Background Several options exist for surgical management of essential tremor (ET), including radiofrequency lesioning, deep brain stimulation and γ knife radiosurgery of the ventralis intermedius nucleus of the thalamus. Recently, magnetic resonance-guided focused ultrasound (MRgFUS) has been developed as a less-invasive surgical tool aimed to precisely generate focal thermal lesions in the brain. Methods Patients underwent tremor evaluation and neuroimaging study at baseline and up to 6 months after MRgFUS. Tremor severity and functional impairment were assessed at baseline and then at 1 week, 1 month, 3 months and 6 months after treatment. Adverse effects were also sought and ascertained by directed questions, neuroimaging results and neurological examination. Results The current feasibility study attempted MRgFUS thalamotomy in 11 patients with medication-resistant ET. Among them, eight patients completed treatment with MRgFUS, whereas three patients could not complete the treatment because of insufficient temperature. All patients who completed treatment with MRgFUS showed immediate and sustained improvements in tremors lasting for the 6-month follow-up period. Skull volume and maximum temperature rise were linearly correlated (linear regression, p=0.003). Other than one patient who had mild and delayed postoperative balance, no patient developed significant postsurgical complications; about half of the patients had bouts of dizziness during the MRgFUS. Conclusions Our results demonstrate that MRgFUS thalamotomy is a safe, effective and less-invasive surgical method for treating medication-refractory ET. However, several issues must be resolved before clinical application of MRgFUS, including optimal patient selection and management of patients during treatment.

Background: Treatment options for patients with drug-resistant essential tremor (ET) are limited. Magnetic resonance-guided focused ultrasound surgery (MRgFUS) is an emerging technique to treat refractory ET. Objectives: To present MRgFUS as an alternative to radiofrequency (RF) thalamotomy or deep brain stimulation (DBS) for ET treatment. Methods: We retrospectively analyzed 59 patients who underwent unilateral surgery for drug-resistant ET. Treatments included RF thalamotomy (n = 17), DBS (n = 19), and MRgFUS (n = 23). The outcomes measured were tremor severity and treatment-related complications. Results: At 1 month postoperatively, 100% of RF thalamotomy patients, 89.5% of DBS patients, and 91.3% of MRgFUS patients exhibited absent/mild tremor (successful treatment); other patients exhibited partial relief. At 12 months postoperatively, treatment success for each procedure was observed in 70.6, 84.2, and 78.3% of patients, respectively. At 1 month postoperatively, treatment-related complications had occurred in 58.8, 5.3, and 13.0% of patients, respectively. At 12 months postoperatively, side effects persisted in 11.8, 21.1, and 4.4% of patients, respectively. No statistical differences in treatment success were observed between treatments or over time. Complication rates differed between treatment modalities (p < 0.01) and were lowest in the MRgFUS group. Conclusions: Patients with drug-resistant ET received equivalent results from RF thalamotomy, DBS, and MRgFUS. DBS and MRgFUS resulted in fewer treatment-related complications.

Current soft neural probes are still operated by bulky, rigid electronics mounted to a body, which deteriorate the integrity of the device to biological systems and restrict the free behavior of a subject. We report a soft, conformable neural interface system that can monitor the single-unit activities of neurons with long-term stability. The system implements soft neural probes in the brain, and their subsidiary electronics which are directly printed on the cranial surface. The high-resolution printing of liquid metals forms soft neural probes with a cellular-scale diameter and adaptable lengths. Also, the printing of liquid metal-based circuits and interconnections along the curvature of the cranium enables the conformal integration of electronics to the body, and the cranial circuit delivers neural signals to a smartphone wirelessly. In the in-vivo studies using mice, the system demonstrates long-term recording (33 weeks) of neural activities in arbitrary brain regions. In T-maze behavioral tests, the system shows the behavior-induced activation of neurons in multiple brain regions.

OBJECT: The authors report different MRI patterns in patients with essential tremor (ET) or obsessive-compulsive disorder (OCD) after transcranial MR-guided focused ultrasound (MRgFUS) and discuss possible causes of occasional MRgFUS failure. METHODS: Between March 2012 and August 2013, MRgFUS was used to perform unilateral thalamotomy in 11 ET patients and bilateral anterior limb capsulotomy in 6 OCD patients; in all patients symptoms were refractory to drug therapy. Sequential MR images were obtained in patients across a 6-month follow-up period. RESULTS: For OCD patients, lesion size slowly increased and peaked 1 week after treatment, after which lesion size gradually decreased. For ET patients, lesions were visible immediately after treatment and markedly reduced in size as time passed. In 3 ET patients and 1 OCD patient, there was no or little temperature rise (i.e., < 52°C) during MRgFUS. Successful and failed patient groups showed differences in their ratio of cortical-to-bone marrow thickness (i.e., skull density). CONCLUSIONS: The authors found different MRI pattern evolution after MRgFUS for white matter and gray matter. Their results suggest that skull characteristics, such as low skull density, should be evaluated prior to MRgFUS to successfully achieve thermal rise.