Unexpected brain imaging findings in patients with seizures

Abstract

New imaging technologies have advanced our ability to localize the epileptogenic zone in patients with epilepsy. As a result of the constant improvement of the image quality, magnetic resonance imaging (MRI) has become the most important ancillary tool in the management of patients with epilepsy. Magnetic resonance imaging for the evaluation of patients with epilepsy should be done using a special temporal lobe protocol and read by physicians experienced with the findings in patients with epilepsy. On the other hand, in the healthy populations, incidental structural brain abnormalities have been reported in 18% of people. Incidental, subtle, or unexpected structural brain abnormalities have also been reported in many patients who were investigated because of having seizures. In the current narrative review, we will discuss some of these instances, where structural brain abnormalities are discovered unexpectedly, are subtle (but important) and/or may be considered as incidental.

A minority of patients with functional seizures have abnormalities on neuroimaging

“…This cognitive bias is present when the result of a study is influenced by how the study is presented or how the question is asked [93]. Many neuroimaging findings associated with medication resistant epilepsy are subtle and are appreciated better with specialized imaging protocols [8,20,94,95]. Even though 45% of our MRIs were obtained at 3T and 23% were obtained with epilepsy protocol, the radiologists were challenged to evaluate uniformly for subtle, clinically relevant findings in a non-ideal setting.…”

“…Consequently, clinicians may presume that neuroimaging of patients with FS would be normal, and abnormal neuroimaging should cast doubt on the diagnosis. However, multiple retrospective studies have demonstrated radiologically apparent abnormalities in 30% of magnetic resonance images (MRIs) from patients with FS without comorbid ES [7][8][9][10][11][12][13][14]. While the majority of these abnormalities were nonspecific, two previous studies found that 5-10% of them had definitive epilepsy-associated findings (EAF) including hippocampal sclerosis [7,10].…”

“…This rate of nonspecific abnormalities is markedly higher than healthy controls, who typically have nonspecific findings on 2-18% of MRIs, with the rate of EAF being too low to quantify reliably [15][16][17][18][19][20][21][22][23][24]. In the years following most of these prior studies, the development of epilepsy-specific scanning protocols and widespread adoption of 3 Tesla scanners have led to higher image quality and sensitivity for subtle abnormalities [8,25]. In patients with temporal lobe epilepsy with hippocampal sclerosis, 86% of 1.5 Tesla MRIs using standard protocols failed to illustrate this key finding [26,27].…”

Structural Changes in Brain Magnetic Resonance Imaging Associated With Psychogenic Non-epileptic Seizures: An Analytical Cross-Sectional Study

“…Combination PNES/epilepsy patients were more likely to have epileptogenic structural brain abnormalities (such as tumors, mesial temporal sclerosis, encephalomalacia, and developmental anomalies [23]. However, previous studies, including ours, lacked adequacy due to being ex post facto and not including healthy controls [16][17][18][19][20].…”

“…Only about a quarter of the 130 participants with PNES in this study had a brain MRI. In most cases, it is clinically reasonable and appropriate to do a magnetic resonance imaging scan of the brain of individuals with epilepsy [ 17 ]. Sixty percent of patients in recent studies of 224 people with PNES solely had brain MRI [ 18 ].…”