Unilateral Brain Lesions Research Articles

Housing conditions influence motor functions and exploratory behavior following focal damage of the rat brain.

The present study investigated influence of housing conditions on motor functions recovery and exploratory behavior following ouabain focal brain lesion in the rat. During 30 days post-surgery period rats were housed individually in standard cages (IS) or in groups in enriched environment (EE) and behaviorally tested. The EE lesioned rats showed enhanced recovery from motor impairments in walking beam task, comparing with IS animals. Contrarily, in the open field IS rats (both lesioned and control) traveled a longer distance, showed less habituation and spent less time resting at the home base than the EE animals. Unlike the EE lesioned animals, the lesioned IS rats, presented a tendency to hyperactivity in postinjury period. Turning tendency was significantly affected by unilateral brain lesion only in the EE rats. We can conclude that housing conditions distinctly affected the rat's behavior in classical laboratory tests.

EPILEPSY SURGERY IN CHILDREN WITH ELECTRICAL STATUS EPILEPTICUS IN SLEEP

Pediatric epilepsy surgery candidates with unilateral congenital or early-acquired brain lesions may present with refractory seizures and generalized electroencephalographic features such as electrical status epilepticus in sleep (ESES). The purpose of our study was to review the clinical presentation, neuroimaging findings, and outcome in a series of children with unilateral brain lesions and ESES undergoing resective surgery for refractory epilepsy. A total of 415 consecutive patients younger than 18 years of age undergoing video electroencephalographic evaluation and epilepsy surgery at Cleveland Clinic were reviewed for ESES, an underlying pathological lesion, and outcome after surgery. Eight patients were included. All patients presented with medically refractory epilepsy, hemiparesis, and developmental delay. The pathogenesis was perinatal infarction in 7 patients and malformation of cortical development in 1 patient. Preoperative electroencephalography demonstrated generalized interictal spikes, electroencephalographic seizures, and ESES in all cases. Age at the time of surgery ranged from 3 to 14 years. Six patients underwent hemispherectomy, and 2 patients underwent focal resection. Six patients became seizure-free after resection. Two patients with functional hemispherectomy continued to have rare seizures, but were much improved. These patients also had perinatal infarctions in the hemisphere contralateral to the resection, possibly indicating a less beneficial outcome. Postoperative electroencephalography demonstrated resolution of generalized interictal discharges and ESES in all. Formal pre- and postoperative neuropsychological testing showed overall improvement of age-equivalent scores. Children with unilateral brain lesions and seizures may become seizure-free after epilepsy surgery, even if the preoperative electroencephalogram shows generalized ESES. The lesion occurring early in life and the location of the lesion may play a role in the development of ESES. Cognitive impairment may be aggravated by the persistence of ESES. Preliminary developmental data in this small sample suggest that termination of seizures and possibly of ESES by epilepsy surgery may have developmental benefits.

Modelling contralesional movement slowing after unilateral brain damage

Effective interaction with the world requires the brain to signal behaviourally relevant events and organise an appropriate and timely motor response to such events. Unilateral brain lesion typically results in a reduction and slowing of motor behaviour directed to contralesional space. Accumulator models of choice and reaction time can distinguish between two possible functional causes of this deficit: slowed extraction of evidence in favour of a motor response or an increase in the required amount of evidence for response generation. Three patients with unilateral damage to the right hemisphere were tested on a visually guided saccade task. All three patients showed a dramatic increase in the latency of their responses to targets in the contralesional visual field. We fit their saccade latency distributions with a number of competing accumulator models that embody the alternative functional causes of this deficit. The latency difference between the two hemifields was best accounted for as an increase in the amount of evidence required for a contralesional response.

Post unilateral lesion response biases modulate memory: Crossed double dissociation of hemispheric specialisations

We propose that what appears to be hemispheric specialisation in the memory domain, as indexed by effects of unilateral brain lesions, is to a great extent explainable as response bias: left hemisphere lesions result in an omissive response bias or error pattern whereas right hemisphere lesions result in a commissive response bias or error pattern. To test this prediction a group of 40 non-confabulatory cases with a verbal and non-verbal retention deficit (hypomnesia), subsequent to a unilateral lesion, was assembled from the literature. A group of non-amnesic cases with confabulation, paramnesia, false memories or memory-laden hallucination (dysfunctional hypermnesia), due to a unilateral lesion, was also assembled from the literature (N=72). Most of the hypomnesic patients had left hemisphere lesions (73%, p<.005, two tailed) while most of the hypermnesic patients had right hemisphere lesions (78%, p<.0005, two tailed). This crossed double dissociation held good despite statistical control of the lesion's locus within the hemisphere, its size or its aetiology, presence of aphasic symptoms, psychiatric comorbidity, the patient's age, gender, or hand preference, and several other potentially confounding variables.

(Re-)Organization of Basal Ganglia in Congenital Hemiparesis with Ipsilateral Cortico-spinal Projections

In congenital hemiparesis after pre- or perinatally acquired unilateral brain lesions, many patients control their paretic hand via ipsilateral cortico-spinal projections from the contralesional hemisphere. In order to clarify the pattern of basal ganglia activation in case of such a shift of the primary motor cortical representation (M1) of the paretic hand to the contralesional hemisphere, fMRI was performed in eight patients with congenital hemiparesis due to unilateral periventricular white matter lesions and ipsilateral corticospinal projections to the paretic hand (as determined by focal transcranial magnetic stimulation). FMRI during active movements of the paretic hand yielded basal ganglia activation in the ipsilateral (=contralesional) hemisphere, but not in the contralateral (lesioned) hemisphere. Thus, (re-)organization in congenital hemiparesis with ipsilateral cortico-spinal projections includes, in addition to the ipsilateral primary motor cortex (M1), also the ipsilateral basal ganglia - in contrast to the primary somatosensory cortex (S1), which is typically preserved in the affected hemisphere.

Combination of Pursuit Eye Movement Training With Prism Adaptation and Arm Movements in Neglect Therapy: A Pilot Study

Objective. The aim of the present study was to determine if a combination of pursuit eye movement training to optokinetic stimulation (OKSP) and prism adaptation leads to greater improvement of neglect symptoms than a single application of OKSP. Additionally, the effect of ipsilesional arm movements during OKSP was tested. Methods. Ten patients with left-sided neglect due to unilateral right-sided vascular brain lesions were studied between 2 and 4.5 months after their stroke. Each patient received 4 different single-session treatments (each lasting 30 minutes): visual scanning treatment (control condition), OKSP, OKSP in conjunction with wearing base-left prisms inducing a shift of the visual field to the right by 10°, and OKSP in conjunction with the right to the left side. Severity of visuospatial neglect was assessed before and directly after each treatment with 4 standard neglect tests. Results. Visual scanning training improved neglect symptoms only slightly. Single OKSP stimulation led to significant improvements in all tests. OKSP in conjunction with prism adaptation was superior to the control condition in the cancellation task. The treatment condition requiring arm movements aggravated neglect symptoms in all tests. A comparison between treatments indicates best improvements may be achieved with OKSP without any additional treatment. Conclusions . The present results give evidence that OKSP significantly reduces symptoms of visuospatial neglect within 1 treatment session. The results suggest that patients should be prevented from performing ipsilesional movements during OKSP.

Further lesion evidence for the neural basis of conceptual knowledge for persons and other concrete entities

The neural underpinnings of conceptual knowledge have been studied intensively, but many unanswered questions remain. In a previous study examining recognition of persons, animals, and tools in 116 participants with unilateral brain lesions, we found no instance of a patient who manifested defective recognition in all three categories. We reasoned that the spatial distribution of the lesion loci critical for the appearance of recognition defects for these different categories explained why this 'three-way' defect could not be found in patients with unilateral lesions, and we proposed that only a suitable bilateral lesion would be likely to produce such a combined defect. In the study reported here, we tested this hypothesis by investigating recognition performances in 55 participants with bilateral cortical lesions. In support of the hypothesis, nine patients, all of whose lesions included bilateral occipitotemporal and/or temporal cortices, had a three-way recognition impairment (persons, M = 18.3%; animals, M = 35.7%; tools, M = 71.3%; all scores >2 SDs below normal). As expected, bilateral lesions to other neural sectors, for example prefrontal cortices, did not lead to recognition impairments. These findings provide further support for the notion that retrieval of knowledge for concrete entities from different conceptual categories depends on partially segregated neural systems, located in different sectors of occipitotemporal and temporal regions in right and left hemisphere.

Somatosensory system in two types of motor reorganization in congenital hemiparesis: Topography and function

This study investigates the (re-)organization of somatosensory functions following early brain lesions. Using functional magnetic resonance imaging (fMRI), passive hand movement was studied. Transcranial magnetic stimulation (TMS) and magnetoencephalography (MEG) were used as complementary methods. fMRI data was analyzed on the first level with regard to topographical variability; second-level group effects as well as the overall integrity of the somatosensory circuitry were also assessed. Subjects with unilateral brain lesions occurring in the third trimester of pregnancy or perinatally with different types of motor reorganization were included: patients with regular, contralateral motor organization following middle cerebral artery strokes (CONTRA(MCA), n = 6) and patients with reorganized, ipsilateral motor functions due to periventricular lesions (IPSI(PL), n = 8). Motor impairment was similar, but sensory impairment was more pronounced in the CONTRA(MCA) group. Using fMRI and MEG, both groups showed a normal pattern with a contralateral somatosensory representation, despite the transhemispherically reorganized primary motor cortex in the IPSI(PL) group, as verified by TMS. Activation topography for the paretic hands was more variable than for the nonparetic hand in both groups. The cortico-cerebellar circuitry was well-preserved in almost all subjects. We conclude that in both models of motor reorganization, no interhemispheric reorganization of somatosensory functions occurred. Also, no relevant intrahemispheric reorganization was observed apart from a higher topographical variability of fMRI activations. This preserved pattern of somatosensory organization argues in favor of a differential lesion effect on motor and somatosensory functions and demonstrates a limited compensatory potential for the latter.

Cerebro-muscular and cerebro-cerebral coherence in patients with pre- and perinatally acquired unilateral brain lesions

The cerebral networks involved in motor control were analyzed in four young hemi-paretic patients (21-25 years) with pre- and perinatally acquired brain lesions (3 with left periventricular brain lesions, 1 with left schizencephaly) by means of MEG source coherence analysis. Previous TMS and fMRI studies on the same patients had investigated their residual ability to move the paretic hand by means of a reorganized primary motor cortex (M1) representation in the contralesional hemisphere. The purpose of this study is to identify the effects of such a cerebral reorganization and the related dynamic aspects which allow the patients to move the paretic arm. Patients underwent a pinch grip task (1-N isometric contraction) using their paretic and non-paretic hands in alternation. MEG signals were recorded using a whole-head 151-channel magnetoencephalograph. EMG was simultaneously recorded as a reference for coherence calculations. 3D coherence mapping was performed in the beta frequency range (14-30 Hz). This approach confirmed the relocation of motor functions from the lesioned (left) to the contralesional (right) hemisphere. In case of left, non-paretic pinch grip, coherent activity originated from contralateral (right) M1 exclusively. In the case of right (paretic) grip, coherent activity in ipsilateral M1 as well as significant coherence of ipsilateral cerebellum with both muscle activity and M1 itself was detected in 3 out of 4 subjects. As expected, the patient with no cerebellar involvement during paretic hand contraction showed the worst motor performance in the grip task. Coupling direction analysis demonstrated that throughout pinch grip the coupling direction goes from M1 to cerebellum. The present study verified the assumption that the intact hemisphere takes over motor control from the paretic (ipsilateral) hand in the presence of early unilateral brain lesion. Moreover, the role of cerebellum in motor deficit compensation and its close interaction with ipsilateral primary motor cortex was studied in detail.

Evaluation of the "spasticity of conjugate gaze phenomenon" in unilateral cerebral lesions

The spasticity of conjugate gaze phenomenon (SCG) is a subtle motor ocular sign that usually indicates unilateral acute cerebral lesion. We analyzed the sensitivity of this sign in a prospective blinded study using 57 patients. All patients had monohemispheric brain lesions without resting deviation of the eyes and no motor complaints. Fourteen individuals without cerebral lesions were included as controls. Patients and controls were submitted to a brain magnetic resonance image. We observed SCG in just 1/57 (sensitivity of 1.7%), while all controls had a normal Bell's phenomenon. We speculate that SCG may disappear over time and is not useful to diagnose a long-lasting unilateral brain lesion.

Assimetrias funcionais em pacientes com hemiparesia: uma revisao da literatura

Physical impairment in patients with unilateral brain lesions and the differences between patients with left- and right-hemisphere lesions have been extensively described in the literature. However, few studies compared the recovery of patients with left- and right-hemisphere lesions. In view of the important differences between the latter, and the respectively specific rehabilitation approaches, it is important to verify what has been investigated on the recovery of each side lesion. This study aimed to review the existing data about rehabilitation of patients with hemispheric lesions and also to evidence the differences between left- and right-hemisphere lesions and the corresponding therapeutic approaches.

Organizing Logopedic Therapy for Babies With Unilateral and Bilateral Brain Lesion in the Prespeech Period

The goal of the research was to point out the importance of early prespeech therapy for babies suffering from at-birth-acquired unilateral or bilateral lesion in the prespeech period of development. On the basis of existing studies and experience in the field, a protocol and methodology for the observation of the phonological development of infants in the period between 6 and 24 months were established. Mothers made notes of the changes in the child's development in a diary specially prepared for the research. The data from the diary and the babies' reaction to the therapy in the logopedic office were inserted into the protocol. The research itself involved an experimental and a control group. The control group consisted of 60 babies without brain lesion, while the experimental group was composed of 30 babies suffering from brain lesion obtained at birth as a result of hemorrhaging, hypoxia, and asphyxia. The phonological development of the babies was observed through the ages of 6, 9, 12, and 24 months. This article demonstrates the significant differences in phonological development between the experimental and the control group. The results of the research show that phonological development in the first 6, 9, 12, and 24 months does indeed exist in the experimental group (despite the differences when compared with the control group) and can be enhanced with early monitoring and logopedic rehabilitation in the case of babies with brain lesion.

Unilateral progressive brain lesions confirmed as multiple sclerosis

Unilateral progressive brain lesions confirmed as multiple sclerosis

Developing somatosensory projections bypass periventricular brain lesions

The authors studied four hemiparetic patients with large unilateral periventricular brain lesions acquired during the early third trimester of pregnancy. fMRI and magnetoencephalography demonstrated that the primary somatosensory representation of their paretic hands was nevertheless located in the contralateral rolandic cortex. Thus, outgrowing thalamocortical somatosensory projections had apparently bypassed the lesion to reach their original cortical destination. Such somatosensory projections curving around the lesion were effectively visualized by magnetic resonance diffusion tractography.

Constructional apraxia after left or right unilateral stroke

The present study re-assesses the question whether deficits, after brain damage, in constructional tasks can be partitioned in different types of disorders of spatial cognition. Based on a current cognitive neuroscience account, originally proposed by Kosslyn [Kosslyn, S. M. (1987). Seeing and imagining in the cerebral hemispheres: A computational approach. Psychological Review, 94, 148–175], that posits two complementary lateralized systems for the encoding of (categorical and coordinate) spatial relations, it is here proposed that two qualitatively different types of “constructional apraxia” can occur and that the nature of the constructional impairment after unilateral lesions closely reflects the loss of lateralized components for the perceptual processing of differing types of spatial relations. New evidence is presented, based on the study of two groups of patients with unilateral posterior brain lesions, which supports such a bipartition of constructional apraxia. In addition, past evidence is reviewed in the light of this new cognitive neuroscience account.

Hemispheric dissociation between motor and sensory hand representations in congenital hemiparesis: TMS, fMRI, MEG

Objectives: Many children with congenital hemiparesis possess ipsilateral cortico-spinal projections, which enable the contra-lesional hemisphere to exert direct motor control over the ipsilateral, paretic hand. A previous TMS and fMRI study on congenital hemiparesis caused by unilateral periventricular brain lesions could demonstrate that all patient with such ipsilateral cortico-spinal pathways nevertheless showed strong fMRI activation of the central (Rolandic) cortex of the affected hemisphere during active movements with the paretic hand, even when no motor tracts could be identified arising in the affected hemisphere. The purpose of the present study was to further characterize these unclear fMRI activation sites.

The sleep – wake cycle in the late stage of cerebral vascular accident recovery

The sleep – wake cycle (SWC) stability and sleep quality in elderly are better preserved if social bonds are kept, whereas social isolation, or absence of a structured daily schedule, contribute to make them worse. Clinical disorders and medicine use also contribute to sleep problem complaints. This study was conducted with patients who had cerebral vascular accident (CVA) in order to evaluate the sleep – wake cycle condition, considering factors such as conditions of living and health, sleep habits, sleep and wake up times and frequency and duration of naps during weekdays as well as weekends. In this study we evaluated 24 volunteers: 12 patients (5 women; 7 men) between 6 and 42 months post-stroke and 12 healthy subjects (7 women and 5 men) all of them aged 50 – 65 years old. The patients exhibited unilateral brain lesions (right or left sides) and made use of medicines. Data were collected by means of a daily sleep log where volunteers recorded the time they slept and woke up and of naps each day, during seven consecutive days. Sleep habits and the Pittsburgh Sleep Quality questionnaires were also applied. Data analysis indicated that living conditions (number of persons in the house and in the bedroom, noise and illumination levels in the bedroom) did not influence the sleep quality of patients. According to the Pittsburgh Sleep Quality Index 67% of patients showed bad sleep quality but only 33% of healthy subjects showed the same result. The sleep duration in patients (8 h 37 min ± 60 min) was statistically greater than in healthy subjects (7 h 15 min ± 85 min) with patients waking up later than healthy subjects. According to the results, the SWC is preserved in patients in the late stage of CVA recovery although it is different from that exhibited by healthy subjects. The difference is due to an increase in sleep duration that seems to compensate for the worse sleep quality, suggesting that patients have suffered behavioral adaptations in order to compensate for the impairments caused by the CVA.

Hemispheric asymmetry in a dissociation between the visuomotor and visuoperceptual streams

We have explored the level of interaction between the putative visuoperceptual (VP) and visuomotor (VM) processing streams within each cerebral hemisphere. Six patients with unilateral brain lesions and 26 intact-brain participants were tested. We presented three-dimensional versions of the Mueller–Lyer illusion separately to the left and to the right hemifields of each participant. In one condition, the participant grasped the central shaft of the illusion object between the thumb and forefinger (visuomotor task). In the other, the participant estimated the size of the shaft using the same fingers (visuoperceptual task). We calculated the magnitude of the illusion in each task for each hemifield. Intact-brain participants had a significantly larger illusion in estimation than in grasping in both hemifields. The two patients with right-hemisphere damage showed a large dissociation between grasping and estimation illusions, whereas the four patients with left-hemisphere damage showed no detectable dissociation. These results are consistent with the idea that the visuomotor and visuoperceptual streams are more dissociated in the left hemisphere than in the right.

Testing forelimb placing “across the midline” reveals distinct, lesion-dependent patterns of recovery in rats

We describe a new test of vibrissae-elicited forelimb placing ability that allows testing of sensorimotor integration across the midline. Rats were given unilateral brain lesions using one of three methods: (1) middle cerebral artery occlusion (MCAo) causing significant damage to the cortex and striatum, (2) aspiration lesions to remove tissue from the sensorimotor cortex, and (3) infusions of the catecholamine neurotoxin 6-hydroxydopamine (6-OHDA) into the medial forebrain bundle, producing a parkinsonian syndrome. Application of the new test to these animals revealed that with some lesion types, the ability of vibrissae on the unimpaired side of the body to trigger placing in the functionally impaired forelimb recovers before vibrissae on the impaired side can elicit placing. This occurs despite the lack of any apparent vibrissae sensory deficit, since the contralesional vibrissae maintained the ability to trigger placing in the unimpaired forelimb in all lesions studied. Chronically, MCAo-lesioned rats do not place the impaired forelimb upon stimulation of the impaired-side vibrissae, but do place if the vibrissae on the good side are stimulated (i.e., when the placing is triggered “across the midline”). This is in contrast to 6-OHDA-lesioned rats which, consistent with parkinsonian akinesia, cannot place the impaired limb regardless of sensory trigger. Also, differences in the pattern of recovery between MCAo- and aspiration-lesioned rats suggest a possible anatomical substrate for cross-midline placing ability and its recovery. Unlike other tests, cross-midline placing methods can readily distinguish between severe stroke and severe parkinsonism in rats.

Visual search in school‐aged children with unilateral brain lesions

In this preliminary study, visual search for targets within and beyond the initial field of view was investigated in seven school‐aged children (five females, two males; mean age at testing 8 years 10 months, SD1 year 3 months; range 6 to 10 years) with various acquired, postnatal, focal brain injuries (haematoma, haemorrhage, meningioma, neuroblastoma, and cerebral abscess) in anterior or posterior sites of the left or right hemisphere, and seven control children (matched for age and sex) were also studied. All participants attended mainstream primary schools. The children with lesions underwent surgery after diagnosis (mean age at diagnosis 5 years 4 months, SD 2 years 7 months). Group results indicated that for the overall scores on three psychometric tests of visuospatial and fine motor abilities (Southern California Figure Ground Perception Test, Visual Organization Test, and Visual‐Motor Integration Test), no difference between the children with left and right lesions was present. However, children with lesions in the right hemisphere, and not in the left hemisphere, took significantly more time than the controls to locate visual targets presented within and beyond the field of view. Examination of individual data suggested that, in accordance with brain imaging research, right‐sided anterior cerebral lesions sustained in early childhood might have an enduring detrimental effect on voluntary visual search performance during development. This persistent effect of early brain injury might imply that developmental plasticity of the brain does not apply to certain specific functions of particular areas of the right hemisphere.