Cognitive impairment in early onset epilepsy is associated with reduced left thalamic volume.

OBJECTIVE

The objective of this study was to investigate whether reduction of thalamic volumes in children with early onset epilepsy (CWEOE) is associated with cognitive impairment.

METHODS

This is a nested case-control study including a prospectively recruited cohort of 76 children with newly-diagnosed early onset epilepsy (onset <5years age) and 14 healthy controls presenting to hospitals within NHS Lothian and Fife. Quantitative volumetric analysis of subcortical structures was performed using volumetric T1-weighted magnetic resonance imaging (MRI) and correlated with the results of formal neurocognitive and clinical assessment. False discovery rate was used to correct for multiple comparisons as appropriate with q<0.05 used to define statistical significance.

RESULTS

Age, gender, and intracranial volume (ICV)-adjusted left thalamic volumes were significantly reduced in CWEOE with cognitive impairment compared to CWEOE without impairment (5295mm vs 6418mm, q=0.008) or healthy controls (5295mm vs 6410mm, q<0.001). The differences in left thalamic volume remained if gray matter or cortical/cerebellar volumes were used as covariates rather than ICV (q<0.05). The degree of volume reduction correlated with the severity of cognitive impairment (q=0.048).

SIGNIFICANCE

Reduced left thalamic volume may be a biomarker for cognitive impairment in CWEOE and could help inform the need for further formal cognitive evaluations and interventions.