Objective: To further evaluate the relationship between the clinical profiles and limbic and motor brain regions and their connecting pathways in psychogenic nonepileptic seizures (PNES). Neurite Orientation Dispersion and Density Indices (NODDI) multicompartment modeling was used to test the relationships between tissue alterations in patients with traumatic brain injury (TBI) and multiple psychiatric symptoms.Methods: The sample included participants with prior TBI (TBI; N = 37) but no PNES, and with TBI and PNES (TBI + PNES; N = 34). Participants completed 3T Siemens Prisma MRI high angular resolution imaging diffusion protocol. Statistical maps, including fractional anisotropy (FA), mean diffusivity (MD), neurite dispersion [orientation dispersion index (ODI)] and density [intracellular volume fraction (ICVF), and free water (i.e., isotropic) volume fraction (V‐ISO)] signal intensity, were generated for each participant. Linear mixed‐effects models identified clusters of between‐group differences in indices of white matter changes. Pearson’s r correlation tests assessed any relationship between signal intensity and psychiatric symptoms.Results: Compared to TBI, TBI + PNES revealed decreases in FA, ICVF, and V‐ISO and increases in MD for clusters within cingulum bundle, uncinate fasciculus, fornix/stria terminalis, and corticospinal tract pathways (cluster threshold α = 0.05). Indices of white matter changes for these clusters correlated with depressive, anxiety, PTSD, psychoticism, and somatization symptom severity (FDR threshold α = 0.05). A follow‐up within‐group analysis revealed that these correlations failed to reach the criteria for significance in the TBI + PNES group alone.Interpretation: The results expand support for the hypothesis that alterations in pathways comprising the specific PNES network correspond to patient profiles. These findings implicate myelin‐specific changes as possible contributors to PNES, thus introducing novel potential treatment targets.

Magnetic resonance imaging of hippocampal internal architecture (HIA) at 3T is challenging. HIA is defined by layers of gray and white matter that are less than 1 mm thick in the coronal plane. To visualize HIA, conventional MRI approaches have relied on sequences with high in-plane resolution (≤0.5 mm) but comparatively thick slices (2–5 mm). However, thicker slices are prone to volume averaging effects that result in loss of HIA clarity and blurring of the borders of the hippocampal subfields in up to 61% of slices as has been reported. In this work we describe an approach to hippocampal imaging that provides consistently high HIA clarity using a commonly available sequence and post-processing techniques that is flexible and may be applicable to any MRI platform. We refer to this approach as High Resolution Multiple Image Co-registration and Averaging (HR-MICRA). This approach uses a variable flip angle turbo spin echo sequence to repeatedly acquire a whole brain T2w image volume with high resolution in three dimensions in a relatively short amount of time, and then co-register the volumes to correct for movement and average the repeated scans to improve SNR. We compared the averages of 4, 9, and 16 individual scans in 20 healthy controls using a published HIA clarity rating scale. In the body of the hippocampus, the proportion of slices with good or excellent HIA clarity was 90%, 83%, and 67% for the 16x, 9x, and 4x HR-MICRA images, respectively. Using the 4x HR-MICRA images as a baseline, the 9x HR-MICRA images were 2.6 times and 16x HR-MICRA images were 3.2 times more likely to have high HIA ratings (p < 0.001) across all hippocampal segments (head, body, and tail). The thin slices of the HR-MICRA images allow reformatting in any plane with clear visualization of hippocampal dentation in the sagittal plane. Clear and consistent visualization of HIA will allow application of this technique to future hippocampal structure research, as well as more precise manual or automated segmentation.

Summary: The purpose of this study is to examine the pattern of mesial temporal lobe activity in patients with left mesial temporal sclerosis (LMTS) and normal control subjects during a verbal memory task using magnetoencephalography. Six LMTS patients and seven normal control subjects performed a word recognition task while event-related neuromagnetic responses were recorded for 248 trials in each of two runs. An equivalent current dipole model was used to localize activity sources and determine if the right or left mesial temporal lobe was active. All six (100%) LMTS patients but only two (28%) normal control subjects had right mesial temporal activity (P < 0.02). Two (33%) LMTS patients and 6 (86%) normal control subjects had left mesial temporal activity (P = 0.27). No significant differences in latency or duration of activity were seen between left and right sides or between groups. Our data suggest that patients with left hippocampal dysfunction are more likely to recruit the right mesial temporal lobe during verbal memory tasks than normal control subjects. A trend toward less left mesial temporal activity in LMTS patients is seen as well. Further study is needed to determine the predictive value of this technique regarding postresection memory outcome.