Is It Effective to Raise the Irradiation Dose from 80 to 85 Gy in Gamma Knife Radiosurgery for Trigeminal Neuralgia?

Abstract

Objective: In order to assess the effect of raising gamma knife radiosurgery (GKS) doses from 80 to 85 Gy for the treatment of trigeminal neuralgia (TN), the authors analyzed the outcomes of GKS in each group. Patients and Methods: The authors retrospectively collected follow-up data of 104 GKS procedures conducted for TN. Doses of 80 and 85 Gy were prescribed for 60 and 44 patients, respectively. The target was 2–4 mm anterior to the junction of the trigeminal nerve and pons. Outcomes were quantified based on facial pain levels and classified using the Barrow Neurological Institute scale. Results: Actuarial rates of a favorable pain control outcome at 1 and 3 years after GKS were 75.0 and 61.2% for 80 Gy and 65.9 and 60.3% for 85 Gy. Post-GKS facial sensory loss developed in 20.6%. There was no statistically significant difference in pain control rate between the two groups. Time to maximal pain relief was shorter in the 85-Gy group. Protracted morbidity before GKS was a favorable prognostic factor of pain control in a multivariate analysis. Conclusion: According to our finding that 85 Gy brought more rapid clinical improvement without causing more complications, 85 Gy seems to be preferable to 80 Gy, but prospective randomized trials are mandatory to get a more definite conclusion on the optimal dose for GKS of TN.

Impact of target location on the response of trigeminal neuralgia to stereotactic radiosurgery

“…The lack of a consistent dose given within the prior studies (doses often ranged from 70 to 90 Gy) renders clinical extrapolation of the effect of target location difficult, as dose has been clearly associated with both PR and complication rate. 7,12,20 The variable doses used and mixed facial pain patient population in prior studies may confound any conclusion regarding target location on SRS outcomes. Park and colleagues presented a study directly comparing 2 targeting locations in a total of 39 patients who underwent SRS with a mean follow-up of 32.8 months in the DREZ group and 16.5 months in the retrogasserian zone (RGZ) group.…”

First-bite syndrome in oncologic patients

“…Radiotherapy for treatment of pain or other benign conditions is not a new concept, presently being used in trigeminal pain [18] and in head and neck paragangliomas [19,20].…”

Clinical, Anatomo-Radiological and Dosimetric Features Influencing Pain Outcome After Gamma Knife Treatment of Trigeminal Neuralgia

“…It seems that clinical results are quite similar using either the proximal target (Brisman 2004;Cheuk, 2004;Dhople, 2007;Han, 2009;Huang, 2008;Kim, 2010;Little, 2008;Longhi, 2007;Matsuda, 2010Nicol, 2000;Pan, 2010;Park, 2011;Pollock, 2002;Rogers, 2000 Tawk;Verheul, 2010;Young, 1998) as well as the distal one (Dellaretti, 2008;Hayashi 2009;Massager, 2007a;Regis, 2009). Matsuda (Matsuda 2008) in a series of 100 patients reports better pain control and lesser morbidity in patients treated with a proximal compared with those treated with a distal target.…”

“…For the analysis of the maximal dose delivered (in the range of 70 to 90 Gray), Many authors (Alpert, 2005;Kim, 2010;Longhi, 2007;Massager, 2007b;Morbidini-Gaffnay, 2006;Regis, 2009;Park, 2011;Shaya, 2004), communicate that using a maximal prescribed dose in the range of 80 to 90 Gray the patients response is better compared with treatment with a lower dose. On the other hand, other authors communicated that maximal dose of irradiation is not a prognostic factor (Aubuchon, 2010;Azar, 2009;Brisman, 2004;Dellaretti, 2008;Hayashi, 2009;Little, 2008;Longhi, 2007;Park, 2011;Petit, 2003;Riesenburger, 2010;Rogers, 2000;Young, 1998;).…”