Transcranial magnetic resonance imaging–guided focused ultrasound: noninvasive central lateral thalamotomy for chronic neuropathic pain

Abstract

<jats:sec> <jats:title>Object</jats:title> <jats:p>Recent technological developments open the field of therapeutic application of focused ultrasound to the brain through the intact cranium. The goal of this study was to apply the new transcranial magnetic resonance imaging–guided focused ultrasound (tcMRgFUS) technology to perform noninvasive central lateral thalamotomies (CLTs) as a treatment for chronic neuropathic pain.</jats:p></jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>In 12 patients suffering from chronic therapy-resistant neuropathic pain, tcMRgFUS CLT was proposed. In 11 patients, precisely localized thermal ablations of 3–4 mm in diameter were produced in the posterior part of the central lateral thalamic nucleus at peak temperatures between 51°C and 64°C with the aid of real-time patient monitoring and MR imaging and MR thermometry guidance. The treated neuropathic pain syndromes had peripheral (5 patients) or central (6 patients) origins and covered all body parts (face, arm, leg, trunk, and hemibody).</jats:p></jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>Patients experienced mean pain relief of 49% at the 3-month follow-up (9 patients) and 57% at the 1-year follow-up (8 patients). Mean improvement according to the visual analog scale amounted to 42% at 3 months and 41% at 1 year. Six patients experienced immediate and persisting somatosensory improvements. Somatosensory and vestibular clinical manifestations were always observed during sonication time because of ultrasound-based neuronal activation and/or initial therapeutic effects. Quantitative electroencephalography (EEG) showed a significant reduction in EEG spectral overactivities. Thermal ablation sites showed sharply delineated ellipsoidal thermolesions surrounded by short-lived vasogenic edema. Lesion reconstructions (18 lesions in 9 patients) demonstrated targeting precision within a millimeter for all 3 coordinates. There was 1 complication, a bleed in the target with ischemia in the motor thalamus, which led to the introduction of 2 safety measures, that is, the detection of a potential cavitation by a cavitation detector and the maintenance of sonication temperatures below 60°C.</jats:p></jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>The authors assert that tcMRgFUS represents a noninvasive, precise, and radiation-free neurosurgical technique for the treatment of neuropathic pain. The procedure avoids mechanical brain tissue shift and eliminates the risk of infection. The possibility of applying sonication thermal spots free from trajectory restrictions should allow one to optimize target coverage. The real-time continuous MR imaging and MR thermometry monitoring of targeting accuracy and thermal effects are major factors in optimizing precision, safety, and efficacy in an outpatient context.</jats:p></jats:sec>

Imaging Findings in MR Imaging-Guided Focused Ultrasound Treatment for Patients with Essential Tremor

“…[1][2][3][4][5][6][7] MR imaging-guided focused sonography is now accepted in the treatment of soft-tissue disorders, including prostate cancer and uterine fibroids. Intracranial applications for brain tumors 8,9 and neuropathic pain syndromes 10,11 are currently under investigation. More recently, MR imaging-guided focused sonography was tested in a clinical trial as a treatment for essential tremor.…”

The use of transcranial focused ultrasound in CNS diseases

“…Процедура термодеструкции при помощи аппарата ExAblate 4000 проводится стандартным образом [18][19][20].…”

“…При дальнейшем увеличении мощности и температуры возможно получение нестойкого клини-ческого эффекта и/или осложнений (парестезий, нару-шений речи и др.). Например, обратимое уменьшение тремора, болевого синдрома было отмечено уже при до-стижении температуры 50 °С [19,20,22]. При получении удовлетворительного обратимого эффекта проводится увеличение мощности до достижения деструктивных температур 55-63 °C [18,19].…”

“…В отдельных ситуа-циях технические параметры (например, точность вырав-нивания данных МР-термометрии по вертикали) могут снижать точность процедуры [19]. Для предотвращения таких ситуаций целесообразно разрабатывать и совер-шенствовать протоколы проведения вмешательства, по-лучения и использования данных МРТ [20].…”

The Use of Magnetic Resonance Imaging-guided Focused Ultrasound in Movement Disorders—A Review

“…These include, but are not limited to, treatment of neuropathic pain, 3 tumor ablation, 34 and sonothrombolysis for stroke therapy. 35 MRgFUS is also being studied as a means for drug delivery across the blood-brain barrier, which may have implications for treating brain tumors, demyelinating disorders, neuroinflammatory conditions, and other disorders where targeted therapy may be indicated.…”