INTRODUCTION: Trigeminal neuralgia remains one of the most painful neurological conditions. While conventional imaging methods can show the structure of the trigeminal nerve, they provide limited insight into its microstructural integrity and functional status. To probe these subtle tissue properties the diffusion tensor imaging can be used. However, this method is still challenging for thin, cranial nerves.

AIM(S): The aim of this study was to reconstruct the trigeminal nerve along its full length using probabilistic method of axons tracking and to characterize how water diffusion directionality changes from the brainstem to Meckel’s cave to explore whether this type of profiling could help to detect early microstructural changes in trigeminal nerve.

METHOD(S): Using probabilistic method of axons tracking, we reconstructed the trigeminal nerve in healthy volunteers and segmented it along the entire length into short parts from the brainstem to Meckel’s cave. Then we measured water molecules diffusion directionality in each of these parts.

RESULTS: A downward trend in diffusion directionality was observed along the nerve’s length, consistently with recent studies. This finding likely reflects the transition from central to peripheral myelination. Similar patterns have been suggested in recent studies on trigeminal neuralgia patients, supporting the idea that profiling of water diffusion directionality may detect early pathological changes.

CONCLUSIONS: These studies demonstrate that the diffusion signal is sensitive to the organization of myelin in nerves. As such, this effect should be carefully considered and validated before diffusion-based approaches are translated to the clinic.

FINANCIAL SUPPORT: Paid from funds of the Polish Ministry of Science and Higher Education under Agreement No. SKN/SP/630850/2025 of 11 April 2025, within the “Student Research Clubs Create Innovations 2024” programme.