Pan European Networks: Science & Technology
Janne Huhtala
Nexstim Oy
tel: +358 40 861 5046
Nexstim has introduced Navigated Brain Therapy:
Navigated Brain Stimulation as a dedicated therapy
Major depressive disorder (MDD) is ranked by the World Health
Organization as one of the most burdensome diseases in the
world. Although a wide range of pharmaceuticals are available for
treatment, still 20-40% of patients with MDD are drug-resistant.
Furthermore, drugs prescribed for depression can have unwanted,
sometimes severe, side-effects.
Reduced activity of the dorsolateral prefrontal cortex (DLPFC) is
implicated in depression. RTMS can be used to induce electric fields
in the DLPFC causing depolarisation of neurons. Release of
neurotransmitters spreads the activation throughout the brain’s
limbic system. RTMS is not associated with the potentially severe
side-effects of pharmaceuticals or those of electroconvulsive therapy,
an established non-drug therapy for severe depression. RTMS has
been proven to be effective with approximately 50% of MDD patients
responding significantly to treatment and 15-37% of patients
sustaining total absence of depression symptoms.The US Practice
Guideline for the Treatment of MDD Patients recommends rTMS as a
second line treatment alternative, when first line treatments,
including pharmacotherapy or psychotherapy, have failed.
In a study by the Rehabilitation
Institute of Chicago, 80% of stroke
patients treated by NBT in addition
to conventional physiotherapy, had
improved in a clinically meaningful
way, six months post treatment,
as opposed to only 20% and
sham stimulation.
Using Navigated Brain Therapy, rTMS treatment is personalised to
accurately and repeatedly target the DLPFC according to the
patient’s individual brain anatomy. Targeting is enabled through
MRI based navigation and unique electric field modelling, already
FDA-cleared for use in neurosurgical planning. According to a
published study (Fitzgerald 2009), in rTMS therapy based on each
individual’s MRI scan, the depression scores were significantly
lower than when therapy was applied using a conventional ‘5cm
anterior from the motor cortex’ rule.
NBT is also the first clinical device which allows stimulation
intensity to be optimised for the individual patient, based on a
measurement of patient’s motor threshold, measured using
electromyography. Optimising intensity allows for a more
comfortable experience and better compliance.
NBT is performed as an outpatient procedure and can be
performed in 45 minutes and without side-effects. Afterwards, the
patient is free to continue with daily activities. A course of rTMS
therapy typically requires a stimulation session five times a week
for four to six weeks.
Navigated Brain Therapy helps stroke patients recover
Despite rehabilitation therapies, few patients with chronic stroke
benefit. It is estimated that 33-60% of patients with hemiparesis
following stroke never recover lost motor functions.
After a stroke, the balance of inhibition between the brain
hemispheres can be severely disrupted.When a patient tries to
voluntarily move the affected hand, inhibition from the healthy
hemisphere interferes, resulting in one-sided paralysis. It is
believed that normalising the brain’s inhibitory balance can help
recovery. TMS can be used for this purpose because slow, 1Hz
TMS down-regulates, or inhibits, local cortical activity. NBT is an
ideal tool for this purpose because it enables the precise
localisation of the motor area – and enables targeting of a known
dose of stimulation every session.
NBT has been shown to be effective in treating stroke patients to
improve paretic limb function. In a study by the Rehabilitation
Institute of Chicago, 80% of stroke patients treated by NBS in
addition to conventional physiotherapy, had improved in a clinically
meaningful way, six months post treatment start, as opposed to
only 20% and sham stimulation. Mean change in Fugl-Meyer
score, which measures recovery in post-stroke hemiplegic patients,
was +13 points or 65% for the active NBT group at six months
versus +2 points or 15% for the sham group (Harvey
et al.,
abstract presented at the European Stroke Conference 2012). As
an example, a ten point increase could mean regaining the ability
to button a shirt.
In pre-surgical diagnostic applications, a map of the vital areas in the
brain is created with the NBS
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