Abnormal respiratory patterns in a series of post-concussive patients

Abstract

BackgroundAutonomic nervous system dysfunction has been identified in patients following traumatic brain injury (TBI), including concussion. Abnormal postural heart rate and blood pressure instability have been identified in post-concussive patients. Recently, we have identified abnormal respiratory patterns during autonomic testing for post-concussive symptoms. Tachypnea is a clinical feature of autonomic instability in paroxysmal sympathetic hyperactivity following severe TBI and the purpose of this study is to identify abnormal respiratory patterns in patients with autonomic nervous system impairment following mild TBI.MethodsA retrospective review of patients in the Mayo Clinic Arizona Concussion Program from October 2017 to March of 2018 was performed. Clinical features and autonomic testing were reviewed. Autonomic testing included blood pressure and heart rate responses to Valsalva, heart rate variability during deep breathing, blood pressure and heart rate responses to head-up tilt, sudomotor testing, and respiratory responses using respiratory inductive plethysmography. Patients with co-morbidities or medications with potential to influence autonomic testing were excluded.ResultsFifteen patients with a history of concussion were studied. Nine of 15 patients had abnormal cardiovascular responses on autonomic testing, typically excessive postural tachycardia with head-up tilt. Abnormal respiratory patterns were identified in 8 of 9 patients with abnormal autonomic testing and in 3 of 6 patients without other abnormalities on autonomic testing. A number of different respiratory patterns were identified including tachypnea, prolonged apneic episodes, Cheyne-Stokes, and other unusual respiratory patterns.ConclusionWe have identified abnormal respiratory patterns in a series of concussion patients with or without other signs of dysautonomia. Tachypnea has been previously reported as a clinical feature of paroxysmal sympathetic hyperactivity following severe TBI and was present in some patients in this series. The clinical significance and mechanisms involved in the generation of respiratory dysrhythmia require further study, but may be another manifestation of post-concussive dysautonomia.