Longitudinal Changes in Magnetic Resonance Spectroscopy in Pediatric Concussion: A Pilot Study

Abstract

Background: Nearly 20% of US adolescents report at least one lifetime concussion. Pathophysiologic models suggest that traumatic biomechanical forces caused by rotational deceleration lead to shear stress, which triggers a neurometabolic cascade beginning with excitotoxicity and leading to significant energy demands and a period of metabolic crisis for the injured brain. Proton magnetic resonance spectroscopy (¹H MRS) offers a means for non-invasive measurement of neurometabolic changes after concussion. Objective: Describe longitudinal changes in metabolites measured in vivo in the brains of adolescent patients with concussion. Methods: We prospectively recruited 9 patients ages 11 to 20 who presented to a pediatric Emergency Department within 24 h of concussion. Patients underwent MRI scanning within 72 h (acute, n = 8), 2 weeks (subacute, n = 7), and at approximately 1 year (chronic, n = 7). Healthy, age and sex-matched controls were recruited and scanned once (n = 9). ¹H MRS was used to measure N-acetyl-aspartate, choline, creatine, glutamate + glutamine, and myo-inositol concentrations in six regions of interest: left and right frontal white matter, posterior white matter and thalamus. Results: There was a significant increase in total thalamus glutamate+glutamine/choline at the subacute (p = 0.010) and chronic (p = 0.010) time points, and a significant decrease in total white matter myo-inositol/choline (p = 0.030) at the chronic time point as compared to controls. Conclusion: There are no differences in ¹H MRS measurements in the acute concussive period; however, changes in glutamate+glutamine and myo-inositol concentrations detectable by ¹H MRS may develop beyond the acute period.

Keywords: adolescent; concussion; magnetic resonance spectroscopy; mild traumatic brain injury; pediatric.

Figure 1

Magnetic resonance spectroscopy excitation grid overlaying T1 MPRAGE images of representative brain. (A) 3D visualization. (B) Bilateral thalamus ROIs indicated by arrows on transverse slice. (C) Bilateral frontal and parietal ROIs.

Figure 2

Boxplot representations comparing median and interquartile range for total thalamus Glx and Glx/Cho between controls and concussed patients at acute, subacute and chronic time points. Individual horizontal bars are presented for each significant group comparison. Glx = glutamate + glutamine, Cho = choline compounds. **P < 0.05 by Mann-Whitney U-test.

Figure 3

Boxplot representations comparing median and interquartile range for total white matter Ins and Ins/Cho between controls and concussed patients at acute, subacute and chronic time points. Individual horizontal bars are presented for each significant group comparison. Ins = myo-inositol, Cho = choline compounds. *P < 0.1, **p < 0.05 by Mann-Whitney U-test.