Main Session
Sep 30
PQA 08 - Gastrointestinal Cancer, Nonmalignant Disease, Palliative Care

3529 - Tracing the Pain Circuits: FCD as a Biomarker for Radiosurgery in Trigeminal Neuralgia

02:30pm - 03:45pm PT
Hall F
Screen: 23
POSTER

Presenter(s)

Vangipuram Shankar, MD, MBBS Headshot
Vangipuram Shankar, MD, MBBS - Apollo Proton Cancer Centre, Chennai , Tamil Nadu

V. Shankar1, S. Ghosh2, S. Cholayil1, D. Arjundas3, G. Laksmipathy4, J. Varghese5, S. Muthukani6, V. L. Arulselvan7, C. Haritha8, and V. Sai Shreya9; 1Apollo Cancer Centers, Chennai, India, 2Dept. of Neurosurgery, Apollo Proton Cancer Center, Chennai, India, 3Chief Neurologist, Mercury Hospital, Chennai, India, 4Dept. of Neurology, Apollo Hospitals, Greams Unit, Chennai, India, 5Dept. of Neurosurgery, Apollo Hospitals, Greams Unit, Chennai, India, 6Dept. of Neurology, Apollo Hospitals, Greams Road, Chennai, India, 7Dept.of Neurology, Apollo Hospitals, Greams Unit, Chennai, India, 8C.R.Reddy Cancer Center, Nellore, India, 9ACSR Govt. Medical College, Nellore, India

Purpose/Objective(s): This study aimed to evaluate whether pretreatment functional connectivity density (FCD) mapping derived from resting-state fMRI (rs-fMRI) correlates with pain outcomes and toxicity in trigeminal neuralgia (TGN) patients undergoing a frameless robotic radiosurgery. We hypothesized that aberrant thalamocortical and default mode network (DMN) connectivity predicts poor pain relief and neurological toxicity.

Materials/Methods:

Eight drug-resistant TGN patients (5 classical, 3 idiopathic; mean age 62 ± 8 years) underwent rs-fMRI (3T technology company, TR=2000ms, voxel=3mm³) pre-SRS and at 6, 12, and 24 months post-treatment. FCD maps were generated using voxel-wise global and local connectivity analysis (DPABI toolbox). Pain outcomes were assessed via VAS, BNI scores, and medication use. Toxicity (facial numbness, dysesthesia) was graded clinically. Pretreatment FCD values in thalamus, somatosensory cortex (S1), insula, and DMN were correlated with outcomes using Pearson/Spearman tests (p<0.05, FDR-corrected).

Results:

Pretreatment FCD and Pain Relief:

  • Thalamic hyperconnectivity (?global FCD) correlated with poor VAS improvement at 12 months (r=-0.82, p=0.01).
  • Preserved DMN connectivity (?FCD variability) predicted better pain relief (BNI I-II in 75% vs. 25% of dysregulated cases).

Post-SRS FCD Evolution:

  • Responders (n=6): Showed ?thalamic/S1 FCD and ?prefrontal FCD by 6 months, sustained at 24 months.
  • Non-responders (n=2): Persistent thalamic hyperconnectivity and ?insula FCD correlated with refractory pain (VAS >4).

Toxicity:

  • Post-SRS facial numbness (n=2) correlated with ?S1-pontine FCD (r=0.71, p=0.03).
  • DMN hypoconnectivity post-treatment correlated with subjective dysesthesia (p=0.04).

Conclusion: Pretreatment thalamocortical and DMN FCD signatures may predict CK efficacy in TGN, with thalamic hyperconnectivity signaling treatment resistance. Successful responders demonstrate FCD normalization, whereas persistent network dysregulation aligns with toxicity. This study suggests FCD mapping as a potential biomarker for personalized radiosurgical planning, warranting validation in larger cohort