Trigeminal motor root anatomy from pons to foramen ovale and its surgical implications: A study using epoxy sheet...

Surgical treatments for trigeminal neuralgia are frequently limited by postoperative pain recurrence and unexpected sensory preservation, while the detailed microanatomy of the trigeminal motor root and its anatomical variants remain incompletely understood. To address this gap, we conducted a detailed anatomical study using ultrathin epoxy sheet plastination and three-dimensional reconstruction on 44 trigeminal nerves from 22 human cadavers. Serial sections were prepared, stained, and examined macroscopically and microscopically from the pons to the foramen ovale. We identified 3-7 motor rootlets per side at the pontine origin. Aberrant sensory rootlets and sensory-motor anastomoses were observed in 26.7% of specimens. The motor root consistently coursed inferomedial to the sensory root and trigeminal ganglion within Meckel's cave, whereas aberrant sensory rootlets followed an independent trajectory without joining the motor trunk. The anastomoses formed bridging connections between the sensory and motor roots within the cerebellopontine cistern, and the meningeal layers investing the motor root underwent a transition within Meckel's cave, where the arachnoid mater appeared to form a distinct perineurial sheath. These findings provide a high-resolution microanatomical map of the trigeminal motor root. The documented variants, including aberrant sensory rootlets and intersystem anastomoses, may represent important anatomical substrates for persistent sensation or pain recurrence after surgery. The inferomedial course of the motor root also highlights its vulnerability during percutaneous foramen ovale procedures. Collectively, these data offer anatomical guidance for optimizing surgical planning and intraoperative strategies in microvascular decompression, partial sensory rhizotomy, and percutaneous procedures, potentially contributing to improved outcomes in trigeminal neuralgia surgery.