Diffusion tensor imaging predicts cognitive function change following partial brain radiotherapy for low-grade and benign tumors.

PURPOSE/OBJECTIVES: Radiation injury to parahippocampal cingulum white matter is associated with cognitive decline. Diffusion tensor imaging (DTI) detects micropathologic changes in white matter. Increased radial diffusion (RD) and decreased axial diffusion (AD) correspond to demyelination and axonal degeneration/gliosis respectively. We aimed to develop a predictive model for radiation-induced cognitive changes based upon DTI changes. MATERIALS/METHODS: Twenty-seven adults with benign or low-grade tumors received partial brain radiation therapy (RT) to a median dose of 54Gy. Patients underwent DTI before RT, during RT, and at the end of RT. Cognitive testing was performed before RT, and 6 and 18months after RT. Parahippocampal cingulum white matter was contoured to obtain mean values of AD and RD. RESULTS: By univariate analysis, decreasing AD and increasing RD during RT predicted declines in verbal memory and verbal fluency. By multivariate analysis, baseline neurocognitive score was the only clinical variable predicting verbal memory change; no clinical variables predicted verbal fluency change. In a multivariate model, increased RD at the end of RT significantly predicted decline in verbal fluency 18months after RT. CONCLUSIONS: Imaging biomarkers of white matter injury contributed to predictive models of cognitive function change after RT.

One center's experience with complications during the Wada test.

This study aimed to define the number and type of complications associated with the Wada test at an academic medical center for comparison to previous reports. We performed a retrospective review of medical records for patients who underwent the Wada test at the University of Michigan between April 1991 and June 2013. Information was collected regarding the angiography procedure and the immediate postoperative period to assess for both clinical and angiographic complications. A total of 436 patients were identified who underwent the Wada procedure between April 1991 and June 2013, and 431 patients were included in the final analysis. Twenty-five patients (5.8%) had notable clinical events associated with the Wada test. Nine patients (2.1%) had clinical events meeting criteria for complication, which included seizures, status epilepticus, internal carotid artery vasospasm, inadvertent injection of anesthetic in the external carotid artery, and transient encephalopathy. No complications were associated with significant morbidity or mortality. This retrospective review of patients undergoing the Wada test found significantly fewer associated complications in comparison to previously published studies, with no patients experiencing long-term morbidity. The Wada test should be considered a safe diagnostic tool for lateralizing language and memory.

The hidden structure of neuropsychology: text mining of the journal Cortex: 1991--2001.

BACKGROUND: The stated mission of Cortex is "the study of the inter-relations of the nervous system and behavior, particularly as these are reflected in the effects of brain lesions on cognitive functions." The purpose of this paper is to explore the relationship between the stated mission and the executed mission as reflected by the characteristics of papers published in Cortex. In addition, we examine whether the results and conclusions of an analysis of this kind are affected by the level of description of the published papers. OBJECTIVES: A) Identify characteristics of contributors to Cortex; B) Identify characteristics of those who cite Cortex; C) Identify recurring themes; D) Identify the relationships among the recurring themes; E) Compare recurring themes and determine their relationships to the mission of Cortex; F) Identify the sensitivity of these results to the level of description of the Cortex papers used as the source database. G) Compare Cortex characteristics with those of Neuropsychologia, another Europe-based international neuropsychology journal. METHODS: Text mining (extraction of useful information from text) was used to generate the characteristics of the journal Cortex. Bibliometrics provided the Cortex contributor infrastructure (author/ organization/ country/ citation distributions), and computational linguistics identified the recurring technical themes and their inter-relationships. Citation mining (the integration of citation bibliometrics and text mining) was used to profile the research user community. Four levels of published article description were compared for the analysis: Full Text, Abstract, Title, Keywords. RESULTS AND CONCLUSIONS: Highly cited documents were compared among Cortex, Neuropsychologia, and Brain, and a number of interesting parametric trends were observed. The characteristics of the papers that cite Cortex papers were examined, and some interesting insights were generated. Finally, the document clustering taxonomy showed that papers in Cortex can be reasonably divided into four categories (papers in each category in parenthesis): Semantic Memory (151); Handedness (145); Amnesia (119); and Neglect (66). It is concluded that Cortex needs to take steps to attract a more diverse group of contributors outside its continental Western European base if it wishes to capture a greater share of seminal neuropsychology papers. Further investigation of the critical citation differences reported in the paper is recommended.

Sodium methohexital (brevital) as an anesthetic in the Wada test.

PURPOSES: We report our experience with sodium methohexital (Brevital) as an anesthetic used in the Wada test for language and memory in 86 epilepsy surgery patients (173 procedures). METHODS: The methods are compared with those of the more commonly used anesthetic sodium amobarbital (Amytal). RESULTS: Despite differences between the methohexital and amobarbital test protocols, the behavioral and neurologic effects of the two anesthetics are similar. Because of the brief duration of methohexital, two successive injections are made on each side rather than one, to lengthen the time available for testing both language and memory. Behavioral and EEG indices return to baseline more quickly and more completely with methohexital than with amobarbital, allowing several repetitions of the procedure without incremental drowsiness, and the total time taken for the procedure is less with methohexital than with amobarbital. CONCLUSIONS: The results of language and memory testing in the Wada test are equivalent for amobarbital and methohexital, except that methohexital has a briefer duration of action and is associated with less sedation.