Lina Raffaella Barzaghi1, Luigi Albano2, Claudia Scudieri3, Carmen Rosaria Gigliotti4, Francesco Nadin3, Antonella Del Vecchio4, Pietro Mortini3. 1. Department of Neurosurgery and Gamma Knife Radiosurgery, IRCCS San Raffaele Scientific Institute and Vita-Salute University, Milan, Italy. Electronic address: barzaghi.linaraffaella@hsr.it. 2. Department of Neurosurgery and Gamma Knife Radiosurgery, IRCCS San Raffaele Scientific Institute and Vita-Salute University, Milan, Italy; Department of Neuroimaging Research Unit, Institute of Experimental Neurology, IRCCS San Raffaele Scientific Institute and Vita-Salute University, Milan, Italy. 3. Department of Neurosurgery and Gamma Knife Radiosurgery, IRCCS San Raffaele Scientific Institute and Vita-Salute University, Milan, Italy. 4. Department of Medical Physics, IRCCS San Raffaele Scientific Institute and Vita-Salute University, Milan, Italy.
Abstract
OBJECTIVE: Gamma Knife radiosurgery (GKRS) is a well-defined treatment for trigeminal neuralgia. The aim of this study was to determine how the GKRS planning might change on the basis of the patient's own anatomy and how to best choose the target location. METHODS: Trigeminal cisternal length, pontotrigeminal angle, and distance between middle of the shot and emergence were evaluated in 112 consecutive GKRS plans for trigeminal neuralgia. Correlations with pain outcomes and facial hypoesthesia were analyzed. RESULTS: The mean angle was 29° ± 4.4° and 37° ± 0.9°, respectively, in patients developing and not developing severe hypoesthesia (P = 0.045), despite no significant difference on brainstem dose (11.9 ± 0.8 and 10.5 ± 0.3 Gy; P = 0.22). The length of the nerve was not relevant on clinical outcomes but the shot-emergence distance (mean 8.1 ± 0.2 mm) depended on both trigeminal length and angle (P = 0.01). At constant prescription dose, 6-month cumulative rates of pain relief and control without therapy were 52.9% when the shot-emergence distance was ≤8 mm, whereas 25% when this distance was >8 mm (P = 0.017). The maintenance of good pain control was more long lasting in the first group (49.5 ± 6.6 vs. 25.4 ± 5 months; P = 0.006) with a 5-year cumulative rate of 70% and 26%, respectively (P < 0.001). CONCLUSIONS: The pontotrigeminal angle and the shot-emergence distance should be considered during GKRS planning: the first as a potential risk factor for hypoesthesia, and the second should not exceed 8 mm.
OBJECTIVE: Gamma Knife radiosurgery (GKRS) is a well-defined treatment for trigeminal neuralgia. The aim of this study was to determine how the GKRS planning might change on the basis of the patient's own anatomy and how to best choose the target location. METHODS: Trigeminal cisternal length, pontotrigeminal angle, and distance between middle of the shot and emergence were evaluated in 112 consecutive GKRS plans for trigeminal neuralgia. Correlations with pain outcomes and facial hypoesthesia were analyzed. RESULTS: The mean angle was 29° ± 4.4° and 37° ± 0.9°, respectively, in patients developing and not developing severe hypoesthesia (P = 0.045), despite no significant difference on brainstem dose (11.9 ± 0.8 and 10.5 ± 0.3 Gy; P = 0.22). The length of the nerve was not relevant on clinical outcomes but the shot-emergence distance (mean 8.1 ± 0.2 mm) depended on both trigeminal length and angle (P = 0.01). At constant prescription dose, 6-month cumulative rates of pain relief and control without therapy were 52.9% when the shot-emergence distance was ≤8 mm, whereas 25% when this distance was >8 mm (P = 0.017). The maintenance of good pain control was more long lasting in the first group (49.5 ± 6.6 vs. 25.4 ± 5 months; P = 0.006) with a 5-year cumulative rate of 70% and 26%, respectively (P < 0.001). CONCLUSIONS: The pontotrigeminal angle and the shot-emergence distance should be considered during GKRS planning: the first as a potential risk factor for hypoesthesia, and the second should not exceed 8 mm.
Authors: Lina R Barzaghi; Luigi Albano; Claudia Scudieri; Carmen R Gigliotti; Antonella Del Vecchio; Pietro Mortini Journal: Neurosurg Rev Date: 2021-01-12 Impact factor: 3.042