Comparison of Fractional Anisotropy Variances in the Trigeminal Nerve at Root Entry and Cisternal Segment Zones in Patients with and without Clinical Features of Trigeminal Neuralgia: A Cross-sectional Study

Introduction: Although vessel impingement on nerves can be detected using High-resolution steady-state free precession sequences, such as Fast Imaging Employing Steady-state Acquisition (FIESTA), it remains uncertain whether the compression is a physiological variation or a pathological cause of symptoms. A non invasive tool is required to confirm the aetiology, as Microvascular Decompression (MVD) can significantly improve prognosis. Diffusion Tensor Imaging (DTI) is commonly utilised to identify white matter tracts in the brain through tractography, providing valuable insights into neural integrity and potential compression. Aim: To compare the Fractional Anisotropy (FA) value at root entry and cisternal segment zones in patients with and without clinical features of Trigeminal Neuralgia (TN). Materials and Methods: A cross-sectional study was conducted in the Radiology Department, Dr. Pinnamaneni Siddhartha Institute of Medical Sciences and Research Foundation, Vijayawada, Andhra Pradesh, India, from January 2024 to May 2024. The study included a total of 60 patients, divided into symptomatic (TN) and asymptomatic groups based on clinical diagnostic criteria. FA values were measured bilaterally in the trigeminal nerve zones, including the root entry and cisternal segments. Statistical analysis was used to compare FA values between the symptomatic and asymptomatic groups. Data was analysed using Statistical Package for the Social Sciences (SPSS) software version 21.0. Results: Sixty patients (25 females, 35 males) with a mean±Standard Deviation (SD) age of 41±14 years participated in the present study. Among them, 47 were asymptomatic and 13 presented with symptoms. The FA values at the Root Entry Zone (REZ) (combined right and left-side) were 0.243, and at the cisternal segment (combined right and left-side) were 0.242 in symptomatic patients, compared to FA values of 0.403 at the REZ (combined right and left-side) and 0.414 at the cisternal segment (combined right and left-side) in asymptomatic patients, with a statistically significant difference (p-value=0.001). Conclusion: The present study highlights the potential of FA values derived from DTI metrics to improve diagnostic precision for identifying pathological vascular compression in patients with TN.