Abstracts

Focal epilepsy is commonly associated with abnormal cortical anatomy and other abberant developmental findings on MRI scan.
We hypothesized that those patients with focal abnormalities on EEG have a greater likelihood of abnormal MRI findings than patients with seizures and normal EEGs. Subtle cortical malformations of anatomical abnormalities may be missed on routine or suboptimal neuroimaging studies but sensitivity may be increased if review of the images is guided by EEG findings and clinical semiology.
We focused on younger patients, as they were felt to be less likely to have other confounding focal abnormalities on MRI scanning such as tumor or stroke., We reviewed MRI reports of 106 children who were labelled as having partial epilepsy based on EEG findings. The ICD 9 codes used included 345.40, 345.41, 345.0, 345.51.
Original MRI films from those patients who were initially reported as having normal scans, were reviewed with a neuroradiologist with particular attention to those areas identified as generating abnormal epileptiform discharges on EEG.
Particular emphasis was placed on the detection of subtle abnormalities of cortical development and mild degrees of hippocampal asymmetry, abnormalities which are frequently overlooked in the absence of clinical or electroencephalographic information., 62 of the 106 children who had EEGs coded for focal epilepsy were followed up with MRIs, leaving 44 children without MRI imaging.
Of the 62 children who had an MRI, 61.3% (38 of 62) were reported as having an abnormal scan.
A wide range of abnormalities were reported ranging from gross developmental abnormalities to gyral asymmetries, porencephaly and asymmetry of the mesial temporal structures.
Of the 24 children who had normal MRIs, six were technically inadequate due to movement artifact and could not be reliably interpreted. None of these imaging studies were repeated., There is an extremely high incidence of abnormal MRI findings among those patients were coded as having focal epilepsy based on EEG findings.
There is an unacceptably low rate of follow-through with neuroimaging in this population. Even when imaging was performed, suboptimal studies which were inadequate to detect subtle abnormalities such as cortical dysplasia, were not repeated.
All patients coded as having focal epilepsy on EEG findings should undergo a high-quality epilepsy protocol MRI scan.
In this population many studies are suboptimal due to movement artifact. Given the high instance of abnormalities in this poplulation, these studies should be repeated under general anesthetic if necessary.
Original films should be reviewed by the clinician in the light of localizing information obtained from EEG or clinical semiology.,