Epilepsy continues to be a serious health problem and is the most
common serious neurological disorder. Medically intractable temporal
lobe epilepsy (TLE) remains the most frequent neurosurgically treated
Many people with this condition will undergo a temporal lobe
resection which is a surgery performed on the brain to control seizures.
In this procedure, brain tissue in the temporal lobe is resected, or
cut away, to remove the seizure focus.
‘Preoperative abnormalities of two temporal lobe white matter tracts were identified in patients who had postoperative seizures but not in patients with no seizures after surgery.’
Unfortunately, approximately one in every two patients with TLE will
not be rendered completely seizure free after temporal lobe surgery,
and the reasons underlying persistent postoperative seizures have not
New research from the University of Liverpool, published in the
, has highlighted the potential reasons why many patients
with severe epilepsy still continue to experience seizures even after
Understanding the reasons why so many patients continue to
experience postoperative seizures, and identifying reliable biomarkers
to predict who will continue to experience seizures, are crucial
clinical and scientific research endeavors.
Researchers from the University's Institute of Translational
Medicine, led by Neuroimaging Lead Dr. Simon Keller and collaborating
with Medical University Bonn (Germany), Medical University of South
Carolina (USA) and King's College London, performed a comprehensive
diffusion tensor imaging (DTI) study in patients with TLE who were
scanned preoperatively, postoperatively and assessed for postoperative
Diffusion tensor imaging (DTI) is a MRI-based neuroimaging technique that provides insights into brain network connectivity.
The results of these scans allowed the researchers to examine
regional tissue characteristics along the length of temporal lobe white
matter tract bundles. White matter is mainly composed of axons of nerve
cells, which form connections between various grey matter areas of the
brain, and carry nerve impulses between neurons allowing communication
between different brain regions.
Through their analysis the researchers could determine how abnormal
the white matter tracts were before surgery and how the extent of
resection had affected each tract from the postoperative MRI scans.
The researchers identified preoperative abnormalities of two
temporal lobe white matter tracts that are not included in standardized
temporal lobe surgery in patients who had postoperative seizures but not
in patients with no seizures after surgery.
The two tracts were in the 'fornix' area on the same side as
surgery, and in the white matter of the 'parahippocampal' region on the
opposite side of the brain.
The tissue characteristics of these white matter tracts enabled
researchers to correctly identify those likely to have further seizures
in 84% of cases (sensitivity) and those unlikely to have further
seizures in 89% of cases (specificity). This is significantly greater
than current estimates.
The researchers also found that a particular temporal lobe white
matter tract called the 'uncinate fasciculus' was abnormal - and
potentially involved in the generation of seizures - in patients with
excellent and suboptimal postoperative outcomes.
However, it was found that significantly more of this tract was
surgically resected/removed in the patients with an excellent outcome.
Dr. Simon Keller, said, "There is scarce information on the
prediction of postoperative seizure outcome using preoperative imaging
technology, and this study is the first to rigorously investigate the
tissue characteristics of temporal lobe white matter tracts with respect
to future seizure classifications."
"Although there is some way to go before this kind of data can
influence routine clinical practice, these results may have the
potential to be developed into imaging prognostic markers of
postoperative outcome and provide new insights for why some patients
with temporal lobe epilepsy continue to experience postoperative