Efficacy of home-based visuomotor feedback training in stroke patients with chronic hemispatial neglect.

Hemispatial neglect is a severe cognitive condition frequently observed after a stroke, associated with unawareness of one side of space, disability and poor long-term outcome. Visuomotor feedback training (VFT) is a neglect rehabilitation technique that involves a simple, inexpensive and feasible training of grasping-to-lift rods at the centre. We compared the immediate and long-term effects of VFT vs. a control training when delivered in a home-based setting. Twenty participants were randomly allocated to an intervention (who received VFT) or a control group (n = 10 each). Training was delivered for two sessions by an experimenter and then patients self-administered it for 10 sessions over two weeks. Outcome measures included the Behavioural Inattention Test (BIT), line bisection, Balloons Test, Landmark task, room description task, subjective straight-ahead pointing task and the Stroke Impact Scale. The measures were obtained before, immediately after the training sessions and after four-months post-training. Significantly greater short and long-term improvements were obtained after VFT when compared to control training in line bisection, BIT and spatial bias in cancellation. VFT also produced improvements on activities of daily living. We conclude that VFT is a feasible, effective, home-based rehabilitation method for neglect patients that warrants further investigation with well-designed randomised controlled trials on a large sample of patients.

The role of right temporal lobe structures in off-line action: evidence from lesion-behavior mapping in stroke patients.

Recent evidence suggests the possibility that not all action modes depend on dorsal visual stream processing but that off-line nontarget-directed actions, such as antipointing, require additional and even distinct neural networks when compared with target-directed online actions. Here, we explored this potential dissociation in a group of 11 patients with left visual neglect, a syndrome characterized by a loss of awareness of the contralesional side of space. Ten healthy participants and 10 right hemisphere-damaged patients without neglect served as controls. Participants had to point either directly toward targets presented on their left or right (i.e., propointing) or to the mirror position in the opposite hemispace (i.e., antipointing). Compared with both control groups, neglect patients showed reduced accuracy when antipointing but not propointing. Lesion-behavior mapping revealed that the areas critically associated with these deficits were located in the middle and superior temporal and parahippocampal gyri. We argue that neglect patients present specific deficits only when the visuomotor task taps into more perceptual representations thought to rely on ventral visual stream processing and that our results indicate that right temporal brain regions are implicated in these off-line actions.

No neglect-specific deficits in reaching tasks.

It is well established that patients with hemispatial neglect present with severe visuospatial impairments, but studies that have directly investigated visuomotor control have revealed diverging results, with some studies showing that neglect patients perform relatively better on such tasks. The present study compared the visuomotor performance of patients with and without neglect after right-hemisphere stroke with those of age-matched controls. Participants were asked to point either directly towards targets or halfway between two stimuli, both with and without visual feedback during movement. Although we did not find any neglect-specific impairment, both patient groups showed increased reaction times to leftward stimuli as well as decreased accuracies for open loop leftward reaches. We argue that these findings agree with the view that neglect patients code spatial parameters for action veridically. Moreover, we suggest that lesions in the right hemisphere may cause motor deficits irrespective of the presence of neglect and we performed an initial voxel-lesion symptom analysis to assess this. Lesion-symptom analysis revealed that the reported deficits did not result from damage to neglect-associated areas alone, but were further associated with lesions to crucial nodes in the visuomotor control network (the basal ganglia as well as occipito-parietal and frontal areas).

Seasonal patterns of cytokinins and microclimate and the mediation of gas exchange among canopy layers of mature Acer saccharum trees.

Seasonal patterns of cytokinins (CKs) and microclimate were examined in the upper, middle and lower canopy layers of mature Acer saccharum Marsh. (sugar maple) trees to elucidate the potential role of CKs in the mediation of gas exchange. The upper canopy showed a distinctly dissimilar microclimate from the middle and lower canopy layers with higher photosynthetically active radiation and wind speed, but showed no corresponding differences in transpiration (E) or stomatal conductance (g(s)). Although E and g(s) tended to be higher in the upper canopy than in the middle and lower canopies, the differences were not significant, indicating regulation beyond the passive response to changes in microclimate. The upper canopy accumulated significantly higher concentrations of CKs, predominantly as ribosides, and all canopy layers showed distinct seasonal patterns in CK profiles. Multiple regression models showed significant relationships between both g(s) and E and foliar CK concentration, although these relationships varied among canopy layers. The relationships were strongest in the middle and lower canopy layers where there was less fluctuation in leaf water status and less variability in abiotic variables. The relationships between gas exchange parameters and leaf CK concentration began to decouple near the end of the growing season as foliar phytohormone concentrations changed with the approach of dormancy.

Immediate and delayed reaching in hemispatial neglect.

Milner and Goodale (The visual brain in action, Oxford: Oxford University Press, 1995; The visual brain in action, 2nd ed., Oxford: Oxford University Press, 2006) propose a model of vision that makes a distinction between vision for perception and vision for action. One strong claim of the model is that the dorsal stream's control of action is designed for dealing with target stimuli in the 'here and now', yet when time is allowed to pass and a reaction has to be made on the basis of a visual memory, the ventral stream is required for successful performance. Regarding the syndrome of hemispatial neglect, Milner and Goodale further claim that the visual dorsal stream is relatively spared in these patients. In the current study we tested whether neglect patients would indeed be unimpaired in immediate pointing, yet show inaccurate pointing in a condition where a delay is interposed between the presentation of the stimulus and the response signal (in particular in left space). We tested the ability of nine neglect patients (and healthy and right hemisphere no neglect control groups) to perform reaches towards immediate and delayed targets, placed in left, central and right locations. Neglect patients showed no accuracy impairments when asked to perform an immediate action. Conversely, when pointing towards remembered leftward locations, they markedly overshoot the target or failed to initiate a reach altogether. These results confirm that patients with neglect are not specifically impaired when performing 'here and now' actions, but rather present deficits when the visuomotor task taps into more perceptual 'off-line' representations thought to depend on ventral visual stream activation.

The neural basis of visuomotor deficits in hemispatial neglect.

We have recently reported that patients with hemispatial neglect demonstrate increased terminal errors when performing delayed leftward reaches and that right-brain damaged patients (irrespective of neglect) take longer to complete their movements [Rossit, S., Muir, K., Reeves, I., Duncan, G., Birschel, P., & Harvey, M. (2009). Immediate and delayed reaching in hemispatial neglect. Neuropsychologiaa 47, 1563-1573]. Here we conducted an initial voxel-based lesion-symptom analysis to examine the neural basis of such deficits in 21 right-brain damaged subjects with 11 patients suffering from hemispatial neglect (2 more than in Rossit et al. [Rossit S., Muir K., Reeves I., Duncan, G., Birschel, P., & Harvey, M. (2009). Immediate and delayed reaching in hemispatial neglect. Neuropsychologia 47, 1563-1573] and 10 control patients without the condition. We found that the accuracy impairments in delayed leftward reaches were associated with damage to occipito-temporal areas. In contrast, the movement time slowing was related to more anterior lesions in the frontal lobe. These findings agree with the view that neglect affects actions thought to depend on the processing carried out by the ventral visual stream. In addition, we suggest that the timing impairments which are not neglect-specific maybe be driven by frontal structures.

Non-lateralised deficits in anti-saccade performance in patients with hemispatial neglect.

We tested patients suffering from hemispatial neglect on the anti-saccade paradigm to assess voluntary control of saccades. In this task participants are required to saccade away from an abrupt onset target. As has been previously reported, in the pro-saccade condition neglect patients showed increased latencies towards targets presented on the left and their accuracy was reduced as a result of greater undershoot. To our surprise though, in the anti-saccade condition, we found strong bilateral effects: the neglect patients produced large numbers of erroneous pro-saccades to both left and right stimuli. This deficit in voluntary control was present even in patients whose lesions spared the frontal lobes. These results suggest that the voluntary control of action is supported by an integrated network of cortical regions, including more posterior areas. Damage to one or more components within this network may result in impaired voluntary control.

Implementation of a stroke thrombolysis service within a tertiary neurosciences centre in the United Kingdom.

BACKGROUND: Intravenous alteplase is licensed for treatment of ischaemic stroke within 3 h of onset. Up to one-third of patients in the UK present to hospital within this time window but few are treated. AIMS: To examine the effect of a stroke thrombolysis protocol on service provision for an acute stroke service in the UK, jointly run by Neurology and Medicine for the Elderly providing a comprehensive stroke service to a local population of 370,000. DESIGN: Prospective observational study. METHODS: Data collected prospectively for all thrombolysis referrals over a 12-month period beginning July 2004. RESULTS: One hundred and eighty-eight patients were referred for potential thrombolysis, 129 transferred, 102 had an ischaemic stroke and 49 received intravenous thrombolysis. Referral rates from primary care and accident and emergency increased after guideline dissemination. Forty-three percent of the 49 patients treated with intravenous rt-PA achieved independence (modified Rankin Scale score 0-2) at 3months. CONCLUSION: A high proportion of ischaemic stroke patients can be treated with alteplase within 3 h of onset with organized hospital services and dissemination of a simple referral protocol to local primary and secondary care services.

Non-lateralised deficits of drawing production in hemispatial neglect.

Spatially lateralised deficits that typically define the hemispatial neglect syndrome have been shown to co-occur with other non-lateralised deficits of attention, memory, and drawing. However even a simple graphic task involves multiple planning components, including the specification of drawing start position and drawing direction. In order to investigate the influence of these factors in neglect we presented patients with a circle-copying task, and specified the drawing start point. The ability to draw from the instructed location was strongly related to tests that measure constructional abilities, but not related to start point laterality. In contrast, the direction in which patients drew the circle was affected by start point laterality: patients with neglect were less likely to draw in a typical direction when the cue was on the affected side of space and this was strongly related to severity of the neglect. Patients with neglect consistently produced circles that were smaller than the model; however, the scaling was not affected by the laterality of the start point, nor was the proportion of drawings correctly started at the cue. These findings demonstrate the complex relationship between neglect and even the simplest test for the syndrome.

Can doctors predict patients' abbreviated mental test scores.

OBJECTIVES: the abbreviated mental test is widely used in the assessment of cognitive impairment in elderly patients. However, many doctors do not administer the full 10 questions, preferring to estimate the patient's score instead. We have studied the accuracy of doctors in predicting patients' abbreviated mental test scores. METHODS: we assessed 102 patients in the geriatric unit. We asked doctors to predict the patient's abbreviated mental test during the admission interview. A true abbreviated mental test was then recorded. RESULTS: mean age was 80.9 years with a male:female ratio of 27:74. The mean predicted abbreviated mental test score was 6.57 (SD 2.9); the mean actual abbreviated mental test score being 6.36 (SD 3.2). Comparing the two groups, abbreviated mental test scores were predicted most accurately at the extremes and correlation between the two groups of scores was high (P<0.001 Spearman test). Kappa statistics revealed moderate agreement between the two groups, (0.56, 95% CI 0.48-0.63). A predicted score of 5/10 showed the greatest spread of true abbreviated mental test scores (0-10, mean 4.5). However in total, only 31% of the predicted abbreviated mental test scores were accurate, with 42% being incorrect by >1. Using the accepted cut-off of <7/10, this revealed that 13% were underdiagnosed and 19% were overdiagnosed as being cognitively impaired. CONCLUSIONS: clinicians are poor at predicting abbreviated mental tests in the midrange but are more accurate at predicting lower and higher scores. This descriptive study reinforces the importance of using an objective assessment of cognitive impairment rather than clinicians estimating its presence or absence.

Evaluation of a transcription-mediated amplification-based HCV and HIV-1 RNA duplex assay for screening individual blood donations: a comparison with a minipool testing system.

BACKGROUND: NAT was introduced for HCV RNA in 1999 to screen blood donations and improve the safety of the blood supply. STUDY DESIGN AND METHODS: The performance of a NAT multiplex for HCV and HIV-1 RNA based on transcription-mediated amplification (TMA) was assessed with various sensitivity panels and by screening 50,000 serologically unscreened, first-time donor plasma samples. Results were compared with a routine NAT screening for HCV RNA by RT-PCR in pools of 96 plasma samples. RESULTS: The TMA multiplex 95 percent sensitivity ranged between 22 and 54 IU per mL for HIV-1 and 15 and 20 IU per mL for HCV RNA. The rate of test failure was 8.6 percent but decreased to 4.7 percent when results of two critical periods of equipment malfunction were excluded. Test failure was related to human error, minute control contamination, and insufficient mixing of reagents at the extraction stage. All 31 repeatedly reactive samples (0.06%) were seropositive for HCV (29) or HIV-1 (2) and contained RNA detectable by discriminatory TMA and confirmatory RT-PCR, indicating 100 percent specificity. A direct comparison of TMA in individual samples and RT-PCR in plasma pools was possible on 27 HCV RNA-containing samples. Twenty-six samples were detected in plasma pools; the lack of detection of 1 sample was due to an identification error at the pooling stage. CONCLUSION: The HCV and HIV-1 multiplex NAT had high specificity and sensitivity.