DTI metrics suggest microstructural tissue changes in symptomatic nerves in the setting of trigeminal neuralgia compared with asymptomatic nerves and may be useful for making treatment decisions [68,86-93]. Advanced MRI techniques have also detected structural alterations in gray matter and white matter in patients with trigeminal neuralgia [94-97]. MR neurography is an emerging technique that may be useful in characterizing the etiology of peripheral trigeminal neuropathy [98]. In patients with clinical features of trigeminal neuralgia, 3-D heavily T2-weighted MRI sequences, MRA, and a combination of these techniques are commonly used noninvasive methods for characterizing the anatomy of vascular loops potentially compressing the cisternal segment of the fifth nerve and correlate well with surgical findings [23,68-76]. Congruence rates of imaging and intraoperative findings for neurovascular contact range from 83% to 100% [68-70,72,75,78]. Both false-positive and false-negative imaging studies occur when assessing for neurovascular contact in the setting of trigeminal neuralgia; consequently, MRI is supportive rather than diagnostic in selecting candidates for microvascular decompression and should be interpreted in the context of the site of symptoms [69,73-75,78]. Imaging evidence of vascular trigeminal nerve root compression, the degree of compression, location of contact, and nerve volume may have prognostic value [73,77,79-81]. Trigeminal nerve size measurements have been reported as smaller on the symptomatic side in trigeminal neuralgia as measured from thin-cut MRI [82-84]. Preoperative imaging is useful for surgical planning [85]. Advanced MRI techniques including DTI, functional MRI, and voxel-based morphometry are being used to research the pathophysiology of trigeminal neuralgia.
Cranial Neuropathy. DTI metrics suggest microstructural tissue changes in symptomatic nerves in the setting of trigeminal neuralgia compared with asymptomatic nerves and may be useful for making treatment decisions [68,86-93]. Advanced MRI techniques have also detected structural alterations in gray matter and white matter in patients with trigeminal neuralgia [94-97]. MR neurography is an emerging technique that may be useful in characterizing the etiology of peripheral trigeminal neuropathy [98]. In patients with clinical features of trigeminal neuralgia, 3-D heavily T2-weighted MRI sequences, MRA, and a combination of these techniques are commonly used noninvasive methods for characterizing the anatomy of vascular loops potentially compressing the cisternal segment of the fifth nerve and correlate well with surgical findings [23,68-76]. Congruence rates of imaging and intraoperative findings for neurovascular contact range from 83% to 100% [68-70,72,75,78]. Both false-positive and false-negative imaging studies occur when assessing for neurovascular contact in the setting of trigeminal neuralgia; consequently, MRI is supportive rather than diagnostic in selecting candidates for microvascular decompression and should be interpreted in the context of the site of symptoms [69,73-75,78]. Imaging evidence of vascular trigeminal nerve root compression, the degree of compression, location of contact, and nerve volume may have prognostic value [73,77,79-81]. Trigeminal nerve size measurements have been reported as smaller on the symptomatic side in trigeminal neuralgia as measured from thin-cut MRI [82-84]. Preoperative imaging is useful for surgical planning [85]. Advanced MRI techniques including DTI, functional MRI, and voxel-based morphometry are being used to research the pathophysiology of trigeminal neuralgia.