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Diagnosing and healing the brain

Nexstim’s Navigated Brain Stimulation (NBS) technology opens up exciting opportunities for studying brain function. A revolutionary new tool for diagnosing disease or trauma, NBS can also be used therapeutically and non-invasively to help the brain heal.

Nexstim’s NBS technology uses 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 brain and displays it on a computer screen.

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

With over 40 systems installed at leading research centres around the world, Nexstim is now building on its initial success to drive adoption of NBS in clinical applications, where it has been shown to be an excellent tool for mapping the brain prior to neurosurgery and predicting the ability of patients to respond to therapy after a stroke.

For the operator, guiding the coil is very much like driving a car with the aid of a satnav. For the patient, the procedure is also stress-free, thanks to a special pair of glasses fitted with optical markers, which keep track of any movements a patient makes and adjusts the measurements accordingly. NBS works equally well with patients who are paralysed or unable to respond to a nurse’s requests.

Helping the brain heal

An inherent feature of repetitive TMS – periods of rapid TMS stimuli, typically faster than one a second – is that it can be used to either excite neurons or, at low frequencies (1Hz), inhibit neural activity. The effects of repetitive TMS are temporary, reversible, and have no side-effects, making NBS an exciting new brain therapy tool.

It has been long known that the human brain has immense capability to adapt to new demands, such as the need to learn new skills. It has only recently been discovered, however, that our ability to overcome the consequences of unexpected brain illness or trauma is heavily dependent on the same natural capability, known as brain plasticity.

A large number of studies over the last 10 years have proven that repetitive TMS can help modulate brain plasticity; and Nexstim has a significant opportunity with NBS to help the natural healing processes of the brain in a number of fields. In stroke rehabilitation, for example, NBS can be used to help patients recover faster and even regain use of a paralysed arm or leg.

> Jukka-Pekka Särkkä
(Published in HighTech Finland 2009)