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. 2011 Nov 15;81(4):1059-65.
doi: 10.1016/j.ijrobp.2010.07.010. Epub 2010 Oct 6.

Repeat gamma knife radiosurgery for trigeminal neuralgia

Adam C Aubuchon  1 , Michael D Chan, James F Lovato, Christopher J Balamucki, Thomas L Ellis, Stephen B Tatter, Kevin P McMullen, Michael T Munley, Allan F Deguzman, Kenneth E Ekstrand, J Daniel Bourland, Edward G Shaw
Affiliations

Repeat gamma knife radiosurgery for trigeminal neuralgia

Adam C Aubuchon et al. Int J Radiat Oncol Biol Phys. .

Abstract

Purpose: Repeat gamma knife stereotactic radiosurgery (GKRS) for recurrent or persistent trigeminal neuralgia induces an additional response but at the expense of an increased incidence of facial numbness. The present series summarized the results of a repeat treatment series at Wake Forest University Baptist Medical Center, including a multivariate analysis of the data to identify the prognostic factors for treatment success and toxicity.

Methods and materials: Between January 1999 and December 2007, 37 patients underwent a second GKRS application because of treatment failure after a first GKRS treatment. The mean initial dose in the series was 87.3 Gy (range, 80-90). The mean retreatment dose was 84.4 Gy (range, 60-90). The dosimetric variables recorded included the dorsal root entry zone dose, pons surface dose, and dose to the distal nerve.

Results: Of the 37 patients, 81% achieved a >50% pain relief response to repeat GKRS, and 57% experienced some form of trigeminal dysfunction after repeat GKRS. Two patients (5%) experienced clinically significant toxicity: one with bothersome numbness and one with corneal dryness requiring tarsorraphy. A dorsal root entry zone dose at repeat treatment of >26.6 Gy predicted for treatment success (61% vs. 32%, p = .0716). A cumulative dorsal root entry zone dose of >84.3 Gy (72% vs. 44%, p = .091) and a cumulative pons surface dose of >108.5 Gy (78% vs. 44%, p = .018) predicted for post-GKRS numbness. The presence of any post-GKRS numbness predicted for a >50% decrease in pain intensity (100% vs. 60%, p = .0015).

Conclusion: Repeat GKRS is a viable treatment option for recurrent trigeminal neuralgia, although the patient assumes a greater risk of nerve dysfunction to achieve maximal pain relief.

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Conflict of interest statement

Conflict of interest: none.

Figures

Fig. 1
Fig. 1
Axial slice magnetic resonance image showing 50% and 95% isodose curves from gamma knife radiosurgery plan using single 4-mm shot. Crosshairs placed at dorsal root entry zone to calculate point dose. “Measure” tool from GammaPlan software calculated distance from shot to pons and gasserian ganglion.
Fig. 2
Fig. 2
Kaplan-Meier curve showing survival time with some degree of pain relief improved from pretreatment intensity.
Fig. 3
Fig. 3
Kaplan-Meier curve showing survival time with complete pain relief.
See this image and copyright information in PMC

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