Focused Ultrasound: An Emerging Therapeutic Modality for Neurologic Disease.

Authors: Fishman PS, Frenkel V

Therapeutic ultrasound is only beginning to be applied to neurologic conditions, but the potential of this modality for a wide spectrum of brain applications is high. Engineering advances now allow sound waves to be targeted through the skull to a brain region selected with real time magnetic resonance imaging and thermography, using a commercial array of focused emitters. High intensities of sonic energy can create a coagulation lesion similar to that of older radiofrequency stereotactic methods, but without opening the skull. This has led to the recent Food and Drug Administration approval of focused ultrasound (FUS) thalamotomy for unilateral treatment of essential tremor. Clinical studies of stereotactic FUS for aspects of Parkinson's disease, chronic pain, and refractory psychiatric indications are underway, with promising results. Moderate-intensity FUS has the potential to safely open the blood-brain barrier for localized delivery of therapeutics, while low levels of sonic energy can be used as a form of neuromodulation.

Introduction

Purpose Thermal ablation

Study Objective To review advances and potential clinical applications of therapeutic focused ultrasound for brain disorders, including lesioning, blood–brain barrier opening, and neuromodulation.

MRI or image guidance method Real-time magnetic resonance imaging and MR thermography (MR-guided)

Targeted brain region(s) Thalamus

Outcomes and Safety

Summary of Outcomes Focused ultrasound produced dose-dependent brain effects: high-intensity FUS creates coagulative lesions enabling MR-guided thalamotomy (FDA-approved for unilateral essential tremor) and shows promise for Parkinson’s, chronic pain, and psychiatric indications; moderate-intensity FUS transiently opens the blood–brain barrier for localized drug delivery; and low-intensity FUS acts as a neuromodulator to alter neural activity.

Safety-related matter No adverse effects are reported in this excerpt; the authors state that moderate-intensity focused ultrasound can "safely" open the blood–brain barrier and note FDA approval of FUS thalamotomy, with no safety issues described.

Brain Region

Ultrasound Parameters

Focal Characteristics Focal depth: None; Focal length: None; Aperture size: None

We are open to feedback. If you see a mistake or have a suggestion, please contact us.