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Issue 18 Understanding Science

Ultrasound, magnetic fields and brain tumors – only fiction or a possible reality?

🕒 5 min

I believe it is safe to say that those of us who were at some point (or maybe still are) glued to our screens watching Grey’s Anatomy often found yourselves intrigued by some of the innovative treatments used on the patients. One of my personal favorites was a clever use of ultrasound waves to treat a hypothalamic hamartoma in a young boy. After that episode, I rushed to the Internet trying to find anything published about the technique. I was amazed by the idea and was trying to find out more about it. Is it really possible? Can it really be used as a completely non-invasive way of treating brain masses, including tumors? Is it safe? Is it maybe already in use? To my disappointment, I found nothing. I’m not sure whether I did a very bad job at googling those facts back then, or maybe really nothing had been published yet. However, I recently stumbled upon a very interesting article about the use of a head-mounted magnetic device that shrinks tumors. Since it reminded me of the cutting-edge treatment from Grey’s Anatomy, I once again googled it, only this time with greater success. As it turns out, a lot has been done and published upon this subject over the past few years.

Focused ultrasound

But let’s start from the beginning – the use of sound waves portraited in Grey’s Anatomy. The idea and device were pioneered at the University of Virginia Health System back in 2018. They’ve been investigating the effects of directed waves on different conditions of the brain for a number of years and found it applicable to a variety of diseases. In fact, in 2016 the FDA approved the first focused ultrasound device that treats essential tremor. Being the most common movement disorder, essential tremor affects the lives of many, but the available medication only works for a relatively small proportion of patients. Besides, up until this device was approved, the only hope for those who weren’t responding to medication was surgery, which comes with its risks and hesitations and was often rejected by patients. On the other hand, focused ultrasound is a completely non-invasive and scalpel-free approach.

So how exactly does it work? As we all know, waves transfer energy and energy can be converted from one form to another. In sound waves, energy is being transferred through vibrations of air particles or the particles of a solid through which the sound travels. This technology focuses ultrasound waves in a specific region of the brain, where the energy they are carrying converts to heat. The created heat then interrupts brain circuits responsible for the tremor. Since there is currently no way of targeting only those brain circuits responsible for the tremor, there are some side effects, including sensory changes like numbness or tingling, but those are mostly transient. Other than that, ultrasound has proved to be safe and is widely used in medicine as a diagnostic tool.

Since then, a number of pioneering preclinical and clinical studies have tested the use of directed ultrasound in people with chronic nerve pain in the face and head, for treating shaking associated with Parkinson’s disease, treating various tumors and, as on Grey’s Anatomy, “giggling epilepsy”. As previously mentioned, in that episode, the team treats young boy’s hypothalamic hamartoma by means of a cutting edge technique which uses directed ultrasound.

The Grey’s Anatomy case

Hypothalamic hamartoma occurs very rare and is therefore often left undiagnosed or misdiagnosed. It is basically a benign mass that doesn’t grow, but causes unpleasant symptoms like premature puberty, epilepsy symptoms and unintentional giggling seizures. There are only two available treatments – brain surgery and laser ablation, both of which are invasive and require opening the skull and cutting into the brain. The episode represented the whole process very accurately – they used concentrated focused ultrasound coming from three different sources and directed all of them to a hypothalamic hamartoma mass. The ultrasound safely travels through the skull, and once it reaches the targeted brain mass, the cumulative energy that those three sources of ultrasound generate causes the mass to heat up and basically “melt away”.

A question that arises naturally is: how do they know exactly where to point the ultrasound waves? The researchers found a clever use of magnetic resonance imaging, which allows them to see inside the brain in real time. The same approach was used in the previously described treatment of essential tremor.

Although the treatment was successful in the show, it still remains experimental in real life, but the ongoing clinical trials are promising.

Using magnetic fields to shrink tumors

Recently, a similar principle was used to shrink brain tumors using an innovative head-mounted device which produces an oscillating magnetic field. The device is portable and wearable, and consists of high-speed electric motors that cause rotation of strong permanent magnets. The treatment-specific rotation frequencies and timing are controlled by a programmable microcontroller and are used to stimulate the brain to treat glioblastoma. The theory behind this single-patient case study lays in reactive oxygen species (ROS). All tumors contain mitochondria, a special part of the cell where many chemical reactions occur. For example, that’s where all the energy is generated from glucose. Some of these reactions, including the energy forming reaction we just mentioned, produce a certain amount of free radicals and free-floating electrons. The rotating magnetic field produced by the device interacts with the free electrons that are being exchanged by free radical intermediates in the chemical reactions taking part in the transmembrane protein complexes of mitochondria. Such disruption of the mitochondrial electron flow increases the amount of ROS in tumor cells and eventually leads to their death, while leaving the healthy cells untouched and unharmed.

Since this was based on one isolated case study, there are still many questions that remain unanswered. How long should a patient wear the device? What frequencies to use and when? How many times a day? Who shouldn’t use the device and why? The team of researchers behind this brilliant idea will try to answer some of these questions and are currently undertaking preclinical studies of the device to determine its biophysical, cellular and molecular mechanisms, as well as its efficacy and safety in mouse models of glioblastoma.

Conclusion

Since brain tumors and neurological pathologies are amongst the worst and with the fewest treatment options, stories like this can raise people’s hopes up very quickly. It’s best not to raise them too high, but the future seems to bring a number of new options for those patients and deserves a little beam of optimism.

Did you learn something new? Let us know if you feel as inspired as we do by medical progress like this.

By Đesika Kolarić

Đesika is a pharmacist with an exceptional love for science. She's particularly interested in neuropharmacology, oncology and clinical pharmacy. In her free time, she loves taking long walks accompanied by her dog and a good beer.

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