A study in the February issue of Neurosurgery, official journal of the Congress of Neurological Surgeons, reveals that deep brain stimulation (DBS), commonly used to treat individuals with movement disorders or chronic pain, also affects respiratory function. Lead researcher of the study was Dr. Jonathan A. Hyam of University of Oxford, United Kingdom.
DBS is a surgical treatment in which a small electrode is implanted in the brain. The electrode sends electrical impulses to stimulate specific parts of the brain, in order to interrupt abnormal brain activity.
The journal is published by Lippincott Williams & Wilkins, a part of Wolters Kluwer Health.
Initial findings from the study help researchers to better understand the brain's role in controlling lung function. In addition, the preliminary findings may provide helpful insights for developing new treatments for diseases, such as chronic obstructive pulmonary disease (COPD), and asthma.
In order to find out if DBS could also affect respiratory (breathing) function, the team conducted a set of experiments in individuals receiving DBS for chronic pain or for movement disorders, such as Parkinson's disease.
Using advanced functional imaging techniques, recent investigations have helped to better understand the regions of the brain controlling the several, complex functions of the autonomic nervous system (ANS). The ANS is part of the peripheral nervous system that controls involuntary functions, such as breathing and heartbeat.
When electrical stimulation was "on" in two brain regions: the subthalamic nucleus (STN), which is stimulated in some individuals with movement disorders, and the periaqueductal gray matter (PAG), stimulated in some individuals with chronic pain, the researchers found considerable changes in some lung function.
In response to stimulation, one vital measure - the peak expiratory flow rate, a key measure of lung function in individuals with asthma, rose by up to 14%.
The researchers found that stimulation has no effect on lung function in other regions of the brain which were tested. The improvements appeared to be specifically associated to alterations in the width of the airways, which is affected by "smooth muscle" controlled by the ANS.
Results showed that forced expiratory volume (FEV1), and some other key measures of lung function, appeared to be unaffected by stimulation. This may be because the majority of the participants had normal lung function, with little room for improvement.
However, mild COPD was identified in one of the participants with chronic pain. When PAG stimulation was "on", the participant had a considerable increase in FEV1 and other lung function measures.
Additional investigations would be required in order to determine if DBS can generate greater improvements in lung function for individuals with established chronic lung disease. The team suspects that the enhancement in peak expiratory flow rate could help explain some of the subjective benefits of DBS.
The study provides vital information about the brain's involvement in controlling lung function through the ANS. According to Dr. Hyam and his team, further studies could potentially result in the development of new methods to treat lung diseases, especially COPD and asthma, that involve narrowing of the airways.
The researchers conclude:
"These results lend support to the importance of the PAG and STN in respiratory performance and provide another potential direction for the application of deep brain stimulation."
Written by Grace Rattue