Controlling the Lungs via the Brain: A novel neurosurgical method to improve lung function in humans
Hyam JA., Brittain JS., Paterson DJ., Davies RJO., Aziz TZ., Green AL.
BACKGROUND: Deep brain stimulation (DBS) of subcortical brain areas such as the periaqueductal grey (PAG) and subthalamic nucleus (STN) has been shown to alter cardiovascular autonomic performance. The supramedullary circuitry controlling respiratory airways is not well defined and has not been tested in humans. OBJECTIVE: Direct electrical stimulation via DBS macroelectrodes was used to test whether airway resistance could be manipulated by these areas in awake humans. METHOD: Thirty-seven patients with in-dwelling deep brain electrodes for movement disorders or chronic pain underwent spirometry as per the European Respiratory Society guidelines. Testing was performed three times On and three times Off stimulation, randomly, in which patients were blinded. Thoracic diameter changes were measured by a circumferential pressure-sensitive thoracic band. Ten PAG and ten STN patients were tested. To control for confounding pain and movement disorder relief, the sensory thalamus in seven patients and globus pallidus interna in ten patients, respectively, were also tested. RESULTS: Peak expiratory flow rate (PEFR) significantly increased with PAG and STN stimulation by up to 14% (p=0.021 and 0.005, respectively, using paired samples Students t-tests). Stimulation of control nuclei produced no significant PEFR change. Similarly, changes in thoracic diameter reflecting skeletal activity rather than airway calibre did not correlate with the improvement in PEFR. Forced expiratory volume in 1 second was unchanged by stimulation. CONCLUSION: DBS can improve PEFR in chronic pain and movement disorder patients. This finding provides insights into the neural modulation of respiratory performance and may explain some of the subjective benefits of DBS.