HLA-DR polymorphisms influence in vivo responses to staphylococcal toxic shock syndrome toxin-1 in a transgenic mouse model

Toxic shock syndrome toxin-1 (TSST-1) is a potent superantigen produced by Staphylococcus aureus. In addition to menstrual and nonmenstrual toxic shock syndromes, TSST-1 is also implicated in the immunopathogenesis of pneumonia, infective endocarditis, neonatal exanthematous disease, and atopic dermatitis among others. Superantigens first bind to major histocompatibility complex (MHC) class II molecules and then activate a large proportion of T cells by cross-linking their T cell receptor. As binding to MHC class II molecules is a critical step in the robust activation of the immune system by TSST-1 and other superantigens, polymorphic variations between different HLA-DR alleles could potentially influence the magnitude of immune activation and immunopathology caused by TSST-1. As TSST-1 is highly toxic to humans and given that multiple variations of alleles of HLA-DR and HLA-DQ are expressed in each individual, it is difficult to determine how HLA-DR polymorphisms quantitatively and qualitatively impact immune activation caused by TSST-1 in humans. However, such investigations can be conducted on transgenic mice lacking all endogenous MHC class II molecules and expressing specific HLA class II alleles. Therefore, transgenic mice expressing different HLA-DRB1 alleles (HLA-DRB1*15:01, HLA-DRB1*15:02, HLA-DRB1*03:01, HLA-DRB1*04:01), and sharing HLA-A1*01:01 chain, were systemically challenged with purified TSST-1 and multiple immune parameters were assessed. Among the HLA-DR alleles, mice expressing HLA-DRB1*15:01 allele elicited a significantly higher serum cytokine/chemokine response; greater splenic T cell expansion and most severe organ pathology. Our study highlights the potential utility of human leukocyte antigen (HLA) transgenic mice in understanding the impact of HLA polymorphisms on the outcomes of diseases caused by TSST-1 and other superantigens.

Temporal IgG Subtype Changes in Recurrent Idiopathic Membranous Nephropathy

Determination of the IgG subtypes within the immune deposits in membranous nephropathy (MN) may be helpful in the differential diagnosis. IgG4 is the predominant subtype in idiopathic MN and recurrent MN, while IgG1, IgG2, and IgG3 subtypes are more common in secondary MN and de novo disease in the allograft. The temporal change of IgG subclasses in individual patients and its correlation with clinical variables have not been studied. We reviewed all posttransplantation protocol and indication biopsies (49) in 18 patients with recurrent MN who underwent transplantation at our center between 1998 and 2013 and performed IgG subtyping (IgG1-4). We tested serum for M-type phospholipase A2 receptor (PLA2 R) autoantibodies or performed PLA2 R antigen staining on the kidney biopsy. IgG4 was the (co)dominant IgG subtype in 10 of 14 biopsies at the diagnosis of recurrence regardless of PLA2 R association. In 8 of 12 transplantations with serial biopsies, the (co)dominant subtype did not change over time. There was a trend toward IgG1 and IgG3 (co)dominance in biopsies >1 year from recurrence and more IgG1 (co)dominant subtyping in the setting of more-advanced EM deposits. Treatment with rituximab did not affect the IgG subtype. In conclusion, the dominant IgG subtype did not change over time in recurrent MN.

Impulsivity and risk-taking behavior in focal frontal lobe lesions

Frontal lobe dysfunction may underlie excessively impulsive and risky behavior observed in a range of neurological disorders. We devised a gambling task to examine these behavior tendencies in a sample of patients who had sustained focal damage to the frontal lobes or nonfrontal cortical regions as well as in a matched sample of healthy control subjects. The main objectives of the study were: (1) to behaviorally dissociate impulsivity and risk-taking; (2) to examine potential associations between specific frontal lesion sites and impulsivity or risk-taking; (3) to investigate the influence of reinforcement and trial timing on both behaviors. Our results indicated that patients and controls were equally likely to perform impulsively. Risk-taking performance strategies, however, were related to left ventrolateral and orbital lesion sites. Moreover, risk-taking was also associated with blunted response alteration following a nonrewarded trial. Patients and control subjects showed identical responses to reward-timing manipulations consistent with formal decision-making theory. These findings suggest that ventrolateral and orbital lesions are related to the reward-based aspects of decision-making (risk-taking) rather than to simple response disinhibition (impulsivity). Reduced reaction to the negative consequences of one's actions may underlie this behavior pattern.

Regional frontal injuries cause distinct impairments in cognitive control

BACKGROUND

Lesions of the frontal lobes may impair the capacity of patients to control otherwise intact cognitive operations in the face of ambiguous sensory input or conflicting possible responses.

OBJECTIVE

To address the question of whether focal lesions in different regions of the frontal lobes produced specific impairments in cognitive control.

METHODS

We evaluated 42 patients with chronic frontal lesions and 38 control subjects on a modified Stroop test that allowed measurement of reaction times and errors. Planned, stratified analyses permitted identification of discrete frontal lesions that are critical for impaired performance.

RESULTS

Lesions of the left ventrolateral region produced an increased number of incorrect responses to distractors. Lesions of a large portion of the right superior medial region, including anterior cingulate, supplementary motor area (SMA), pre-SMA, and dorsolateral areas, caused a slow reaction time and a decreased number of correct responses to targets.

CONCLUSION

Lesions in two distinct frontal regions impair cognitive control for a Stroop task, and the mechanisms of impairment are specific to the region of injury. This is support for a general proposal that the supervisory system is constructed of distinct subsystems.

Impaired concentration due to frontal lobe damage from two distinct lesion sites

BACKGROUND

Investigations of cognitive deficits after frontal lobe damage have commonly relied on multidimensional tests and relatively coarse specification of lesion anatomy. Some form of impairment in attention is often asserted to cause the revealed deficits.

OBJECTIVE

To describe a disorder of attention in patients with frontal damage using a theoretical model of the fundamental cognitive processes that underlie attention.

METHODS

The ability to perform a task of concentrated responding was studied in 43 patients with well-defined chronic frontal lesions and 38 control subjects using a continuous reaction time (RT) test. Performance measures were mean RT, RT across blocks of the test, and errors. Lesion measures were coarse localization and a hot-spot analysis to detect finer grained lesion effects.

RESULTS

Only patients with lesions in the right superomedial (SM) frontal regions had significantly prolonged RT consistently across the entire test. The critical lesion was in Brodmann's areas 24, 32, 9, and 46 days and in the adjacent corpus callosum. Patients with lesions in left lateral frontal (LL) regions made significantly more errors on the 20% of trials in the first block. The critical lesion was in areas 44, 45, and 47/12.

CONCLUSION

Concentrating attention to respond is affected by lesions in two different frontal regions for reasons that reflect impairments in different cognitive processes. Right superomedial lesions cause an insufficient energizing of attention to respond. Left lateral lesions cause defective setting of specific stimulus-response contingencies. Constrained tests of attention can demonstrate impairments in specific cognitive operations following lesions to different regions of the frontal lobes.

MEG analysis of "theory of mind" in emotional vignettes comprehension

OBJECTIVE

Several studies suggested that an impaired "theory of mind" might play a key role in psychiatric disorders, such as autism and schizophrenia. Medial frontal lobe lesions of the right frontal lobe were reported to impair this ability. The aim of our study was to locate areas of the brain associated with the process of "theory of mind" in normal subjects.

METHODS

In order to index the activity of brain areas related to "theory of mind" reasoning in sixteen normal adults, we administered an emotional ("happy", "sad", "angry" and "neutral") vignettes comprehension task during magnetoencephalography (MEG) recordings and analyzed these data by using SAM (synthetic aperture magnetometry), SPM99 and the permutation method. Subjects were presented with eight different videotaped social situations (each emotion has two vignettes) and were asked to indicate which emotion they represented.

RESULTS

Statistically significant activation in the comparison of "happy"-"sad" and "angry"-"sad" was observed in the bilateral medial prefrontal cortices in the alpha frequency band. There were no significant differences in comparisons of each type of emotional vignette to the neutral vignettes, "happy"-"angry" comparison, and male-female comparisons. There was no significant difference in other frequency bands.

CONCLUSION

This result suggests that bilateral medial prefrontal cortex are involved in the comprehension of emotional states of others.

The neurological and cognitive sequelae of cardiac arrest

BACKGROUND

Although cardiac arrest (CA) is commonly cited as a cause of amnesia, patients referred to the authors' center with a diagnosis of "amnesia" after CA rarely have isolated memory deficits.

OBJECTIVE

To determine whether CA is a cause of pure amnesia and to assess patterns of cognitive deficits after CA.

METHODS

The authors used cognitive assessment of 11 consecutive patients referred for memory deficits after CA, targeted at deficit domains identified in the literature reviews, and analysis of specific case reports and prospective studies of cognition after CA.

RESULTS

The most common pattern of impairment in their patients was a combination of memory and motor deficits with variable executive impairment. No patient had isolated memory impairment. The case reports do not support the claim that isolated amnesia is a residual of CA; most cases of isolated amnesia are caused by subacute episodes of anoxia or excitotoxic injury. The prospective reports identify highly variable patterns of impairment, but isolated amnesia remains rare.

CONCLUSIONS

Diffuse, sudden ischemic-hypoxic injury caused by cardiac arrest (CA) does not preferentially damage memory systems. Subacute or stepwise hypoxic or excitotoxic injury may cause isolated hippocampal injury and amnesia. The common pattern of impairment in the postacute phase after CA is a combination of memory, subtle motor, and variable executive deficits.

California Verbal Learning Test: performance by patients with focal frontal and non-frontal lesions

Although frontal lobe lesions do not cause classic amnesia, they may disrupt learning and memory in a number of ways. To investigate in finer detail the regions of frontal injury that are associated with impaired learning and to define the cognitive processing deficits specific to each region that disrupt memory, we compared 33 patients with focal frontal injury with patients with non-frontal injury and with normal controls on a standard neuropsychological instrument, the California Verbal Learning Test (CVLT). Subgroups of patients with distinct lesion site profiles were compared in a number of learning measures. All of the subgroups of patients with frontal lesions (with one exception) had inefficient learning due to poor implementation of a strategy of subjective organization. Despite this organizational deficiency, the performance of patients with frontopolar lesions normalized across trials. Only the subgroups with lesions centred either on the left posterior dorsolateral frontal region or the posterior medial frontal region had overall impaired learning and recall. The left posterior dorsolateral frontal group was most significantly impaired on all measures. This recall impairment was secondary to a mild lexical-semantic deficit. A recognition memory deficit in the same group was due to an abnormal response bias. Several groups had a modest increase in perseverative recalls; the underlying mechanisms differed. Disruption of different cognitive processes associated with specific frontal regions underlies the varied patterns of memory impairment. This study has demonstrated even finer differentiations within the frontal region than previously known.

Age-related differences in movement representation

Repetitive movements have been used as motor activation tasks in the investigation of various neurological disorders. To determine the importance of an age-matched control group in such studies we investigated whether there are significant age-related changes in the pattern of cortical activation seen during simple repetitive movements. Sixteen right-handed healthy subjects were studied-8 young and 8 old. Functional magnetic resonance images were acquired while subjects performed a motor task or a nonmovement rest condition. Two continuous motor tasks, index finger abduction/adduction and wrist extension/flexion, were performed by each hand, paced using a metronome. The fMRI data were processed and analyzed with SPM '99. For the between-group comparisons, for each motor task, contralateral primary sensorimotor cortex and premotor cortex had significantly greater activation in the Young group and caudal supplementary motor area had significantly greater activation in the Old group. Ipsilateral sensorimotor cortex was more significantly activated in the Old group for index finger motor tasks of both hands. All noted differences in the Old group were more prominent for the index finger movement and most prominent when using the nondominant hand. In conclusion, there are significant age-related differences in the activation pattern associated with repetitive movements. This may represent compensatory recruitment of motor cortical units in the older subjects as larger differences are noted in the older group during the more difficult motor tasks, those of isolated finger movement and nondominant hand use. This study has important implications for functional imaging experiments of neurological disorders in older subjects.

Chronic akinetic mutism after mesencephalic-diencephalic infarction: remediated with dopaminergic medications

OBJECTIVE

Akinetic mutism (AKM) is an uncommon disorder with a complex neuropathology. There is no generally accepted treatment, and it is not known if late treatments are effective. The relationship between AKM and abulia is uncertain.

METHODS

The effects of dopaminergic treatment of a patient with chronic AKM after discrete bilateral infarctions of the mesencephalic ventral tegmental area and the lateral hypothalamus were studied with motor measures, the Functional Independence Measure (FIM), and neuropsychological tests.

RESULTS

Treatment with a combination of carbidopa/levodopa and pergolide produced prompt amelioration of AKM with dramatic and rapid improvement in FIM. An apathetic, amotivational state persisted despite resolution of akinesia and normal frontal executive functions.

CONCLUSIONS

AKM may respond to dopaminergic treatment even after months of severe akinesia. The mechanism of abulia is more complex than simply a partial dopaminergic deficiency state and may persist even when AKM is treated and frontal cognitive functions are normal.

Triangular backgrounds shift the bias of line bisection performance in hemispatial neglect

OBJECTIVE

Patients with left neglect on line bisection show normal implicit sensitivity to manipulations of both the stimulus and the visual background. Three experiments were designed to define this sensitivity more exactly.

METHODS

Normal controls and patients with left neglect performed a series of horizontal line bisection tasks. Independent variables were the configurations of the backgrounds for the line-rectangle, square, circle, left and right pointing isosceles triangles-and whether the background was the shape of the piece of paper or an outline drawn on a standard piece of paper. In a separate experiment different components of the triangle were outlined on a piece of paper. Deviation from true midpoint was calculated.

RESULTS

Simply placing the target lines in a symmetric background such as a square or circle did not reliably reduce neglect. A triangle asymmetric in the horizontal plane caused a shift in bisection away from the triangle's vertex. With right pointing triangles the perceived midpoint shifted to the left of true centre (crossed over). The effects of the triangles were comparable in the patients and the controls when controlled for baseline bisection bias. The critical components of the triangles were the angular legs. This effect of background was not influenced by lesion site or by hemianopia.

CONCLUSIONS

Patients with left visual neglect remain sensitive to covert manipulations of the visual background that implicitly shift the perceived midpoint of a horizontal line. This effect is strong enough to eliminate neglect on a bisection task. The mechanism of this effect is expressed through preattentive visual capacities.

The Trail Making Test: a study in focal lesion patients

The relationship of the Trail Making Test (TMT) to the frontal lobes was tested by comparing patients with damage to the frontal and nonfrontal regions to control participants. Although the analysis of time measurements, both raw and transformed, showed notable slowing of frontal groups, error analysis proved to be a more useful method of categorizing performance. Analysis of errors on Part B indicated that all patients who made more than 1 error had frontal lesions. Dividing the frontal damaged patients into subgroups on the basis of the number of errors yielded specificity of brain-behavior relations within the frontal lobes. Patients with damage in dorsolateral frontal areas were most impaired. Those with inferior medial damage to the frontal lobes were not significantly affected in TMT Part B performance.

What Are Preschool Children Eating? A Review of Dietary Assessment

Accurate assessment of dietary intake among preschool-aged children is important for clinical care and research, for nutrition monitoring and evaluating nutrition interventions, and for epidemiologic research. We identified 25 studies published between January 1976 and August 2000 that evaluated the validity of food recalls (n = 12), food frequency questionnaires (n = 9), food records (n = 2), or other methods (n = 2). We identified four studies that evaluated the reproducibility of food frequency questionnaires. Validity studies varied in validation standard and study design, making comparisons between studies difficult. In general, food frequency questionnaires overestimated total energy intake and were better at ranking, than quantifying, nutrient intake. Compared with the validation standard, food recalls both overestimated and underestimated energy intake. When choosing a method to estimate diet, both purpose of the assessment and practicality of the method must be considered, in addition to the validity and reproducibility reported in the scientific literature.

Recovery rates after stroke and their impact on outcome prediction

Current assessments do not provide reliable factors predictive of outcome from stroke for stroke survivors of intermediate age and severity of deficit. We sought to investigate whether early rate of functional improvement can facilitate prediction of functional outcome, length of stay, and disposition beyond that afforded by age and initial severity of deficit. Prospective study of consecutive admissions to acute rehabilitation (N = 244) with diagnosis of ischemic or hemorrhagic stroke. Independent measures were age, marital status, living situation, social situation, lag from symptom onset to rehabilitation, stroke type, admission score on the Functional Independence Measure (FIM), rate of FIM change (ROFC) as assessed by the best weekly FIM change in the first 3 weeks of rehabilitation. Dependent measures were functional status on discharge as assessed by a modification of Steinman's method, length of stay, and discharge disposition. Logistic regression analyses on each of the dependent measures identified significant factors, and interactions of significant factors were assessed by analysis of variance on continuous dependent variables. Cross-tabulations using significant factors from the logistic regression analyses were performed to identify groups with homogeneous outcomes. Groups with >80% homogeneity were considered likely to have predictive value. Discharge functional status: Admission FIM (AFIM) again fractionated the population into groups with poor outcome (AFIM <50 remained dependent), good outcome (AFIM >70 achieved nondependence), and an intermediate group with unpredictable outcome. In this intermediate group, ROFC had significant effect only for a small number of patients (n = 9) with rapid improvement (ROFC >25) who achieved nondependence. LOS: AFIM >70 had less than average LOS, ROFC = 10-15 FIM/week had longer than average LOS. LOS was significantly prolonged in patients with poor outcomes. Disposition: AFIM >70 and age <60 were strongly associated with home discharge. Patients not living at home before admission were not discharged home. Married patients had a greater tendency to home discharge than did those not married. ROFC had no bearing on disposition. ROFC has an independent influence on outcome but was sufficiently powerful in our sample to identify reliably only a very small subset of patients with otherwise indeterminate prognosis. LOS seems inordinately prolonged in patients with poor outcomes. Both of these results can guide efficient rehabilitation management.

Disorders of frontal lobe functioning

The neurology of frontal lobe disorders can be summarized in descriptions of behavioral problems (apathy, etc.), of cognitive impairments (poor planning, etc.), and of motor deficits (grasp reflex, etc.). Reviews of this sort do not indicate, however, any regional specificity to the deficit profiles or identify any of the component processes of the complex deficits-what exactly is "poor planning"? In this review we present specific steps that assist in overcoming the limitations: (1) identify weaknesses in current understanding, (2) operationally define the processes to be analyzed, (3) review some methodologies that allow parsing of discreet processes into specific frontal regions, (4) review the unique advantages and disadvantages of the various neurological disorders that provide us with subjects for study, and (5) propose approaches to advance further a useful clinical neurology of frontal lobe disorders as well as a more finely grained scientific description of core frontal processes.

The frontal lobes are necessary for 'theory of mind'

Patients with limited focal frontal and nonfrontal lesions were tested for visual perspective taking and detecting deception. Frontal lobe lesions impaired the ability to infer mental states in others, with dissociation of performance within the frontal lobes. Lesions throughout the frontal lobe, with some suggestion of a more important role for the right frontal lobe, were associated with impaired visual perspective taking. Medial frontal lesions, particularly right ventral, impaired detection of deception. The former may require cognitive processes of the lateral and superior medial frontal regions, the latter affective connections of the ventral medial frontal with amygdala and other limbic regions.

Stroop performance in focal lesion patients: dissociation of processes and frontal lobe lesion location

There were three primary objectives: to examine the usefulness of the Stroop interference effect as a measure of frontal lobe function; to investigate the possibility of distinct lesion effects for word reading or color naming; and to specifically determine the brain regions necessary for the performance of the incongruent condition. Fifty-one patients with single focal brain lesions in frontal and non-frontal regions and 26 normal control subjects (CTL) were administered the word reading, color naming and incongruent conditions of the Stroop task. Only frontal lesions produced significant impairment. Patients with posterior lesions were not significantly deficient in any condition. Damage to the left dorsolateral frontal lobe resulted in increased errors and slowness in response speed for color naming. Contrary to Perret (Neuropsychology, 1974; 12: 323-330), lesions of the left frontal lobe did not result in a selective interference deficit on the Stroop incongruent condition. Rather, bilateral superior medial frontal damage was associated with increased errors and slowness in response time for the incongruent condition. This result is interpreted as failure of maintenance of consistent activation of the intended response in the incongruent Stroop condition. The results and conclusion are compatible with the prevalent theories of both the Stroop effect and the role of the superior medial frontal regions. The role of the anterior cingulate cortex on performance of the Stroop task is likely related to task and patient context.

Executive functions and the frontal lobes: a conceptual view

Several problems in understanding executive functions and their relationships to the frontal lobes are discussed. Data are then presented from several of our studies to support the following statements: (1) the examination of patients with focal frontal lobe lesions is a necessary first step in defining the relation of executive functions to the frontal lobes; (2) there is no unitary executive function. Rather, distinct processes related to the frontal lobes can be differentiated which converge on a general concept of control functions; (3) a simple control-automatic distinction is inadequate to explain the complexity of control-automatic processes; (4) the distinction between complex and simple tasks cannot explain the differences in functions between the frontal lobes and other brain regions; and (5) the most important role of the frontal lobes may be for affective responsiveness, social and personality development, and self-awareness and unconsciousness.

Semantic capacities of the right hemisphere as seen in two cases of pure word blindness

Two patients with pure alexia were studied with tachistoscopically presented stimuli to examine factors influencing their ability to distinguish words from nonwords and to derive semantic information at exposures too brief for explicit letter identification. Both patients had profound right hemianopia and computerized tomography (CT) evidence of splenial destruction. Both patients were successful in making word/nonword decisions for high-frequency, but not low-frequency, words. They could judge semantic class membership reliably for such common categories as animals and vegetables, but not for arbitrarily selected categories, such as office-related items. Judgments about the gender of people's names and place versus person name distinctions were made with high reliability. Results are interpreted as evidence for limited word recognition and semantic-processing capacity in the right hemisphere.

Wisconsin Card Sorting Test performance in patients with focal frontal and posterior brain damage: effects of lesion location and test structure on separable cognitive processes

Forty-six patients with single focal lesions (35 frontal, 11 nonfrontal) were administered the Wisconsin Card Sorting Test (WCST) under three conditions of test administration. The three conditions varied in the amount of external support provided via specificity of instructions. The WCST, while a multifactorial test, is specifically sensitive to the effects of frontal lobe damage if deficits in language comprehension and visual-spatial search are controlled. There is also specificity of functioning within the frontal lobes: patients with inferior medial frontal lesions, unilateral or bilateral, were not impaired on the standard measures although they had increased loss of set when informed of the sorting categories. Verbal instructions may provide a probe to improve diagnosis and prognosis, assessment of the potential efficacy of treatment, and the time frame of plasticity of specific cognitive operations.

Acquisition of novel semantic information in amnesia: effects of lesion location

Two patients with severe global amnesia are described who differ in the extent to which they have acquired new semantic information. Patient SS, who has extensive medial temporal lobe damage including the hippocampus as well as surrounding cortical areas, has failed to acquire virtually any new information regarding vocabulary or famous faces that entered the public domain since the onset of his amnesia. In contrast, patient PS, who has a selective lesion of the hippocampus proper, has gained a sense of familiarity of novel vocabulary and famous people, even though her effortful retrieval of this new semantic knowledge remains impaired. These findings extend to amnesia of adult onset, the proposal of Vargha-Khadem and colleagues that in patients with selective hippocampal injury, cortical areas surrounding the hippocampus may play an important role in new semantic learning [Vargha-Khadem, F., Gadian, D.G., Watkins, K. E., Connelly, A., Van Paesschen, W. and Mishkin, M., regarding the importance of the subhippocampal cortices in the mediation of new semantic learning in children with hippocampal lesions, Science, 1997, 277, 376-380].

Dissociation of attentional processes in patients with focal frontal and posterior lesions

A location-based ('select-what, respond-where') priming task was used to examine three measures of selective attention (interference (INT), negative priming (NP), and inhibition of return (IOR)) as a function of focal brain pathology and the complexity of target selection. Control subjects showed different patterns of performance for the three attentional measures as a function of complexity, suggesting some independence among INT, NP, and IOR. Brain-damaged subjects showed significant response slowing, as well as a number of lesion-specific attentional abnormalities. Right frontal (including bifrontal) damage resulted in proportionally increased interference related to task complexity. Left posterior damage increased IOR in the most complex task, while left frontal damage reversed the control pattern of IOR as a function of complexity. Right hemisphere (right posterior and right frontal damage) pathology resulted in a virtual loss of negative priming at all levels of task complexity; left and bifrontal damage resulted in diminished NP only related to increases in the complexity of selection. INT, NP, and IOR are mediated by different brain regions and their expression can be modulated by the complexity of the selection task.

Lesion site patterns in severe, nonverbal aphasia to predict outcome with a computer-assisted treatment program

OBJECTIVE

To test whether lesion site patterns in patients with chronic, severe aphasia who have no meaningful spontaneous speech are predictive of outcome following treatment with a nonverbal, icon-based computer-assisted visual communication (C-ViC) program.

DESIGN

Retrospective study in which computed tomographic scans performed 3 months after onset of stroke and aphasia test scores obtained before C-ViC therapy were reviewed for patients after receiving C-ViC treatment.

SETTING

A neurology department and speech pathology service of a Department of Veterans Affairs medical center and a university aphasia research center.

PATIENTS

Seventeen patients with stroke and severe aphasia who began treatment with C-ViC from 3 months to 10 years after onset of stroke.

MAIN OUTCOME MEASURE

Level of ability to use C-ViC on a personal computer to communicate.

RESULTS

All patients with bilateral lesions failed to learn C-ViC. For patients with unilateral left hemisphere lesion sites, statistical analyses accurately discriminated between those who could initiate communication with C-ViC from those who were only able to answer directed questions. The critical lesion areas involved temporal lobe structures (Wernicke cortical area and the subcortical temporal isthmus), supraventricular frontal lobe structures (supplementary motor area or cingulate gyrus 24), and the subcortical medial subcallosal fasciculus, deep to the Broca area. Specific lesion sites were also identified for appropriate candidacy for C-ViC.

CONCLUSIONS

Lesion site patterns on computed tomographic scans are helpful to define candidacy for C-ViC training, and to predict outcome level. A practical method is presented for clinical application of these lesion site results in combination with aphasia test scores.

Clustering and switching on verbal fluency: the effects of focal frontal- and temporal-lobe lesions

We examined the hypothesis that, on verbal fluency, clustering (i.e. generating words within subcategories) is related to temporal-lobe functioning, whereas switching (i.e. shifting between subcategories) is related to frontal-lobe functioning. Tests of phonemic and semantic fluency were administered to 53 patients with focal frontal-lobe lesions (FL), 23 patients with unilateral temporal-lobe lesions (TL) and 55 matched controls. Performance by FL patients was consistent with our hypothesis: in comparison to controls, patients with left-dorsolateral or superior-medial frontal lesions switched less frequently and produced normal cluster sizes on both phonemic and semantic fluency. Performance by TL patients was not consistent across fluency tasks and provided partial support for our hypothesis. On phonemic fluency, TL patients were unimpaired on both switching and clustering. On semantic fluency, TL patients were impaired on switching in comparison to controls and left TL patients produced smaller clusters than right TL patients. The best indices for discriminating the patient groups, therefore, were phonemic-fluency switching (impaired only with frontal lesions) and semantic-fluency clustering (impaired only with temporal-lobe lesions).

The effects of focal anterior and posterior brain lesions on verbal fluency

Seventy-four patients with focal brain lesions were compared to a neurologically normal control group on tasks of letter-based and category-based list generation. When patients were divided only by right frontal, left frontal, or nonfrontal lesion sites, the pattern of fluency impairments confirmed prior claims. When more precise lesion sites within the frontal lobes were compared between groups classified based on their fluency performance, much more specific brain-behavior relations were uncovered. Damage to the right dorsolateral cortical or connecting striatal regions, the right posterior area, or the medial inferior frontal lobe of either hemisphere did not significantly affect letter-based fluency performance. Superior medial frontal damage, right or left, resulted in moderate impairment. Patients with left dorsolateral and/or striatal lesions were most impaired. Left parietal damage led to performance relatively equivalent to the superior medial and left dorsolateral groups. The same lesion sites produced impairments in category based fluency, but so did lesions of right dorsolateral and inferior medial regions. Task analysis and correlations with other measures revealed that different cognitive processes related to different brain regions underlie performance on verbal fluency tests.

The effects of focal and diffuse brain damage on strategy application: evidence from focal lesions, traumatic brain injury and normal aging

A new test of strategy application was designed to be relatively free of the constraints that limit the standard neuropsychological assessment of supervisory abilities. The validity of the test was assessed in 3 samples of participants with varying degrees of supervisory deficits and frontal systems dysfunction: focal frontal lesions, traumatic brain injury (TBI), and normal aging. Inefficient strategy application varied systematically across the 3 groups and was not due to extraneous factors such as forgetting the test instructions. Previous case studies have emphasized strategy application deficits in the face of normal neuropsychological test performance. In this study, it was shown that strategically impaired participants from a consecutive series can include those both with and without deficient neuropsychological test performance. When neuropsychological impairment was present, it was greatest on executive functioning tasks. Among participants with nonstrategic performance, there was evidence for a dissociation of knowledge from action. This finding was not specific to focal frontal lesions. A number of supervisory processes contributing to strategy application were identified. Exploratory analyses indicated differential effects of lesion location on these processes, especially inferior medial frontal and right hemisphere lesions. Overall, the results supported the use of unstructured tasks in the assessment of supervisory abilities.

Recovery of arm function in patients with paresis after traumatic brain injury

OBJECTIVE

To characterize the frequency of recovery of arm paresis in patients with traumatic brain injury (TBI) admitted to rehabilitation.

DESIGN

Retrospective review identifying a cohort of patients with moderate or severe arm paresis after TBI followed at least 6 months postinjury.

SETTING

Freestanding acute rehabilitation hospital TBI unit.

PATIENTS AND METHODS

Forty-four patients with moderate to severe arm paresis were selected from 264 consecutive admissions and characterized by injury pathology subtype, injury severity (duration of unconsciousness [loss of consciousness, LOC] and posttraumatic amnesia [PTA]), age, and level of paresis according to Brunnstrom Stages of Recovery (BS 1 to 6). Patient groups with and without arm paresis were compared according to these variables (t tests and chi(2)).

MAIN OUTCOME MEASURES

Recovery of arm paresis to isolated motor function (BS 5 or 6) and time to achieve recovery. Recovered and nonrecovered patients were compared (Mann-Whitney, t tests, and chi(2)) on injury severity, initial level of paresis, age, time to rehabilitation admission, and pathology subtype. Time to recovery was compared for patients at different levels of initial paresis, ranges of LOC, and pathology subtypes (Mann-Whitney and Kruskal-Wallis tests).

RESULTS

Forty-four patients (17%) had moderate (BS 3 to 4) or severe (BS 1 to 2) paresis at rehabilitation admission. They were more severely injured than nonparetic patients based on longer LOC (p < .002) and PTA (p < .009). Thirty-six patients (82%) recovered by 6 months; 72% of these recovered by 2 months. If still paretic at 2 months, only 56% recovered. Mean recovery time was 6.9 weeks (SD, 6.1) from injury. Time to recovery was best predicted by initial level of paresis and injury severity (r2 = .48), but not age. Patients with diffuse injury tended towards a more protracted recovery (7.9 weeks, SD 6.5) than patients with focal injury (4.2 weeks, SD 3.9) (p = .08) and only those with diffuse injury showed further recovery after 3 months.

CONCLUSIONS

Arm paresis after TBI is relatively infrequent. Most patients recover by 2 months but later recovery is possible, especially in patients with primarily diffuse brain damage. Recovery is highly related to initial impairment, injury severity, and distribution of brain injury.

Comparison of older people and patients with frontal lesions: evidence from world list learning

We examined the hypothesis that changes in memory performance of older normal participants are due to frontal lobe dysfunction by comparing three groups of normal individuals (young, middle-aged, and older) with three groups of patients who had documented lesions in specific frontal regions: unilateral right, unilateral left, and bilateral. All participants were given 4 successive learning trials on each of 3 lists of words: unrelated, related but presented in a pseudo-random order, and related and presented in a blocked format. We found significant correspondences in performance between the older normal participants and the (younger) frontal damaged groups. The qualitative nature of recall performance, particularly as measured by indices of organizational control processes, was similar between older normals and patients with frontal damage, particularly those with right frontal damage, but different from that normally exhibited by patients with focal limbic/memory dysfunction. These results add to the evidence that at least some of the decline in older people in tasks which measure executive or supervisory abilities is due to frontal system dysfunction.

Specific semantic memory loss after hypoxic-ischemic injury

A patient is reported who suffered hypoxic-ischemic injury causing isolated and eventually partially reversible semantic memory loss. Despite normal MRI findings, single-photon emission CT demonstrated dysfunction in posterior cortical association areas. Semantic memory is the sum of categorical, perceptual, and conceptual knowledge. While not localized in a strict sense like visual fields, semantic memory is thought to be broadly organized in the posterior association cortices, with a particular focus in the inferior temporal regions. Evidence for this has come from patients with herpes simplex encephalitis, temporo-occipital infarctions, and dementias. This case confirms the importance of these cortical regions for semantic memory. The rapid recovery in this case, as opposed to the encephalitis or infarction cases, suggests an important role for preservation of white matter connections in the region for reconstitution of function.

Atypical cerebral dominance: predictions and tests of the right shift theory

Alexander and Annett (Brain and Language, in press) described new cases of atypical cerebral specialization, and suggested that these observations and others in the literature could be explained by the right shift (RS) theory. The theory generates specific predictions as to the prevalence of different patterns of cerebral dominance and their distribution among right-handers and left-handers. Predictions differ between strict and generous criteria of sinistrality, as between left writers and non-right-handers. Tests of the predictions against reports in the literature reveal good fits for most data. New studies will test the RS theory if their design permits examination of the present predictions.

Crossed aphasia and related anomalies of cerebral organization: case reports and a genetic hypothesis

Anomalous lateralization of cognitive functions is observed in a small percentage of right-handed patients with unilateral brain damage, either crossed aphasia (aphasia after right brain damage) or "crossed nonaphasia" (left brain damage without aphasia but with visuospatial and other deficits typical of right brain damage). No comprehensive theory of these anomalous cases has been proposed. Nine new right-handed cases (plus one left-handed case) were analyzed and the literature was reviewed. The dramatically anomalous organization of cognitive functions is best explained by random lateralization of all cognitive functions in a small subset of the population. The RS theory of cerebral dominance can account for this pattern of anomalies in right-handers and may account for the most common patterns of dominance observed in left-handers.

Recovery of memory and executive function following anterior communicating artery aneurysm rupture

We studied the recovery of memory and executive function in 10 patients following anterior communicating artery aneurysm (ACoA) rupture and repair. Patients were tested at 2 consecutive points in time following surgery (approximately at 2 and 3 months). At the first testing, the patients divided into 2 groups based on the severity of impairment on executive measures. Both groups had severe anterograde amnesia, but only patients with severe executive impairments had retrograde amnesia with a temporal gradient. At second testing, both groups had persistent severe anterograde amnesia. The dysexecutive group showed significant improvement in executive deficits and in retrograde amnesia, with attenuation of the temporal gradient. Patients with more severe executive impairments had more extensive bilateral frontal lesions than other patients. These results suggest that the cognitive profile following ACoA rupture changes with time. Time postonset following aneurysm rupture and lesion site are both critical for defining the neuropsychological profile, and determining the underlying cognitive mechanisms in this neurological disorder.

Incontinence after stroke in a rehabilitation setting: outcome associations and predictive factors

Urinary incontinence (UI) after stroke is common and associated with overall poor functional outcomes. There is controversy regarding which factors contribute to incontinence after stroke and which factors may be predictive of recovery of continence. This study investigated consecutive stroke admissions to an inpatient rehabilitation hospital and evaluated the impact of several pre-selected factors on the presence of UI and its recovery. We also studied the impact of UI on outcome in terms of functional abilities with the Functional Independence Measure (FIM) and in terms of disposition. UI on admission was associated with severe functional impairment with large infarctions and was probably caused by general severity rather than specific impairment of neuromicturition control. Patients with less impairment (admission FIM > 60) and small vessel strokes were likely to recover continence. UI on admission had a negative impact on outcome.

Verbal memory function in mild aphasia

Verbal material may be processed by semantic and phonologic systems. Damage to these language systems may also impair memory. We classified 16 mildly aphasic patients according to phonologic and lexicosemantic abilities, tested them on a variety of short- and long-term memory measures, and correlated behavioral deficits with lesion location. Aphasia impaired both short- and long-term memory. Phonologic impairment affected only digit span performance. Lexicosemantic deficits impaired self-organized encoding of word lists. Memory impairment was not associated with specific lesion locations. Persistent verbal-memory impairments accompanying even mild residual aphasia may be responsible for much of the difficulty mildly aphasic patients experience returning to vocational, academic, and social life. Co-occurrence of these deficits probably reflects their underlying dependence on similar processing systems.

Comparison of older people and patients with frontal lesions: evidence from world list learning

We examined the hypothesis that changes in memory performance of older normal participants are due to frontal lobe dysfunction by comparing three groups of normal individuals (young, middle-aged, and older) with three groups of patients who had documented lesions in specific frontal regions: unilateral right, unilateral left, and bilateral. All participants were given 4 successive learning trials on each of 3 lists of words: unrelated, related but presented in a pseudo-random order, and related and presented in a blocked format. We found significant correspondences in performance between the older normal participants and the (younger) frontal damaged groups. The qualitative nature of recall performance, particularly as measured by indices of organizational control processes, was similar between older normals and patients with frontal damage, particularly those with right frontal damage, but different from that normally exhibited by patients with focal limbic/memory dysfunction. These results add to the evidence that at least some of the decline in older people in tasks which measure executive or supervisory abilities is due to frontal system dysfunction.

Factors predictive of stroke outcome in a rehabilitation setting

Accurate outcome prediction following stroke is important for proper delivery of poststroke care. It has been difficult to determine specific factors that provide reliable and accurate predictions of outcome, particularly for patients with intermediate deficit severities. Age and severity of deficit have repeatedly been found to be most reliable, but only as rough estimates and for patients at either extreme of the disability spectrum. This paper reports a prospective study of consecutive rehabilitation admissions (N = 536) to determine the influence of preselected factors. Outcome was analyzed in terms of functional improvement and disposition. Patients younger than 55 years or with an admission Functional Independence Measure (FIM) greater than 80 almost universally went home. Admission FIMs less than 40 were associated with nearly certain nursing home discharge. The comprehensive FIM score was a stronger predictor of outcome than motor impairment in isolation. An admission FIM of 60 or greater was associated with a higher probability of functional improvement during rehabilitation. Small-vessel strokes had the best outcome. Intracerebral hemorrhages improved more than ischemic strokes but more slowly. Right hemisphere lesions did worse than left. Comorbidities influenced outcome only when several conditions accumulated. The absence of a committed caregiver at home increased the risk of nursing home discharge. Suggestions for rehabilitation triage are given.

Differential recovery from impairment to the phonological lexicon

Word production was examined in four aphasics diagnosed acutely with neologistic jargon and who displayed impairment to the lexical stage of phonological production (Kohn & Smith, 1993, 1994a). To investigate the major source of their nonword errors (i.e., neologisms, phonemic paraphasias), single word production was tested at three different times over the first 6 months postonset, with one subject receiving additional testing at 14 months postonset. Two subjects showed signs of recovery to the phonological output system with respect to: (1) improved word production scores, (2) increased frequency of phonemic paraphasias versus neologisms, and (3) increased production of target phonemes. These subjects also displayed above-chance production of target phonemes and no significant tendency to perseverate phonemes across picture-naming trials. It was argued that this pattern reflects a resolving disturbance in retrieving entries from the phonological lexicon. The other two subjects showed no improvement in word production. They also consistently produced target phonemes at chance levels and had a tendency to perseverate phonemes across picture-naming trials. This static pattern of performance was considered to reflect loss of information from the phonological lexicon. The neuroanatomical damage sustained by each case was consistent with these two recovery patterns.