EDUCATION CORNER - NEUROANESTHESIA KEYWORD

Focused Ultrasound

Tasha Welch, MD
Assistant Professor
Mayo Clinic

Overview
Focused ultrasound (FUS) is an evolving technology for providing permanent, noninvasive treatment of numerous neurologic and psychiatric disorders. This technology can treat a variety of intracranial lesions by generating a high-intensity energy that is directed at a focal intracranial lesion. FUS technology has evolved so therapy can be completed with an intact skull and an invasive intracranial procedure can be avoided. Indications for FUS treatments are expanding and can be used to treat various movement disorders such as Parkinson’s disease, essential tremor, certain psychiatric disorders and even brain tumors.

FUS Technology and Treatment
FUS technology has been coupled with the development of magnetic resonance (MR) thermography, allowing for real time evaluation of target temperatures. This enables accurate localization of intracranial lesions and facilitates temperature targeted treatment for accurate tissue ablation. A pre-procedure computed tomography (CT) scan is completed to determine skull thickness and density.  The CT images are then fused with anatomic MR images to aid in treatment. The targets for FUS are defined by using a series of low-power sonications to increase the target temperature to 40 to 45 degrees Celsius. This temperature increase is detected by real-time MR thermal imaging. After the final target is confirmed, the final temperature targets range between 55 and 63 degrees Celsius, allowing the desired tissue ablation to be achieved and thereby the desired functional effects.

Benefits and Adverse Effects
FUS allows treatment of numerous conditions by using a non-invasive approach to treatment. This spares patients from risks of infection and from complications related to hardware placement that is associated with more traditional treatment methods such as deep brain stimulator placement. Possible adverse effects related to FUS treatment include possible transient to permanent sensory disturbances, and cerebellar, motor and speech impairments. 

References
Darrow, DP. Focused Ultrasound for Neuromodulation. Neurotherapeutics. 2019; 16:88-89.

Dunn LK, Durieux ME, Elias J, et al. Innovations in Functional Neurosurgery and Anesthetic Implications. J Neurosurg Anesthesiol 2018; 30(1):18-25.

Prada F, Kalani MYS, Yagmurlu K, et al. Applications of Focused Ultrasound in Cerebrovascular Disease and Brain Tumors. Neurotherapeutics. 2019;16:67-07.

 

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