Isolated accessory nerve palsy is typically iatrogenic (due to injury from surgery or internal jugular vein cannulation) or may be due to trauma [175]. Accessory nerve palsy can also be accompanied by variable palsies of the glossopharyngeal (CN IX), vagus (CN X), and hypoglossal nerves (CN XII) in combined syndromes, particularly from lesions arising in the brainstem or jugular foramen, as discussed in Variant 9. CT Head There is no relevant literature to support the use of routine CT head alone in the evaluation of unilateral isolated CN XI palsy. CT Maxillofacial There is no relevant literature to support the use of maxillofacial CT in the evaluation of unilateral isolated CN XI palsy. CT Temporal Bone There is no relevant literature to support the use of temporal bone CT in the evaluation of unilateral isolated CN XI palsy. CT Neck Accessory nerve palsy is clinically manifested by weakness and atrophy of the sternocleidomastoid muscle and trapezius muscle and, as an isolated palsy, is typically due to iatrogenic injury. Contrast-enhanced CT neck may be useful to characterize lesions in the carotid space or posterior cervical space along the extracranial course of CN XI, as well as demonstrating atrophy of the trapezius or sternocleidomastoid muscles. MRI offers superior soft tissue contrast to demonstrate denervation changes or directly image features of neuritis and offers the benefit of being able to directly image the intracranial and high cervical portions of the nerve [2]. Imaging protocols should include thin-cut high-resolution bone windows through the posterior skull base. Noncontrast neck CT offers limited evaluation of the neck and may be an alternate option for this clinical scenario. There is no relevant literature to support the use of combined pre- and postcontrast imaging. CTA Head and Neck There is no relevant literature to support the use of CTA in the evaluation of unilateral isolated CN XI palsy.
Cranial Neuropathy. Isolated accessory nerve palsy is typically iatrogenic (due to injury from surgery or internal jugular vein cannulation) or may be due to trauma [175]. Accessory nerve palsy can also be accompanied by variable palsies of the glossopharyngeal (CN IX), vagus (CN X), and hypoglossal nerves (CN XII) in combined syndromes, particularly from lesions arising in the brainstem or jugular foramen, as discussed in Variant 9. CT Head There is no relevant literature to support the use of routine CT head alone in the evaluation of unilateral isolated CN XI palsy. CT Maxillofacial There is no relevant literature to support the use of maxillofacial CT in the evaluation of unilateral isolated CN XI palsy. CT Temporal Bone There is no relevant literature to support the use of temporal bone CT in the evaluation of unilateral isolated CN XI palsy. CT Neck Accessory nerve palsy is clinically manifested by weakness and atrophy of the sternocleidomastoid muscle and trapezius muscle and, as an isolated palsy, is typically due to iatrogenic injury. Contrast-enhanced CT neck may be useful to characterize lesions in the carotid space or posterior cervical space along the extracranial course of CN XI, as well as demonstrating atrophy of the trapezius or sternocleidomastoid muscles. MRI offers superior soft tissue contrast to demonstrate denervation changes or directly image features of neuritis and offers the benefit of being able to directly image the intracranial and high cervical portions of the nerve [2]. Imaging protocols should include thin-cut high-resolution bone windows through the posterior skull base. Noncontrast neck CT offers limited evaluation of the neck and may be an alternate option for this clinical scenario. There is no relevant literature to support the use of combined pre- and postcontrast imaging. CTA Head and Neck There is no relevant literature to support the use of CTA in the evaluation of unilateral isolated CN XI palsy.