Deep Brain Stimulation Without Surgery

Stimulating specific brain structures has marked therapeutic potential.

Posted Jan 03, 2018

Changes in specific brain networks are associated with various psychiatric disorders. For instance, several pathways associated with depression have been mapped. Networks associated with drug addiction have also been identified. These findings have the potential to influence diagnosis and treatment.

Current therapeutic approaches in psychiatry include psychotherapies, medications, and a variety of brain stimulation techniques, including electroconvulsive therapy (ECT), transcranial magnetic stimulation (TMS), vagus nerve stimulation (VNS), and deep brain stimulation with surgically implanted electrodes. Other approaches that can add benefit include exercise, improved sleep hygiene, and mindfulness training. Various factors are taken into account when specific treatment recommendations are made, including the specific illness, the severity of the illness, and other considerations such as safety, cost, and patient preference.

For example, depressive symptoms improve for many individuals with psychotherapy, medication, or a combination of both. Some patients suffer from a treatment-resistant form of depression, meaning that their symptoms do not respond to several well-administered treatment trials. Many individuals who fail to respond to multiple trials of medications and psychotherapies may improve with ECT. Some patients whose symptoms don’t improve with ECT may respond to VNS, a treatment that requires surgery to implant the stimulation device. Improvement with VNS may not become evident for many months.

Deep brain stimulation involves stimulating specific regions of the brain by means of a surgically implanted “neurostimulator” (electrode).  Such procedures are being utilized successfully in the treatment of Parkinson’s disease. Research studies examining the use of this approach to treat persons with severe, treatment-resistant depression and obsessive-compulsive disorder are currently underway.

Techniques like ECT and TMS do not require surgery, but they are not able to target specific brain areas that lie deep in the brain. With deep brain stimulation, it is possible to stimulate very specific brain regions, but this technique requires neurosurgery and is obviously invasive and expensive. This may be about to change.

Nir Grossman and colleagues recently published a paper in the journal Cell describing a non-invasive technique that allows selective targeting of specific brain regions deep in the brain. Nerve cells respond to electrical impulses within a certain range of frequencies. These investigators were able to develop techniques that involved sending very high-frequency impulses deep into the brains of mice. The frequencies of these impulses were too high to stimulate nerve cells on their own, but where the impulses intersected, they produced lower frequency impulses that were capable of stimulating neurons. By varying the parameters and location of the high-frequency stimulation, the authors were able to influence specific brain regions without affecting brain regions above or below them.

This research is exciting because it may lead to the development of devices that can target specific functional pathways that are involved with different psychiatric disorders. Clearly, such devices would have to be carefully evaluated in terms of safety and efficacy. In addition, research involving selective stimulation of brain regions has the potential to advance our knowledge about the roles of various brain pathways in the development of psychopathology.

Most individuals with psychiatric disorders can be helped with less invasive approaches, but, unfortunately, there are many patients who don’t respond well to current treatments. The ability to influence specific brain regions has been useful in the treatment of a variety of neurological and neurosurgical conditions. The possibility of utilizing these approaches to help individuals with severe psychiatric conditions in a manner that does not involve neurosurgical approaches is exciting.

References

Grossman, N., Bono, D., Dedic, N., Kodandaramaiah, S.B., Rudenko, A., Suk, H.-J., Cassara, A.M., et al. (2017). Noninvasive deep brain stimulation via temporally interfering electric fields. Cell. 169:1029-1041.