Left Hemisphere Lesions Research Articles

Function-specific Tractography of Language Pathways Based on nTMS Mapping in Patients with Supratentorial Lesions.

In patients with supratentorial lesions diffusion tensor imaging fiber tracking (DTI-FT) is increasingly used to visualize subcortical fiber courses. Navigated transcranial magnetic stimulation (nTMS) was applied in this study to reveal specific cortical functions by investigating the particular language errors elicited by stimulation. To make DTI-FT more function-specific, the identified language-positive nTMS spots were used as regions of interest (ROIs). In this study 40 patients (mean age 53.8 ± 16.0 years) harboring language-eloquent left hemispheric lesions underwent preoperative nTMS language mapping. All induced error categories were separately defined as aROI and used for function-specific nTMS-based DTI-FT. The fractions of patients showing various subcortical language-related pathways and the fibers-per-tract ratio (number of visualized fibers divided by the number of visualized tracts) were evaluated and compared for tractography with the single error types against less specific tractography including all identified cortical language sites (all errors except hesitations). The nTMS-based DTI-FT using all errors except hesitations led to high fractions of visualized tracts (81.1% of patients), with afibers-per-tract ratio of 538.4 ± 340.5. When only using performance errors, apredominant visualization of the superior longitudinal fascicle (SLF) occurred, which is known to be involved in articulatory processes. Fibers-per-tract ratios were comparatively stable for all single error categories when compared to all errors except hesitations (p > 0.05). This is one of the first studies aiming on function-specific tractography. The results demonstrated that when using different error categories as ROIs, more detailed nTMS-based DTI-FT and, therefore, potentially superior intraoperative guidance becomes possible.

The involvement of left inferior frontal and middle temporal cortices in word production unveiled by greater facilitation effects following brain damage

In stroke-induced aphasia, left hemispheric lesions generally disturb the word production network. The left inferior frontal gyrus (LIFG) and the left middle temporal gyrus (LMTG) are involved in word production, but their respective contribution remains ambiguous. Previous investigations have largely focused on semantic interference to gather information about word production. Here we assessed the sensitivity of twenty-five aphasic speakers with either LIFG or LMTG lesions and matched controls to both semantic facilitation and interference in word production using the picture-word (PWP) and the blocked-cyclic naming (BCNP) paradigms. In the PWP (Exp. 1), semantic facilitation was exaggerated in participants with LIFG damage as compared to age-matched controls. In the BCNP (Exp. 2), repetition priming on production speed was larger in participants with LMTG damage than in controls, without any decrease of semantic errors. In the light of the results in the PWP, the LIFG appears to be a necessary structure to shape semantic facilitation. It might play an important role in properly adjusting the lexical selection threshold within the word production network. The results in the BCNP suggest that the LMTG conveys semantic-to-lexical connections likely involved in repetition priming and in mapping concepts to their correct lexical label. As consequences, participants with LIFG lesions possibly rely more on strategic vs automatic processes to efficiently select lexical entries in semantically competitive contexts, whereas participants with LMTG might exploit residual semantic-to-lexical activation.

Abnormal Functional Connectivity Density in Post-Stroke Aphasia.

Post-stroke aphasia (PSA), which refers to the loss or impairment of language, is typically caused by left hemisphere lesions. Previous neuroimaging studies have indicated that the pathology of PSA may be related to abnormalities in functional integration. In this study, we used resting-state functional magnetic resonance imaging (rs-fMRI) to examine functional connectivity density (FCD) in PSA. We compared short- and long-range FCD between individuals with PSA (n = 17) and healthy controls (HC, n = 20). We then performed Pearson's correlation analysis on the FCD values from the affected brain regions and the speech scores in the PSA group. Compared with HCs, individuals with PSA showed increased short-range FCD in the contralesional temporal gyrus, the inferior frontal gyrus, the thalamus, the insula, and the mesial temporal gyrus [hippocampus/parahippocampus (HIP/ParaHIP)]. PSA demonstrated an increased long-range FCD in the contralesional mesial temporal gyrus (HIP/ParaHIP). PSA also displayed decreased short-range FCD in the ipsilesional part of the frontal gyrus, the caudate, the thalamus, the fusiform gyrus, and the mesial temporal gyrus (HIP/ParaHIP), and decreased long-range FCD in the ipsilesional superior temporal gyrus, the fusiform gyrus, and the mesial temporal gyrus (HIP/ParaHIP). The decreased long-range FCD in the left superior temporal gyrus in PSA subjects was positively correlated with the spontaneous speech score. The altered FCD observed due to disrupted functional connectivity after stroke may lead to language production, semantic processing, and cognitive impairments. Our findings expand previous functional studies on stroke and provide new evidence of the intraregional and interregional interactions at the voxel level in the pathophysiology of PSA.

Impact of Ischemic Lesion Location on the mRS Score in Patients with Ischemic Stroke: A Voxel-Based Approach.

Previous studies indicated that ischemic lesion volume might be a useful surrogate marker for functional outcome in ischemic stroke but should be considered in the context of lesion location. In contrast to previous studies using the ROI approach, which has several drawbacks, the present study aimed to measure the impact of ischemic lesion location on functional outcome using a more precise voxelwise approach. Datasets of patients with acute ischemic strokes from the Multicenter Randomized Clinical Trial of Endovascular Therapy for Acute Ischemic Stroke in the Netherlands (MR CLEAN) were used. Primary outcome was functional outcome as assessed by the modified Rankin Scale 3 months after stroke. Ischemic lesion volume was determined on CT scans 3-9 days after stroke. Voxel-based lesion-symptom mapping techniques, including covariates that are known to be associated with functional outcome, were used to determine the impact of ischemic lesion location for outcome. Of the 500 patients in the MR CLEAN trial, 216 were included for analysis. The mean age was 63 years. Lesion-symptom mapping with inclusion of covariates revealed that especially left-hemispheric lesions in the deep periventricular white matter and adjacent internal capsule showed a great influence on functional outcome. Our study confirms that infarct location has an important impact on functional outcome of patients with stroke and should be considered in prediction models. After we adjusted for covariates, the left-hemispheric corticosubcortical fiber tracts seemed to be of higher functional importance compared with cortical lesions.

Study of Simplified Coma Scales: Acute Stroke Patients with Tracheal Intubation.

Background:Whether the Glasgow Coma Scale (GCS) can assess intubated patients is still a topic of controversy. We compared the test performance of the GCS motor component (GCS-M)/Simplified Motor Score (SMS) to the total of the GCS in predicting the outcomes of intubated acute severe cerebral vascular disease patients.Methods:A retrospective analysis of prospectively collected observational data was performed. Between January 2012 and October 2015, 106 consecutive acute severe cerebral vascular disease patients with intubation were included in the study. GCS, GCS-M, GCS eye-opening component, and SMS were documented on admission and at 24, 48, and 72 h after admission to Neurointensive Care Unit (NCU). Outcomes were death and unfavorable prognosis (modified Rankin Scale: 5–6) at NCU discharge. The receiver operating characteristic (ROC) curve was obtained to determine the prognostic performance and best cutoff value for each scoring system. Comparison of the area under the ROC curves (AUCs) was performed using the Z-test.Results:Of 106 patients included in the study, 41 (38.7%) patients died, and 69 (65.1%) patients had poor prognosis when discharged from NCU. The four time points within 72 h of admission to the NCU were equivalent for each scale's predictive power, except that 0 h was the best for each scale in predicting outcomes of patients with right-hemisphere lesions. Nonsignificant difference was found between GCS-M AUCs and GCS AUCs in predicting death at 0 h (0.721 vs. 0.717, Z = 0.135, P = 0.893) and 72 h (0.730 vs. 0.765, Z = 1.887, P = 0.060), in predicting poor prognosis at 0 h (0.827 vs. 0.819, Z = 0.395, P = 0.693), 24 h (0.771 vs. 0.760, Z = 0.944, P = 0.345), 48 h (0.732 vs. 0.741, Z = 0.593, P = 0.590), and 72 h (0.775 vs. 0.780, Z = 0.302, P = 0.763). AUCs in predicting death for patients with left-hemisphere lesions ranged from 0.700 to 0.804 for GCS-M and from 0.700 to 0.824 for GCS, in predicting poor prognosis ranged from 0.841 to 0.969 for GCS-M and from 0.875 to 0.969 for GCS, with no significant difference between GCS-M AUCs and GCS AUCs within 72 h (P > 0.05). No significant difference between GCS-M AUCs and GCS AUCs was found in predicting death (0.964 vs. 0.964, P = 1.000) and poor prognosis (1.000 vs. 1.000, P = 1.000) for patients with right-hemisphere lesions at 0 h. AUCs in predicting death for patients with brainstem or cerebella were poor for GCS-M (<0.700), in predicting poor prognosis ranged from 0.727 to 0.801 for GCS-M and from 0.704 to 0.820 for GCS, with no significant difference between GCS-M AUCs and GCS AUCs within 72 h (P > 0.05). The SMS AUCs (<0.700) in predicting outcomes were poor.Conclusions:The GCS-M approaches the same test performance as the GCS in assessing the prognosis of intubated acute severe cerebral vascular disease patients. The GCS-M could be accurately and reliably applied in patients with hemisphere lesions, but caution must be taken for patients with brainstem or cerebella lesions.

Measuring the sense of self in brain-damaged patients

Recently, researchers have focused on the embodied sense of self (ESS), which consists of the minimal and narrative selves. Although a study demonstrated that the ESS is related to brain dysfunction empirically, the subjective aspects of the ESS, and a systematic approach to it, have not yet been examined in brain-damaged patients. To examine this, we measured the ESS of patients with brain tumors before and after awake craniotomy.A self-reported questionnaire called the Embodied Sense of Self Scale (ESSS) was used to measure the ESS in patients with brain tumors before and after surgery. For comparison, age-matched controls also completed the ESSS.The ESSS scores of the patients with brain tumors before surgery were higher than those of the controls and improved after surgery. Before surgery, patients with left hemispheric lesions had a poorer ESSS than those with right hemispheric lesions. Episodic memory disturbance was highly correlated with malfunction of narrative self and ownership.Brain lesions were associated with anomalous ESSS, associated with hemispheric laterality and cognitive dysfunction.

Anosognosia in degenerative brain diseases: The role of the right hemisphere and of its dominance for emotions

Earlier studies, which suggested that anosognosia of hemiplegia might be related to right hemisphere (RH) lesions did not control for the influence of confounding variables, such as aphasia, in patients with left-hemisphere lesions and unilateral neglect in those with RH lesions. These confounding variables are absent in patients with degenerative brain disease, where a prevalence of right-sided lesions is often associated with emotional and behavioural disturbances. This review, which can be considered a ‘qualitative synthesis’, aimed, therefore, to determine whether the unawareness phenomena observed in degenerative brain diseases are linked to the RH dominance for emotions. Results of the review confirmed that the neural correlates of anosognosia are often right lateralised in patients with degenerative brain diseases and that emotional disturbances are associated with right frontal lesions and anosognosia in the behavioural variant, i.e., frontotemporal dementia (bvFTD). However, they also showed that anosognosia is a heterogeneous phenomenon and that the role of right frontal lesions is much greater when the loss of insight concerns emotion-linked aspects of personality or behaviour than when it concerns particular aspects of cognition or memory.

Brain network topology influences response to intensive comprehensive aphasia treatment.

Recent imaging studies indicate that aphasia is associated with large-scale reorganization of brain networks. Today, neuroimaging studies show that various brain connectivity properties, as measured by resting state fMRI, can partially explain different behavioral symptoms in and across various patient groups. Despite these observations, the neural networks underlying the progress and recovery of aphasia following intensive treatment remains relatively obscure. To examine the role of brain network properties in determining recovery of aphasia following intensive therapy in stroke patients. We studied eight patients with left hemispheric lesions who completed an intensive comprehensive aphasia program (ICAP). Language and cognition were assessed before and after four weeks of intensive treatment. In addition, all patients underwent resting state fMRI prior to and after treatment. We used graph theory analysis to evaluate relationships of baseline brain network properties, such as efficiency, modularity, and connectivity to clinical improvements. We found global properties such as efficiency and interhemispheric connectivity could partially explain recovery. More importantly, we identified two unique brain networks that are significantly associated with improvement in language and attention related behavior. These results suggest baseline brain functional properties play a key role in determining responsiveness of patients with aphasia to intensive comprehensive aphasia treatment. Furthermore, these results indicate that brain mechanisms underlying language comprehension and processes are different from those involved in spatial attention.

Types of Neuroplasticity and Factors Affecting Language Recovery in Patients with Aphasia: A Systematic Review

Introduction: Aphasia is an acquired language injury apart from cognitive, motor, or sensory damages, as the result of a brain injury and stroke in the left hemisphere. In the acute phase of aphasia (the first two or three months) a preponderance of people show certain degrees of recovery, the neural mechanisms of which are yet to be detected, other than the fact that it is related to the plasticity changes in the patient’s brain. Neuroplasticity is the capacity of a brain to change or be modified at cellular or behavioral levels. Objectives: The current study aimed at reviewing the literature on neuroplasticity and factors affecting language recovery of patients with aphasia. Data Sources: PubMed, Google Scholar, ScienceDirect, Irandoc, Magiran, SID, Web of Knowledge, Ovid, Springer, and manual search of reference lists from January 1990 to April 2017. Inclusion Criteria: Neuroplasticity and aphasia keywords in the title of the article, studies conducted only on human samples, and adult samples with acquired aphasia. Results: Out of the 6637 retrieved studies, eight articles met the inclusion and exclusion criteria and two related papers were further reported. Recent studies show that three types of changes, in the nervous activity following stroke are closely related to aphasia recovery: reactivation of the injured areas of the left hemisphere or perilesional left hemisphere regions regarding language assignments, the ability to process language in the right hemisphere, and compensatory activity of the right hemisphere, which can hinder language recovery. Conclusions: Most studies demonstrated that areas around the left hemisphere lesion engage in the recovery of the language; certain studies, on the other hand, reported that areas around the right hemisphere are involved, and some consider both hemispheres to be involved in the language recovery. It is difficult to predict the improvement of language owing to the involvement of various factors. Limitations: One of the most important limitations was the unavailability of the full-text of three articles.

Can age-related hearing loss affect language rehabilitation in aphasic patients?

Aphasia is a language disorder caused by left hemispheric lesion, compromising functional recovery. Age-related hearing loss (ARHL) decreases understanding spoken language, and represents a major public health issue despite the little attention received, affecting around 30% of Europeans by the age of 70 years. The populations most susceptible to hearing loss and to aphasia overlap and co-occurrence of both conditions can lead to compounded communication impairment. Our goal was to review existing data about occurrence of ARHL in patients with aphasia, concerning language rehabilitation. A search of PubMed database and selection of eligible studies was performed. We applied a combination of keywords including: age-related hearing loss, aphasia, stroke, peripheral auditory system, hearing aids and language. A total of 94 studies were found, from which 19 met our selection criteria. We found that the assessment of ARHL in aphasic patients remains under-investigated. ARHL is a possible biomarker and modifiable risk factor for cognitive decline, and there is strong cross-sectional association between stroke and hearing loss. Studies support that hearing evaluation should be performed in aphasic patients. Pure tone audiometry can be used as hearing screening in the post-acute phase, and a study showed that 72.82% of patients successfully underwent this test. Speech audiometry can be compromised, but the performance in this exam is largely determined by hearing loss rather than by aphasia, so clinicians should not hesitate to use this tool if patients are able to repeat single words. Therapeutic success in aphasia can be reduced by an existing ARHL, and hearing evaluation is justified in all patients. Despite the evidences, hearing screenings are being conducted only inconsistently with this population. There is a need to develop tools that are easily accessible and validated for aphasia. Moreover, the role of hearing aids in aphasic patients’ rehabilitation remains unclear.

Effect of Computerized Neuropsychologic Test in Subacute Post-Stroke Patient With Cognitive Impairment

Objectives To investigate the effects of Computerized Neuropsychologic Test (CNT) on cognitive function and daily life performance in subacute post-stroke patients with cognitive impairment. Methods Korean Mini-Mentals State Examination (K-MMSE), Korean version of Modified Barthel Index (K-MBI) were investigated in 125 subacute post-stroke patients with cognitive impairment. We analyzed K-MMSE and K-MBI which were conducted 63 patients who had received CNT and 62 patient who had not received CNT from baseline to 8 weeks follow-up. In the experimental group, initial K-MMSE and K-MBI were conducted 13.3 ± 6.8 weeks after the onset of stroke and their age was 63.4 ± 13.3. In the control group, initial K-MMSE and K-MBI were conducted 13.2 ± 7.7 weeks after the onset of stroke and their age was 65.1 ± 11.6. Results The 8 weeks follow-up total K-MMSE score and total K-MBI score of experimental group were significantly higher than control group ( P &amp;lt; 0.05). In K-MMSE subsection, orientation, judgement, recall, language &amp;amp; visual reconstruction were significantly higher in experimental group than control group ( P &amp;lt; 0.05). In K-MBI subsection, personal hygiene, bathing self, toilet, dressing, ambulation, chair/bed transfer were significantly higher in experimental group than control group ( P &amp;lt; 0.05). The change of total K-MMSE score of experimental group was significantly correlated with change of total K-MBI score ( P &amp;lt; 0.05), but control group was not ( P &amp;gt; 0.05). In K-MMSE subsection, change of orientation, registration, language and visual reconstruction were correlated with total K-MBI s core after CNT. Especially, the experimental group, total K-MBI score of the left hemisphere damage group was significantly higher than the right hemisphere damage group ( P &amp;lt; 0.05). Conclusions This study shows that CNT is effective on subacute post-stroke patients with cognitive impairment. Improvement of cognitive function can expect a positive outcome on daily life performance, in particular, it can be expected to improve the prognosis of patients with stroke, the left hemisphere lesions.

Auditory neglect in children following perinatal stroke

Auditory neglect has been found in adults with right hemisphere focal brain lesions following strokes. Visual and tactile neglect has been found in children following both left and right hemisphere lesions resulting from perinatal strokes. The present cross-sectional study assessed auditory neglect in children with early unilateral brain damage from perinatal stroke. Twenty-six children with perinatal stroke and matched controls participated. All were asked to identify the location of a pure tone presented in left or right auditory fields. We found that children who had experienced left hemisphere perinatal strokes were significantly better at localizing sounds on the left side of space than the right side of space, and that response times improved with age on a normal trajectory relative to controls in left hemispace, while they did not improve normally in right hemispace. Children with right hemisphere perinatal strokes were significantly worse at localizing sounds on the right side of space relative to typically developing controls, and did not follow control trajectories for improvement in response times on the left or the right sides of space. Our preliminary results suggest that left hemisphere perinatal strokes may result in contralateral auditory neglect, while right hemisphere perinatal strokes may result in bilateral auditory neglect. Neglect was more severe in children with parietal lobe involvement, suggesting that the parietal lobe may play a dominant role in auditory attention in the developing brain.

Inference comprehension in text reading: Performance of individuals with right- versus left-hemisphere lesions and the influence of cognitive functions.

BackgroundRight-hemisphere lesions (RHL) may impair inference comprehension. However, comparative studies between left-hemisphere lesions (LHL) and RHL are rare, especially regarding reading comprehension. Moreover, further knowledge of the influence of cognition on inferential processing in this task is needed.ObjectivesTo compare the performance of patients with RHL and LHL on an inference reading comprehension task. We also aimed to analyze the effects of lesion site and to verify correlations between cognitive functions and performance on the task.MethodsSeventy-five subjects were equally divided into the groups RHL, LHL, and control group (CG). The Implicit Management Test was used to evaluate inference comprehension. In this test, subjects read short written passages and subsequently answer five types of questions (explicit, logical, distractor, pragmatic, and other), which require different types of inferential reasoning. The cognitive functional domains of attention, memory, executive functions, language, and visuospatial abilities were assessed using the Cognitive Linguistic Quick Test (CLQT).ResultsThe LHL and RHL groups presented difficulties in inferential comprehension in comparison with the CG. However, the RHL group presented lower scores than the LHL group on logical, pragmatic and other questions. A covariance analysis did not show any effect of lesion site within the hemispheres. Overall, all cognitive domains were correlated with all the types of questions from the inference test (especially logical, pragmatic, and other). Attention and visuospatial abilities affected the scores of both the RHL and LHL groups, and only memory influenced the performance of the RHL group.ConclusionsLesions in either hemisphere may cause difficulties in making inferences during reading. However, processing more complex inferences was more difficult for patients with RHL than for those with LHL, which suggests that the right hemisphere plays an important role in tasks with higher comprehension demands. Cognition influences inferential processing during reading in brain-injured subjects.

Modification of Cerebellar Afferent Pathway in the Subacute Phase of Stroke

This study aims to identify the relationship between corticopontocerebellar tract (CPCT) and corticospinal tract (CST) integrity as well as motor function after stroke. A total of 33 patients with stroke (18 left, 15 right hemispheric lesions) who underwent diffusion tensor imaging within 2 months of stroke onset and 17 age- and sex-matched healthy controls were retrospectively enrolled. Tract volume and the asymmetry index based on tract volume (AITV) of the CST and CPCT were used to identify structural changes in individual tracts and the correlation between those tracts. Motor function was assessed using the Medical Research Council (MRC) muscle scale, manual function test (MFT), functional ambulation category, and modified Barthel index. The volume of the affected CPCT was lower, and that of the unaffected CPCT was higher than the volumes in the control group (P < .001, P = .001, respectively). The CPCT AITV showed a strong positive correlation with the CST AITV in patients with either left or right hemispheric lesions (rs = .779, P < .001; rs = .732, P = .003, respectively). The CPCT AITV negatively correlated with the MRC muscle scale of the shoulder, wrist, and ankle muscles (r = -.490, -.490, -.416; P = .004, .004, .016, respectively). A higher unaffected CPCT volume was indicative of less affected upper extremity function, as assessed by MFT (rs = -.546, P = .029). Modification of the CPCT depended on CST integrity and was associated with the severity of hemiplegia and hemiplegic upper extremity function. The CPCT may complement the role of the CST and help to predict the motor function.

Assessment of cognitive functions in patients with metabolic syndrome after ischemic stroke

Post-stroke cognitive impairment (PSCI) occupies a prominent position among cognitive impairment associated with vascular brain pathology. The purpose – to assess cognitive functions in patients with the history of ischemic stroke, depending on the metabolic syndrome (MS) presence and to determine the peculiarities of cognitive functions dynamics in the early recovery period after ischemic stroke in the anterior circulation area in patients with and without metabolic syndrome depending on ischemic lesion localization. Materials and methods. There were 122 patients in the early recovery period after ischemic stroke enrolled into the study. Depending on the MS presence, patients with the history of ischemic stroke were divided into 2 groups: with MS (n = 72) and without MS (n = 50). All the patients were divided into 3 age subgroups: 45 – 59 years – middle age, 60 – 74 years – elderly, 75 – 89 years - senile age. All patients had general clinical, neuropsychological examination, laboratory tests; MRI of the brain. Results. There was no significant difference among patients of the main clinical groups on the frequency of pre-mild and mild cognitive impairment; however the incidence of post-stroke dementia was significantly higher among patients with MS comparing with those without MS. There was significant augmentation of PSCI severity with age in patients with MS and without it. According to the results of neuropsychological tests, the best cognitive functions recovery in 6 months after the stroke (in the early recovery period) was observed in patients without MS, especially in the cases of left hemisphere ischemic lesions. Conclusions. Patients with MS had significantly more pronounced PSCI than patients without MS. The increase in age had a negative effect on the PSCI severity both in patients with and without metabolic syndrome. The presence of MS worsened the process of cognitive functions restoration in patients with PSCI.

A Case-Control Study Investigating Simulated Driving Errors in Ischemic Stroke and Subarachnoid Hemorrhage.

Stroke can affect a variety of cognitive, perceptual, and motor abilities that are important for safe driving. Results of studies assessing post-stroke driving ability are quite variable in the areas and degree of driving impairment among patients. This highlights the need to consider clinical characteristics, including stroke subtype, when assessing driving performance. We compared the simulated driving performance of 30 chronic stroke patients (>3 months), including 15 patients with ischemic stroke (IS) and 15 patients with subarachnoid hemorrhage (SAH), and 20 age-matched controls. A preliminary analysis was performed, subdividing IS patients into right (n = 8) and left (n = 6) hemispheric lesions and SAH patients into middle cerebral artery (MCA, n = 5) and anterior communicating artery (n = 6) territory. A secondary analysis was conducted to investigate the cognitive correlates of driving. Nine patients (30%) exhibited impaired simulated driving performance, including four patients with IS (26.7%) and five patients with SAH (33.3%). Both patients with IS (2.3 vs. 0.3, U = 76, p < 0.05) and SAH (1.5 vs. 0.3, U = 45, p < 0.001) exhibited difficulty with lane maintenance (% distance out of lane) compared to controls. In addition, patients with IS exhibited difficulty with speed maintenance (% distance over speed limit; 8.9 vs. 4.1, U = 81, p < 0.05), whereas SAH patients exhibited difficulty with turning performance (total turning errors; 5.4 vs. 1.6, U = 39.5, p < 0.001). The Trail Making Test (TMT) and Useful Field of View test were significantly associated with lane maintenance among patients with IS (rs > 0.6, p < 0.05). No cognitive tests showed utility among patients with SAH. Both IS and SAH exhibited difficulty with lane maintenance. Patients with IS additionally exhibited difficulty with speed maintenance, whereas SAH patients exhibited difficulty with turning performance. Current results support the importance of differentiating between stroke subtypes and considering other important clinical characteristics (e.g., side of lesion, vascular territory) when assessing driving performance and reinforce the importance of physicians discussing driving safety with patients after stroke.

Abstract TMP48: Subcortical Volumes Associated With Post-Stroke Motor Performance Vary Across Impairment Severity, Time Since Stroke, and Lesion Laterality: an ENIGMA Stroke Recovery Analysis

Associations between subcortical gray matter volume and motor performance post-stroke are unclear, partly because many stroke MRI studies are underpowered. Potential influences of the severity of motor impairment, lesion laterality, and time since stroke on these associations is also unknown. Here, we addressed these questions using a large dataset (n=629) from the ENIGMA Stroke Recovery working group (http://enigma.usc.edu). Regression analyses examined brain volumes as predictors of motor scores. ENIGMA FreeSurfer protocols extracted volumes from 16 subcortical regions on T1-weighted MRIs; segmentations were manually quality controlled. Motor scores were calculated as a percentage of the maximum possible score (100% = no impairment). Covariates (e.g., age, sex, intracranial volume) were modeled. Statistical significance was assessed nonparametrically by permutation. Separate analyses were performed, stratifying by motor severity and time since stroke. Each analysis was also subdivided by lesioned hemisphere. The motor severity analysis (Table 1A) used subgroups of mild (66.7-99.9%), moderate (33.3-66.6%), and severe (0-33.2%). Significant associations were found for mild and moderate, but not severe, stroke; only the left hemisphere stroke group showed further significant results. The time since stroke analysis (Table 1B) used subgroups of acute (&lt;1 month), subacute (1-6 months), and chronic (&gt;6 months). Significant associations were found in chronic stroke, but not acute, subacute. Left versus right hemisphere lesions generated different results in chronic stroke. Overall, these results show that the most significant associations between subcortical volumes and motor outcomes are in chronic mild-to-moderate stroke. Stroke subgroups may recover via disparate mechanisms; establishing biomarkers of impairment and disability across stroke subgroups may be useful for clinical trials.

Unilateral Apraxic Agraphia without Ideomotor Apraxia from a callosal lesion in a patient with Marchiafava-Bignami disease

ABSTRACTApraxic agraphia can be caused by left hemispheric cerebral lesions in the area that contains the spatial representations of the movements required to write, from a lesion in, or connections to, the frontal premotor cortex that converts these spatial representations to motor programs (Exner’s area). A right-handed woman with Marchiafava Bignami disease and lesions of the genu and splenium of her corpus callosum had apraxic agraphia without ideomotor apraxia of her left. A disconnection of Exner’s area in the left hemisphere from the right hemisphere’s premotor and motor areas may have led to her inability to write with her left hand.

Left hemispheric lesion was correlated with erectile dysfunction in stroke subjects

Left hemispheric lesion was correlated with erectile dysfunction in stroke subjects

Altered functional connectivity differs in stroke survivors with impaired touch sensation following left and right hemisphere lesions.

One in two survivors experience impairment in touch sensation after stroke. The nature of this impairment is likely associated with changes associated with the functional somatosensory network of the brain; however few studies have examined this. In particular, the impact of lesioned hemisphere has not been investigated. We examined resting state functional connectivity in 28 stroke survivors, 14 with left hemisphere and 14 with right hemisphere lesion, and 14 healthy controls. Contra-lesional hands showed significantly decreased touch discrimination. Whole brain functional connectivity (FC) data was extracted from four seed regions, i.e. primary (S1) and secondary (S2) somatosensory cortices in both hemispheres. Whole brain FC maps and Laterality Indices (LI) were calculated for subgroups. Inter-hemispheric FC was greater in healthy controls compared to the combined stroke cohort from the left S1 seed and bilateral S2 seeds. The left lesion subgroup showed decreased FC, relative to controls, from left ipsi-lesional S1 to contra-lesional S1 and to distributed temporal, occipital and parietal regions. In comparison, the right lesion group showed decreased connectivity from contra-lesional left S1 and bilateral S2 to ipsi-lesional parietal operculum (S2), and to occipital and temporal regions. The right lesion group also showed increased intra-hemispheric FC from ipsi-lesional right S1 to inferior parietal regions compared to controls. In comparison to the left lesion group, those with right lesion showed greater intra-hemispheric connectivity from left S1 to left parietal and occipital regions and from right S1 to right angular and parietal regions. Laterality Indices were significantly greater for stroke subgroups relative to matched controls for contra-lesional S1 (left lesion group) and contra-lesional S2 (both groups). We provide evidence of altered functional connectivity within the somatosensory network, across both hemispheres, and to other networks in stroke survivors with impaired touch sensation. Hemisphere of lesion was associated with different patterns of altered functional connectivity within the somatosensory network and with related function was associated with different patterns of altered functional connectivity within the somatosensory network and with related functional networks.