Left Hemisphere Damage Group Research Articles

Motor Deficits in the Ipsilesional Arm of Severely Paretic Stroke Survivors Correlate With Functional Independence in Left, but Not Right Hemisphere Damage.

Chronic stroke survivors with severe contralesional arm paresis face numerous challenges to performing activities of daily living, which largely rely on the use of the less-affected ipsilesional arm. While use of the ipsilesional arm is often encouraged as a compensatory strategy in rehabilitation, substantial evidence indicates that motor control deficits in this arm can be functionally limiting, suggesting a role for remediation of this arm. Previous research has indicated that the nature of ipsilesional motor control deficits vary with hemisphere of damage and with the severity of contralesional paresis. Thus, in order to design rehabilitation that accounts for these deficits in promoting function, it is critical to understand the relative contributions of both ipsilesional and contralesional arm motor deficits to functional independence in stroke survivors with severe contralesional paresis. We now examine motor deficits in each arm of severely paretic chronic stroke survivors with unilateral damage (10 left-, 10 right-hemisphere damaged individuals) to determine whether hemisphere-dependent deficits are correlated with functional independence. Clinical evaluation of contralesional, paretic arm impairment was conducted with the upper extremity portion of the Fugl-Meyer assessment (UEFM). Ipsilesional arm motor performance was evaluated using the Jebsen-Taylor Hand Function Test (JTHFT), grip strength, and ipsilesional high-resolution kinematic analysis during a visually targeted reaching task. Functional independence was measured with the Barthel Index. Functional independence was better correlated with ipsilesional than contralesional arm motor performance in the left hemisphere damage group [JTHFT: [r(10) = −0.73, p = 0.017]; grip strength: [r(10) = 0.64, p = 0.047]], and by contralesional arm impairment in the right hemisphere damage group [UEFM: [r(10) = 0.66, p = 0.040]]. Ipsilesional arm kinematics were correlated with functional independence in the left hemisphere damage group only. Examination of hemisphere-dependent motor correlates of functional independence showed that ipsilesional arm deficits were important in determining functional outcomes in individuals with left hemisphere damage only, suggesting that functional independence in right hemisphere damaged participants was affected by other factors.

Right Hemisphere Contributions to Bilateral Force Control in Chronic Stroke: A Preliminary Report

BackgroundBilateral motor control deficits poststroke may be lateralized by hemisphere damage. This preliminary study investigated bilateral force control between left and right hemisphere-damaged groups at baseline and after coupled bilateral movement training with neuromuscular stimulation. MethodsStroke participants (8 left hemisphere and 6 right hemisphere cerebrovascular accidents) performed a bilateral isometric force control task at 3 submaximal force levels (5%, 25%, and 50% of maximum voluntary contraction [MVC]) before and after training. Force accuracy, force variability, and interlimb force coordination were analyzed in 3-way mixed design ANOVAs (2 × 2 × 3; Group × Test Session × Force Level) with repeated measures on test session and force level. ResultsThe findings indicated that force accuracy and variability at 50% of MVC in the right hemisphere-damaged group were more impaired than lower targeted force levels at baseline, and the impairment at the highest target level was improved after coupled bilateral movement training. However, these patterns were not observed in the left hemisphere-damaged group. ConclusionsCurrent findings support a proposition that the right hemisphere presumably contributes to controlling bilateral force production.

Asymmetries in force matching are related to side of stroke in right-handed individuals

Asymmetries in grasp force matching extend beyond quantifying a single measure of maximum grip strength and advance our application of side-specific treatment interventions. A cross sectional study design investigated grasp-force matching performance in right-handed individuals with a stroke and age-matched healthy controls. A visual representation of the 20% Maximum Voluntary Contraction (MVC) was matched in three conditions in the absence of visual feedback with the same (Ipsilateral Remembered – IR) or opposite hand (Concurrent – CC and Contralateral Remembered – CR). Greater overall relative error (RE) was found in contralateral compared to ipsilateral matching tasks. In the CR condition, post hoc analysis revealed significant differences between control and right hemisphere damage (RHD) group (95% CI [16.41–88.59]; p < 0.01) as well as left hemisphere damage (LHD) group and RHD (95% CI [23.4–95.09]; p < 0.01). Right hand matching relative error was 2.49 times larger in the RHD compared to the LHD group. Within the RHD group, matching errors were greater for the right than left hand in both contralateral conditions (95% CI [34.25–101.07]; p < 0.001).Individuals with RHD showed greater asymmetries in contralateral matching tasks compared to LHD and controls. More specifically, the RHD group had the greatest difficulty matching tasks with their right (non-paretic) than left (paretic) hand. In order to elucidate this asymmetry in the clinic the use of complementary grasp measures may be considered.

Effects of lesion extent and location on upper limb spasticity following hemispheric stroke

Spasticity of the hemiparetic upper limb (UL) leading to difficulty performing activities of daily living is a major concern in stroke rehabilitation. Spasticity results from impaired control of motoneuronal activation thresholds exerted by descending direct and indirect pathways. This is reflected by pathological alteration of the specific muscle length/joint angle at which the stretch reflex and other proprioceptive reflexes begin to act (tonic stretch reflex threshold, TSRT). The relationship between lesion location and the appearance of spasticity is poorly understood. We investigated the relationship between lesion characteristics and elbow-flexor (biceps) TSRT in the hemiparetic UL, as part of an international multicenter RCT (ENHANCE project; ClinicalTrials.gov, ID: NCT02725853 ). Elbow-flexor TSRT (°) was examined in 8 right-hemisphere damaged (RHD) and 15 left hemisphere damaged (LHD) stroke patients using the Montreal Stretch Reflex Threshold device. Normalized lesion data were used for voxel-based lesion-symptom mapping (VLSM) analyses of lesion impact on biceps spasticity. Application of VLSM using 10 continuous affected voxels as a minimum for consideration, showed in the LHD group, a cluster localized in the superior part of the corona radiata, where damage affected the level of spasticity in the biceps as revealed by its TSRT (smaller clusters were recognized in the external capsule and insula). In the RHD group, VLSM failed to reveal voxel clusters where damage affected the biceps TSRT. The paucity of hemispheric voxels where damage is related to increased spasticity levels may indicate that impaired regulation of motoneuronal activation threshold after stroke is attributed to the sum effect of various brainstem control substrates (which cannot be analyzed using VLSM), rather than to direct corticospinal control.

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.

Relationship Between Arm Usage and Instrumental Activities of Daily Living After Unilateral Stroke

Haaland KY, Mutha PK, Rinehart JK, Daniels M, Cushnyr B, Adair JC. Relationship between arm usage and instrumental activities of daily living after unilateral stroke. ObjectiveTo determine whether the preferred pattern of arm use after unilateral hemispheric damage was associated with better everyday functioning. Our previous work showed that right-handed stroke patients with right hemisphere damage (RHD) used their right, ipsilesional arm most frequently, while those with left hemisphere damage (LHD) used both arms together most frequently. This effect was explained by right-hand preference, but its relationship to functional performance is not known. DesignObservational cohort. SettingResearch laboratory. ParticipantsStroke patients (n=60; 30 RHD, 30 LHD) and healthy controls (n=52). InterventionsNot applicable. Main Outcome MeasuresThe Functional Impact Assessment was used to assess performance on instrumental activities of daily living (IADLs). ResultsThe preferred patterns of arm use were similar to those in our previous report. However, it was the greater use of both arms together that was associated with better IADL performance in both stroke groups. Ipsilesional arm use alone was not significantly associated with IADL performance in the RHD group and was associated with poorer performance in the LHD group. ConclusionsThe modal arm use pattern did not always optimize IADL functioning. Better IADL functioning in both stroke groups was associated with the use of both arms together, which is the most common arm use pattern of healthy individuals doing these same IADLs. An important practical question that arises from these findings is whether bilateral arm rehabilitation should be emphasized, because using both arms together is the best predictor of better performance on everyday tasks.

A dual task priming investigation of right hemisphere inhibition for people with left hemisphere lesions

BackgroundDuring normal semantic processing, the left hemisphere (LH) is suggested to restrict right hemisphere (RH) performance via interhemispheric suppression. However, a lesion in the LH or the use of concurrent tasks to overload the LH's attentional resource balance has been reported to result in RH disinhibition with subsequent improvements in RH performance. The current study examines variations in RH semantic processing in the context of unilateral LH lesions and the manipulation of the interhemispheric processing resource balance, in order to explore the relevance of RH disinhibition to hemispheric contributions to semantic processing following a unilateral LH lesion.MethodsRH disinhibition was examined for nine participants with a single LH lesion and 13 matched controls using the dual task paradigm. Hemispheric performance on a divided visual field lexical decision semantic priming task was compared over three verbal memory load conditions, of zero-, two- and six-words. Related stimuli consisted of categorically related, associatively related, and categorically and associatively related prime-target pairs. Response time and accuracy data were recorded and analyzed using linear mixed model analysis, and planned contrasts were performed to compare priming effects in both visual fields, for each of the memory load conditions.ResultsControl participants exhibited significant bilateral visual field priming for all related conditions (p < .05), and a LH advantage over all three memory load conditions. Participants with LH lesions exhibited an improvement in RH priming performance as memory load increased, with priming for the categorically related condition occurring only in the 2- and 6-word memory conditions. RH disinhibition was also reflected for the LH damage (LHD) group by the removal of the LH performance advantage following the introduction of the memory load conditions.ConclusionsThe results from the control group are consistent with suggestions of an age related hemispheric asymmetry reduction and indicate that in healthy aging compensatory bilateral activation may reduce the impact of inhibition. In comparison, the results for the LHD group indicate that following a LH lesion RH semantic processing can be manipulated and enhanced by the introduction of a verbal memory task designed to engage LH resources and allow disinhibition of RH processing.

Perceptual discrimination of Shona lexical tones and low-pass filtered speech by left and right hemisphere damaged patients

Background: While the role of the right hemisphere (RH) in prosodic processing is prominent, research on the perception of lexical tones has shown that left hemisphere damaged (LHD) patients are more impaired than right hemisphere damaged (RHD) patients. Dichotic listening and imaging studies with healthy speakers of tone languages demonstrate that at least at the phonemic and lexical level, prosody is processed in the left hemisphere (LH) when the variations in pitch are phonemically distinctive. There is no report available yet on the perceptual discrimination of a Bantu language in patients after unilateral brain damage. Aims: We addressed the question of how well Shona aphasic patients and right hemisphere damaged patients perceive pitch contrasts in Shona lexical words and also in their homologous low-pass filtered counterparts. We also sought to discover the validity of the current hypotheses on hemispheric lateralisation particularly the hypothesis on hemispheric lateralisation based on language function to account for the Shona data. Methods & Procedures: A total of 7 LHD and 7 RHD patients and 14 healthy controls participated in two discrimination tasks that examined perception of lexical tone in (a) bisyllabic Shona words and (b) low-pass filtered stimuli. In both tasks the participants were tasked with judging the pitch as the same or different in 120 bisyllabic words and 120 low-pass filtered stimuli. Outcomes & Results: The results demonstrated that the tonal discrimination of the LHD group was more reduced in comparison to the RHD group and control participants. However, the performance of the RHD patients was not error free relative to the control participants, although significantly better than the LHD patients in both tasks. Conclusions: At least for the phonemic and lexical levels, brain damage to the dominant hemisphere results in lexical tone impairment for LHD patients, and cognitive load processing results in a subdued but good performance for RHD patients. The LH is therefore dominant for processing tone when it is lexically distinctive.

Arm Use After Left or Right Hemiparesis Is Influenced by Hand Preference

Despite strong evidence for hand preference and its impact on motor performance, its influence on stroke rehabilitation has not been routinely considered. Previous research demonstrates that patients with hemiparetic stroke use their ipsilesional, nonparetic arm 5 to 6 times more frequently than their paretic arm, but it is unknown if such use varies with laterality of hemiparesis. The purpose of our study was to determine if the right arm is used more frequently in right-handed patients with stroke. We assessed relative use of the right, left, and both arms with wrist accelerometers on patients with unilateral, paretic stroke matched for degree of paresis (12 with right hemisphere damage, 17 with left hemisphere damage) and 25 neurologically intact control participants as they performed the Arm Motor Ability Test. We showed: (1) ipsilesional arm use was greater after right hemisphere damage than left hemisphere damage; (2) the left hemisphere damage group used both arms together more often than the right hemisphere damage group but less often than the control group; and (3) both stroke groups used their contralesional, paretic arm to the same degree. These findings emphasize the influence of hand preference on arm use after stroke for the ipsilesional but not the contralesional arm. Although both stroke groups used their ipsilesional more than their contralesional arm, the difference was greater for the right hemisphere damage group who used their ipsilesional arm 4 times more frequently than their contralesional arm, whereas the left hemisphere damage group used their ipsilesional arm 2 times more frequently than their contralesional arm.

Perception of emotions from faces and voices following unilateral brain damage

The importance of the right hemisphere in emotion perception in general has been well documented but its precise role is disputed. We compared the performance of 30 right hemisphere damaged (RHD) patients, 30 left hemisphere damaged (LHD) patients, and 50 healthy controls on both facial and vocal affect perception tasks of specific emotions. Brain damaged subjects had a single episode cerebrovascular accident localised to one hemisphere. The results showed that right hemisphere patients were markedly impaired relative to left hemisphere and healthy controls on test performance: labelling and recognition of facial expressions and recognition of emotions conveyed by prosody. This pertained at the level of individual basic emotions, positive versus negative, and emotional expressions in general. The impairment remained highly significant despite covarying for the group’s poorer accuracy on a neutral facial perception test and identification of neutral vocal expressions. The LHD group were only impaired relative to controls on facial emotion tasks when their performance was summed over all the emotion categories and before age and other cognitive factors were taken into account. However, on the prosody test the LHD patients showed significant impairment, performing mid-way between the right hemisphere patients and healthy comparison group. Recognition of positive emotional expressions was better than negative in all subjects, and was not relatively poorer in the LHD patients. Recognition of individual emotions in one modality correlated weakly with recognition in another, in all three groups. These data confirm the primacy of the right hemisphere in processing all emotional expressions across modalities—both positive and negative—but suggest that left hemisphere emotion processing is modality specific. It is possible that the left hemisphere has a particular role in the perception of emotion conveyed through meaningful speech.

Role of the left hemisphere in sign language comprehension

We investigated the relative role of the left versus right hemisphere in the comprehension of American Sign Language (ASL). Nineteen lifelong signers with unilateral brain lesions [11 left hemisphere damaged (LHD) and 8 right hemisphere damaged (RHD)] performed three tasks, an isolated single-sign comprehension task, a sentence-level comprehension task involving simple one-step commands, and a sentence-level comprehension task involving more complex multiclause/multistep commands. Eighteen of the participants were deaf, one RHD subject was hearing and bilingual (ASL and English). Performance was examined in relation to two factors: whether the lesion was in the right or left hemisphere and whether the temporal lobe was involved. The LHD group performed significantly worse than the RHD group on all three tasks, confirming left hemisphere dominance for sign language comprehension. The group with left temporal lobe involvement was significantly impaired on all tasks, whereas each of the other three groups performed at better than 95% correct on the single sign and simple sentence comprehension tasks, with performance falling off only on the complex sentence comprehension items. A comparison with previously published data suggests that the degree of difficulty exhibited by the deaf RHD group on the complex sentences is comparable to that observed in hearing RHD subjects. Based on these findings we hypothesize (i) that deaf and hearing individuals have a similar degree of lateralization of language comprehension processes and (ii) that language comprehension depends primarily on the integrity of the left temporal lobe.

Anosognosia for hemiplegia in stroke rehabilitation.

The purpose of this study was to investigate anosognosia for hemiplegia (AHP) in the rehabilitation phase after onset of stroke. Forty-six hemiplegic stroke patients, 29 with right hemisphere damage (RHD) and 17 with left hemisphere damage (LHD) were evaluated approximately 1 month after onset of stroke. Anosognosia was evaluated with an implicit measure designed to assess anosognosic behaviors (choosing between unimanual and bimanual tasks), in addition to a traditional explicit verbal measure. AHP was found in 28% of the RHD and 24% of the LHD group. The majority of patients with AHP in the RHD group had large lesions involving the frontal, parietal, or temporal lobes and had coexisting sensory deficits and unilateral spatial neglect, whereas the LHD patients with AHP had predominantly small subcortical lesions and no sensory or attentional deficits. The functional outcomes of AHP patients in both hemisphere groups revealed their inability to retain safety measures at discharge from rehabilitation (p < 0.036) and their need for assistance in basic and instrumental activities of daily living at follow-up. AHP presents a significant risk for negative functional outcome in stroke rehabilitation. The underlying mechanisms of AHP may be different for left and right hemisphere patients, therefore requiring different intervention approaches.

The Ability to Perceive and Comprehend Intonation in Linguistic and Affective Contexts by Brain-Damaged Adults

Receptive tasks of linguistic and affective prosody were administered to 9 right-hemisphere-damaged (RHD), 10 left-hemisphere-damaged (LHD), and 10 age-matched control (NC) subjects. Two tasks measured subjects' ability to discriminate utterances based solely on prosodic cues, and six tasks required subjects to identify linguistic or affective intonational meanings. Identification tasks manipulated the degree to which the auditory stimuli were structured linguistically, presenting speech-filtered, nonsensical, and semantically well-formed utterances in different tasks. Neither patient group was impaired relative to normals in discriminating prosodic patterns or recognizing affective tone conveyed suprasegmentally, suggesting that neither the LHD nor the RHD patients displayed a receptive disturbance for emotional prosody. The LHD group, however, was differentially impaired on linguistic rather than emotional tasks and performed significantly worse than the NC group on linguistic tasks even when semantic information biased the target response.

Production and Perception of Word Tones (Pitch Accents) in Patients with Left and Right Hemisphere Damage

The present paper addresses the question of the functional lateralization of tones in tone languages. Tonal perception and production of right-hemisphere-damaged (RHD) and left-hemisphere-damaged (LHD) speakers of East Norwegian were investigated. East Norwegian is a tone language with an opposition between two tones (pitch accents). The ability to distinguish auditorily between the two accents was normal in the RHD group but reduced in the LHD group. Tonal production was near normal in the RHD group, whereas the LHD group tended to have a production deficit.

Dissociation of autonomic and subjective responses to emotional slides in right hemisphere damaged patients

Autonomic and subjective responses to emotional and neutral slides were studied in patients with right hemisphere damage (RHD), left hemisphere damage (LHD) and normal controls (CON). Orienting and habituation to a series of pure tones (1000 Hz) were also examined. All subjects showed appropriate slide recognition and there were no group differences in subjective ratings. The CON group showed higher skin conductance responses (SCRs) to the emotional slides relative to the neutral slides, while the RHD group showed lower SCRs to both sets of slides. The LHD group showed higher SCRs independent of slide type. The results support the hypothesis (H EILMAN and W ATSON, Handbook of Neurology, Elsevier Science, 1989) that emotional paucity in RHD patients may be related to reduced autonomic arousal. However, there were no significant differences between groups in the orienting response or habituation to loud tones, suggesting that decreased arousal following RHD is not ubiquitous.

Differential Effects of Semantic and Identity Priming in Patients with Left and Right Hemisphere Lesions

Abstract Patients with single brain lesions in the anterior or posterior left and right hemispheres and a group of controls were studied in two priming experiments. The first experiment employed associative pairs (DOCTOR-NURSE) and the second employed identical pairs (NURSE-nurse). Short and long prime-target stimulus onset asynchronies (SOAs) (i.e., 250 and 1850 msec) were manipulated within block in both experiments. In the first experiment, patients with left hemisphere injury showed a deficient priming effect while patients with right hemisphere injury and controls showed a normal pattern. In contrast, all groups showed an identity priming effect in the second experiment. These results indicate that while entries in the mental lexicon are available for the groups of patients studied, the spread of activation to related concepts in this lexicon is disrupted in the left hemisphere-damaged group.

Another look at VIQ-PIQ scores and unilateral brain damage.

The relationship of WAIS, VIQ, PIQ and Aphasia Screening scores to unilateral brain damage was investigated using 18 subjects with left hemisphere damage (LHD) and 19 subjects with right hemisphere damage (RHD). Expected VIQ-PIQ difference scores were demonstrated only for the RHD subjects. Aphasia was significantly associated with PIQ in the LHD group. ANCOVAR using Aphasia Screening as a covariate produced significant LHD versus RHD differences on PIQ. These data question the utility of VIQ-PIQ difference scores in the diagnosis of unilateral brain damage. Second, the data suggest that LHD "non-verbal" deficits are the result of underlying language disturbance and not the consequence of impaired visuoperceptive or visuospatial processes.