Hemispheric Stroke Research Articles

Crossed Wernicke’s Aphasia With Focal Clonic Cluster Seizures With Secondary Generalization Mimicking Faciobrachial Seizures Following a Right Middle-Cerebral-Artery Ischemic Stroke: A Novel Phenotypic Presentation

Crossed Wernicke’s aphasia (CWA) following a stroke is a rare clinical phenomenon, particularly when associated with seizures. This case report presents a unique instance of crossed CWA accompanied by focal clonic cluster seizures affecting the left arm and face, with secondary generalization, in a monolingual Bengali-speaking patient following a right middle cerebral artery ischemic stroke. The patient, a 70-year-old male from rural India, presented with acute behavioral abnormalities and language impairment. He experienced left-sided focal motor-onset clonic seizures with impaired awareness, followed by fluent yet unintelligible speech, characterized by phonemic and semantic paraphasias, as well as neologistic jargon. Neuroimaging revealed a right parieto-occipital infarct. Although initially misdiagnosed and treated for acute psychosis, thorough clinical evaluation ultimately led to the diagnosis of CWA—a rare form of aphasia in a right-handed individual after a right hemisphere stroke. This case underscores the diagnostic challenges associated with stroke-related language disorders and highlights the importance of recognizing variations in language lateralization. Furthermore, the occurrence of CWA in a Bengali-speaking individual emphasizes the potential impact of linguistic and cultural factors on brain organization and language processing. This case also adds to the limited body of literature regarding the co-occurrence of post-stroke seizures and aphasia, particularly in atypical presentations such as CWA.

Prediction of Aphasia Outcome Using Low Frequency Transcranial Magnetic Stimulation in Post-Stroke Non-Fluent Aphasia

Background: Stroke, a global health concern, often leads to language impairment (aphasia). In Egypt, with a high stroke prevalence, aphasia affects a significant number of survivors. Noninvasive techniques like repetitive transcranial magnetic stimulation (rTMS) show promise in rehabilitation. Cultural variations in test results emphasize the need for region-specific considerations in standardized assessments for post-stroke care. Aim of the work: To evaluate the role of low frequency rTMS to speed up the recovery of post-stroke aphasia for a better quality of life. Patients and Methods: This randomized clinical trial investigates the effects of (rTMS) on post-stroke aphasia. Patients with post-stroke non-fluent aphasia were divided into two groups, with one receiving inhibitory rTMS and the other sham sessions. Inclusion criteria involve adults with a single left hemisphere stroke, while exclusion criteria include prior strokes. The study includes comprehensive assessments for aphasia, and depression. The stimulation protocol involves 20 minutes of daily rTMS for ten days, targeting the right inferior frontal gyrus. The study aims to evaluate the rTMS impact on language recovery. Results: The study evaluated low-frequency rTMS for post-stroke aphasia recovery in 30 patients, comparing TMS and sham groups. No significant demographic or cerebrovascular risk factor differences were found. While rTMS group showed improvement in depression, there were no significant differences between TMS and sham groups in aphasia improvement. Conclusion: Low-frequency rTMS demonstrated no significant superiority over sham stimulation in post-stroke aphasia recovery. Both groups exhibited improved depression without notable distinctions.

The impact of rehabilitation on the recovery of executive functions in stroke patients with different location of the ischemic focus.

Cognitive dysfunction is part of the clinical picture of stroke. Most of the executive dysfunctions are diagnosed in the early stage of rehabilitation, a few weeks after the vascular incident. Coexistence of executive dysfunctions with other disorders in stroke patients may hinder patient's functions, slow down the rehabilitation process, and disrupt self-awareness, interpersonal communication, and professional activity in everyday life. Ninety patients after ischemic stroke were examined (right hemisphere stroke: N = 33, left hemisphere stroke: N = 57). The study group (N = 45) consisted of patients rehabilitated in the Department of Rehabilitation and Physical Medicine of the University Teaching Hospital of the Military Medical Academy in Lodz, Łódź, Poland, in whom a comprehensive neurorehabilitation program was implemented, consisting of motor and neuropsychological rehabilitation. The control group (N = 45) consisted of patients awaiting admission to the department, who were covered by comprehensive environmental rehabilitation including exercise therapy and neuropsychological therapy. Executive function was measured with 3 popular diagnostic tools: the Wisconsin Card Sorting Test (WCST), the Trail Making Test (TMT part A, TMT part B), and the letter test and category test with the Verbal Fluency Test (VFT). The tests were carried out twice: the first time before the start of rehabilitation and 5 weeks later after its completion. Although patients with right-hemispheric stroke showed better improvement in executive functions, stroke location did not prove to have significant impact on how effective the rehabilitation was. Right hemisphere stroke patients showed greater improvement in restoring executive functions after rehabilitation compared to left hemisphere stroke patients. The location of the stroke did not significantly correlate with the efficiency of the rehabilitation setting. Int J Occup Med Environ Health. 2024;37(4).

Reaching the cognitive-motor interface: effects of cognitive load on arm choice and motor performance after stroke.

A vexing characteristic of motor disability after stroke is that many individuals fail to use their affected arm effectively despite having the capacity to do so, a phenomenon termed arm nonuse. Based on the hypothesis that nonuse is influenced by the competing cognitive demands of many daily activities, we examined the effects of cognitive load on arm choice and motor performance in individuals with stroke using a novel virtual reality paradigm that mimics the demands of real-life visual search, object selection, and reaching to targets. Twenty individuals with single left or right hemispheric chronic stroke (11 left cerebrovascular accident; 9 right cerebrovascular accident) and 10 age-matched neurotypical participants completed the Virtual Reality Arm Choice task, in which they reached for target objects in an array under varied cognitive demand. To manipulate cognitive demand, we varied the semantic similarity of objects in the reaching space and the presence or absence of a secondary task. The results showed reduced use of the paretic arm under increased demand. Under cognitive load, participants with stroke also showed slower reach initiation, slower movements, increased reach curvature, and increased performance differences between the paretic and non-paretic arms. The arm choice of neurotypical individuals was also modulated under cognitive load. These data indicate that cognitive factors influence arm choice and motor performance in naturalistic reaching tasks in individuals with chronic stroke. Performance decrements under cognitive load may in turn influence reduced paretic arm use during daily activities.

7668 Rhabdomyolysis Associated with Severe Hypothyroidism

Abstract Disclosure: H. Soe: None. P. Mikkilineni: None. Background: Over 70% of the patients with newly diagnosed hypothyroidism can present with muscle complaints such as weakness, fatigability, cramps, myalgia. However, rhabdomyolysis, which is the rapid breakdown of skeletal muscle cells, is the rare presentation. Clinical Case: A 70-year old male patient with history of rheumatoid arthritis, hyperlipidemia, prior CVA (left hemispheric subcortical stroke) 6 months ago without residual deficit presented to the hospital with poor oral intake and generalized muscle weakness for 3 weeks. He was unable to get out of bed without assistance and also needed adult diapers. Found to have new-onset severe hypothyroidism with TSH 228 uIU/ml (Ref: 0.350-4.940) and FT4 <0.40 ng/dL (Ref: 0.70-1.50), positive TPO antibody 197 IU/ml (Ref: 0-34). No prior thyroid labs were available and no known history of thyroid disorder was recorded. He has never been on Amiodarone or Lithium before. On physical exam, he was alert and oriented. There was no goiter or palpable thyroid nodule. There was no focal neurological deficit and no peripheral edema. There were no other signs and symptoms pertinent to hypothyroidism except mild bradycardia (HR 56-60) and borderline low blood pressure. AM cortisol was 10.1 ug/dL (Ref: 3.7-19.4). EKG showed low-voltage sinus bradycardia. Echocardiogram was normal. Urinalysis was positive for large blood but only 3 RBCs were present which raised the suspicion of rhabdomyolysis. Creatinine kinase (CK) was 15,584 IU/L (Ref: 30-200). Other laboratory studies were significant for acute renal failure with mild hyperkalemia and mild hypocalcemia, also transaminitis; BUN 130 mg/dl (Ref: 8-26), Creatinine 9.51 mg/dl (Ref: 0.72-1.25), eGFR 5 ml/min/1.73 m2 (Ref: >59), AST 435 IU/L (Ref: 5-34), ALT 269 IU/L (Ref: <55), ALP 171 IU/L (Ref: 40-150). On medication review, he was started on Atorvastatin 80 mg daily during prior admission for CVA 6 months ago. He received IV fluids, s/p 1 dose of Hydrocortisone 100 mg IV, Levothyroxine IV 200 mcg, followed by Levothyroxine IV 50 mcg daily x 3 days and switched to Levothyroxine PO 100 mcg daily (weight-based dose). Atorvastatin was on hold. He became anuric during the hospital course and received 2-3 sessions of hemodialysis. 3-4 days later, CK was trending down to 3000 IU/L, FT4 improved to 0.54 ng/dl and there was also significant improvement in kidney and liver functions. The patient was diagnosed with acute renal failure secondary to rhabdomyolysis associated with severe hypothyroidism caused by Hashimoto's thyroiditis, in the setting of high dose statin use. Conclusion: Clinicians should raise the suspicion of rhabdomyolysis in a patient with severe hypothyroidism, especially in patients with recent high dose statin use as rhabdomyolysis can be a rare and fatal complication of severe hypothyroidism, in the presence of precipitating factors. Presentation: 6/2/2024

The association between serum S100β levels and prognosis in acute stroke patients after intravenous thrombolysis: a multicenter prospective cohort study

BackgroundS100β is a biomarker of astroglial damage, the level of which is significantly increased following brain injury. However, the characteristics of S100β and its association with prognosis in patients with acute ischemic stroke following intravenous thrombolysis (IVT) remain unclear.MethodsPatients in this multicenter prospective cohort study were prospectively and consecutively recruited from 16 centers. Serum S100β levels were measured 24 h after IVT. National Institutes of Health Stroke Scale (NIHSS) and hemorrhagic transformation (HT) were measured simultaneously. NIHSS at 7 days after stroke, final infarct volume, and modified Rankin Scale (mRS) scores at 90 days were also collected. An mRS score ≥ 2 at 90 days was defined as an unfavorable outcome.ResultsA total of 1072 patients were included in the analysis. The highest S100β levels (> 0.20 ng/mL) correlated independently with HT and higher NIHSS at 24 h, higher NIHSS at 7 days, larger final infarct volume, and unfavorable outcome at 3 months. The patients were divided into two groups based on dominant and non-dominant stroke hemispheres. The highest S100β level was similarly associated with the infarct volume in patients with stroke in either hemisphere (dominant: β 36.853, 95% confidence interval (CI) 22.659–51.048, P < 0.001; non-dominant: β 23.645, 95% CI 10.774–36.516, P = 0.007). However, serum S100β levels at 24 h were more strongly associated with NIHSS scores at 24 h and 3-month unfavorable outcome in patients with dominant hemisphere stroke (NIHSS: β 3.470, 95% CI 2.392–4.548, P < 0.001; 3-month outcome: odds ratio (OR) 5.436, 95% CI 2.936–10.064, P < 0.001) than in those with non-dominant hemisphere stroke (NIHSS: β 0.326, 95% CI − 0.735–1.387, P = 0.547; 3-month outcome: OR 0.882, 95% CI 0.538–1.445, P = 0.619). The association of S100β levels and HT was not significant in either stroke lateralization group.ConclusionsSerum S100β levels 24 h after IVT were independently associated with HT, infarct volume, and prognosis in patients with IVT, which suggests the application value of serum S100β in judging the degree of disease and predicting prognosis.

An experimental investigation of decompressive craniectomy in a rat model of hemispheric stroke treated with decompressive craniectomy

An experimental investigation of decompressive craniectomy in a rat model of hemispheric stroke treated with decompressive craniectomy

Validation of the abbreviated version of the Token Test in Latin American Spanish stroke patients.

The abbreviated version of the Token Test (aTT) is widely used to assess language comprehension deficits in stroke patients (SPs). However, aTT has not been validated for Latin American Spanish speakers, so clinicians tend to use cut-off scores for aTT validated in developed countries. To provide normative data for the Spanish aTT (Sp-aTT) in healthy Chilean Spanish-speaking and SP, determining the influence of sociodemographic variables such as gender, age and education on Sp-aTT performance. A total of 210 healthy volunteers (age range = 18-88 years) and 197 SPs (age range = 23-94 years), all native speakers of Chilean Spanish, were recruited. The association of age, gender and years of education on the Sp-aTT performance was analysed. Specificity and sensibility analyses of the Sp-aTT to diagnose language comprehension deficits were completed. Only age (p < 0.001) and years of education (p < 0.001) impacted the total score of Sp-aTT. Gender did not show an association with Sp-aTT performance (p = 0.181). For SPs, the Sp-aTT score showed a significant positive correlation (rho = 0.4, p < 0.001) with the aphasia severity rating scale (ASRS) score. For Sp-aTT, the area under the curve was 0.97, and the optimal cut-off score for the Sp-aTT was 30 (0.73 of sensitivity, 0.92 of specificity and a Youden index of 0.644). Age and years of education are two key factors to be controlled for when determining the optimal cut-off points for the Sp-aTT. Our results also highlight the need for language-specific norms in stroke and aphasia research. What is already known on the subject The aTT has been validated and adapted in several countries. Its properties in screening and detecting comprehensive deficits in SPs highlight its potential as a screening tool in clinical practice. Moreover, considering that stroke is the third largest cause of death worldwide, research and clinical practice have focused on how to improve early detection of deficits in these people, especially those related to cognition, language and functionality in SPs. Therefore, counting with validated and adapted tools is essential for clinicians because it could contribute to accurate intervention and classification of language disorders. What this paper adds to the existing knowledge The main contribution of this study is to provide normative data for the aTT in Latin American Spanish speakers. No previous studies have focused on validating this test and analysing the influence of three critical variables (age, gender and years of education) on its performance in SPs from Latin America. In addition, we propose a classification of the severity of comprehension deficits in SPs. Finally, we found comprehension deficits in patients with right and left hemisphere stroke, which would imply that these deficits would not be exclusive to left hemisphere stroke. What are the potential or actual clinical implications of this work? Contribute with validation of language comprehension tools, such as the aTT, could improve early diagnosis of patients with language disorders. This validation provides a test based on the sociodemographic characteristics of Latin American Speakers, which has yet to be established. Due to this, normative data considering the sociodemographic characteristics of the target population is crucial for accurately classifying comprehension deficits after brain damage.

Visual self-face and self-body recognition in a left-brain-damaged prosopagnosic patient.

The present case study describes the patient N.G., who reported prosopagnosia along with difficulty in recognising herself in the mirror following a left-sided temporo-occipital hemispheric stroke. The neuropsychological and experimental investigation revealed only a mild form of apperceptive prosopagnosia, without visual agnosia, primarily caused by an impaired visual processing of face-parts and body parts but not of full faces. Emotional expressions did not modulate her face processing. On the other hand, N.G. showed a marked impairment of visual self-recognition, as assessed with visual matching-to-sample tasks, both at the level of body-part and face-part processing and at a full-face level, featured by a deficit in the perceptual discrimination of her own face and body, as compared to the others' face and body. N.G.'s lesion mapping showed damage to the left inferior occipito-temporal cortex, affecting the inferior occipital gyrus and compromising long-range connections between the occipital/temporo-occipital areas and the anterior fronto-temporal areas. Overall, the present case report documents that visual processing of the person's own face may be selectively compromised by a left-sided hemispheric lesion disconnecting extra-striate body- and face-selective visual areas to self-representation regions. Moreover, others' (full) face processing may be preserved, as compared with the impaired ability to discriminate others' body and face parts.

Organization of conceptual tool knowledge following left and right brain lesions: Evidence from neuropsychological dissociations and multivariate disconnectome symptom mapping

The aim of this work was to better understand the organization of conceptual tool knowledge following stroke. We explored specifically the link between manipulation kinematics and manipulation hand posture; and the link between manipulation kinematics and function relations in left brain-damaged (n = 30) and right brain-damaged (n = 30) patients. We examined the performance of brain-damaged patients in conceptual tool tasks using neuropsychological dissociations and disconnectome symptom mapping. Our results suggest that manipulation kinematics is more impaired than function relations, following left or right brain lesions. We also observed that manipulation kinematics and manipulation hand posture are dissociable dimensions but are still highly interrelated, particularly in left brain-damaged patients. We also found that the corpus callosum and bilateral superior longitudinal fasciculus are involved in action and semantic tool knowledge following left brain lesions. Our results provide evidence that the right hemisphere contains conceptual tool representations. Further studies are needed to better understand the mechanisms supporting the cognitive recovery of conceptual tool knowledge. An emerging hypothesis is that the right hemisphere may support functional recovery through interhemispheric transfer following a left hemisphere stroke.

Voxel-Based Lesion Analysis of Ideomotor Apraxia.

Ideomotor apraxia is a cognitive disorder most often resulting from acquired brain lesions (i.e., strokes or tumors). Neuroimaging and lesion studies have implicated several brain regions in praxis and apraxia, but most studies have described (sub)acute patients. This study aimed to extend previous research by analyzing data from 115 left hemisphere chronic stroke patients using the praxis subtest of the Western Aphasia Battery, which is divided into four action types: facial, upper limb, complex, and instrumental. Lesion-symptom mapping was used to identify brain regions most critically associated with difficulties in each of the four subtests. Complex and instrumental action deficits were associated with left precentral, postcentral, and superior parietal gyri (Brodmann areas 2, 3, 4, 5, and 6), while the facial and upper limb action deficits maps were restricted to left inferior, middle, and medial temporal gyri (Brodmann areas 20, 21, 22, and 48). We discuss ideas about neuroplasticity and cortical reorganization in chronic stroke and how different methodologies can reveal different aspects of lesion and recovery networks in apraxia.

The Right ICD Code, Right Now: A Call to Action for Pragmatic Language Disorders After Right Hemisphere Stroke.

Diagnosis of language impairments after stroke is important to optimizing stroke outcomes. After right hemisphere brain damage (RHD), apragmatism can impact the comprehension and production of pragmatic language. However, despite decades of empirical evidence, there is no International Classification of Diseases (ICD) code for RHD pragmatic language impairments. The absence of an ICD code has far reaching ramifications that impact patient outcomes, including reduced clinical and public awareness, limited curricular content, and underdiagnosis. This viewpoint justifies the need to appropriately classify the pragmatic language symptomology after RHD with an ICD code. An ICD code can positively influence health care practitioner knowledge, education, and practice while informing public health considerations vital to epidemiological analyses.

Recovery of Verbal Working Memory Depends on Left Hemisphere White Matter Tracts.

Researchers propose that the recovery of language function following stroke depends on the recruitment of perilesional regions in the left hemisphere and/or homologous regions in the right hemisphere (Kiran, 2012). Many investigations of recovery focus on changes in gray matter regions (e.g., Turkeltaub et al., 2011), whereas relatively few examine white matter tracts (e.g., Schlaug et al., 2009) and none address the role of these tracts in the recovery of verbal working memory (WM). The present study addressed these gaps, examining the role of left vs. right hemisphere tracts in the longitudinal recovery of phonological and semantic WM. For 24 individuals with left hemisphere stroke, we assessed WM performance within one week of stroke (acute timepoint) and at more than six months after stroke (chronic timepoint). To address whether recovery depends on the recruitment of left or right hemisphere tracts, we assessed whether changes in WM were related to the integrity of five white matter tracts in the left hemisphere which had been implicated previously in verbal WM and their right hemisphere analogues. Behavioral results showed significant improvement in semantic but not phonological WM from the acute to chronic timepoints. Improvements in semantic WM significantly correlated with tract integrity as measured by functional anisotropy in the left direct segment of the arcuate fasciculus, inferior fronto-occipital fasciculus and inferior longitudinal fasciculus. The results confirm the role of white matter tracts in language recovery and support the involvement of the left rather than right hemisphere in the recovery of semantic WM.

Hebbian plasticity induced by temporally coincident BCI enhances post-stroke motor recovery

Functional electrical stimulation (FES) can support functional restoration of a paretic limb post-stroke. Hebbian plasticity depends on temporally coinciding pre- and post-synaptic activity. A tight temporal relationship between motor cortical (MC) activity associated with attempted movement and FES-generated visuo-proprioceptive feedback is hypothesized to enhance motor recovery. Using a brain–computer interface (BCI) to classify MC spectral power in electroencephalographic (EEG) signals to trigger FES-delivery with detection of movement attempts improved motor outcomes in chronic stroke patients. We hypothesized that heightened neural plasticity earlier post-stroke would further enhance corticomuscular functional connectivity and motor recovery. We compared subcortical non-dominant hemisphere stroke patients in BCI-FES and Random-FES (FES temporally independent of MC movement attempt detection) groups. The primary outcome measure was the Fugl-Meyer Assessment, Upper Extremity (FMA-UE). We recorded high-density EEG and transcranial magnetic stimulation-induced motor evoked potentials before and after treatment. The BCI group showed greater: FMA-UE improvement; motor evoked potential amplitude; beta oscillatory power and long-range temporal correlation reduction over contralateral MC; and corticomuscular coherence with contralateral MC. These changes are consistent with enhanced post-stroke motor improvement when movement is synchronized with MC activity reflecting attempted movement.

Plasma Levels of Neuron/Glia-Derived Apoptotic Bodies, an In Vivo Biomarker of Apoptosis, Predicts Infarct Growth and Functional Outcome in Patients with Ischemic Stroke.

Evidence demonstrating the involvement of apoptosis in the death of the potentially salvageable area (penumbra zone) in patients during stroke remains limited. Our aim was to investigate whether apoptotic processes occur in penumbral brain tissue by analyzing circulating neuron- and glia-derived apoptotic bodies (CNS-ApBs), which are vesicles released into the bloodstream during the late stage of apoptosis. We have also assessed the clinical utility of plasma neuronal and glial apoptotic bodies in predicting early neurological evolution and functional outcome. The study included a total of 71 patients with acute hemispheric ischemic stroke (73 ± 10years; 30 women). Blood samples were collected from these patients immediately upon arrival at the hospital (within 9h) and at 24 and 72h after symptom onset. Subsequently, isolation, quantification, and phenotypic characterization of CNS-ApBs during the first 72h post-stroke were performed using centrifugation and flow cytometry techniques. We found a correlation between infarct growth and final infarct size with the amount of plasma CNS-ApBs detected in the first 72h after stroke. In addition, patients with neurological worsening (progressive ischemic stroke) had higher plasma levels of CNS-ApBs at 24h after symptom onset than those with a stable or improving course. Circulating CNS-ApB concentration was further associated with patients' functional prognosis. In conclusion, apoptosis may play an important role in the growth of the cerebral infarct area and plasma CNS-ApB quantification could be used as a predictive marker of penumbra death, neurological deterioration, and functional outcome in patients with ischemic stroke.

Alterations of contralesional hippocampal subfield volumes and relations to cognitive functions in patients with unilateral stroke.

The volumes of the hippocampal subfields are related to poststroke cognitive dysfunctions. However, it remains unclear whether contralesional hippocampal subfield volume contributes to cognitive impairment. This study aimed to investigate the volumetric differences in the contralesional hippocampal subfields between patients with left and right hemisphere strokes (LHS/RHS). Additionally, correlations between contralesional hippocampal subfield volumes and clinical outcomes were explored. Fourteen LHS (13 males, 52.57±7.10 years), 13 RHS (11 males, 51.23±15.23 years), and 18 healthy controls (11 males, 46.94±12.74 years) were enrolled. Contralesional global and regional hippocampal volumes were obtained with T1-weighted images. Correlations between contralesional hippocampal subfield volumes and clinical outcomes, including the Montreal Cognitive Assessment (MoCA) and Mini-Mental State Examination (MMSE), were analyzed. Bonferroni correction was applied for multiple comparisons. Significant reductions were found in contralesional hippocampal as a whole (adjusted p=.011) and its subfield volumes, including the hippocampal tail (adjusted p=.005), cornu ammonis 1 (CA1) (adjusted p=.002), molecular layer (ML) (adjusted p=.004), granule cell and ML of the dentate gyrus (GC-ML-DG) (adjusted p=.015), CA3 (adjusted p=.009), and CA4 (adjusted p=.014) in the RHS group compared to the LHS group. MoCA and MMSE had positive correlations with volumes of contralesional hippocampal tail (p=.015, r=.771; p=.017, r=.763) and fimbria (p=.020, r=.750; p=.019, r=.753) in the LHS group, and CA3 (p=.007, r=.857; p=.009, r=.838) in the RHS group, respectively. Unilateral stroke caused volumetric differences in different hippocampal subfields contralesionally, which correlated to cognitive impairment. RHS leads to greater volumetric reduction in the whole contralesional hippocampus and specific subfields (hippocampal tail, CA1, ML, GC-ML-DG, CA3, and CA4) compared to LHS. These changes are correlated with cognitive impairments, potentially due to disrupted neural pathways and interhemispheric communication.

Is Broca's area critical for speech and language? Evidence from lesion-symptom mapping in chronic aphasia

IntroductionThe specific role that Broca's area plays in speech and language has been hotly debated in the literature. Some research has pointed to a specific role in particular aspects of speech production, while other findings have suggested additional roles in aspects of language comprehension. In the current study, we had the opportunity to take a broad approach by analyzing lesion and behavioral data from a large cohort of left hemisphere stroke patients. In this brief report, our objective was to identify which speech-language measures show a significant association with Broca's area, specifically pars opercularis and pars triangularis.MethodsLesion site and neuropsychological data from 173 chronic left hemisphere stroke patients were analyzed in the current study. Univariate lesion-symptom mapping (LSM) with rigorous correction was used to identify brain regions associated with individual test performance on a large battery of speech and language tasks. Multivariate LSM analyses were conducted in subsequent runs to confirm findings.ResultsThe LSM results identified many predictable left hemisphere gray and white matter regions significantly associated with the speech-language data, but Broca's area was not implicated in performance on any speech or language measure. Regions adjacent to Broca's area, however, in left central opercular, precentral, and insular cortices were associated with speech production and motor speech performance.DiscussionThe current study failed to identify a single speech or language measure in our comprehensive test battery that was dependent on Broca's area. This finding could not be attributed to a lack of power, as Broca's area had among the highest power values and substantial lesion coverage. Interrogation of data at the individual patient level revealed the likely source of this null finding: Patients with lesions involving Broca's area varied widely in their speech-language performance, with profiles ranging from non-aphasic to Broca's to global aphasia. Given previous studies in acute stroke patients and healthy participants implicating Broca's area in speech-language, the current findings suggest that Broca's area plays a more supplementary than critical role and can be compensated by surrounding brain regions in chronic stroke.

A preliminary study of white matter disconnections underlying deficits in praxis in left hemisphere stroke patients.

Limb apraxia is a higher-order motor disorder often occurring post-stroke, which affects skilled actions. It is assessed through tasks involving gesture production or pantomime, recognition, meaningless gesture imitation, complex figure drawing, single and multi-object use. A two-system model for the organisation of actions hypothesizes distinct pathways mediating praxis deficits via conceptual, 'indirect', and perceptual 'direct' routes to action. Traditional lesion- symptom mapping techniques have failed to identify these distinct routes. We assessed 29 left hemisphere stroke patients to investigate white matter disconnections on deficits of praxis tasks from the Birmingham Cognitive Screening. White matter disconnection maps derived from patients' structural T1 lesions were created using a diffusion-weighted healthy participant dataset acquired from the human connectome project (HCP). Initial group-level regression analyses revealed significant disconnection between occipital lobes via the splenium of the corpus callosum and involvement of the inferior longitudinal fasciculus in meaningless gesture imitation deficits. There was a trend of left fornix disconnection in gesture production deficits. Further, voxel-wise Bayesian Crawford single-case analyses performed on two patients with the most severe meaningless gesture imitation and meaningful gesture production deficits, respectively, confirmed distinct posterior interhemispheric disconnection, for the former, and disconnections between temporal and frontal areas via the fornix, rostrum of the corpus callosum and anterior cingulum, for the latter. Our results suggest distinct pathways associated with perceptual and conceptual deficits akin to 'direct' and 'indirect' action routes, with some patients displaying both. Larger studies are needed to validate and elaborate on these findings, advancing our understanding of limb apraxia.

Cognitive neuropsychological and neuroanatomic predictors of naturalistic action performance in left hemisphere stroke: a retrospective analysis.

Individuals who have experienced a left hemisphere cerebrovascular accident (LCVA) have been shown to make errors in naturalistic action tasks designed to assess the ability to perform everyday activities such as preparing a cup of coffee. Naturalistic action errors in this population are often attributed to limb apraxia, a common deficit in the representation and performance of object-related actions. However, naturalistic action impairments are also observed in right hemisphere stroke and traumatic brain injury, populations infrequently associated with apraxia, and errors across all these populations are influenced by overall severity. Based on these and other data, an alternative (though not mutually exclusive) account is that naturalistic action errors in LCVA are also a consequence of deficits in general attentional resource availability or allocation. In this study, we conducted a retrospective analysis of data from a large group of 51 individuals with LCVA who had completed a test of naturalistic action, along with a battery of tests assessing praxis, attention allocation and control, reasoning, and language abilities to determine which of these capacities contribute uniquely to naturalistic action impairments. Using a regularized regression method, we found that naturalistic action impairments are predicted by both praxis deficits (hand posture sequencing and gesture recognition), as well as attention allocation and control deficits (orienting and dividing attention), along with language comprehension ability and age. Using support vector regression-lesion symptom mapping (SVR-LSM), we also demonstrated that naturalistic action impairments are associated with lesions to posterior middle temporal gyrus and anterior inferior parietal lobule - regions known to be implicated in praxis; as well the middle frontal gyrus that has been implicated in both praxis and attention allocation and control. Taken together, these findings support the hypothesis that naturalistic action impairments in LCVA are a consequence of apraxia as well as deficits in attention allocation and control.

A simple psychophysical procedure separates representational and noise components in impairments of speech prosody perception after right-hemisphere stroke

After a right hemisphere stroke, more than half of the patients are impaired in their capacity to produce or comprehend speech prosody. Yet, and despite its social-cognitive consequences for patients, aprosodia following stroke has received scant attention. In this report, we introduce a novel, simple psychophysical procedure which, by combining systematic digital manipulations of speech stimuli and reverse-correlation analysis, allows estimating the internal sensory representations that subtend how individual patients perceive speech prosody, and the level of internal noise that govern behavioral variability in how patients apply these representations. Tested on a sample of N = 22 right-hemisphere stroke survivors and N = 21 age-matched controls, the representation + noise model provides a promising alternative to the clinical gold standard for evaluating aprosodia (MEC): both parameters strongly associate with receptive, and not expressive, aprosodia measured by MEC within the patient group; they have better sensitivity than MEC for separating high-functioning patients from controls; and have good specificity with respect to non-prosody-related impairments of auditory attention and processing. Taken together, individual differences in either internal representation, internal noise, or both, paint a potent portrait of the variety of sensory/cognitive mechanisms that can explain impairments of prosody processing after stroke.