Dyspnea as a side effect of subthalamic nucleus deep brain stimulation for Parkinson's disease

• Dyspnea may be a side effect of subthalamic nucleus deep brain stimulation.
• Many subthalamic nucleus patients had elevated dyspnea scores post-operatively.
• Many subthalamic nucleus patients had reduced quality of life due to dyspnea.
• Many patients may not mention dyspnea with the neurosurgery team unless prompted.
• Deep brain stimulation offers a unique opportunity to investigate aspects of the human respiratory control system in vivo.

Bilateral subthalamic nucleus deep brain stimulation for Parkinson's disease improves limb function. Unpublished observations from our clinic noted that some subthalamic nucleus deep brain stimulation patients complain of post-operative dyspnea. Therefore, we designed a prospective, longitudinal study to characterize this in greater depth. We used specific questionnaires to assess dyspnea in patients with electrodes in the subthalamic nucleus (n = 13) or ventral intermediate thalamus (n = 7). St. George's Hospital Respiratory Questionnaire symptom subscale scores were greater in subthalamic nucleus patients (median = 18.60, interquartile range = 40.80) than ventral intermediate thalamus patients (median  =  0.00, interquartile range = 15.38) at greater than 6 months post-operatively (p < 0.05). Several of the subthalamic nucleus patients exhibited functional impairments as judged by the St. George's Hospital Respiratory Questionnaire impact subscale, the Medical Research Council Dyspnoea Scale, and the Dyspnoea-12 Questionnaire. There was no correlation between limb function ratings, stimulation parameters, or precise electrode position and dyspnea severity. We have shown, for the first time, that dyspnea can be a side effect of subthalamic nucleus deep brain stimulation, and that this dyspnea may be highly disabling.