Faculty Bibliography

Purpose: To examine distributed patterns of language processing in healthy controls and patients with epilepsy using magnetoencephalography (MEG), and to evaluate the concordance between laterality of distributed MEG sources and language laterality as determined by the intracarotid amobarbital procedure (IAP). Methods: MEG was performed in 10 healthy controls using an anatomically constrained, noise-normalized distributed source solution (dynamic statistical parametric map, dSPM). Distributed source modeling of language was then applied to eight patients with intractable epilepsy. Average source strengths within temporoparietal and frontal lobe regions of interest (ROIs) were calculated, and the laterality of activity within ROIs during discrete time windows was compared to results from the IAP. Results: In healthy controls, dSPM revealed activity in visual cortex bilaterally from approximately 80 to 120 ms in response to novel words and sensory control stimuli (i.e., false fonts). Activity then spread to fusiform cortex approximately 160-200 ms, and was dominated by left hemisphere activity in response to novel words. From approximately 240 to 450 ms, novel words produced activity that was left-lateralized in frontal and temporal lobe regions, including anterior and inferior temporal, temporal pole, and pars opercularis, as well as bilaterally in posterior superior temporal cortex. Analysis of patient data with dSPM demonstrated that from 350 to 450 ms, laterality of temporoparietal sources agreed with the IAP 75% of the time, whereas laterality of frontal MEG sources agreed with the IAP in all eight patients. Discussion: Our results reveal that dSPM can unveil the timing and spatial extent of language processes in patients with epilepsy and may enhance knowledge of language lateralization and localization for use in preoperative planning

The Neuropsychological Screening Battery for Hispanics (NeSBHIS) was developed to address the growing need for linguistically appropriate Spanish-language assessment measures. Despite the potential benefits to clinical practice, no prior study has assessed its diagnostic validity in populations with epilepsy. One hundred and fifteen patients with confirmed epilepsy were evaluated via the NeSBHIS; these data were standardized according to age- and education-based norms. Performance decrements were observed in more than 40% of participants on measures of processing speed and naming. Deficits in verbal and visual recall were also exhibited by 29 and 26% of the sample, respectively. No significant differences in test performance emerged between patients with VEEG evidence of left (N=48) versus right (N=24) temporal lobe epilepsy. Although the NeSBHIS is sensitive to the cognitive impairments commonly observed in populations with epilepsy, there are limitations to its ability to identify lateralized neuropsychological impairment in patients with temporal lobe epilepsy

The diagnosis and treatment of mild traumatic brain injury (MTBI)have historically been hampered by an incomplete base of scientific evidence to guide clinicians. One question has been most elusive to clinicians and researchers alike: What is the true natural history of MTBI? Fortunately, the science of MTBI has advanced more in the last decade than in the previous 50 years, and now reaches a maturity point at which the science can drive an evidence-based approach to clinical management. In particular, technological advances in functional neuroimaging have created a powerful bridge between the clinical and basic science of MTBI in humans. Collectively, findings from clinical, basic science, and functional neuroimaging studies now establish a foundation on which to build integrative theories and testable hypotheses around a comprehensive model of MTBI recovery. We review the current scientific literature on postconcussion symptom recovery, neuropsychological outcome, and neurophysiological healing after MTBI. Special emphasis is placed on how the new evidence base can help guide clinicians in the evaluation and management of military-related MTBI

Data from lesion studies suggest that the ability to perceive speech sounds, as measured by auditory comprehension tasks, is supported by temporal lobe systems in both the left and right hemisphere. For example, patients with left temporal lobe damage and auditory comprehension deficits (i.e., Wernicke's aphasics), nonetheless comprehend isolated words better than one would expect if their speech perception system had been largely destroyed (70-80% accuracy). Further, when comprehension fails in such patients their errors are more often semantically-based, than-phonemically based. The question addressed by the present study is whether this ability of the right hemisphere to process speech sounds is a result of plastic reorganization following chronic left hemisphere damage, or whether the ability exists in undamaged language systems. We sought to test these possibilities by studying auditory comprehension in acute left versus right hemisphere deactivation during Wada procedures. A series of 20 patients undergoing clinically indicated Wada procedures were asked to listen to an auditorily presented stimulus word, and then point to its matching picture on a card that contained the target picture, a semantic foil, a phonemic foil, and an unrelated foil. This task was performed under three conditions, baseline, during left carotid injection of sodium amytal, and during right carotid injection of sodium amytal. Overall, left hemisphere injection led to a significantly higher error rate than right hemisphere injection. However, consistent with lesion work, the majority (75%) of these errors were semantic in nature. These findings suggest that auditory comprehension deficits are predominantly semantic in nature, even following acute left hemisphere disruption. This, in turn, supports the hypothesis that the right hemisphere is capable of speech sound processing in the intact brain.

The aim of the study was to compare the performance of Robust and Conventional neuropsychological norms in predicting clinical decline among healthy adults and in mild cognitive impairment (MCI). The authors developed Robust baseline cross sectional and longitudinal change norms from 113 healthy participants retaining a normal diagnosis for at least 4 years. Baseline Conventional norms were separately created for 256 similar healthy participants without follow-up. Conventional and Robust norms were tested in an independent cohort of longitudinally studied healthy (n=223), MCI (n=136), and Alzheimer's disease (AD, n=162) participants; 84 healthy participants declined to MCI or AD (NL-->DEC), and 44 MCI declined to AD (MCI-->AD). Compared to Conventional norms, baseline Robust norms correctly identified a higher proportion of NL-->DEC with impairment in delayed memory and attention-language domains. Both norms predicted decline from MCI-->AD. Change norms for delayed memory and attention-language significantly incremented baseline classification accuracies. These findings indicate that Robust norms improve identification of healthy individuals who will decline and may be useful for selecting at-risk participants for research studies and early interventions

OBJECTIVE: Divergent findings among prior studies on correlates of risk for postictal psychosis (PIP) suggest the value of a controlled study involving a relatively large number of patients. METHODS: The study population consisted of a consecutive series of 59 patients with partial epilepsy and a history of PIP, and 94 control patients with partial epilepsy and no history of PIP evaluated as inpatients with video-electroencephalography. The groups did not differ significantly regarding demographic features. Exact tests yielded a subset of variables and a tentative interpretation that were evaluated further utilizing principal components analysis and logistic regression. RESULTS: PIP was associated with extratemporal versus temporal (p = 0.036) or undetermined (p = 0.001) localization of seizure onset, bilateral interictal epileptiform activity (p = 0.017), secondary generalization (p = 0.049), and history of encephalitis (p = 0.018). Interictal slow activity was more frequently absent in control patients (p = 0.045). PIP was associated with family histories of psychiatric disorders (p = 0.007) and epilepsy (p = 0.042), which themselves were significantly intercorrelated (r = 0.225; p = 0.006). Age of onset or duration of epilepsy and lateralized electroencephalographic or magnetic resonance imaging asymmetries did not differ significantly between control and PIP groups. The analysis indicated four underlying domains of risk for PIP: ambiguous/extratemporal localization, family neuropsychiatric history, abnormal interictal electroencephalographic activity, and encephalitis. Each unit increase on a simple additive scale composed of 9 dichotomous independent variables multiplied the odds ratio for PIP by 1.71 (95% confidence interval, 1.36-2.15; p < 0.0001). INTERPRETATION: PIP in partial epilepsy is associated with relatively broadly and bilaterally distributed epileptogenic networks, genetic determinants of psychiatric disorders and seizures, and encephalitis