Role of the thalamus in natural recovery of cognitive impairment in patients with mild traumatic brain injury

Abstract

Introduction: Patients with mild traumatic brain injury (mTBI) may have normal neuroimaging but manifest with a broad-spectrum of cognitive-deficits, which may resolve eventually. The function of the thalamus in the process of natural-recovery remains elusive. The current study investigates the role of the thalamus in natural-recovery of cognitive-deficits in patients with mTBI.Methods: Twenty-one patients with mTBI were evaluated with an initial MRI scan, within 36 hours of injury and assessed with neuropsychological tests(NPT) at 3–4 weeks after injury. First and second follow-up MRI and NPT were performed at 3–4 months and 6–7 months, respectively. The volume and tensor measures of the thalamus and cognitive-scores were analysed at each assessment using repeated-measures of variance. The association of cognitive-scores with corresponding period imaging measures was analysed using bivariate-correlation.Results: Serial evaluation showed that all the cognitive-domains improved significantly. During this period there was a significant increase in mean thalamic volume (p = 0.049, effect-size = 0.18). After 3–4 months there was emergence of anisotropic thalamo-cortical connections. At 2–3 weeks and 6–7 months after injury, the alterations in diffusivity values were positively associated with improvement in memory-scores. Improvement in attention-scores correlated significantly with changes in tensor values at the 6–7 months after-injury.Conclusion: The correlation between improvement in cognitive-scores and changes in thalamic tensor and volume measures reflect the role of the thalamus in natural-recovery after mTBI.