Evidence of altered interhemispheric communication after pediatric concussion

ABSTRACT

OBJECTIVES: To investigate neurophysiological alterations within the typical symptomatic period after concussion (1-month) and throughout recovery (6-months) in adolescents; and (2) to examine relationships between neurophysiological and upper limb kinematic outcomes.

METHODS: 18 adolescents with concussion were compared to 17 healthy controls. Transcranial magnetic stimulation (TMS) was used to assess neurophysiological differences between groups including: short- and long-interval intracortical inhibition, intracortical facilitation, short- and long-latency afferent inhibition, afferent facilitation, and transcallosal inhibition (TCI). Behavioral measures of upper limb kinematics were assessed with a robotic device.

RESULTS: Mixed model analysis of neurophysiological data identified two key findings. First, participants with concussion demonstrated delayed onset of interhemispheric inhibition, as indexed by TCI, compared to healthy controls. Second, our exploratory analysis indicated that the magnitude of TCI onset delay in adolescents with concussion was related to upper limb kinematics.

CONCLUSIONS: Our findings indicate that concussion in adolescence alters interhemispheric communication. We note relationships between neurophysiological and kinematic data, suggesting an affinity for individuals with less concussion-related physiological change to improve their motor behavior over time. These data serve as an important step in future development of assessments (neurobiological and clinical) and interventions for concussion.

KEYWORDS:

• Concussion
• transcranial magnetic stimulation
• interhemispheric communication
• adolescents
• upper limb function

Highlights

• After concussion, adolescents show altered interhemispheric communication

• Changed neurophysiological patterns after concussion appear to be compensatory and enable movement patterns more typical to those seen in healthy controls

• These data serve as an important step in futures development of assessments (neurobiological and clinical) and interventions for concussion

Abbreviations

Akaike Information Criterion (AIC)

Afferent facilitation (AF)

Abductor pollicis brevis (APB)

Cortical silent period (CSP)

Dorsolateral prefrontal cortex (DLPFC)

Electromyography (EMG)

Health and Behavior Inventory (HBI)

Intracortical facilitation (ICF)

Ipsilateral silent period (iSP)

Long-interval intracortical inhibition (LICI)

Long-latency interval afferent inhibition (LAI)

Motor evoked potential (MEP)

Resting motor threshold (RMT)

Short-interval intracortical inhibition (SICI)

Short-latency interval afferent inhibition (SAI)

Sport Concussion Assessment Tool (SCAT)

Transcallosal conduction time (TCT)

Test stimulus (TS)

Transcallosal inhibition (TCI)

Transcranial magnetic stimulation (TMS)

Visual Ocular Motor Scale (VOMS)

Additional information

Funding

JS received scholarship funding from Michael Smith Foundation for Health Research (MSFHR). This work was funded by Jakeway Family Neurorehabilitation Seed Fund (awarded to LB and JS). KEB and SJF received funding from the Natural Sciences and Engineering Council of Canada. JGZ is funded by the MSFHR, Canadian Child Health Clinician Scientist Program, BC Children’s Hospital Research Institute, Sunny Hill Foundation, and Canadian Institutes of Health Research;