Spinal accessory nerve palsy: associated signs and symptoms

Abstract

Study design: Retrospective case series.

Background: Spinal accessory nerve palsy (SANP) is common following neck dissection surgery and can occur with blunt or penetrating trauma to the lateral neck region and cervical stretch injuries. Early detection of SANP remains a clinical challenge and the condition is often misdiagnosed. The purpose of this case series is to describe the associated history, signs, and symptoms related to SANP and increase awareness of the scapular flip sign as a clinical sign associated with SANP. CASE SERIES DESCRIPTION: Twenty subjects (13 male, 7 female) presented with pain and decreased shoulder function following head and neck surgery or posttrauma. All patients were thoroughly examined and the scapular flip sign was assessed. All patients presented with a cluster of signs and symptoms including trapezius atrophy, shoulder girdle depression, limited active shoulder abduction to less than 90 degrees , shoulder pain, and shoulder weakness. A positive scapular flip sign was present in all cases. The middle and lower trapezius were rated as 0/5, based on manual muscle testing, indicating no identifiable muscle activation against resistance.

Discussion: A typical history and consistent signs and symptoms were found related to SANP. A strong relationship appeared between the presence of the scapular flip sign and SANP. The suspected mechanism for the scapular flip sign is the unopposed pull of the humeral external rotators by the inactive middle and lower trapezius. Early identification of SANP can assist with the prognosis, explain persistent impairments and functional deficits, motivate appropriate diagnostic testing and interventions, and help maximize outcome. Further research to validate the scapular flip sign and establish a clinical prediction rule for the diagnosis of SANP should be performed.