Auditory-verbal analysis in aphasia

Background: Comprehension deficits are more pervasive in aphasic syndromes than initially believed. They affect differentially distinct levels of auditory-verbal comprehension. Current evidence from functional imaging studies in healthy subjects indicates that distinct levels of auditory-verbal analysis involve specific networks.

Aims: The aim of this study is (1) to assess the different levels of auditory-verbal analysis with real-time monitoring tasks in patients with aphasia, (2) to compare the performance profiles across aphasia types, (3) to analyse patterns of dissociations vs. co-occurrence at specific levels, and (4) to establish correlations between disturbances at specific levels of auditory-verbal analysis and sites of lesions.

Methods & Procedures: Forty-two right-handed patients with aphasia associated with a first unilateral left-hemispheric lesion underwent tests monitoring (1) phonetic-phonological, (2) lexical, (3) morphosyntactic, (4) semantic-pragmatic (at sentence level), and (5) linguistic prosody processing. Anatomo-clinical correlations were established by means of voxel-based lesion-symptom mapping.

Outcomes & Results: Widespread deficits at multiple levels occurred across aphasic syndromes. In a given patient, more levels tended to be impaired in Wernicke’s and global aphasia than in Broca’s or conduction aphasia. Syllable and word processing double-dissociated behaviourally and partially anatomically. Morphosyntactic deficits were always accompanied by semantic-pragmatic deficits. Anatomo-clinical correlations implicated the dorsal auditory stream in syllable discrimination, the ventral stream in semantic processing at lexical level and in linguistic prosody and both streams in lexical frequency effect. Basal ganglia were implicated in syntactic and semantic processing at sentence level.

Conclusions: At prelexical and lexical levels, syllable and word processing appear to be independent of each other. At sentence level, parsing of syntactic structure appears to be necessary for successful semantic-pragmatic analysis. Thus, the fine-grained evaluation of auditory-verbal processing capacities and of the integrity of specialised processing networks in brain-damaged patients provides a sensitive diagnostic tool.     

Cost-utility analysis in schizophrenia

Estimation of quality of life is important to the study of the pharmacoeconomics of schizophrenia. The subject has gained popularity among policymakers, clinicians, and patients and their families, since the advent of new antipsychotic medications that are more expensive than older drugs yet have been shown to cause fewer side effects. Quantifying quality of life has been difficult, since studies often inconsistently define the concept or use rating scales that are inappropriate for the patient population. Utility analysis is a procedure that calculates subjects' preferences regarding living with various health states, given such options as trading more years of life at a lowered health state for dying sooner but having a strong health state during the last years of life. The feasibility of performing utility analysis among patients with schizophrenia was recently examined in a study carried out by the authors. This article reflects initial observations from that study of utility analysis and includes a discussion of problems still facing the study of quality of life and utility analysis.     

HBM functional imaging analysis contest data analysis in wavelet space

An analysis of the Functional Imaging Analysis Contest (FIAC) data is presented using spatial wavelet processing. This technique allows the image to be filtered adaptively according to the data itself, rather than relying on a predetermined filter. This adaptive filtering leads to better estimation of the parameters and contrasts in terms of mean squared error. It will be shown that by introducing a slight bias into the estimation, a large reduction in the variance can be achieved, leading to better overall mean squared error estimates. As no single filter needs to be preselected, results containing many scales of information can be found. In the FIAC data, it is shown that both small-scale and large-scale (smoother, more dispersed) effects occur. The combination of small- and large-scale effects detected in the FIAC data would be easy to miss using conventional single filter analysis.     

Turns-amplitude analysis and motor unit potential analysis in myasthenia gravis

OBJECTIVES: The aims of this study were to investigate myopathic changes in myasthenia gravis (MG) by using turns-amplitude analysis (TAA) and quantitative motor unit potential duration analysis (MUPan), to correlate myopathic changes with severity and duration of the disease and the results of diagnostic tests including repetitive nerve stimulation test (RNS), single fiber electromyography (SFEMG), and anti-acetylcholine receptor antibody (AChR-ab), and to compare the sensitivities of these two methods in detecting myopathic changes in MG. MATERIALS AND METHODS: We studied both MUPan and TAA in 32 patients with MG. RESULTS: The MUPan study showed myopathic changes in 12 patients (37.5%); TAA revealed a myopathic pattern in 4 (12.5%) and a neurogenic pattern in 4 cases (12.5%). Two of the 4 patients with a myopathic change by TAA also had short-duration mean MUP on the MUPan. No statistically significant association was found between the myopathic changes either by MUPan or TAA, and the various clinical and laboratory features. CONCLUSION: We conclude that MUPan is a more sensitive method than TAA in showing myopathic changes in MG, and that TAA is of limited help in demonstrating them.