MRA Head and Neck There is no relevant literature to support the use of MRA in the evaluation of vasculature in unilateral isolated CN XI palsy. Cranial Neuropathy Contrast-enhanced modified balanced SSFP sequences and MRA focused on the posterior skull provide detailed imaging of the lower CNs within the jugular foramen and as they exit the skull base [24]. Thin-cut high-resolution heavily T2-weighted imaging combined with MRA provides variable direct visualization of CN XI with the cranial segment identified in 88% of the sides and the spinal segment identified in 93% of the sides in one study [149]. Another study reported lower rates with the spinal root of CN XI visualized in 51% of subjects using contrast- enhanced modified balanced SSFP sequences [24]. Contrast-enhanced modified balanced SSFP sequences and MRA focused on the posterior skull provide detailed imaging of the lower CNs within the jugular foramen and as they exit the skull base [24]. Thin-cut high-resolution heavily T2-weighted imaging combined with MRA provides variable direct visualization of CN XI with the cranial segment identified in 88% of the sides and the spinal segment identified in 93% of the sides in one study [149]. Another study reported lower rates with the spinal root of CN XI visualized in 51% of subjects using contrast- enhanced modified balanced SSFP sequences [24]. MRI offers excellent soft tissue contrast to directly image features of neuritis or nerve sheath tumors as well as fully characterize the carotid space and posterior cervical space [2]. In patients with accessory nerve palsy, atrophy, and denervation, signal changes can be seen in the trapezius muscle on MRI [2,176]. US Neck The accessory nerve can be directly imaged by US within the posterior cervical triangle and can provide a supportive role in the diagnosis of spinal accessory nerve injuries, although sensitivity may be user dependent [177-180]. Variant 8: Unilateral isolated weakness or paralysis of the tongue (hypoglossal nerve, CN XII).
Cranial Neuropathy. MRA Head and Neck There is no relevant literature to support the use of MRA in the evaluation of vasculature in unilateral isolated CN XI palsy. Cranial Neuropathy Contrast-enhanced modified balanced SSFP sequences and MRA focused on the posterior skull provide detailed imaging of the lower CNs within the jugular foramen and as they exit the skull base [24]. Thin-cut high-resolution heavily T2-weighted imaging combined with MRA provides variable direct visualization of CN XI with the cranial segment identified in 88% of the sides and the spinal segment identified in 93% of the sides in one study [149]. Another study reported lower rates with the spinal root of CN XI visualized in 51% of subjects using contrast- enhanced modified balanced SSFP sequences [24]. Contrast-enhanced modified balanced SSFP sequences and MRA focused on the posterior skull provide detailed imaging of the lower CNs within the jugular foramen and as they exit the skull base [24]. Thin-cut high-resolution heavily T2-weighted imaging combined with MRA provides variable direct visualization of CN XI with the cranial segment identified in 88% of the sides and the spinal segment identified in 93% of the sides in one study [149]. Another study reported lower rates with the spinal root of CN XI visualized in 51% of subjects using contrast- enhanced modified balanced SSFP sequences [24]. MRI offers excellent soft tissue contrast to directly image features of neuritis or nerve sheath tumors as well as fully characterize the carotid space and posterior cervical space [2]. In patients with accessory nerve palsy, atrophy, and denervation, signal changes can be seen in the trapezius muscle on MRI [2,176]. US Neck The accessory nerve can be directly imaged by US within the posterior cervical triangle and can provide a supportive role in the diagnosis of spinal accessory nerve injuries, although sensitivity may be user dependent [177-180]. Variant 8: Unilateral isolated weakness or paralysis of the tongue (hypoglossal nerve, CN XII).