Deep brain stimulation (DBS), which has become a common treatment for patients with chronic pain or movement disorders, may improve lung function. A unique set of experiments, conducted by researchers at Oxford University, shows that electrical stimulation in some of the same brain areas can also effect respiratory function.
The findings appear in the journal Neurosurgery, the official journal of the Congress of Neurological Surgeons.
The preliminary findings help to clarify the brain’s involvement in controlling lung function, and may lead to useful insights for developing new treatments for diseases such as asthma and chronic obstructive pulmonary disease (COPD), according to the researchers.
For the study, the researchers performed a series of experiments in patients undergoing DBS for chronic pain or for movement disorders, such as Parkinson’s disease, to determine whether DBS could also affect respiratory function. In DBS, a small electrode is surgically placed in a precise location in the brain. A mild electrical current is delivered to stimulate that are of the brain, with the goal of interrupting abnormal brain activity.
The results showed significant changes in some lung function when electrical stimulation was "on" in two brain areas: the periaqueductal gray matter (PAG), which is stimulated in some patients with chronic pain; and the subthalamic nucleus (STN), which is stimulated in some patients with movement disorders. One key measure—the peak expiratory flow rate—increased by up to 14% in response to stimulation.
In other brain areas tested, stimulation had no effect on lung function. The improvements seemed specifically related to changes in the width of the airways, which is affected by "smooth muscle" under the control of the autonomic nervous system.
Some other key measures of lung function—including forced expiratory volume (FEV1)—seemed unaffected by stimulation. This may have reflected the fact that most of the patients had normal lung function, with little room for improvement.
However, in one of the patients with chronic pain, tests performed for the study identified mild COPD. This patient had a significant increase in FEV1 and other lung function measures when PAG stimulation was "on."
Further studies would be needed to find out whether DBS can produce larger improvements in lung function for patients with established chronic lung disease. The researchers speculate that the improvement in peak expiratory flow rate may help to explain some of the subjective benefits of DBS.
Source: Wolters Kluwer Health: Lippincott Williams & Wilkins