Sir,Spinal accessory nerve (SAN) palsy is an uncommon pure motor mononeuropathy. Fibers of the spinal branch of the SAN innervate the sternocleidomastoid and trapezius muscles.[1] We present a case with SAN palsy.A 34-year-old man presented with the complaint of asymmetry of the shoulders since 9 months. He denied any neck or shoulder pain and could not recall a specific precipitating traumatic event. On neurologic examination, he had an asymmetric neckline and drooping of left shoulder. He was able to abduct his arms beyond the horizontal position and actively complete a full range of motion. He had mild weakness of the left trapezius muscle with no wasting or weakness of the ipsilateral sternocleidomastoid muscle. Magnetic resonance imaging (MRI) revealed atrophy of the left trapezius muscle [Figure 1]. Nerve conduction study (NCS) of the left spinal accessory nerve, with surface stimulation along the posterior border of the sternocleidomastoid muscle and recording from the trapezius, recorded compound muscle action potential with lower amplitude compared to the right side (4.2 mV vs. 6.6 mV). Rest of the NCS was normal. Needle examination of left upper trapezius muscle showed intense positive sharp waves and fibrillation potentials and moderatly reduced recruitment of motor unit potentials, with prolonged duration and slightly increased amplituded. Rest of the needle examination was normal. These findings were consistent with SAN palsy distal to the innervation site of the sternocleidomastoid muscle. Consequently,
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