Magnetic Resonance Neurography of Traumatic And Non-traumatic Peripheral Trigeminal Neuropathies
John randall Zuniga, DMD, MS, PhD; Cyrus Mistry, DDS MD; Igor Tikhonov, DDS, MD; Riham Dessouky, MD; Avneesh Chhabra, MD; University of Texas Southwestern, Dallas, TX
INTRODUCTION: Clinical neurosensory testing (NST) is currently the gold-standard for the diagnosis of traumatic and non-traumatic peripheral trigeminal neuropathies (PTN) but exhibits both false positive and negative results when compared to surgical findings and frequently delays treatment decisions as the results are dependent upon patients’ subjective responses and observer skill. We tested the hypothesis that Magnetic Resonance Neurography (MRN) of PTN can serve as a diagnostic modality similar or better than NST by correlating NST, MRN and surgical findings.
MATERIALS & METHODS: Sixty patients from 4/2015 to 5/2017 with traumatic and non-traumatic PTN of varying etiologies and Sunderland classifications underwent NST followed by MRN at 1.5T and 3.0 T scanners. The protocol included 2D and 3D imaging, including diffusion imaging and isotropic 3D PSIF (0.9mm voxel). The MRN findings were read by two readers in consensus in the light of clinical findings, but blinded to the side of abnormality. The MRN results were summarized using Sunderland Classification. In 25 patients, surgery was performed and Sunderland Classification was assigned based on surgical photos and/or histology. Agreement between MRN and NST/Surgical classification was evaluated using Kappa statistics. Pearson’s Correlation Coefficient (PCC) was used to assess the correlation between continuous measurements of MRN/NST and surgical classification.
RESULTS: Twenty males and 40 females, mean age 41, ranging 12 to 75, with 54 complaints of altered sensation of the lip/chin/or tongue, including 16 with neuropathic pain and 4 with no neurosensory complaint were included. Third molar surgery (n=29) represented the most common cause of traumatic PTN. MRN was indeterminate in none of the cases. Assuming one nerve abnormality per patient, the lower class was accepted, a Kappa of 0.57 was observed between MRN and NST classification. A Kappa of 0.5 existed between MRN and Surgical findings with a PCC of 0.67.
CONCLUSIONS: MRN anatomically maps PTN and stratifies the nerve injury and neuropathies with moderate to strong agreement with NST and surgical findings for clinical use. The application of a non-invasive objective modality like MRN to determine the classification and characteristics of an injured or abnormal trigeminal nerve earlier than NST can be tested in prospective studies in the future as it could serve as an important technique for outlining treatment decisions and determining patient outcomes.
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