Hemorrhagic transformation in patients with acute ischaemic stroke and an indication for anticoagulation.

BACKGROUND AND PURPOSE: Intracerebral hemorrhage (ICH) can occur in patients following acute ischaemic stroke in the form of hemorrhagic transformation, and results in significant long-term morbidity and mortality. Anticoagulation theoretically increases risk. We evaluated stroke patients with an indication for anticoagulation to determine the factors associated with hemorrhagic transformation. METHODS: Three-hundred and forty-five patients with ICD-9 codes indicating: (i) acute ischaemic stroke; and (ii) an indication for anticoagulation were screened. One-hundred and twenty-three met inclusion criteria. Data were collected retrospectively. Neuroimaging was reviewed for infarct volume and evidence of ICH. Hemorrhages were classified as: hemorrhagic conversion (petechiae) versus intracerebral hematoma (a space occupying lesion); symptomatic versus asymptomatic. Using multivariable logistic regression, we determined the hypothesized factors associated with intracerebral bleeding. RESULTS: Age [odds ratio (OR) = 1.50 per 10-year increment, 95% confidence interval (CI) 1.07-2.08], infarct volume (OR = 1.10 per 10 ccs, 95% CI 1.06-1.18) and worsening category of renal impairment by estimated glomerular filtration rate (eGFR; OR = 1.95, 95% CI 1.04-3.66) were predictors of hemorrhagic transformation. Ninety- nine out of 123 patients were anticoagulated. Hemorrhage rates of patients on and off anticoagulation did not differ (25.3% vs. 20.8%; P = 0.79); however, all intracerebral hematomas (n = 7) and symptomatic bleeds (n = 8) occurred in the anticoagulated group. CONCLUSIONS: The risk of hemorrhagic transformation in patients with acute ischaemic stroke and an indication for anticoagulation is multifactorial, and most closely associated with an individual's age, infarct volume and eGFR.

Action versus animal naming fluency in subcortical dementia, frontal dementias, and Alzheimer's disease.

Accumulating evidence indicates action naming may rely more on frontal-subcortical circuits, and noun naming may rely more on temporal cortex. Therefore, noun versus action fluency might distinguish frontal and subcortical dementias from cortical dementias primarily affecting temporal and/or parietal cortex such as Alzheimer's disease (AD). We hypothesized patients with subcortical dementia, e.g., normal pressure hydrocephalus (NPH) and patients with dementias predominantly affecting frontal cortex, e.g., behavioral variant frontotemporal dementia (bv-FTD) and progressive nonfluent aphasia (PNFA) have more difficulty on action fluency versus noun fluency (e.g., animal naming). Patients with AD, who have temporo parietal cortical dysfunction, should have more difficulty on noun versus verb fluency. A total of 234 participants, including healthy controls (n = 20) and patients diagnosed with NPH (n =144), AD (n = 33), bv-FTD (n = 22) or PNFA (n =15) were administered animal fluency, action fluency, and letter fluency tasks, and the Mini-Mental State Examination (MMSE, to control for dementia severity). NPH and bv-FTD/PNFA patients had significantly higher MMSE scores and animal fluency than AD patients (after adjusting for age), but their action fluency tended to be lower than in AD. Only NPH and bvFTD/PNFA patients showed significantly lower action verb than animal fluency. Results provide novel evidence that action naming relies more on frontal-subcortical circuits while noun naming relies more on temporoparietal cortex, indicating action verb fluency may be more sensitive than noun fluency, particularly for detecting frontal-subcortical dysfunction.

Unintended changes in cognition, mood, and behavior arising from cell-based interventions for neurological conditions: ethical challenges.

The prospect of using cell-based interventions (CBIs) to treat neurological conditions raises several important ethical and policy questions. In this target article, we focus on issues related to the unique constellation of traits that characterize CBIs targeted at the central nervous system. In particular, there is at least a theoretical prospect that these cells will alter the recipients' cognition, mood, and behavior-brain functions that are central to our concept of the self. The potential for such changes, although perhaps remote, is cause for concern and careful ethical analysis. Both to enable better informed consent in the future and as an end in itself, we argue that early human trials of CBIs for neurological conditions must monitor subjects for changes in cognition, mood, and behavior; further, we recommend concrete steps for that monitoring. Such steps will help better characterize the potential risks and benefits of CBIs as they are tested and potentially used for treatment.

Neural substrates of word generation during stroke recovery: the influence of cortical hypoperfusion.

Several studies have demonstrated reorganization of cognitive and motor function caused by stroke. This study examined the influence of hypoperfused brain regions, in addition to the area of the infarct itself, on reorganization of the cognitive processes underlying word generation in stroke patients. In addition, we also sought to determine the influence of hypoperfusion on the blood oxygen level dependent/(BOLD) effect. Subjects with left and right subacute or chronic subcortical strokes, along with normal controls, were imaged while performing a verbal fluency task (word generation). The study population included six normal subject and six stroke patients with subcortical infarcts and cortical hypoperfusion in the middle cerebral artery territory who had recovered or improved markedly in word fluency. While normal subjects displayed a left-lateralized fronto-temporo-parietal and bilateral cingulo-striatal-thalamic-cerebellar network, the activation pattern of stroke patients was determined both by the hypoperfused regions and infarcted areas of the brain. Specifically, patients showed diminished BOLD effect in the cortical regions that were hypoperfused, even though their infarcts were subcortical, and showed increased BOLD effect in the homologous regions of the normal hemisphere. This finding raises the possibility that cortical hypoperfusion in the absence of infarct can cause shift of language functions to the opposite, intact hemisphere. However, reduced BOLD effect in the task relative to rest was found in hypoperfused regions in two patients, raising the possibility that regional function persisted, even though vascular reactivity was impaired. Results illustrate the complexities of functional imaging studies of recovery in patients with vascular lesions.

Rehabilitation of unilateral spatial neglect and neuroimaging.

We review the literature on current knowledge of the role of unilateral spatial neglect as an independent predictor of poor functional outcome after right brain injury, the neural mechanisms and neural substrates that are responsible for the manifestation of neglect behaviors, and the available rehabilitation techniques for neglect amelioration. We focus on the neuroimaging correlates of these rehabilitation techniques and rehabilitation amelioration, their mode of action and their potential to make a difference in functional outcomes, by assessing their potential to improve patients' performance in activities of daily living. We recognize that there is no consensus on efficacious treatments for neglect rehabilitation, and acknowledge that the lack of complete clarity of the neural substrates and mechanisms underlying neglect phenomena may hinder the development of efficacious rehabilitation techniques. We discuss current opinions on the neural mechanisms of hemispatial neglect and delved into the neural substrates of neglect based on functional and structural imaging. We explore the role of damage or dysfunction within specific right hemisphere structures in generating certain neglect subtypes and discussed how such knowledge may guide treatments for the rehabilitation of unilateral neglect. From this foundation, we proceed to explore the available rehabilitation techniques for neglect amelioration and how neuroimaging may guide the choice of therapies for different forms of unilateral neglect. We discuss cognitive rehabilitation approaches which form the bedrock of most traditional rehabilitation programs and follow with a description of other available, but less well utilized methods of neglect rehabilitation, including sensory stimulation, sensorimotor adaptation to visual perturbations by prism adaptation, and pharmacological agents (mainly dopamine agonists) that might augment rehabilitation. We also discuss the efficacy of these techniques in neglect rehabilitation and compare the potential of these diverse techniques to ameliorate not only the different symptoms of neglect, but also the different subtypes of neglect. Finally, we make suggestions about future research that could enhance the rehabilitation of neglect.

Vigilance behaviors and EEG activity in sustained attention may affect acute pain.

During Sustained Attention to stimuli across many modalities neural activity often decreases over time on task, while Errors in task performance increase (Vigilance Decrement). Sustained Attention to pain has rarely been investigated experimentally despite its clinical significance. We have employed a Sustained Attention protocol (Continuous Performance Task, CPT) in which the subject counts painful laser stimuli (targets) when they occur randomly in a prolonged train of nonpainful nontargets. We hypothesize that the magnitude of the poststimulus oscillatory power divided by baseline power (Event-Related Spectral Perturbation, ERSP - scalp EEG) over Frontoparietal structures will decrease at all frequencies with time on task, while Beta ERSP (14-30Hz) will be correlated with Error Rates in performance of the CPT. During the CPT with a painful target ERSP was found in four separate Windows, as defined by both their frequency band and the time after the stimulus. A Vigilance Decrement was found which confirms that Sustained Attention to pain was produced by this CPT. In addition, Error Rates was correlated inversely with laser energy, and with ratings of pain unpleasantness and salience. Error Rates also were related directly to the Beta ERSP Window at scalp EEG electrodes over the central sulcus. Over time on task, the ERSP magnitude decreased in Alpha (8-14Hz) Window, was unchanged in early and late Delta/Theta Windows (0-8Hz), and increased in the Beta Window. The increase in Beta ERSP and a decrease in the Alpha ERSP occurred at the same EEG electrode over the parietal lobe to a significant degree across subjects. Overall, Beta activity increases with time on task, and with higher Error Rates as in the case of other modalities. In the case of pain increased Errors correspond to misidentification of painful and nonpainful stimuli and so modulate the sensation of pain under the influence of Sustained Attention.

Oscillatory EEG activity induced by conditioning stimuli during fear conditioning reflects Salience and Valence of these stimuli more than Expectancy.

Imaging studies have described hemodynamic activity during fear conditioning protocols with stimulus trains in which a visual conditioned stimulus (CS+) is paired with an aversive unconditioned stimulus (US, painful laser pulse) while another visual stimulus is unpaired (CS-). We now test the hypothesis that CS Event Related Spectral Perturbations (ERSPs) are related to ratings of CS Expectancy (likelihood of pairing with the US), Valence (unpleasantness) and Salience (ability to capture attention). ERSP windows in EEG were defined by both time after the CS and frequency, and showed increased oscillatory power (Event Related Synchronization, ERS) in the Delta/Theta Windows (0-8Hz) and the Gamma Window (30-55Hz). Decreased oscillatory power (Event Related Desynchronization - ERD) was found in Alpha (8-14Hz) and Beta Windows (14-30Hz). The Delta/Theta ERS showed a differential effect of CS+ versus CS- at Prefrontal, Frontal and Midline Channels, while Alpha and Beta ERD were greater at Parietal and Occipital Channels early in the stimulus train. The Gamma ERS Window increased from habituation to acquisition over a broad area from frontal and occipital electrodes. The CS Valence and Salience were greater for CS+ than CS-, and were correlated with each other and with the ERD at overlapping channels, particularly in the Alpha Window. Expectancy and CS Skin Conductance Response were greater for CS+ than CS- and were correlated with ERSP at fewer channels than Valence or Salience. These results suggest that Alpha ERSP activity during fear conditioning reflects Valence and Salience of the CSs more than conditioning per se.

Diffusion- and perfusion-weighted brain magnetic resonance imaging in patients with neurologic complications after cardiac surgery.

BACKGROUND: Neurologic complications after cardiac surgery include stroke, encephalopathy, and persistent cognitive impairments. More precise neuroimaging of patients with these complications may lead to a better understanding of the etiology and treatment of these disorders. OBJECTIVE: To study the pattern of ischemic changes on diffusion- and perfusion-weighted magnetic resonance imaging (DWI, and MRPI, respectively) in patients with neurologic complications after cardiac surgery. METHODS: All records were reviewed of our patients undergoing cardiac surgery in the previous year who also underwent postoperative DWI or MRPI. Neurologic symptoms, vascular studies, and the pattern of ischemic changes were recorded. Acute ischemic lesions were classified as having a territorial, watershed, or lacunar pattern of infarction. Patients with multiple territorial infarcts in differing vascular distributions that were not explained by occlusive vascular lesions were classified as having multiple emboli. RESULTS: Fourteen patients underwent DWI and 4 underwent MRPI. Acute infarcts were found in 10 of 14 patients by DWI as compared with 5 of 12 patients by computed tomography. Eight patients presented with encephalopathy (associated with focal neurologic deficits in 4), 4 with focal deficits alone, and 2 with either fluctuating symptoms or transient ischemic attacks. Among patients with encephalopathy, 7 of 8 had patterns of infarction suggestive of multiple emboli, including 3 of 4 patients with no focal neurologic deficits. Several patients had combined watershed and multiple embolic patterns of ischemia. Findings of MRPI studies were abnormal in 2 of 4 patients, showing diffusion-perfusion mismatch; both patients had either fluctuating deficits or transient ischemic attacks, and their conditions improved with blood pressure manipulation. CONCLUSIONS: In patients with neurologic symptoms after cardiac surgery, DWI is more sensitive to ischemic change than computed tomographic scanning and can demonstrate patterns of infarction that may help us understand etiology. The most common pattern was multiple embolic infarcts. Preliminary experience with MRPI suggests that some patients have persistent diffusion-perfusion mismatch after surgery and may benefit from therapeutic intervention.

Making sense out of jargon: a neurolinguistic and computational account of jargon aphasia.

OBJECTIVE: To identify the cognitive and neuroanatomic bases of neologistic jargon aphasia with spared comprehension and production of written words. METHODS: Detailed analysis of performance across experiments of naming, reading, writing, repetition, and word/picture matching by a 68-year-old woman (J.B.N.) served to identify which cognitive mechanisms underlying naming and word comprehension were impaired. J.B.N.'s impairments were then simulated by selectively "lesioning" a computer model of word production that has semantic, word form, and subword phonologic levels of representation (described by Dell in 1986). RESULTS: In comprehension experiments, J.B.N. made far more errors with spoken word input than with written word or picture input (chi-square = 40-59; df = 1; p < 0.0001) despite intact auditory discrimination. In naming experiments (with picture, definition, or tactile input), J.B.N. made far more errors in spoken output relative to written output (chi-square = 14-56; df = 1; p < 0.0001). These selective impairments of spoken word processing were simulated by reducing connection strength between word-level and subword-level phonologic units but maintaining full connection strength between word-level and semantic units in Dell's model. The simulation yielded a distribution of error types that was nearly identical to that of J.B.N., and her CT and MRI scans showed a small subarachnoid hemorrhage in the left sylvian fissure without infarct. Cerebral angiogram showed focal vasospasm in sylvian branches of the left middle cerebral artery. CONCLUSION: Focal left perisylvian dysfunction can result in a highly selective "disconnection" between word-level and subword-level phonologic representations manifest as neologistic jargon aphasia with intact understanding and production of written words.

MR perfusion imaging reveals regions of hypoperfusion associated with aphasia and neglect.

OBJECTIVE: To evaluate diffusion-weighted imaging (DWI) and MR perfusion imaging (MRPI) as tools for identifying regions of infarct and hypoperfusion associated with aphasia and neglect in hyperacute stroke. Secondary goal: to establish a functional correlate of a radiologically defined "ischemic penumbra." METHODS: Forty subjects underwent DWI, MRPI, and standardized tests for lexical deficits or hemispatial neglect within 24 hours of stroke onset or progression. Ten patients had repeat DWI, MRPI, and cognitive testing after 3 days (in some cases after reperfusion therapy). Pearson correlations between error rate on cognitive testing and volume of abnormality on DWI versus MRPI were determined at each time period, and regions of hypoperfusion corresponding to specific cognitive deficits were identified. RESULTS: Error rate was more strongly correlated with volume of hypoperfused tissue on MRPI (r = 0.65 to 0.93; p < 0.01 to p < 0.0003) than with volume of lesion on DWI (r = 0.54 to 0.75; p = 0.14 to p < 0.01) for dominant and nondominant hemisphere stroke, at each time point. Forty-eight percent of aphasic patients and 67% of those with hemispatial neglect had either no infarct or only small subcortical infarct on DWI, but had focal cortical hypoperfusion. Patients who had successful reperfusion therapy showed resolution of the hypoperfused territory beyond the infarction on repeat MRPI and showed resolution of corresponding deficits. CONCLUSIONS: MRPI shows regions of hypoperfused cortex associated with lexical deficits or hemispatial neglect, even when DWI shows no infarct or only small subcortical infarct. MRPI-DWI mismatch indicates regions of functionally salvageable tissue.

Restoring blood pressure reperfused Wernicke's area and improved language.

Longitudinal clinical and imaging data from a patient who sustained a left frontal-temporal stroke with hypoperfusion of the adjacent Wernicke's area are reported. His language deficits were partially ameliorated by pharmacologically increasing his blood pressure, and were exacerbated when blood pressure dropped. There was a striking temporal and statistical correlation between mean arterial pressure and language accuracy. MR perfusion imaging showed that language gains were accompanied by improved perfusion of Wernicke's area when mean arterial pressure was increased.

Deficit to stimulus-centered, letter shape representations in a case of "unilateral neglect".

A brain-damaged subject is described whose pattern of performance in various reading tasks can be explained by proposing damage at a level of the word recognition process in which a representation with stimulus-centered, rather than retinal- or word-centered, coordinates is processed. Analysis of her reading performance as a function of topographical arrangement of letters, position of errors in the letter string, and the effects of letter spacing and of adding a prefix or suffix provide evidence not only for the existence of this level of representation (the letter-shape map in a model proposed by Caramazza and Hillis [3]), but also for specific assumptions about its functioning and structure.

Unilateral spatial neglect in dissociable frames of reference: a comment on Farah, Brunn, Wong, Wallace, and Carpenter (1990)

We comment on a paper by Farah et al. in which it is claimed that averaged performance on a letter naming task by a group of patients with left unilateral spatial neglect (USN) provides evidence that spatial allocation of attention is defined by environment-centered and viewer-centred coordinates, but not by object-centred coordinates. We re-analyze the raw data from that paper, and present statistical analyses of the data from individual subjects which show dissociations in the coordinate frames used by the individual subjects with USN. The data from individual cases demonstrate that object-centered USN occurs alone (without evidence of USN in other reference frames) in some cases, and in association with USN in other reference frames other cases. In contrast to the conclusions drawn from the group performance, results from individual subjects provide evidence for the role of dissociable frames of reference, including an object-centred coordinate frame, in the spatial allocation of attention.

Red cell antigens and renal transplantation.

Donor-specific transfusion was performed with and without cyclosporine between haplomismatched relatives prior to living-donor renal transplantation. Red cell antigen mismatching was not taken as a contraindication to DST. Of 80 patients included in the trial; eleven were ABO-mismatched, 15 were Rh(D)-mismatched, and a further 11 were transfused in the presence of atypical red cell antibodies (anti-D, -C, -Fya, -Kell -N, -H/I -I, -P1, -Wra). Patients were randomized to receive cyclosporine (10 mg/kg) daily during DST or not (control group). The presence of atypical red cell antibodies, with the exception of Rh anti-D, did not appear to influence DST or renal transplantation. DST did not act as a primary stimulus to Rh anti-D production but stimulated preexisting anti D levels. ABO mismatching did not appear to influence DST or subsequent renal transplantation except in one group A [corrected] patient who received group O [corrected] blood and cyclosporine. This patient developed a severe, but self-limiting, autoimmune hemolytic anemia due to auto-anti A antibodies. A similar group A patient in the control group developed an auto-antibody with no clinical sequelae. The influence of cyclosporine on the development of this auto-antibody is uncertain. We conclude that, with the exception of preexisting anti-D antibodies, minor red cell antigen disparities should not preclude pretransplant conditioning with donor-specific transfusions.

Lexical morphology and its role in the writing process: evidence from a case of acquired dysgraphia.

A case of acquired dysgraphia is presented in which the deficit is attributed to an impairment at the level of the Graphemic Output Buffer. It is argued that this patient's performance can be used to identify the representational character of the processing units that are stored in the Orthographic Output Lexicon. In particular, it is argued that the distribution of spelling errors and the types of lexical items which affect error rates indicate that the lexical representations passed from the lexical output system to the Graphemic Output Buffer correspond to the productive morphemes of the language.

A mathematical model for the epidemiologic study of infectious diseases.

Many infectious diseases have been hypothesized to represent common virus infections in which only small proportions of cases result in clinically recognizable disease. In order to find a method of studying this class of diseases, a mathematical model of the age distribution of clinical disease was developed using poliomyelitis as a prototype. The model is shown to fit the age distribution of reported poliomyelitis in a variety of localities before the use of artificial immunization. The true yearly rate of infection is easily estimated and ranges from .11 in rural Sweden to 1.20 in Chile. The model accounts for several major features of poliomyelitis epidemiology, including the shift to older ages and the high rate of clinically apparent disease which were frequently observed in populations which could be expected to have a comparatively low rate of spread. An examination of the age distribution of other diseases by these methods may provide a method of identifying other common infections which only occasionally result in clinically apparent disease.

The second eye of patients with senile macular degeneration.

Patients with senile macular degeneration and exudative maculopathy in one eye and drusen in the second eye have a 3% to 7% risk per year of exudative maculopathy developing in the second eye during the first three years following their initial presentation. The risk is the same for patients with new vessel membranes or other types of exudative maculopathy in the first eye. Second eyes in which exudative changes develop are more likely to have larger numbers of drusen or greater confluence of drusen (or both) initially. The data from this study were analyzed using the Kaplan-Meier technique of estimation, a method (to our knowledge) not previously employed by other investigators. The demographic features of the overall study population, as well as the photographic features associated with increased risk of development of exudative maculopathy, were in agreement with those previously reported.

Ocular findings in osteogenesis imperfecta congenita.

Osteogenesis imperfecta is a rare, inherited, connective-tissue disorder. The three main signs of this disease are multiple bone fractures, blue scleras, and deafness (osteosclerotic type). In our research, only a few reports of the morphologic studies of the eyes of patients with osteogenesis imperfecta were found. This report describes the ocular histopathologic condition of four cases of osteogenesis imperfecta congenita, with emphasis on the ultrastructural characteristics of the collagen in the cornea and sclera.

Scleropachynsis maculopathy.

To our knowledge, this is the first clinicopathologic report of a previously unrecognized maculopathy in which there is thickening and mucopolysaccharide deposition in the sclera subjacent to the macula. A healthy 50-year-old man had bilateral mottling of the retinal pigment epithelium (RPE) in the macular region. The left eye was enucleated because of a choroidal melanoma. Histopathologic examination disclosed a thickened sclera with abnormal collagen fibrils with diameters up to 5,800 A and compressed choroid. The overlying RPE had areas of hypopigmentation, hyperpigmentation, and hyperplasia and contained intracytoplasmic lipofuscin.

Tests for departure from normal in laboratory data.

This study was undertaken to compare several methods of evaluating the common assumption that laboratory data may be treated as if they had been drawn from an underlying Gaussian distribution. As had been described earlier, the usual Kolmogorov-Smirnov test was found to be unsatisfactory due to its sensitivity to rounding. In addition, a recently suggested modification also was shown to be unsuitable, because it was quite insensitive when applied to simulated data known to be positively skewed. The authors suggest the following: that the coefficients of kurtosis and skewness are valuable for use against specified alternatives; that the traditional Kolmogorov-Smirnov test is appropriate if the degree of rounding is minimal; and that a satisfactory "omnibus" test is not yet available.