Spinal Accessory Nerve Palsy following Cervical Cooled Radiofrequency Ablation: A Case Report and Review of the Literature

Abstract

Chronic neck pain is a common cause of functional impairment in the general population. A significant percentage has a component of cervical facet arthropathy for which cervical radiofrequency ablation (RFA) has been successful in treating. We present a case of spinal accessory nerve (SAN) palsy after water-cooled cervical RFA. A 37-year-old female with history of fibromyalgia and occipital neuralgia presented with cervicalgia. Magnetic resonance imaging (MRI) revealed degenerative changes and central canal stenosis at C5-6. After positive result to diagnostic cervical medial branch blocks (MBB), she underwent staged bilateral C2-3-4-5 medial branch watercooled RFA. On subsequent follow up, she noted new left shoulder pain. On exam, difficulty with left arm abduction and scapular winging was noted. Electrodiagnostics (EDX) revealed mild denervation and mild decreased motor units on needle EMG study. Nerve stimulation study of the SAN to the upper trapezius revealed latency prolongation and amplitude reduction, consistent with an acute spinal accessory neuropathy. Repeat EDX study, 7 months later, no longer showed denervation in upper trapezius, normal latency, and improved (although still decreased) amplitude. SAN palsy after multilevel cervical RFA has not been reported in the literature to our knowledge. Cervical RFA is generally considered safe with most complications being transient and minor with no lasting adverse effects. Spinal accessory nerve palsy is one cause of scapular winging. This case highlights the importance of physical exam and knowledge of anatomical structures in promptly diagnosing SAN palsy. Key words: Spinal accessory nerve palsy, medial scapular winging, lateral scapular winging, cervical radiofrequency ablation, cervical facet arthropathy, cervical medial branch blocks, cervicalgia, water-cooled radiofrequency ablation