Trigeminal nucleus caudalis anatomy: guidance for radiofrequency dorsal root entry zone lesioning.

Object: This study seeks to improve the accuracy of trigeminal nucleus caudalis dorsal root entry zone (DREZ) radiofrequency lesioning by quantifying the size and orientation of the nucleus caudalis.

Methods: Using serial axial photographs of 6 formalin-fixed cadaver brainstems, digital nucleus caudalis measurements were taken at 1-mm intervals from the level of the obex to the C(2) dorsal nerve roots.

Results: From the obex to the C(2) dorsal nerve roots, the nucleus caudalis decreases in width (from 2.6 ± 0.2 to 1.0 ± 0.3 mm) and, excluding superficial tract thickness, decreases in axial nucleus depth (from 2.4 ± 0.3 to 1.7 ± 0.2 mm). At levels between the obex and 10 mm caudal to the obex, the accessory nerve rootlets exit the brainstem at the junction of the spinal trigeminal tract and the dorsal spinocerebellar tract.

Conclusion: This study details the anatomic dimensions and orientation of the nucleus caudalis for surgeons who perform DREZ lesioning.