The Clinical Utility of Assessing Orthostatic Intolerance in Adolescents with Sport-Related Concussion, a Retrospective Study.

BACKGROUND/OBJECTIVE: Assessing Orthostatic Intolerance (OI, symptoms upon standing from supine) is recommended in athletes with sport-related concussions (SRCs), as this is caused by impairments in the cardiovascular autonomic nervous system (cANS). Early Exercise Intolerance (Early EI, symptoms on light physical exertion) is also due to impairments in the cANS but is difficult to incorporate into outpatient clinical practice (cost of personnel, time, equipment). The purpose of this study was to determine if we could use OI to screen for Early EI, as well as understand differences between adolescents who do and do not report OI.

METHODS

Retrospective chart review. Adolescents with physician-diagnosed SRC performed the 2 min supine to 1 min standing OI test and the Buffalo Concussion Treadmill Test (BCTT) during their first post-SRC visit. Early EI was defined as more-than-mild symptom exacerbation at a heart rate (HR) below 135 bpm on the BCTT; OI was defined as new or increased symptoms of dizziness or lightheadedness on postural change. The sensitivity, specificity and diagnostic accuracy were calculated. Participants with and without OI were compared.

RESULTS

In total, 166 adolescents (mean 15.4 years, 58.8% male) were seen a mean of 5.5 days after injury; 48.2% had OI and 52.4% had Early EI, but there was no association between the two measures (Phi = 0.122, = 0.115). The sensitivity and specificity (with 95% confidence intervals) for OI to screen for Early EI were 54.0% (43.5, 64.3) and 58.2% (47.2, 68.7), respectively. Adolescents with OI had a higher incidence of delayed recovery (24% vs. 9%, = 0.012).

CONCLUSIONS

Although both measures seem to be related to impaired autonomic function after SRC, OI has limited accuracy in screening for Early EI, which suggests that their etiologies may be different. Nevertheless, the assessment of OI has clinical utility in the management of SRC.