Stereotactic radiosurgery for trigeminal pain secondary to recurrent malignant skull base tumors.

OBJECTIVE The objective of this study was to assess outcomes after Gamma Knife radiosurgery (GKRS) re-irradiation for palliation of patients with trigeminal pain secondary to recurrent malignant skull base tumors. METHODS From 2009 to 2016, 26 patients who had previously undergone radiation treatment to the head and neck received GKRS for palliation of trigeminal neuropathic pain secondary to recurrence of malignant skull base tumors. Twenty-two patients received single-fraction GKRS to a median dose of 17 Gy (range 15-20 Gy) prescribed to the 50% isodose line (range 43%-55%). Four patients received fractionated Gamma Knife Extend therapy to a median dose of 24 Gy in 3 fractions (range 21-27 Gy) prescribed to the 50% isodose line (range 45%-50%). Those with at least a 3-month follow-up were assessed for symptom palliation. Self-reported pain was evaluated by the numeric rating scale (NRS) and MD Anderson Symptom Inventory-Head and Neck (MDASI-HN) pain score. Frequency of as-needed (PRN) analgesic use and opioid requirement were also assessed. Baseline opioid dose was reported as a fentanyl-equivalent dose (FED) and PRN for breakthrough pain use as oral morphine-equivalent dose (OMED). The chi-square and Student t-tests were used to determine differences before and after GKRS. RESULTS Seven patients (29%) were excluded due to local disease progression. Two experienced progression at the first follow-up, and 5 had local recurrence from disease outside the GKRS volume. Nineteen patients were assessed for symptom palliation with a median follow-up duration of 10.4 months (range 3.0-34.4 months). At 3 months after GKRS, the NRS scores (n = 19) decreased from 4.65 ± 3.45 to 1.47 ± 2.11 (p < 0.001); MDASI-HN pain scores (n = 13) decreased from 5.02 ± 1.68 to 2.02 ± 1.54 (p < 0.01); scheduled FED (n = 19) decreased from 62.4 ± 102.1 to 27.9 ± 45.5 mcg/hr (p < 0.01); PRN OMED (n = 19) decreased from 43.9 ± 77.5 to 10.9 ± 20.8 mg/day (p = 0.02); and frequency of any PRN analgesic use (n = 19) decreased from 0.49 ± 0.55 to 1.33 ± 0.90 per day (p = 0.08). At 6 months after GKRS, 9 (56%) of 16 patients reported being pain free (NRS score 0), with 6 (67%) of the 9 being both pain free and not requiring analgesic medications. One patient treated early in our experience developed a temporary increase in trigeminal pain 3-4 days after GKRS requiring hospitalization. All subsequently treated patients were given a single dose of intravenous steroids immediately after GKRS followed by a 2-3-week oral steroid taper. No further cases of increased or new pain after treatment were observed after this intervention. CONCLUSIONS GKRS for palliation of trigeminal pain secondary to recurrent malignant skull base tumors demonstrated a significant decrease in patient-reported pain and opioid requirement. Additional patients and a longer follow-up duration are needed to assess durability of symptom relief and local control.