Getting rid of anesthesia and scalpel with powerful ultrasound

Brain surgery is now entering a new era without scalpel or anesthesia. Thanks to ultra-powerful ultrasound, surgeons can destroy tumors the size of a grain of rice deep in the brain under control of an MRI (magnetic resonance imaging) performed in real time.

For now, only a few patients have benefited from this promising therapy. In Switzerland a dozen of people with chronic pain refractory to medication have been treated, with a device called ExAblate, developed by Israeli firm Insightec.

The specialists are planning to try the device on the Parkinson's disease soon. A study should begin within one to two years in patients with chronic pain, Parkinson's disease or brain tumors. Ultimately, this approach is considered appropriate while treating other diseases, including epilepsy.

The principle of ultrasound therapy is quite simple. Directed to a predetermined target, focused ultrasound of high intensity (HIFU) increases the temperature to around 60°C. It can clot and thus destroy tissues with millimeter precision.

Used for the first time in 1993 for localized cancers of the prostate, the method is growing increasingly coupled with an MRI, to treat tumors in other organs.

The ExAblate is proposed in many countries to treat uterine fibroids. Trials are underway for breast and liver. But until recently, application to brain seemed impossible.

The main problem is the skull. Bone partially absorbs and distorts beams of ultrasound. To solve this problem, the Swiss team has used a kind of helmet with 1024 transducers, small devices that produce ultrasound and focus on the target area.

Twelve patients with severe chronic pain of various origins (amputation, trauma, etc.) have already been treated. Ultrasounds have been issued at the medial thalamus, a structure involved in controlling pain. The temperature and impacts were monitored in real time by MRI. The positive results were observed in 56% of patients, which is just a great number for chronic pain. A man has been weaned from the morphine he took for twelve years.

Ultimately, this therapy could become an alternative to current treatments by radiosurgery, as Gamma Knife or Linac, which work by irradiating the brain tumor, again without opening the skull.

Ultrasound has many potential benefits. First, it is not radiating. Then, it acts immediately while the radiosurgery results can be achieved in several weeks . Finally, the intervention is guided by real-time MRI, which can not be applied for radiotherapy techniques.

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