Presenter(s)
H. S. Vangipuram1, V. Shankar2, S. Cholayil3, S. Ghosh4, D. Arjundas5, G. Laksmipathy6, V. L. Arulselvan7, and V. R. Anand8; 1Department of Undergradute Education, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India, 2Division of Radiosurgery, Apollo Cancer Centers, Chennai, India, 3Apollo Cancer Centers, Chennai, India, 4Dept. of Neurosurgery, Apollo Proton Cancer Center, Chennai, India, 5Chief Neurologist, Mercury Hospital, Chennai, India, 6Dept. of Neurology, Apollo Hospitals, Greams Unit, Chennai, India, 7Dept.of Neurology, Apollo Hospitals, Greams Unit, Chennai, India, 8Sai Neuro Hospital, Chennai, India
Purpose/Objective(s):
Weather-related triggers are well recognized in classical trigeminal neuralgia (TN), with cold exposure traditionally identified as the most prominent environmental precipitant. However, the influence of temperature extremes on symptom behavior after stereotactic radiosurgery (SRS) has not been systematically examined. India’s pronounced climatic variability — marked by intense heat waves and episodic cold spells — offered a natural setting to evaluate whether environmental stressors modulate pain stability in patients with otherwise durable post-SRS outcomes.
Materials/Methods:
We retrospectively reviewed 270 patients with classical TN treated between 2013–2020 using a standardized CyberKnife DREZ protocol (85 Gy). Durable response was defined as BNI I–II. Weather-linked flares were identified as transient paroxysmal exacerbations occurring within ±48 hours of a documented heat wave, cold wave, or abrupt temperature shift. Daily meteorological data and district-level extreme-weather bulletins were obtained from the India Meteorological Department (IMD), which certifies heat and cold waves based on established national thresholds. Each patient’s residential district was mapped to IMD datasets to categorize regions as climate-extreme or thermally stable. Statistical analysis included chi-square testing, risk ratios (RR), and multivariate logistic regression adjusting for demographic and clinical covariates.
Results:
At a median follow-up of 5 years, 75% of patients maintained BNI I–II outcomes. Among the 85 individuals living in climate-extreme regions, 50 (58.8%) experienced =1 weather-associated flare annually, compared with 12/185 (6.5%) in thermally stable zones (p < 0.001). Residence in high-variability regions conferred significantly elevated risk (RR 9.1; 95% CI 5.1–16.0). On multivariate analysis, climatic exposure remained the only independent predictor (aOR 7.8; 95% CI 4.2–14.5). Flares were short-lived, reversible, and responsive to temporary lamotrigine escalation. Both heat and cold acted as triggers, although heat events accounted for the majority. No patient demonstrated clinical or radiologic evidence of radiosurgical failure.
Conclusion:
Weather-triggered pain fluctuations represent a distinct, benign post-SRS phenotype in TN. Although both heat and cold provoked transient exacerbations, heat occurred more frequently, suggesting a radiosurgically induced recalibration of thermosensory balance. SRS achieves durable relief by disrupting hyperexcitable, demyelinated A-delta pathways at the dorsal root entry zone, reducing ephaptic cross-firing and stabilizing neural transmission. In this modified landscape, residual C-fiber/TRPV activity becomes more influential during weather-related thermal stress, producing brief, reversible hyperexcitability rather than recurrence. Recognizing this mechanism may refine counseling and support anticipatory management as global weather extremes rise.
