Introduction: Laser interstitial thermal therapy (LITT) has revealed promising preliminary results in treatment of difficult to access (DTA) tumors. There is limited data regarding clinical outcome as it correlates with hyper-thermic field exposure to the corticospinal tracts (CST), we evaluated the clinical relevance of thermal exposure to functional white matter tracts.
Methods: We retrospectively evaluated 36 DTA tumors, which underwent LITT therapy. Thermal damage is delineated by thermal damage threshold (TDT) lines, which include white-line (60 min at 43°), blue-line (10 min at 43°), and yellow-line (2 min at 43°). Fiber tracking was conducted for CST, as well as the pre-motor (PM) region using i-plan volumetric software. The maximum surface area of overlap between CST fibers and the TDT lines of white, blue, and yellow were analysed post-operatively. Clinical review was conducted for pre-operative and immediate post-op motor deficit with either complete or partial resolution. The data was further analysed to correlate between the degree of thermal exposure to the CST and manifestation of motor deficit post-operatively.
Results: Median age was 58 years, with 41.7% male (5) and 58.3% female (7). Overlap of TDT lines in number of patients treated were as follows: white (UE:6, LM:7, PM:6), blue (UE:9, LE:10, PM:2), yellow (UE:12, LE:10, PM:10). Median overlap of yellow TDT lines with UM, LM, PM, were 1.9 mm2, 1.5mm2, 2.6mm2 respectively, blue TDT lines with UM, LM, PM, were 0.4mm2, 1mm2, 1.8mm2 respectively, and white TDT lines with UM, LM, PM, were 0.1mm2, 0mm2, 0mm2, respectively. Deficits with complete resolution of motor movements of arms (3), and legs (3), as well as deficits with partial resolution of arms (2), and legs (1) were evaluated. In three occasion permanent motor deficit, thermal exposure of white, blue, and yellow lines were =2.2m2, =4.6mm2,= 5.9mm2respectively.
Conclusions: Based on the above results, permanent deficit can be noted in minimal overlap of TDT lines and CST, therefore, in pursing LITT therapy, there is a need for conformal treatment of tumor borders without overlap to white motor tracts.
Patient Care: By utilizing our research neurosurgeons will be able to better plan LITT interventions resulting in less motor deficits
Learning Objectives: By the conclusion of this session, participants should be able to: 1) better understand LITT therapy 2)be able to demonstrate the importance of CST and TDT overlap