Brain Regional Predictors of Surgical Response Are Dynamically Associated with Post-Surgical Pain Relief in Trigeminal Neuralgia.

Background/Objectives: Trigeminal neuralgia (TN) is a severe chronic neuropathic facial pain condition. Although TN can be amenable to surgical treatments, ~25% of patients may have recurrence of pain. Understanding the role of the central nervous system (CNS) gray matter and its impact on surgical treatment effect remains unclear but is of increasing interest. Previous machine learning models identified 13 neuroanatomical regional predictors of TN surgical response. The implications of these regions and how they might relate to clinical status and surgical outcome are not clear. Here, we attempt to further understand CNS alterations in TN by investigating how these potential regional predictors of surgical response may change following surgical treatment, and whether this is related to the degree of pain relief achieved. Methods: Retrospective imaging was acquired from 115 surgically naïve TN patients who underwent Gamma Knife Radiosurgery at Toronto Western Hospital. Patients obtained magnetic resonance imaging scans and reported pain intensity scores before and 3-12 months after surgery. Patients were categorized as responders (≥75% pain relief), partial responders (50-74% pain relief), and non-responders (<50% pain relief). Results: Eight regions spanning default mode, visual, limbic, and dorsal attention networks had significant changes in cortical thickness. Responders demonstrated post-operative neuroplasticity in a greater number of regions with higher within-group statistical significance than both partial and non-responders. Thickening of the contralateral fusiform gyrus was correlated with the degree of pain reduction. Conclusions: Our findings identify key regions impacted by chronic neuropathic pain, which may be associated with pain relief in TN.