Focused ultrasound and other lesioning in the treatment of tremor.

There has been a long history of lesioning procedures to treat tremor associated with both essential tremor (ET) and Parkinson's disease (PD). These include radiofrequency (RF) thalamotomy, gamma knife radiosurgical (GKRS) thalamotomy, and magnetic resonance-guided focused ultrasound (MRgFUS). In this review, we summarize the clinical studies of lesioning procedures for tremor focusing on these ablative therapies for ET and tremor-predominant PD (TDPD). We then consider clinical treatment variables that influence decision-making regarding ablative therapies versus consideration of deep brain stimulation (DBS) and conclude with ongoing and future studies. This article is part of the Special Issue "Tremor" edited by Daniel D. Truong, Mark Hallett, and Aasef Shaikh.

Three-year follow-up of prospective trial of focused ultrasound thalamotomy for essential tremor.

OBJECTIVE: To test the hypothesis that transcranial magnetic resonance-guided focused ultrasound (tcMRgFUS) thalamotomy is effective, durable, and safe for patients with medication-refractory essential tremor (ET), we assessed clinical outcomes at 3-year follow-up of a controlled multicenter prospective trial. METHODS: Outcomes were based on the Clinical Rating Scale for Tremor, including hand combined tremor-motor (scale of 0-32), functional disability (scale of 0-32), and postural tremor (scale of 0-4) scores, and total scores from the Quality of Life in Essential Tremor Questionnaire (scale of 0-100). Scores at 36 months were compared with baseline and at 6 months after treatment to assess for efficacy and durability. Adverse events were also reported. RESULTS: Measured scores remained improved from baseline to 36 months (all p < 0.0001). Range of improvement from baseline was 38%-50% in hand tremor, 43%-56% in disability, 50%-75% in postural tremor, and 27%-42% in quality of life. When compared to scores at 6 months, median scores increased for hand tremor (95% confidence interval [CI] 0-2, p = 0.0098) and disability (95% CI 1-4, p = 0.0001). During the third follow-up year, all previously noted adverse events remained mild or moderate, none worsened, 2 resolved, and no new adverse events occurred. CONCLUSIONS: Results at 3 years after unilateral tcMRgFUS thalamotomy for ET show continued benefit, and no progressive or delayed complications. Patients may experience mild degradation in some treatment metrics by 3 years, though improvement from baseline remains significant. CLINICALTRIALSGOV IDENTIFIER: NCT01827904. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that for patients with severe ET, unilateral tcMRgFUS thalamotomy provides durable benefit after 3 years.

Focused Ultrasound and Other Lesioning Therapies in Movement Disorders.

PURPOSE OF REVIEW: Lesioning therapies have been some of the earliest, most effective surgical treatments in movement disorders. This review summarizes recent studies, emerging modalities, and trends in lesioning procedures for movement disorders. RECENT FINDINGS: Magnetic resonance-guided high-intensity focused ultrasound (MRgFUS) is the newest incisionless technology for lesioning procedures in movement disorders. It has recent FDA approval for thalamotomy in essential tremor and tremor-dominant Parkinson disease. There are current studies exploring subthalamotomy and pallidotomy in PD. Gamma knife is another incisionless modality that has been studied for decades and remains an effective treatment, albeit with less recent studies and more risks for adverse events, in movement disorders. Radiofrequency lesioning remains an efficacious treatment, particularly for unilateral pallidotomy in PD, but has fallen out of favor compared with other modalities, particularly MRgFUS. Lesioning therapies in movement disorders have shown efficacy in treating a variety of movement disorders. Enthusiasm for their use has waned with the advent of deep brain stimulation. The recent development of MRgFUS has recentered attention on lesioning therapy and its potential. Patient preference and access to care will remain determinants in the use of lesioning therapy as more data are being collected on the long-term benefit and safety.

Focused ultrasound thalamotomy in Parkinson disease: Nonmotor outcomes and quality of life.

OBJECTIVE: To examine nonmotor outcomes and correlates of quality of life (QoL) 3 and 12 months after unilateral focused ultrasound thalamotomy in tremor-dominant Parkinson disease (TDPD). METHODS: Twenty-seven patients with TDPD in a double-blind, sham-controlled, randomized clinical trial underwent comprehensive neuropsychological evaluations. These included assessment of mood, behavior, and QoL at baseline, 3 months, 3 months post crossover in the sham group, and 12 months after active treatment. We used Mann-Whitney U tests to assess differences between the active (n = 20) and sham (n = 7) groups at 3 months and Friedman tests to assess within-group changes after active treatment. We assessed correlations between disease variables and postoperative QoL using Kendall tau-b tests. RESULTS: There were no differences in cognition, mood, or behavior between the active and sham groups at 3-month blinded assessment. After active treatment, there were no differences in mood or behavior. Only declines in Stroop Color Naming and phonemic fluency were observed. Patients experienced postoperative improvements in QoL and activities of daily living (ADL). Mood and behavioral symptoms, aspects of cognitive functioning, ADL, and overall motor symptom severity, but not tremor severity specifically, were associated with QoL. CONCLUSIONS: In TDPD, unilateral focused ultrasound thalamotomy appears safe from a cognitive, mood, and behavioral perspective. QoL and ADL significantly improved following surgery. Nonmotor symptoms and ADL were more closely associated with QoL than tremor severity. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that for patients with TDPD, unilateral focused ultrasound thalamotomy did not adversely change cognition, mood, or behavior at 3 months.

A prospective trial of magnetic resonance-guided focused ultrasound thalamotomy for essential tremor: Results at the 2-year follow-up.

OBJECTIVE: Magnetic resonance guided focused ultrasound (MRgFUS) has recently been investigated as a new treatment modality for essential tremor (ET), but the durability of the procedure has not yet been evaluated. This study reports results at a 2- year follow-up after MRgFUS thalamotomy for ET. METHODS: A total of 76 patients with moderate-to-severe ET, who had not responded to at least two trials of medical therapy, were enrolled in the original randomized study of unilateral thalamotomy and evaluated using the clinical rating scale for tremor. Sixty-seven of the patients continued in the open-label extension phase of the study with monitoring for 2 years. Nine patients were excluded by 2 years, for example, because of alternative therapy such as deep brain stimulation (n = 3) or inadequate thermal lesioning (n = 1). However, all patients in each follow-up period were analyzed. RESULTS: Mean hand tremor score at baseline (19.8 ± 4.9; 76 patients) improved by 55% at 6 months (8.6 ± 4.5; 75 patients). The improvement in tremor score from baseline was durable at 1 year (53%; 8.9 ± 4.8; 70 patients) and at 2 years (56%; 8.8 ± 5.0; 67 patients). Similarly, the disability score at baseline (16.4 ± 4.5; 76 patients) improved by 64% at 6 months (5.4 ± 4.7; 75 patients). This improvement was also sustained at 1 year (5.4 ± 5.3; 70 patients) and at 2 years (6.5 ± 5.0; 67 patients). Paresthesias and gait disturbances were the most common adverse effects at 1 year-each observed in 10 patients with an additional 5 patients experiencing neurological adverse effects. None of the adverse events worsened over the period of follow-up, and 2 of these resolved. There were no new delayed complications at 2 years. INTERPRETATION: Tremor suppression after MRgFUS thalamotomy for ET is stably maintained at 2 years. Latent or delayed complications do not develop after treatment. Ann Neurol 2018;83:107-114.

Safety and Efficacy of Focused Ultrasound Thalamotomy for Patients With Medication-Refractory, Tremor-Dominant Parkinson Disease: A Randomized Clinical Trial.

Importance: Clinical trials have confirmed the efficacy of focused ultrasound (FUS) thalamotomy in essential tremor, but its effectiveness and safety for managing tremor-dominant Parkinson disease (TDPD) is unknown. Objective: To assess safety and efficacy at 12-month follow-up, accounting for placebo response, of unilateral FUS thalamotomy for patients with TDPD. Design, Setting, and Participants: Of the 326 patients identified from an in-house database, 53 patients consented to be screened. Twenty-six were ineligible, and 27 were randomized (2:1) to FUS thalamotomy or a sham procedure at 2 centers from October18, 2012, to January 8, 2015. The most common reasons for disqualification were withdrawal (8 persons [31%]), and not being medication refractory (8 persons [31%]). Data were analyzed using intention-to-treat analysis, and assessments were double-blinded through the primary outcome. Interventions: Twenty patients were randomized to unilateral FUS thalamotomy, and 7 to sham procedure. The sham group was offered open-label treatment after unblinding. Main Outcomes and Measures: The predefined primary outcomes were safety and difference in improvement between groups at 3 months in the on-medication treated hand tremor subscore from the Clinical Rating Scale for Tremor (CRST). Secondary outcomes included descriptive results of Unified Parkinson's Disease Rating Scale (UPDRS) scores and quality of life measures. Results: Of the 27 patients, 26 (96%) were male and the median age was 67.8 years (interquartile range [IQR], 62.1-73.8 years). On-medication median tremor scores improved 62% (IQR, 22%-79%) from a baseline of 17 points (IQR, 10.5-27.5) following FUS thalamotomy and 22% (IQR, -11% to 29%) from a baseline of 23 points (IQR, 14.0-27.0) after sham procedures; the between-group difference was significant (Wilcoxon P = .04). On-medication median UPDRS motor scores improved 8 points (IQR, 0.5-11.0) from a baseline of 23 points (IQR, 15.5-34.0) following FUS thalamotomy and 1 point (IQR, -5.0 to 9.0) from a baseline of 25 points (IQR, 15.0-33.0) after sham procedures. Early in the study, heating of the internal capsule resulted in 2 cases (8%) of mild hemiparesis, which improved and prompted monitoring of an additional axis during magnetic resonance thermometry. Other persistent adverse events were orofacial paresthesia (4 events [20%]), finger paresthesia (1 event [5%]), and ataxia (1 event [5%]). Conclusions and Relevance: Focused ultrasound thalamotomy for patients with TDPD demonstrated improvements in medication-refractory tremor by CRST assessments, even in the setting of a placebo response. Trial Registration: ClinicalTrials.gov identifier NCT01772693.

A Randomized Trial of Focused Ultrasound Thalamotomy for Essential Tremor.

BACKGROUND: Uncontrolled pilot studies have suggested the efficacy of focused ultrasound thalamotomy with magnetic resonance imaging (MRI) guidance for the treatment of essential tremor. METHODS: We enrolled patients with moderate-to-severe essential tremor that had not responded to at least two trials of medical therapy and randomly assigned them in a 3:1 ratio to undergo unilateral focused ultrasound thalamotomy or a sham procedure. The Clinical Rating Scale for Tremor and the Quality of Life in Essential Tremor Questionnaire were administered at baseline and at 1, 3, 6, and 12 months. Tremor assessments were videotaped and rated by an independent group of neurologists who were unaware of the treatment assignments. The primary outcome was the between-group difference in the change from baseline to 3 months in hand tremor, rated on a 32-point scale (with higher scores indicating more severe tremor). After 3 months, patients in the sham-procedure group could cross over to active treatment (the open-label extension cohort). RESULTS: Seventy-six patients were included in the analysis. Hand-tremor scores improved more after focused ultrasound thalamotomy (from 18.1 points at baseline to 9.6 at 3 months) than after the sham procedure (from 16.0 to 15.8 points); the between-group difference in the mean change was 8.3 points (95% confidence interval [CI], 5.9 to 10.7; P<0.001). The improvement in the thalamotomy group was maintained at 12 months (change from baseline, 7.2 points; 95% CI, 6.1 to 8.3). Secondary outcome measures assessing disability and quality of life also improved with active treatment (the blinded thalamotomy cohort)as compared with the sham procedure (P<0.001 for both comparisons). Adverse events in the thalamotomy group included gait disturbance in 36% of patients and paresthesias or numbness in 38%; these adverse events persisted at 12 months in 9% and 14% of patients, respectively. CONCLUSIONS: MRI-guided focused ultrasound thalamotomy reduced hand tremor in patients with essential tremor. Side effects included sensory and gait disturbances. (Funded by InSightec and others; ClinicalTrials.gov number, NCT01827904.).

Deep Brain Stimulation in the Setting of Cochlear Implants: Case Report and Literature Review.

BACKGROUND/AIMS: As technology continues to advance for our aging population, an increasing number of deep brain stimulation (DBS) candidates will have preexisting implanted electrical devices. In this article, we discuss safe and successful DBS in a patient with Parkinson's disease (PD) and bilateral cochlear implants. METHODS: A 70-year-old male with PD and bilateral cochlear implants underwent successful microelectrode-guided DBS implantation into bilateral subthalamic nuclei (STN). The patient's cochlear implant magnets were removed and replaced in the outpatient clinic for preoperative MRI and stereotactic targeting. The cochlear implants were turned off intraoperatively for STN microelectrode recordings. RESULTS: Precise, MRI-guided stereotactic DBS implantation was possible. Intraoperative high-fidelity microelectrode recordings confirmed STN neurons with the cochlear implants turned off. These recordings were not possible with active cochlear implant devices. Our literature review describes the other approaches/techniques that have been used to manage DBS surgery in the setting of cochlear implants. CONCLUSIONS: Despite the risk of electrical interference between implanted medical devices, DBS and cochlear implants may be safe and compatible in the same patient if necessary precautions are taken.

Functional assessment and quality of life in essential tremor with bilateral or unilateral DBS and focused ultrasound thalamotomy.

BACKGROUND: Thalamic deep brain stimulation (DBS) has largely replaced radiofrequency thalamotomy as the treatment of choice for disabling, medication-refractory essential tremor. Recently, the development of transcranial, high-intensity focused ultrasound has renewed interest in thalamic lesioning. The purpose of this study is to compare functional outcomes and quality of life in essential tremor patients treated with either bilateral Vim DBS or unilateral procedures (focused ultrasound or DBS). We hypothesized that all three would effectively treat the dominant hand and positively impact functional outcomes and quality of life as measured with the Clinical Rating Scale for Tremor and the Quality of Life in Essential Tremor Questionnaire. METHODS: This is a retrospective study of medication-refractory essential tremor patients treated at the University of Virginia with bilateral Vim DBS (n = 57), unilateral Vim DBS (n = 13), or unilateral focused ultrasound Vim thalamotomy (n = 15). Tremor was rated for all patients before and after treatment, using the Clinical Rating Scale for Tremor and Quality of Life in Essential Tremor Questionnaire. RESULTS: Patients undergoing bilateral DBS treatment had more baseline tremor and worse quality of life scores. Patients had significant improvements in tremor symptoms and quality of life with all three treatments. Both DBS procedures improved axial tremor. No difference was seen in the degree of improvement in upper extremity tremor score, disability, or overall quality of life between bilateral and either unilateral procedure. CONCLUSIONS: Bilateral thalamic DBS improves overall tremor more than unilateral DBS or focused ultrasound treatment; however, unilateral treatments are equally effective in treating contralateral hand tremor. Despite the greater overall tremor reduction with bilateral DBS, there is no difference in disability or quality of life comparing bilateral versus unilateral treatments.

Thalamic connectivity in patients with essential tremor treated with MR imaging-guided focused ultrasound: in vivo fiber tracking by using diffusion-tensor MR imaging.

PURPOSE: To use diffusion-tensor (DT) magnetic resonance (MR) imaging in patients with essential tremor who were treated with transcranial MR imaging-guided focused ultrasound lesion inducement to identify the structural connectivity of the ventralis intermedius nucleus of the thalamus and determine how DT imaging changes correlated with tremor changes after lesion inducement. MATERIALS AND METHODS: With institutional review board approval, and with prospective informed consent, 15 patients with medication-refractory essential tremor were enrolled in a HIPAA-compliant pilot study and were treated with transcranial MR imaging-guided focused ultrasound surgery targeting the ventralis intermedius nucleus of the thalamus contralateral to their dominant hand. Fourteen patients were ultimately included. DT MR imaging studies at 3.0 T were performed preoperatively and 24 hours, 1 week, 1 month, and 3 months after the procedure. Fractional anisotropy (FA) maps were calculated from the DT imaging data sets for all time points in all patients. Voxels where FA consistently decreased over time were identified, and FA change in these voxels was correlated with clinical changes in tremor over the same period by using Pearson correlation. RESULTS: Ipsilateral brain structures that showed prespecified negative correlation values of FA over time of -0.5 or less included the pre- and postcentral subcortical white matter in the hand knob area; the region of the corticospinal tract in the centrum semiovale, in the posterior limb of the internal capsule, and in the cerebral peduncle; the thalamus; the region of the red nucleus; the location of the central tegmental tract; and the region of the inferior olive. The contralateral middle cerebellar peduncle and bilateral portions of the superior vermis also showed persistent decrease in FA over time. There was strong correlation between decrease in FA and clinical improvement in hand tremor 3 months after lesion inducement (P < .001). CONCLUSION: DT MR imaging after MR imaging-guided focused ultrasound thalamotomy depicts changes in specific brain structures. The magnitude of the DT imaging changes after thalamic lesion inducement correlates with the degree of clinical improvement in essential tremor.