proceeded to Botulinum injection. Those with good response to injection but subsequent recurrence of symptoms were offered pectoralis minor tenotomy. Oxford shoulder Scores were collected at baseline and after interventions.

Results: Twenty-one patients received Botulinum injection; at six weeks following injection, mean change in Oxford Shoulder Score was +12.4, with only one patient reporting a worsening of symptoms. Of the 17 patients with clinically significant response to injection, 12 have subsequently undergone tenotomy; three months following tenotomy, mean change in Oxford Shoulder Score from baseline was +22.3. Improvement was maintained in all patients at prolonged follow-up (average 20 months post-tenotomy).

Discussion: This pathway has shown to be extremely effective in patients not responding to first-line treatment for pectoralis minor syndrome, with 85% of patients post-injection and 100% of patients post-tenotomy showing significant (greater than published minimal clinically important difference value of six points) improvements in Oxford Shoulder Score, maintained at follow-up.