Temporal lobe epilepsy and affective disorders: the role of the subgenual anterior cingulate cortex

OBJECTIVE

Reduced deactivation within the default mode network (DMN) is common in individuals with primary affective disorders relative to healthy volunteers (HVs). It is unknown whether similar network abnormalities are present in temporal lobe epilepsy (TLE) patients with a history of affective psychopathology.

METHODS

17 TLE patients with a lifetime affective diagnosis, 31 TLE patients with no formal psychiatric history and 30 HVs were included. We used a visuo-spatial 'n-back' paradigm to compare working memory (WM) network activation between these groups. Post hoc analyses included voxel-based morphometry and diffusion tensor imaging. The Beck Depression Inventory-Fast Screen and Beck Anxiety Inventory were completed on the day of scanning.

FINDINGS

Each group activated the fronto-parietal WM networks and deactivated the typical DMN in response to increasing task demands. Group comparison revealed that TLE patients with lifetime affective morbidity showed significantly greater deactivation in subgenual anterior cingulate cortex (sACC) than either the TLE-only or the HVs (p<0.001). This effect persisted after covarying for current psychotropic medication and severity of current depressive/anxiety symptoms (all p<0.001). Correlational analysis revealed that this finding was not driven by differences in task performance. There were no significant differences in grey matter volume or structural connectivity between the TLE groups.

CONCLUSIONS

Our results provide novel evidence suggesting that affective psychopathology in TLE has a neurobiological correlate, and in this context the sACC performs differently compared with network activity in primary affective disorders.

Clinical language fMRI with real-time monitoring in temporal lobe epilepsy: online processing methods

The increasing demand for clinical fMRI data has resulted in a need to translate research methods to clinical use. Referrals for language lateralization prior to epilepsy surgery are becoming more common, but time constraints make this unachievable in many busy neuroimaging departments. This study examines whether a single covert verbal fluency paradigm with real-time monitoring and online processing (BrainWave) could replace conventional offline processing (SPM) for the purpose of establishing expressive language dominance prior to epilepsy surgery. We analyzed language fMRI results of 30 patients (17 female; 24 right-handed; median age: 30.5) with temporal lobe epilepsy. Concordance between visual assessment of SPM and BrainWave was 92.8%. Lateralization indices correlated closely with visual assessments of lateralization with a concordance of 85.7%. BrainWave provided a real-time, fast and accurate display of language lateralization easily applied in a clinical setting using only online image processing.

Neural correlates of working memory in Temporal Lobe Epilepsy--an fMRI study

It has traditionally been held that the hippocampus is not part of the neural substrate of working memory (WM), and that WM is preserved in Temporal Lobe Epilepsy (TLE). Recent imaging and neuropsychological data suggest this view may need revision. The aim of this study was to investigate the neural correlates of WM in TLE using functional MRI (fMRI). We used a visuo-spatial 'n-back' paradigm to compare WM network activity in 38 unilateral hippocampal sclerosis (HS) patients (19 left) and 15 healthy controls. WM performance was impaired in both left and right HS groups compared to controls. The TLE groups showed reduced right superior parietal lobe activity during single- and multiple-item WM. No significant hippocampal activation was found during the active task in any group, but the hippocampi progressively deactivated as the task demand increased. This effect was bilateral for controls, whereas the TLE patients showed progressive unilateral deactivation only contralateral to the side of the hippocampal sclerosis and seizure focus. Progressive deactivation of the posterior medial temporal lobe was associated with better performance in all groups. Our results suggest that WM is impaired in unilateral HS and the underlying neural correlates of WM are disrupted. Our findings suggest that hippocampal activity is progressively suppressed as the WM load increases, with maintenance of good performance. Implications for understanding the role of the hippocampus in WM are discussed.

A prospective study comparing rapid assessment of smears and ThinPrep for endoscopic ultrasound-guided fine-needle aspirates

BACKGROUND AND STUDY AIMS

ThinPrep is often used for endoscopic ultrasound fine-needle aspiration (EUS-FNA) samples but the sensitivity of this method is unknown. The objective of the study was to compare sensitivity and accuracy of ThinPrep versus the smear method in pancreas and lymph node samples obtained by EUS-FNA.

PATIENTS AND METHODS

Patients with suspected malignancy in the pancreas or lymph node underwent EUS-FNA. On-site rapid assessment of all aspirates using the smear method was performed. After rapid assessment, three additional passes from each site were submitted into ThinPrep liquid medium. Cytopathologists interpreting the smear method and ThinPrep slides were blinded to each other. The gold standard was final cytology or pathology results.

RESULTS

A total of 130 patients (36 % women, mean age 63 years) underwent EUS-FNA of 139 sites (50 pancreas, 89 lymph node). Malignancy was confirmed in 47 pancreas samples (94 %) and 48 lymph node samples (54 %). Mean +/- SD number of passes made for the smear method was 2.6 +/- 1.3. For pancreatic cancer, the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of the ThinPrep versus the smear method were: 62 % versus 98 %, 100 % versus 100 %, 100 % versus 100 %, 14 % versus 75 %, and 64 % versus 98 %, respectively. For lymph nodes the values were 67 % versus 92 %, 100 % versus 98 %, 100 % versus 98 %, 72 % versus 72 %, and 82 % versus 94 %, respectively.

CONCLUSIONS

The smear method is more sensitive and accurate than ThinPrep in detecting malignancy from EUS-FNA samples of the pancreas and lymph nodes. Smear method with on-site rapid assessment should be favored over ThinPrep in suspected malignancy.

A review of structural magnetic resonance neuroimaging

Magnetic resonance imaging (MRI) is often divided into structural MRI and functional MRI (fMRI). The former is a widely used imaging technique in research as well as in clinical practice. This review describes the more important developments in structural MRI in recent years, including high resolution imaging, T2 relaxation measurement, T2*-weighted imaging, T1 relaxation measurement, magnetisation transfer imaging, and diffusion imaging. The principles underlying these techniques, as well as their use in research and in clinical practice, will be discussed.

A study of bipolar disorder using magnetization transfer imaging and voxel-based morphometry

Bipolar disorder (BP) traditionally has been considered as a recurrent illness with full recovery between episodes, and the absence of neuropathological abnormalities has usually been taken for granted. In recent times, the realization that, for many BP carries a poor prognosis, that cognitive deficits are often persistent and that structural brain abnormalities are detectable with modern imaging techniques has spurred the search for its neuropathological substrate. The shortcomings of post-mortem studies make the use of imaging techniques sensitive to neuropathological changes compelling. We report here the first study of BP patients using two such techniques in conjunction: magnetization transfer imaging (MTI) and voxel-based morphometry (VBM). Thirty-nine patients with BP (13 males and 26 females; 28 with BPI and 11 with BPII) and 35 healthy controls were investigated. Both high-resolution volumetric T1-weighted images and MT images were acquired from all subjects. Images were processed using a voxel-by-voxel analysis in statistical parametric mapping 2 (SPM2). The magnetization transfer ratio MTR, an index indicative of loss of macromolecular density, was reduced in the right subgenual anterior cingulate and adjacent white matter in bipolar patients compared with controls. VBM did not reveal significant volumetric differences between BP patients and controls in grey and white matter, but white matter density was significantly reduced bilaterally in prefrontal areas encompassing fronto-striatal connections. Our findings suggest that subtle abnormalities are present in the anterior cingulate and subgyral white matter in patients with BP in the absence of significant volumetric changes. These findings are in keeping with those of previously reported neuropathological studies and illustrate important similarities (involvement of the anterior cingulate) and differences (lack of widespread cortical abnormalities in BP) with our previous studies in schizophrenic patients using the same methodology.