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TU_34_3015 - Obesity Predicts Poor Outcomes to Stereotactic Radiosurgery for Trigeminal Neuralgia

Tuesday, October 23
1:00 PM - 2:30 PM
Location: Innovation Hub, Exhibit Hall 3

Obesity Predicts Poor Outcomes to Stereotactic Radiosurgery for Trigeminal Neuralgia
M. H. Khattab1, A. D. Sherry2, J. L. Anderson2, E. Kim2, H. Yu2, G. Luo2, A. Yock2, M. Morales3, A. J. Cmelak3, and A. Attia3; 1Vanderbilt University Medical center, Nashville, TN, 2Vanderbilt University Medical Center, Nashville, TN, 3Department of Radiation Oncology, Vanderbilt University Medical Center, Nashville, TN

Purpose/Objective(s): Obesity has been associated with chronic pain sensitization in humans and more recently, multiple mouse models have shown evidence for abnormal trigeminal sensory processing and nociceptive activation of the trigeminal system in obese mice. Stereotactic radiosurgery (SRS) is used as a noninvasive treatment option for patients with trigeminal neuralgia (TN), but the effect of obesity on pain relief post SRS, if any, is unknown. We hypothesized that obesity would not affect post SRS pain relief.

Materials/Methods: We conducted an IRB approved retrospective review of patients treated with single fraction SRS for TN at our institution from 2010-2017. Overweight patients were defined as those with a Body Mass Index (BMI) >=25. Barrow Neurologic Institute (BNI) Score (1: No pain; 2: Occasional pain; 3: Some pain, adequately controlled with medication; 4: Some pain, not adequately controlled with medication; 5: Severe pain or no relief) was measured pre-and post-SRS to quantify pain level. Improvement in BNI score was defined as the initial (pre-SRS) BNI score subtracted from the final (post-SRS) BNI score. Follow up was defined as time from SRS treatment to last follow up with Neurology or Radiation Oncology, and post-SRS BNI score was taken from this visit.

Results: A total of 34 patients met selection criteria, including 14 (41%) treated for left and 20 (59%) treated for right sided disease; 14 (41%) were men and 20 (59%) women. Five patients had bilateral symptoms. Median prescription dose was 85 Gy (range 75-90), and there was no correlation between overweight status and the SRS dose (Wilcoxan rank sum test P=0.24). Median follow up time was 13.3 months (range 3 to 88), and duration of follow up was not associated with overweight status (p=0.37). Overweight patients had a lower pre-SRS BNI score (22% vs 0% with BNI score of 0) and had a smaller trigeminal nerve distribution region affected (21% vs 15% affecting one CN V region). Overweight patients were less likely to have constant or lancinating pain (30% vs 47%), and more likely to have multiple sclerosis (9% vs 3%). Overweight patients were less likely to have any improvement in BNI score (63% vs 90% with any reduction in BNI score) and had a smaller improvement (median score improvement of 1 vs 2). Despite poorer response rates, overweight patients were less likely to receive salvage therapy (30% vs 64%). All 3 of the patients who received salvage SRS were overweight. Overweight patients were also more likely to experience any acute or chronic side effect (17% vs 9%). The most common side effect was new facial numbness (13% vs 9%).

Conclusion: While the vast majority (90%) of normal weight TN patients had a reduction in BNI pain score, our study shows that obese patients with TN were less likely to achieve pain relief, more likely to develop side effects, and less likely to be eligible to receive salvage therapies. These results suggest that further investigation is warranted to guide better management for this subgroup of patients.

Author Disclosure: M.H. Khattab: None. A.D. Sherry: None. J.L. Anderson: None. E. Kim: None. H. Yu: None. A. Yock: None. M. Morales: None. A. Cmelak: None. A. Attia: Employee; Vanderbilt University. Honoraria; Brainlab, qfix. Advisory Board; AstraZeneca. Travel Expenses; qfix. Director of Radiosurgery Program; Vanderbilt University. Nashville Volunteer Leadership Board Member; American Cancer Society.

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