Free
The Somatic Connection  |   May 2017
The Fundamental Frequency: A New Approach to Concussion Diagnosis in Children
Author Notes
  • Western University of Health Science College of Osteopathic Medicine of the Pacific-Northwest, Lebanon, Oregon 
Article Information
The Somatic Connection   |   May 2017
The Fundamental Frequency: A New Approach to Concussion Diagnosis in Children
The Journal of the American Osteopathic Association, May 2017, Vol. 117, 336-337. doi:10.7556/jaoa.2017.065
The Journal of the American Osteopathic Association, May 2017, Vol. 117, 336-337. doi:10.7556/jaoa.2017.065
Kraus N, Thompson EC, Krizman J, Cook K, White-Schwoch T, LaBella CR. Auditory biological marker of concussion in children. Sci Rep. 2016;6:39009. doi:10.1038/srep39009 
Concussions are increasingly being identified as a significant health concern, especially among children who participate in sport-related activities. Approximately 1.6 to 3.8 million traumatic brain injuries (TBIs) occur each year in the United States1 and result in neurocognitive sequelae that can affect the physical, social, and emotional well-being of children who sustain them. Despite the potential negative effects of TBIs, there is no reliable, objective test to effectively identify and assess the severity of concussion or TBI. Because of the broad symptoms that frequently present after sustaining a concussion and the subjective reporting of those symptoms, researchers at Northwestern University sought to determine whether concussions could be identified and stratified in severity based on an auditory biological marker, the frequency following response (FFR). The FFR is an evoked potential of the nervous system relating to the auditory brainstem response. After a concussive episode, demyelination, axonal injury, and tau protein accumulation have all been established as potential corollary to damage within the neocortex.2 Thus, the researchers hypothesized that there would be a measurable disruption in the processing of the fundamental frequency (F0), an acoustic cue that facilitates pitch perception and identification of sound, and the ability to understand rhythm and stress in speech in patients with a concussion. They predicted that the disruption would result in delayed and smaller response of the FFR. 
The researchers evaluated 2 groups of children (N=40) (mean age, 13.32 years), 1 group of children with concussion and a matched control group of children. Children in the concussion group were evaluated at an average 27 days after injury using a Bio-logic Navigator Pro System (Natus Medical Inc), which delivered the F0 and collected responses measuring how quickly and accurately the F0 was processed. 
Results showed a significant difference in processing of the F0 between the concussion and control groups in amplitude and timing. Specifically, researchers found that processing of the F0 is disrupted, and a diminished neural response to speech was observed after concussion. The response rate to the F0 of children in the concussion group was about 35% smaller than that of the control group. Additionally, a clinically significant difference was found in the timing of neural processing between the children in each group. Children with concussion were an average of 0.4 milliseconds slower than the children in the control group. 
In this study, FFR was shown to identify a concussion with a positive predictive value of 94.7% and a negative predictive value of 90.4%, which is demonstrably higher than the Immediate Post-Concussion Assessment and Cognitive Test.3 Limitations of this study include its small sample size and a potentially biased sample of children in the concussion group, as they had already sought tertiary care for their symptoms. 
These findings support the hypothesis that auditory biomarkers can play a role in the diagnosis and management of concussion and other TBIs in children as a noninvasive and objective measure of neural processing. Further research is necessary to examine potential causality and feasibility of the measurement of FFR on a practical scale. 
References
Langlois JA, Rutland-Brown W, Wald MM. The epidemiology and impact of traumatic brain injury: a brief overview. J Head Trauma Rehabil. 2006;21(5):375-378. [CrossRef] [PubMed]
McKee AC, Cantu R, Nowinski CJ, et al Chronic traumatic encephalopathy in athletes: progressive tauopathy following repetitive head injury. J Neuropathol Exp Neurol. 2009;68(7):709-735. doi: 10.1097/NEN.0b013e3181a9d503 [CrossRef] [PubMed]
Schatz P, Pardini JE, Lovell MR, Collins MW, Podell K. Sensitivity and specificity of the ImPACT Test Battery for concussion in athletes. Arch Clin Neuropsychol. 2006;21(1):91-99. doi: 10.1016/j.acn.2005.08.001 [CrossRef] [PubMed]