Multimodal assessment of primary motor cortex integrity following sport concussion in asymptomatic athletes.
OBJECTIVE
Recent studies have shown, in asymptomatic concussed athletes, metabolic disruption in the primary motor cortex (M1) and abnormal intracortical inhibition lasting for more than six months. The present study aims to assess if these neurochemical and neurophysiological alterations are persistent and linked to M1 cortical thickness.


METHODS
Sixteen active football players who sustained their last concussion, on average, three years prior to testing and 14 active football players who never sustained a concussion were recruited for a single session of proton magnetic resonance spectroscopy ((1)H-MRS) and transcranial magnetic stimulation (TMS). Measures of M1 and whole brain cortical thickness were acquired, and (1)H-MRS data were acquired from left M1 using a MEGA-PRESS sequence. Cortical silent period (CSP) and long-interval intracortical inhibition (LICI) were measured with TMS applied over left M1.


RESULTS
No significant group differences were observed for metabolic concentrations, TMS measures, and cortical thickness. However, whereas GABA and glutamate levels were positively correlated in control athletes, this relationship was absent in concussed athletes.


CONCLUSIONS
These data suggest the general absence of neurophysiologic, neurometabolic and neuroanatomical disruptions in M1 three years following the last concussive event. However, correlational analyses suggest the presence of a slight metabolic imbalance between GABA and glutamate concentrations in the primary motor cortex of concussed athletes.


CONCLUSIONS
The present study highlights the importance of multimodal assesments of the impacts of sport concussions.
Centre de recherche en neuropsychologie et cognition, Université de Montréal, Canada; Centre de recherche du Centre Hospitalier Universitaire de l'Hôpital Sainte-Justine, Canada.
Sara
S
Tremblay
Centre de recherche en neuropsychologie et cognition, Université de Montréal, Canada; Centre de recherche du Centre Hospitalier Universitaire de l'Hôpital Sainte-Justine, Canada.
Vincent
V
Beaulé
Unité de Neuroimagerie Fonctionnelle, Centre de recherche de l'institut universitaire de gériatrie de Montréal, Canada; Montreal Neurological Institute, McGill University, Canada.
Sébastien
S
Proulx
Unité de Neuroimagerie Fonctionnelle, Centre de recherche de l'institut universitaire de gériatrie de Montréal, Canada.
Sébastien
S
Tremblay
Center for Magnetic Resonance Research and Department of Radiology, University of Minnesota, United States.
Małgorzata
M
Marjańska
Unité de Neuroimagerie Fonctionnelle, Centre de recherche de l'institut universitaire de gériatrie de Montréal, Canada.
Julien
J
Doyon
Centre de recherche en neuropsychologie et cognition, Université de Montréal, Canada; Centre de recherche du Centre Hospitalier Universitaire de l'Hôpital Sainte-Justine, Canada.
Maryse
M
Lassonde
Centre de recherche en neuropsychologie et cognition, Université de Montréal, Canada; Centre de recherche du Centre Hospitalier Universitaire de l'Hôpital Sainte-Justine, Canada. Electronic address: hugo.theoret@umontreal.ca.
Hugo
H
Théoret
D001265:Athletic Injuries / Q000175:diagnosis* / Q000378:metabolism*; D001924:Brain Concussion / Q000175:diagnosis* / Q000378:metabolism*; D001931:Brain Mapping; D005538:Football / Q000293:injuries* / Q000502:physiology; D018698:Glutamic Acid / Q000378:metabolism; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009044:Motor Cortex / Q000378:metabolism* / Q000473:pathology*; D011795:Surveys and Questionnaires; D050781:Transcranial Magnetic Stimulation; D015599:Trauma Severity Indices; D055815:Young Adult; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid
GABA; Glutamate; Magnetic resonance spectroscopy; Sport concussion; Transcranial magnetic stimulation; Traumatic brain injury