POST-THALAMOTOMY NEUROFUNCTIONAL FINDINGS ON PATIENTS TREATED WITH TRANS-CRANIAL MAGNETIC RESONANCE GUIDED FOCUSED ULTRASOUND SURGERY (TCMRGFUS): PRELIMINARY RESULTS

BACKGROUND AND PURPOSE: We present functional connectivity (FC) changes found in the very first patients treated with the first Italian installation of a trans-cranial MRI-guided Focused Ultrasound Surgery (tcMRgFUS) certified system for functional neurosurgery. TcMRgFUS is a promising new technique for non-invasive treatment of neurologic disorders such as Essential Tremor, tremor associated to Parkinson's Disease and Neuropathic Pain. TcMRgFUS is able to focally target and destroy specific regions in the brain through intact skull, by using a high intensity focused ultrasound beam. Resting state functional Magnetic Resonance Imaging (RS-fMRI) analyses focuses on spontaneous low frequency fluctuations (< 0.1 Hz) in the BOLD signal and investigates synchronous activations between spatially independent brain regions (FC), occurring in the absence of a task or stimulus. METHOD AND MATERIALS: Patient enrollment was based on indication for functional neurosurgery and evidence of medication-refractory disease; we treated three patients, respectively affected by: neuropathic pain, intentional tremor due to ischemic lesion and essential tremor. A detailed medical history was collected together with a complete clinical examination and a neurophysiological assessment. TcMRgFUS treatments were performed by a neurosurgeon with proven experience in functional neurosurgery, and an experienced neuroradiologist, optimizing treatment parameters case by case. All patients underwent a 10’ RS-fMRI session immediately before and two days after the treatment. Functional connectivity data was analyzed by the use of the MELODIC tool from FMRIB Software Library (FSL) in a single-subject fashion, comparing post- and pre-treatment data. RESULTS: All the patients experienced an important and almost immediate improvement of their symptoms, with a complete recovery of the tremor and a partial pain relief in the patient with neuropathic pain. No adverse events were reported. We found modifications of FC within sensory-motor networks in all patients. CONCLUSION AND DISCUSSION: Although this is a very preliminary experience and our sample is very small, the FC changes we found pave the way to the use of RS-fMRI as a powerful tool to be correlated to clinical-neurologic outcomes.