Unilateral hypoplasia of the trapezius muscle in a 10-year-old boy: a case report.

We present a 10-year-old boy with a partial absence of or a hypoplastic right trapezius. At present, his only concern is shoulder asymmetry. No family history of significance and no history of trauma exist. His radiographs confirm changes in bony anatomy secondary to the altered balance of muscle forces on the skeleton. We have not identified any other clinical report of a partial or total absence of the trapezius although it has been defined in cadaveric cases. Similarly, some papers have described an absence of trapezius in combination with other abnormalities. In these cases, an abnormal blood supply has been described in contrast to the normal neurovascular anatomy identified in the cadaveric cases with partial absence. If this patient develops painful disability, the Eden-Lange procedure may be an appropriate treatment as for patients with spinal accessory nerve palsies.