MRI findings of spinal accessory neuropathy

Abstract

Aim: To characterise the magnetic resonance imaging (MRI) appearance of patients with spinal accessory nerve (SAN) denervation.

Material and methods: Twelve patients who had SAN denervation on electromyography (EMG) were included. The sternocleidomastoid and trapezius muscles and the SAN were assessed using MRI.

Results: Trapezius muscle atrophy was seen in 11 (92%), and of those patients, T2/short tau inversion recovery (STIR) signal hyperintensity was also demonstrated in seven (58%). All three patients with prior neck surgery had scarring around the SAN, and one of these patients demonstrated a neuroma, which was confirmed surgically.

Conclusion: Features of SAN neuropathy on MRI include atrophy and T2/STIR signal hyperintensity of the trapezius, and in patients who have had posterior triangle neck surgery, scarring may be seen around the nerve.