The utility of diffusion tensor imaging in the assessment of trigeminal neuralgia pathophysiology and clinical outcome: a systematic review

Trigeminal neuralgia (TN) is a prevalent and debilitating condition. Despite significant advancements in the management of TN, its etiopathogenesis remains unclear, and predicting clinical outcomes following surgical or radiosurgical interventions continues to pose challenges. Diffusion tensor imaging (DTI) has emerged as a valuable tool in various neurosurgical domains, offering insights into the myelination, inflammation, and infiltration of neural fibers, including cranial nerves. Over the past two decades, numerous studies have sought to characterize DTI parameters in patients with TN. The present review aims to synthesize the current understanding of the utility of DTI in trigeminal neuralgia. In line with PRISMA-P guidelines, we therefore identified relevant studies reported in literature, and 28 papers were included. For each study reviewed, specific DTI parameters—namely fractional anisotropy (FA), apparent diffusion coefficient (ADC), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD)—were individually extracted, analyzed, and correlated with TN etiology and post-treatment clinical outcomes. We categorized results into two sections. In the first we examine the trends in DTI parameters across different subtypes of TN, including those with microvascular compression, without microvascular compression, and associated with demyelinating diseases. In the second we seek to highlight the key DTI features that may be predictive of more favorable clinical outcomes.