Basic NeuroscienceInter-rater and intra-rater reliability of cerebral blood flow measures obtained using the Brain Acoustic Monitor

- The Brain Acoustic Monitor is a portable, non-invasive device that allows expeditious measurement of cerebral blood flow acoustics.
- We used repeated measures design used to assess the reliability of serial assessments and assessments made by different clinicians.
- Resultant reliability values are comparable to current techniques used in concussion management, specifically neurocognitive testing.

BackgroundCurrent assessment of sport-related concussion involves a multifaceted approach including neurocognitive testing, symptom report, and balance assessment. Lacking from this paradigm is a truly objective measure of the physiological changes associated with concussion.New methodA device called the Brain Acoustic Monitor (BAM) has been developed to detect cerebral blood flow changes resulting from traumatic brain injury by amplification and comparison of sound waves created by cerebral arteries and a reference artery. The reliability of its measures is unknown, limiting its use in day-to-day assessment of concussion. Therefore, the purpose of this study was to determine the inter- and intra-rater reliability associated with BAM measures. Twenty healthy participants were assessed on two occasions, separated by at least 24 h. Ten subjects were measured during the initial session by two assessors for inter-rater comparisons. Measures of positive-to-negative signal deflection (ratio) and frequency divergence from a reference arterial signal (divergence) were calculated and analyzed using Intra-class correlations (2,1).ResultsInter-rater reliability ranged from poor to excellent, showing greater reliability in right brain vs. left brain measures. Intra-rater reliability was similar with a range of poor to good.Comparison with existing methodsThese findings are comparable to the reliability of current methods of concussion assessment, specifically neurocognitive testing.ConclusionAll BAM values obtained in our healthy subjects were well below scores that would reflect potential head injury. These findings emphasize the potential usefulness of this device in future research concerning serial measurement of cerebral perfusion pressure changes associated with sport concussion.