Sports related mild traumatic brain injury (mTBI) is a serious and increasing health incident in the United States, particularly in young children and adolescents, often affecting developing frontal and temporal lobes. Literature comparing various methods of cognitive assessment tools as well as the utility of various non-invasive brain imaging technologies in the diagnosis and follow up of mTBI lacks standardized methods and requires further investigation. We investigated the stability of intercortical and intracortical inhibition parameters and their relationship to white matter integrity, in athletes without mTBI. We hypothesized that a single season of soccer, without a concussion, would result in no significant neurophysiologic differences, in female adolescents.
Ten female soccer athletes, between the ages of 14–17 years were evaluated pre and post season using: neuropsychological testing, transcranial magnetic stimulation (TMS), anatomical MRI, and diffusion tensor imaging (DTI). One athlete sustained a concussion and was subsequently removed from analysis.
There was no significant difference when comparing pre- and post-season measures for: neuropsychological testing; intercortical (p = 0.812) or intracortical (p = 0.888) inhibition, measured by duration of silent periods during TMS; motor evoked potential onset (p = 0.227) or duration (p = 0.977); and interhemispheric conduction times (p = 0.092). In addition, no significant difference was found between pre and post assessments of fractional anisotropy, for white matter tracts of interest: posterior limb of internal capsule; cortical spinal tracts; and genu, body, and splenium of the corpus callosum.
Following a season of soccer, there was no difference in any neurologic parameters that would elicit concern for the continuation of the sport at this level. We demonstrate that the inter- and intra-cortical inhibitory parameters derived from TMS are stable; therefore, TMS and DTI can be used as reliable measures for further investigation of patients sustaining mTBI.