Epilepsy is associated with thickness and volume differences in the grey matter of several brain regions, according to new research by an international consortium in which the University of Eastern Finland and Kuopio University Hospital participate.
Published in Brain, the largest-ever neuroimaging study of people with epilepsy shows that epilepsy involves more widespread physical differences than previously assumed, even in types of epilepsy that are typically considered to be more benign if seizures are under control. The brain abnormalities the researchers identified were subtle, and have not yet been implicated in any loss of function.
Epilepsy is a neurological disorder that affects 0.6-1.5% of the global population, comprising many different syndromes and conditions, and defined by a tendency for seizures.
The study was conducted by the global ENIGMA-Epilepsy consortium. The researchers pooled data from 24 research centres across Europe, North and South America, Asia and Australia. Structural brain measures were extracted from MRI brain scans of 2,149 people with epilepsy, and compared with 1,727 healthy controls. The epilepsy group was analysed together for common patterns, and divided into four subgroups to identify differences.
The team found reduced grey matter thickness in parts of the brain's outer layer (cortex) and reduced volume in subcortical brain regions in all epilepsy groups when compared to the control group. Reduced volume and thickness were associated with longer duration of epilepsy. Notably, people with epilepsy exhibited lower volume in the right thalamus - a region which relays sensory and motor signals, and has previously only been associated with certain epilepsies - and reduced thickness in the motor cortex, which controls the body's movement.
These patterns were even present among people with idiopathic generalised epilepsies, a type of epilepsy characterised by a lack of any noticeable changes in the brain, such that typically an experienced neuroradiologist would not be able to see anything unusual in their brain scans.
The researchers also identified differences between the subgroups, which they say must reflect differences in underlying biology, as suggested by recent genetic studies.
According to the researchers, the findings inform our understanding of epilepsy as a network disorder and give direction for further studies. For instance, the researchers cannot tell yet what causes the structural brain differences or how this might progress over time.
At the University of Eastern Finland and at the KUH Epilepsy Centre, this line of research will continue as part of an epilepsy biomarker study funded by the Saastamoinen Foundation and led by Professor Reetta Kälviäinen. The study seeks to identify genetic and other predictors of epilepsy in order to enable better targeted and more personalised treatments.
Picture: Christopher Whelan
For further information, please contact:
Professor Reetta Kälviäinen, reetta.kalviainen (a) kuh.fi, tel. +358 405839249
Research article:
Structural brain abnormalities in the common epilepsies assessed in a worldwide ENIGMA study. Christopher D Whelan et al. Brain 22.1.2018, awx341, https://doi.org/10.1093/brain/awx341
Source: University College London
UCL press release: https://www.eurekalert.org/pub_releases/2018-01/ucl-elt011818.php