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A new way to diagnose and heal the brain

Nexstim’s Navigated Brain Stimulation (NBS) technology opens up exciting new opportunities for mapping brain function prior to neurosurgery. Potentially a revolutionary tool for predicting recovery from strokes or trauma, NBS can also be used therapeutically to help the brain heal.

Nexstim’s NBS System employs transcranial magnetic stimulation (TMS) generated by a small electromagnetic coil held close to the patient’s head to gently stimulate precise areas of the cortex of the brain, while simultaneously measuring the effect of stimuli on the central nervous system and peripheral nerves. Using information from a standard head MRI scan taken earlier as part of normal diagnostics, the NBS System builds a 3-D model of the patient’s brain and displays it on a computer screen.

With the help of sophisticated modelling techniques, an operator can see precisely where stimuli are given inside the brain. A standard stereotactic navigation system, comprising a camera and optical trackers, allows the operator to guide the stimulating coil, knowing where the coil is in relation to the brain structure at all times.

Guiding the coil is like driving a car with a sat-nav. The procedure is also stress-free for the patient, thanks to a special pair of glasses fitted with optical markers, which keep track of any head movements the patient makes and adjusts the measurements accordingly. NBS works equally well with patients who are paralysed or unable to respond to a nurse’s commands.

Helping the healing process

NBS is a promising new brain therapy tool and is now FDA-cleared for clinical diagnostic purposes prior to neurosurgery. Unlike pharmaceuticals, which affect the entire body, repetitive TMS has only a local effect in the brain.
An inherent feature of repetitive TMS – periods of TMS stimuli given at five times a second or faster – is that it can be used to excite neurons in the cortex. Conversely at a low frequency (1Hz), rTMS inhibits neural activity in the cortex, sufficiently so, in fact, to ‘knock out’ parts of the brain responsible for specific actions, such as speech, on a temporary and fully reversible basis.

While it has been long known that the human brain has an immense capability to adapt to new demands, such as learning new skills, it has only been discovered recently that our ability to overcome the consequences of unexpected brain illness or trauma is heavily dependent on the same natural capability. A large number of studies over the last 10 years have shown that repetitive TMS can help modulate this brain plasticity.

Thanks to Nexstim’s NBS, doctors now have significant new ways to help the natural healing processes of the brain in a number of fields. NBS can be used to help stroke patients, for example, recover faster and even regain use of a paralysed arm or leg.

With over 50 systems installed at research centres around the world, Nexstim is now concentrating on the hospital adoption of NBS for routine clinical use, where it has been shown to be an excellent tool for mapping the brain prior to neurosurgery. Nexstim recently had its application to market NBS in the US cleared by the FDA , making it the first-ever company able to sell TMS-based technology to hospitals for clinical diagnostic purposes.

> Lothar Koob
(Published in HighTech Finland 2010)