Analysis of morphological measurements of the trigeminal nerve in the linac stereotactic radiosurgery simulation targeting the root entry zone in trigeminal neuralgia

• Published in: Neurocirugía (Asturias, Spain) Spain), 2019-05, Vol.30 (3), p.105-114
• Main Authors: Medélez-Borbonio, Rafael, Perdomo-Pantoja, Alexander, Serrano-Rubio, Alejandro Apolinar, Tomberlin, Colson, Revuelta-Gutiérrez, Rogelio, Moreno-Jiménez, Sergio
• Format: Article
• Language: English
• Subjects: Fiesta sequence; Linac; Mediciones morfológicas; Morphological measurements; Neuralgia trigeminal; Radiocirugía estereotáctica; Secuencia FIESTA; Simulación; Simulations; Stereotactic radiosurgery; Trigeminal neuralgia
• ISSN: 1130-1473; 2529-8496
• DOI: 10.1016/j.neucir.2018.10.001

To describe the anatomical measurements of the trigeminal nerve in patients with trigeminal neuralgia (TN) during Linac (linear accelerator)-based stereotactic radiosurgery (SRS) simulation, targeting the root entry zone (REZ), with a 30% isodose line tangential to the pons, using 4-mm and 6-mm collimators. In this retrospective study, 53 TN patients, who underwent Fiesta sequence scanning prior to any treatment modality, were assessed. Bilateral measurements were obtained from the cisternal segment of the trigeminal nerve, the trigeminal-pontine angle, and the lateral width of the pontine cistern on the Fiesta MRI sequence. Linac-based SRS simulations were estimated with a radiation dosage of 90Gy to 30% isodose line tangential to the pons, with both 4- and 6-mm collimators. Distances from the calculated targets to the pons and the Gasserian ganglion were measured for later analysis. The statistical analysis was performed comparing the affected side against the unaffected side. Right trigeminal nerve was affected in 36 patients (67.9%), and left one in 17 (32.1%) patients. The mean length of the trigeminal nerve was 9.8mm (range: 4.6–16.8mm) on the affected side, and 10.5mm (range: 5.6–18.4mm) on the unaffected side (p=.02). The mean trigeminal-pontine angle was 12.5° (range: 5.4° to 19.5°) on the affected side, and 10.2° (range: 5.0° to 30.5°) on the unaffected side (p=.01). In the simulations, the distances from the estimated targets to the pons and the Gasserian ganglion were not statistically different between sides. The variation of target-pons and target-ganglion distances was statistically significant on the affected side with the change of collimators (p