Purpose: Serratus anterior palsy is usually part of a Parsonnage and Turner syndrome. When occurring alone, it may be secondary to compression of the long thoracic nerve. The anatomic point of contact has been described at the level of the second rib. We report our experience with a musculofascial serratus anterior flap showing that the crossing point of the long thoracic nerve and the thoracic branch of the thoracodorsal artery, the serratus anterior fascia could also be a potential point of compression.

Material and method: We cared for two patients with complete and isolated palsy of the serratus anterior. In the first patient, the paralysis developed over one year and in the second had started three months before treatment. In both patients, the preoperative electromyogram showed an absence of serratus anterior activity. We therefore performed exoneurolysis of the long thoracic nerve in both cases. At surgery, the nerve was clearly compressed at the point where the long thoracic nerve crossed the thoracic branch of the thoracodorsal artery.

Results: The first patient recovered normal muscle activity one year after surgery. Complete recovery was achieved in the second patient at three months.

Discussion: These two cases would support the hypothesis that the long thoracic nerve can become compressed within the serratus anterior fascia. In all cases with serratus anterior palsy secondary to suspected mechanical compression, we propose exoneurolysis of the long thoracic nerve.