The purpose of this study is to identify changes in salivary ribosomal nucleic acid (RNA) expression that are predictive of symptom duration and character following mild traumatic brain injury (mTBI) in children.

The purpose of this study is to characterize longitudinal salivary RNA expression in 600 children with mTBI and identify RNA patterns that predict length and characterof concussive symptoms, as well as the response to therapy.

Hypothesis: Specific RNAs will be differentially regulated in children with prolonged mTBI symptoms across the acute and sub-acute time periods. The investigators predict that a set of RNAs with differential expression in children with mTBI will be statistically associated with functional measures of mTBI symptoms as well as the duration of concussive symptoms.

Rationale: Preliminary studies show that miRNA is altered in adults with varying degrees of TBI and that salivary RNA is altered by disorders of the CNS. These studies indicate that serum-based miRNA may be used as an accurate biomarker for differentiating adults with and without TBI. Whether similar patterns can seen in the saliva of children following mTBI remains to be seen. Furthermore, the influence of confounding variables such as gender, mechanism of injury, and previous mTBIs on RNA profiles has not been explored. The investigators propose to investigate these questions by examining salivary RNA from 600 children (ages five to twenty-one years) with a clinical diagnosis of mTBI (as well as 100 age-and gender-matched controls, recruited from the Penn State Pediatric Concussion Clinic, Emergency Department, and the affiliated primary care clinics). The investigators plan to prospectively follow 600 children with mTBI for 1-month post-concussion, tracking subjective symptoms with the Child Sports Concussion Assessment Tool (SCAT-5), and objective symptoms of balance and cognition. Saliva will be collected via swab at three time-points (at initial clinical presentation, 1-2 weeks, and 4-weeks after the date of initial mTBI). Expression of salivary RNA taken at initial presentation will be compared against symptom duration (where prolonged post-concussive symptoms are defined as those lasting >4 weeks) and character (as measured numerically by Post-concussion symptom inventory self-report and ClearEdge scoring). The investigators plan to identify a set of salivary RNAs that can easily be used to predict clinical course for pediatric patients following a diagnosis of mTBI.

Inclusion Criteria:

• 5-21 years with mild traumatic brain injury that occurred within 7 days of enrollment

Exclusion Criteria:

• Sever traumatic brain injury
• Skull fracture
• Concurrent upper respiratory infection
• Patients whose primary language is not English
• Periodontal infection
• Wards of the state
• Ongoing seizure disorder,
• Drug or alcohol dependency

Children 5-21 years with mild traumatic brain injury