116 Steroid Responsiveness Predicts the Feasibility of LITT in the Motor Cortex

INTRODUCTION:

Laser interstitial thermal therapy (LITT) is increasingly employed for radiographically progressive brain metastases post-radiosurgery. For eloquent area lesions, open resection (OR) with functional mapping has historically been favored due to concerns over LITT-induced white matter damage.

METHODS:

We retrospectively reviewed patients undergoing either OR (n=39) or LITT (n=28) for metastases involving or adjacent to the primary motor cortex between December 2014 and June 2023. Lesion location was confirmed radiographically. Functional outcomes (Karnofsky Performance Status [KPS], modified Rankin Scale [mRS], and symptom status) were assessed serially to one year. Freedom from local progression (FFLP) was evaluated via Kaplan-Meier analysis. A multivariate logistic regression model identified predictors of favorable 30-day functional outcomes, approximating peak post-LITT edema. Volumetric lesion mapping was performed using deep learning-based segmentation and normalization to MNI space.

RESULTS:

LITT-treated tumors were smaller (median 2.80 vs 7.27 cm³, P<0.0001) and more frequently previously irradiated (100% vs 51.28%, P<0.0001). OR resulted in more ICU admissions (74.36% vs 17.86%, P<0.0001) and longer stays (median 2 vs 1 days, P=0.0004). Functional outcomes (KPS, mRS, symptom trajectory) were equivalent across groups at all timepoints, except for transient 30-day symptom worsening in LITT patients (56.00% vs 80.64%, P=0.046). FFLP did not differ by procedure (P=0.41). On multivariate analysis, preoperative steroid response was the sole independent predictor of favorable 30-day composite outcome (P=0.04), irrespective of pathology, systemic disease status, or procedure type.

CONCLUSIONS:

LITT provides a viable, less invasive alternative to resection for motor cortex-adjacent metastases, with equivalent long-term functional outcomes. Steroid responsiveness, rather than tumor size or treatment modality, best predicts short-term functional recovery and may guide patient selection in treatment of eloquent area metastasis.