Interscapular pain with Chiari Type I malformation attributed to atypical spinal accessory neuralgia

BACKGROUND: The spinal accessory nerve (XI) is traditionally considered a motor nerve. However, as some studies have documented the presence of nociceptive fibers in XI, vascular XI neural compression may lead to an atypical neuralgia. CASE DESCRIPTION: A 27-year-old male presented with a Chiari Type I malformation contributing to interscapular pain. Following a posterior fossa and microvascular decompression of XI, the patient improved, thus confirming the underlying diagnosis of a XI atypical neuralgia. CONCLUSION: Unilateral, posterior-interscapular deep pain may be due to an atypical spinal accessory nerve (XI) neuralgia rather than a Chiari Type I malformation or syrinx. Posterior fossa decompression, subpial tonsillar resection, and XI nerve microvascular decompression resolved this patient’s complaints. In the future, CTA or MRA vascular studies along with a balanced steady-state gradient echo MRI sequence would be better to document the presence of XI nerve neurovascular compromise.