A Pilot Prospective Observational Study of Cerebral Autoregulation and 12-Month Outcomes in Children With Complex Mild Traumatic Brain Injury: The Argument for Sufficiency Conditions Affecting TBI Outcomes

Background: The relationship between cerebral autoregulation and outcomes in pediatric complex mild traumatic brain injury (TBI) is unknown, and explored in this study. Methods: We conducted a prospective observational study of patients aged 0 to 18 years hospitalized with complex mild TBI (admission Glasgow Coma Scale score 13 to 15 with either abnormal computerized tomogram of the head or history of loss of consciousness). Cerebral autoregulation was tested using transcranial Doppler ultrasonography, and impaired autoregulation defined as autoregulation index<0.4. We collected Glasgow Outcome Scale Extended-Pediatrics score and health-related quality of life data at 3, 6, and 12 months after discharge. Results: Twenty-four patients aged 1.8 to 16.6 years (58.3% male) with complete 12-month outcome data were included in the analysis. Median admission Glasgow Coma Scale score was 15 (range: 13 to 15), median injury severity score was 12 (range: 4 to 29) and 23 patients (96%) had isolated TBI. Overall, 10 (41.7%) patients had impaired cerebral autoregulation. Complete recovery was observed in 6 of 21 (28.6%) children at 3 months, in 4 of 16 (25%) children at 6 months, and in 8 of 24 (33.3%) children at 12 months. There was no difference in median (interquartile range) Glasgow Outcome Scale Extended-Pediatrics score (2 [2.3] vs. 2 [interquartile range 1.3]) or health-related quality of life scores (91.5 [21.1] vs. 90.8 [21.6]) at 12 months between those with intact and impaired autoregulation, respectively. Age-adjusted hypotension occurred in 2/24 (8.3%) patients. Conclusion: Two-thirds of children with complex mild TBI experienced incomplete functional recovery at 1 year. The co-occurrence of hypotension and cerebral autoregulation may be a sufficiency condition needed to affect TBI outcomes.