Muscle weakness and cocontraction in upper limb hemiparesis: relationship to motor impairment and physical disability

The purpose of this article is to describe the relationship between poststroke upper limb muscle weakness and cocontraction, and clinical measures of upper limb motor impairment and physical disability. Electrormyographic (EMG) activity of the paretic and nonparetic wrist flexors and extensors of 26 chronic stroke survivors were recorded during isometric wrist flexion and extension. The root mean square (RMS) of the EMG signal was used as a measure of strength of contraction. A ratio of RMS of antagonist and agonist muscles was used as a measure of cocontraction. Upper limb motor impairment and physical disability were assessed with the Fugl-Meyer motor assessment (FMA) and the arm motor ability test (AMAT), respectively. The strength of muscle contraction was significantly stronger in the nonparetic limb (P < 0.001). The degree of cocontraction was significantly greater in the paretic limb (P < 0.001). The strength of muscle contraction in the paretic limb correlated significantly with FMA (r = 0.62 to 0.87, P < or = 0.001) and AMAT (r = 0.66 to 0.80, P < or = 0.001) scores. Similarly, the degree of cocontraction correlated significantly with FMA (r = -0. 70 to -0.64, P < or = 0.001) and AMAT (r = -0. 72 to -0.62, P < or = 0.001) scores. Muscle weakness and degree of cocontraction correlate significantly with motor impairment and physical disability in upper limb hemiplegia. This relationship may provide insights toward development of specific interventions. However, additional studies are needed to demonstrate a cause and effect relationship.     

Capsular infarcts: location, size and etiology of pure motor hemiparesis, sensorimotor stroke and ataxic hemiparesis

We investigated the types of syndrome, location, size and presumed causes of 72 patients with acute capsular lacunar infarction. Clinical syndromes were classified into pure motor hemiparesis (PM), sensorimotor stroke (SM) and ataxic hemiparesis (AH). Lesion sizes of AH were significantly smaller than those of PM (p<0.01) or SM (p<0.01). When the lesion volume was classified into two groups, ≥ 1 ml and < 1 ml, the large volume group had more frequent cardioembolic sources than the small volume group (41% and 18% respectively, p<0.05). In AH patients no cardioembolic sources could be detected. Significant carotid stenosis was found in only 4% of patients. Patients with anterior choroidal artery territory infarction had infrequent cardioembolic sources (7%). The results suggest that the lesion size varies with clinical syndrome and some etiological trends are seen in the volume and the location of lesions.     

Effect of intensive motor training with repetitive transcranial magnetic stimulation on upper limb motor function in chronic post-stroke patients with severe upper limb motor impairment

Background Intensive motor training with low-frequency repetitive transcranial magnetic stimulation (rTMS) has efficacy as a therapeutic method for motor dysfunction of the affected upper limb in patients with mild to moderate stroke. However, it is not clear whether this combination therapy has the same effect in chronic post-stroke patients with severe upper limb motor impairment.

Objectives The aim of this study was to test the treatment effects of intensive motor training with low-frequency rTMS in chronic post-stroke patients with severe upper limb motor impairment.

Methods A convenience sample of 26 chronic post-stroke patients with severe upper limb motor impairment participated in this study with the non-randomized, non-controlled clinical trial. All subjects were hospitalized to receive intensive motor training with low-frequency rTMS. During 2 weeks in which Sundays were excluded, a total of 24 sessions (2 sessions per day) of the intervention were conducted. The Fugl–Meyer Assessment (FMA) and Wolf Motor Function Test (WMFT) were used to assess motor impairment and function of the affected upper limb, respectively, before and after intervention. Paired t-test was used to analyze the effects of the intervention.

Results The FMA total score and WMFT log performance time significantly improved from before to after intervention (FMA: 12.6–18.0; WMFT: 3.6–3.3, p < 0.001).

Conclusions The present results suggest that intensive motor training with low-frequency rTMS could improve motor impairment in chronic post-stroke patients with severe upper limb motor impairment and contribute to the expansion of the application range of this combination therapy.     

An unusual presentation of hypokalemic paralysis with evolving pure motor hemiparesis

Pure motor hemiparesis is a vascular syndrome that is occasionally mimicked by central or spinal pathologies. However, metabolic neuromuscular disorders have not been reported to mimic this condition. We present a 52-year-old male patient with hypokalemic paralysis who presented with the early symptoms of acute-onset pure motor hemiparesis. Neurological examinations revealed right-sided weakness without bulbar, extraocular, or respiratory involvement. Ischemic stroke was initially diagnosed on the basis of the acute-onset unilateral motor deficit and the patient’s history of hypertension, stroke, and previous cerebral infarctions. The right hemiparesis and weakness of the left limbs worsened on the day after admission. The patient’s weakness rapidly reversed after correction of hypokalemia, and a diagnosis of hypokalemic paralysis was finally established. This unusual hemineurological presentation should alert medical personnel to the possibility of reversible metabolic neuromuscular disorders, thereby avoiding delayed diagnosis.     

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.     

Pure motor hemiparesis due to pontine infarction as the presenting sign of neurosyphilis

A 50-year-old man with minimal risk factors for cerebrovascular disease had a pure motor hemiparesis due to a pontine infarction. Syphilis serology and CSF findings indicated a previously unrecognized meningovascular syphilis as the cause of the stroke. At variance with the majority of recently reported cases, no prodromal syndrome preceded the cerebrovascular event, and there was no HIV coinfection. Treatment with erythromycin and minocycline was followed by clinical improvement and normalization of main CSF parameters including VDRL; oligoclonal bands and local IgG synthesis, however, were still detectable in post-treatment CSF.     

Turns-amplitude analysis of the electromyographic recruitment pattern following upper motor neuron lesions

OBJECTIVE: To assess the pattern of motor unit recruitment of weak muscles in upper motor neuron (UMN) lesions. MATERIALS AND METHODS: Ten patients underwent turns-amplitude analysis (TAA) on the paretic and healthy brachial biceps muscles, in the acute and subacute stages of hemiparesis. The control group comprised 10 age- and sex-matched subjects. RESULTS: Although absent in the acute stage, five patients developed a myogenic cloud pattern in their paretic extremities in the subacute stage; which was statistically significant when compared with controls (P = 0.033). Mean amplitude was reduced in both acute and subacute stages of the hemiparesis compared with controls (P = 0.000). The turns/mean amplitude ratio in the subacute stage was increased compared with both the paretic limbs examined in the acute stage (P = 0.000) and to controls (P = 0.000). CONCLUSION: Abnormalities in the recruitment of motor units in UMN lesions give rise to a myogenic cloud pattern in the TAA, which is prominent in the third month after the initial insult. This may result from the increase in motor unit activity, while the recruitment of bigger motor units is still defective.     

Everyday memory impairment,neuroradiological findings and physical disability in multiple sclerosis

Thirty-five multiple sclerosis (MS) patients diagnosed according to the Poser criteria were examined in a variety of cognition and memory tasks. Their performance was compared to age- and gender-matched healthy individuals. While there was no difference in overall intellectual performance and short-term memory between the MS group and control subjects, the patient group showed significant deficits in several everyday memory tasks including story recall, object and face recognition, procedural, topographical and prospective memory tasks. An intra-group comparison in the MS cohort revealed that those patients with a chronic-progressive MS course exhibited the most substantial everyday memory impairments and highest EDSS scores. These findings coincide with the neuroradiological, semiquantitative lesion analysis which was also performed. In this analysis, the latter MS subgroup also had the highest lesion score, as a sign of an overall brain involvement     

Explicit and implicit anosognosia or upper limb motor impairment

If asked directly, anosognosic patients deny or seriously underestimate their motor difficulties. However explicit denial of hemiplegia does not necessarily imply a lack of insight of the deficit. In this study we explored explicit and implicit awareness for upper limb motor impairment in a group of 30 right-brain damaged patients. Explicit awareness was assessed using a questionnaire (the VATAm) in which patients are asked to rate their motor abilities, whereas implicit awareness was assessed by means of a newly developed test (BMT - bimanual task). This test requires the performance of a series of bimanual tasks that can be better performed using two hands, but could also be performed using one hand only. With the BMT, patients’ performance rather than their verbal reports is evaluated and scored as an index of awareness. Paretic patients with anosognosia tend to approach these tasks as if they could use both hands. Our findings showed that explicit and implicit awareness for motor deficits can be dissociated, and they may be differently affected by feedback suggesting that different underlying mechanisms may account for the multi-factorial phenomenon of anosognosia.     

The comparable size and overlapping nature of upper limb distal and proximal muscle representations in the human motor cortex

The purpose of this study was to determine the relative size and location of proximal and distal upper limb muscle representations in the human motor cortex. Motor-evoked potentials (MEPs) evoked by transcranial magnetic stimulation were recorded in the proximal muscle anterior deltoid (AD) and in the distal muscles extensor carpi radialis (ECR) and first dorsal interosseus (1DI). The coil was moved in steps of 1 cm along a grid drawn on a tight-fitting polyester cap placed on the subject's head. At each location, four stimuli were delivered at 1.2 times the active motor threshold (AMT), and MEPs averaged in real-time. The peak-to-peak amplitude of each muscle's mean MEP was measured at each stimulation site. The area of a muscle's representation was measured by a pixel-counting algorithm. The optimal point of each muscle's areal representation, which corresponds to the locus near which the largest MEPs are obtained, was determined by fitting a 3D Lorentzian function to the data points. The optimal point of distal muscles tended to be situated more laterally along the motor strip than that of proximal muscles. However, there was no statistically significant difference between the size of the areal representations and they overlapped considerably. Additionally, in another five subjects, using a small 45-mm coil placed in a hyper-focal orientation, maps were obtained at a stimulus intensity of 1.1-1.15 times the AMT of the muscle with the lowest threshold, usually the 1DI. Even in this very stringent condition, the mapped representations of the AD, ECR and 1DI overlapped, notwithstanding that sharp demarcations between borders were also apparent. These observations demonstrate that stimulus spread alone does not explain the overlap of muscle representations. These results show that commonly used proximal and distal upper-limb muscles, taken individually, are controlled by motor cortical territories of approximately equal size that significantly overlap despite differences in the location of their optimal points.     

Denial and neglect of hemiparesis in right-sided apoplectic lesions

In a prospective investigation of 55 consecutively selected patients with right-sided apoplectic lesions, denial and neglect of hemiparesis was registered in a standardized way using fixed criteria.
The patients were all fully conscious and could cooperate in a detailed investigation. About half of the patients had denial and neglect of hemiparesis (1/4 denial, 1/5 neglect). The syndrome(s) of denial/neglect was not related to sensory defects or defects in the sense of position. Denial of hemiparesis was related to extent of lesion, neglect of hemiparesis was not. Both syndromes were related to age of patients. The resemblance between denial and neglect of hemiparesis is pointed out. It is argued, that the two phenomena could be seen as one syndrome released by right-sided brain lesions, the difference being a matter of degree. The cognitive factors in denial/neglect are thought upon as factors, than can be seen in right-sided lesions together with paresis, visual defects, but apparently not necessarily associated with the named defects.     

Investigation of raising burden of children with autism, physical disability and mental disability in China

The family economic burden of raising autistic children, physical disabled children and mental disabled children were evaluated in China. 227 parents of children with autism, children with physical disability, children with mental disability and normal children were interviewed for children's costs, family income and economic assistance, etc. The medical cost and caring cost of disabled children were significantly more than those of normal children, and the education cost, clothes cost and amusement cost of disabled children were significantly less than those of normal children. Family income was only predicted by parents’ education level. Families of disabled children received more economic assistance than families of normal children except families of autistic children. More children the family had, less economic assistance the family acquired. Compared with normal children, the raising burden of children with disabilities were as follows: children with autism (19582.4 RMB per year), children with physical disability (16410.1 RMB per year), children with mental disability (6391.0 RMB per year). Families of autistic children, physical disabled children and mental disabled children have heavier raising burden than families of normal children, they need more help from many aspects.     

Motor network reorganization after motor imagery training in stroke patients with moderate to severe upper limb impairment

Background

Motor imagery training (MIT) has been widely used to improve hemiplegic upper limb function in stroke rehabilitation. The effectiveness of MIT is associated with the functional neuroplasticity of the motor network. Currently, brain activation and connectivity changes related to the motor recovery process after MIT are not well understood. Aim: We aimed to investigate the neural mechanisms of MIT in stroke rehabilitation through a longitudinal intervention study design with task-based functional magnetic resonance imaging (fMRI) analysis.

Methods

We recruited 39 stroke patients with moderate to severe upper limb motor impairment and randomly assigned them to either the MIT or control groups. Patients in the MIT group received 4 weeks of MIT therapy plus conventional rehabilitation, while the control group only received conventional rehabilitation. The assessment of Fugl-Meyer Upper Limb Scale (FM-UL) and Barthel Index (BI), and fMRI scanning using a passive hand movement task were conducted on all patients before and after treatment. The changes in brain activation and functional connectivity (FC) were analyzed. Pearson's correlation analysis was conducted to evaluate the association between neural functional changes and motor improvement.

Results

The MIT group achieved higher improvements in FM-UL and BI relative to the control group after the treatment. Passive movement of the affected hand evoked an abnormal bilateral activation pattern in both groups before intervention. A significant Group × Time interaction was found in the contralesional S1 and ipsilesional M1, showing a decrease of activation after intervention specifically in the MIT group, which was negatively correlated with the FM-UL improvement. FC analysis of the ipsilesional M1 displayed the motor network reorganization within the ipsilesional hemisphere, which correlated with the motor score changes.

Conclusions

MIT could help decrease the compensatory activation at both hemispheres and reshape the FC within the ipsilesional hemisphere along with functional recovery in stroke patients.     

Effect of upper limb deformities on gross motor and upper limb functions in children with spastic cerebral palsy

The aims of this study were to investigate the nature and extent of upper limb deformities via the use of various classifications, and to analyze the relationship between upper limb deformities and gross motor or upper limb functionality levels. Upper extremity data were collected from 234 children with spastic cerebral palsy (CP) who were admitted to the university hospital for intensive rehabilitation. Upper limb deformities were classified according to the Zancolli classification for finger and wrist extension ability, the Gshwind and Tonkin classification for supination ability, and the House classification for thumb-in-palm deformity. Digital deformity was also classified. Upper limb function was assessed using the Upper Extremity Rating Scale (UERS) and the Upper Limb Physician's Rating Scale (ULPRS). Gross motor function was assessed using the Gross Motor Functional Classification System (GMFCS). Among the 234 children observed, 70.5% had a limitation in forearm supination, and 62.8% had problems with wrist and finger extension in at least one limb. Thumb-in-palm deformity of at least one hand was found in 47.0% of patients. Swan neck deformity was the most common finger deformity. Upper limb functional measures, the ULPRS and the UERS, significantly correlated with the degree of upper limb deformity, as assessed by the Gschwind and Tonkin, Zancolli, and House classifications. Further, the degree of upper limb deformity was significantly related to the GMFCS level in children with bilateral CP, but not in children with unilateral CP. Limitation of forearm supination was the most common upper limb deformity in children with spastic CP. The degree of upper limb deformity significantly affected upper limb function in these children.     

Functional relevance of ipsilateral motor activation in congenital hemiparesis as tested by fMRI-navigated TMS

Many, but not all patients with congenital hemiparesis (i.e., hemiparesis due to a pre-, peri- or neonatally acquired brain lesion) control their paretic hands via ipsilateral cortico-spinal projections from the contra-lesional hemisphere (CON-H). Patients who still control their paretic hands via preserved crossed cortico-spinal projections from the damaged hemisphere nevertheless show increased fMRI activation during paretic hand movements in the CON-H. We used fMRI-navigated rTMS induced functional lesions over the primary motor cortex (M1) hand area, the dorsal premotor cortex (dPMC) and the superior parietal lobe (SPL) of the CON-H in four of these patients to investigate whether this increased ipsilateral activation during finger movements of the paretic hand contributes to movement performance. Functional lesions of the dPMC and M1 but not SPL of the CON-H induced decreased temporal preciseness of finger sequences. The present results argue for a possible role of dPMC and M1 of the CON-H on complex motor behavior even in those patients with congenital hemiparesis who control their paretic hands via crossed cortico-spinal projections from the damaged hemisphere.     

Immediate improvement of motor function after epilepsy surgery in congenital hemiparesis

Hemispherectomy often leads to a loss of contralateral hand function. In some children with congenital hemiparesis, however, paretic hand function remains unchanged. An immediate improvement of hand function has never been reported. A 17‐year‐old boy with congenital hemiparesis and therapy‐refractory seizures due to a large infarction in the territory of the middle cerebral artery underwent epilepsy surgery. Intraoperatively, electrical cortical stimulation of the affected hemisphere demonstrated preserved motor projections from the sensorimotor cortex to the (contralateral) paretic hand. A frontoparietal resection was performed, which included a complete disconnection of all motor projections originating in the sensorimotor cortex of the affected hemisphere. Surprisingly, the paretic hand showed a significant functional improvement immediately after the operation. This observation demonstrates that, in congenital hemiparesis, crossed motor projections from the affected hemisphere are not always beneficial, but can be dysfunctional, interfering with ipsilateral motor control over the paretic hand by the contralesional hemisphere.     

兔腓肠肌表面肌电信号与肌肉收缩及运动中枢的关系

背景：以往的验证实验均采用电刺激方法诱发肌肉收缩,施加电流的影响使接收到的表面肌电信号混有外来电流成分,无法有效分析其与肌肉收缩,特别是与高位运动中枢的关系。 目的：观察新西兰兔腓肠肌表面肌电信号与肌肉收缩及高位、低位运动中枢的关系。 方法：在新西兰兔清醒状态下通过针刺右侧跟腱诱发腓肠肌收缩,局麻清醒状态下离断右侧坐骨神经,分别在针刺跟腱、钳夹离断的坐骨神经远侧断端、针刺腓肠肌和被动活动腓肠肌时,检测腓肠肌表面肌电信号的强弱及类型。局麻下于L3平面横断脊髓,针刺左侧跟腱诱发腓肠肌收缩,检测腓肠肌表面肌电信号的强弱和类型。 结果与结论：正常状态下经针刺跟腱诱发腓肠肌随意收缩时,可接收到400 μV、持续4 s的宽底随意波;横断脊髓后针刺跟腱诱发的反射性腓肠肌收缩接收到的信号小于100 μV、持续时间小于1 s;离断坐骨神经后刺激跟腱、神经和肌肉时,均未引起肌肉收缩,但可接收到强度小于10 μV、持续时间小于0.5 s的干扰波;被动活动关节牵拉腓肠肌时未检测到肌电信号活动。说明兔腓肠肌表面肌电信号产生于肌肉收缩之前,是以高位运动中枢为主、低位运动中枢为辅发放到肌肉的驱动电信号的综合,而非肌肉收缩本身产生。     

Characteristics of motor unit discharge in subjects with hemiparesis

We studied the discharge rates recruitment characteristics of single motor units in paratic and contralateral arm muscles of 6 hemiparetic subjects. Motor unit activity in bicapes brachii was recorded at different elbow torques, and the activity related both to the mean level of surface electromyographic activity, and to the degree of weakness. In 3 of the 6 subjects, there were significant reductions in mean discharge rate of motor units in the paretic muscle. All 6 subjects showed compression of the range of motoneuron recuitment forces, and a failure to increase motor unit discharge rate during voluntary force increases in paretic muscles. These rate reductions could potentially alter the precise match of motoneuron properties to the mechanical properties of the innerved muscle fibers, and reduce the efficiency of muscle contraction. This reduction could lead, in turn to increased effort, to fatigue, and ultimately to a sense of weaknes for voluntary force generation.© 1995 John Wiley & Sons, Inc.