Introduction: Cytoreductive surgery of thalamic neoplasms is challenging due to eloquence and anatomical complexity. Prognosis for thalamic high grade gliomas (HGG) remains poor, though largely undefined (1-3). Radiosurgery is also an option for treatment of thalamic metastasis, but therapeutic dose is usually limited by size and eloquence. Here we report a minimally invasive treatment for thalamic neoplasms using intraoperative real-time iMRI thermometry-guided laser interstitial thermal therapy (LITT) (NeuroBlate System, Monteris Medical).

Methods: Five patients with thalamic tumors (3 HGG, 2 non-small-cell lung cancer (NSCCA) underwent six LITT treatments. GBM patients had been previously treated with concurrent radio-chemotherapy. Both brain metastasis had been treated with systemic chemotherapy and one had prior radiosurgery.

Results: Median age was 57; median pre-operative tumor size was 22.6 +/- 9.4 cm3. All tumors demonstrated increased regional swelling for 3 days. The median post-treatment tumor size 3 days post-op was 22.6 +/- 7.8 cm3; EBL was < 10cc; length of stay was 5.5 days. One patient with GBM who underwent bilateral treatments in two sessions developed hydrocephalus and expired shortly after EVD was withdrawn. Another GBM patient experienced transient aphasia and increased hemiparesis which improved POD 14. Three had no adverse events. After LITT, one GBM patient was subsequently treated with avastin, and the patient with brain metastasis who had not had previously been treated with radiosurgery to the thalamic and other metastasis underwent radiosurgical treatment. Excluding the patient transferred to hospice, median survival for remaining patients was 109 +/- 278 days (range 52-729 days).

Conclusions: LITT is a minimally invasive option for patients with otherwise inoperable thalamic neoplasms. All patients had transient early post-operative swelling. One patient who underwent a staged procedure developed hydrocephalus. None-the less, Median survival in this complex group of challenging patients was 109 days and one patient survived two years. Larger studies are necessary.

Patient Care: This work demonstrates the feasibility of LITT as a minimally invasive option for thalamic neoplasms.

Learning Objectives: By the conclusion of this session, participants should be able to: 1) Describe the challenges of treating thalamic neoplasms; 2) Discuss, LITT in small groups; 3) Identify a minimally invastiv treatment option for thalamic neoplasms

References: 1. Steiger HJ et al. Thalamic Astrocytomas: surgical anatomy and results of a pilot series using maximum microsurgical removal. Acta Neurochir (Wien) 2000. 142(12):1327-36. 2. Kelly PJ. Stereotactic biopsy and resection of the thalamic astrocytomas. Neurosurgery, 1989. 25(2): 185-94. 3. Nishio S et al. Thalamic, gliomas: a clinicopathologic analysis of 20 cases with reference to patient age. Acta Neurochir (Wien) 1997. 139 (4): 336-42.