A feasibility study on pinpointing the branches of trigeminal nerve in radiofrequency ablation

To propose a pinpointing method and to obtain technique parameters for puncture of the branches of the trigeminal nerve through anatomical radiological study.

Trigeminal ganglions and intracranial branches of 25 pieces (50 sides) of adult skull wet-specimens were dissected and coated with contrast agent. X-ray images of the skull in lateral cranial position were collected with the tube inclining towards head at 15°, 20° and 25°. 'Porus-Clinoid Line' and 'FO-PC axis' were delineated on the images. The latter set as the base line, Point A, B and C were settled separately as the upper rim of the trigeminal ganglion, the axis of Brach V₂ and the junction of the extended border lines of Branch V₂ and V₃ all intersected with it. The collected data was processed afterwards.

In the cases of 50 sides, the maximum value of the 'FO-PC Distance' was 17.8 mm; Distance A, 6.6 mm; Distance B, 10.1 mm; and Distance C, 6.6 mm, while the minimum of each was 9.4 mm, 0.3 mm, 4.4 mm and 6.6 mm respectively. Ratios of the 'FO-PC Distance' to Distance B were respectively 2.00 ± 0.15 mm, 1.98 ± 0.15 mm and 1.95 ± 0.16 mm when tube inclined towards head at angles of 15°, 20° and 25°; to Distance C were 3.06 ± 0.53 mm, 3.36 ± 0.60 mm and 3.75 ± 0.96 mm and to Distance A were 10.65 ± 9.17 mm, 7.33 ± 5.28 mm, 5.16 ± 2.30 mm under the same condition.

The results showed that Distances from each branch of trigeminal nerve to the medial rim of foramen ovale vary on different individuals while the proportional relationship between each branch and 'FO-PC Distance' has regularity.