Initial Motor Impairment Research Articles

Corticospinal Tract Diffusion Abnormalities Early After Stroke Predict Motor Outcome

Background. Prognosis of long-term motor outcome of acute stroke patients with severe motor impairment is difficult to determine. Objective. Our primary goal was to evaluate the prognostic value of corticospinal tract (CST) injury on motor outcome of the upper limb compared with motor impairment level and lesion volume. Methods. In all, 10 acute stroke patients with moderately severe to severe motor impairment of the upper limb underwent diffusion tensor imaging (DTI) and testing of upper limb strength and dexterity at acute, subacute, and chronic poststroke time points. A density-weighted CST atlas was constructed using DTI tractography data from normal participants. This CST atlas was applied, using a largely automated process, to DTI data from patients to quantify CST injury at each time point. Differences in axial diffusivity (AD), radial diffusivity (RD), and fractional anisotropy (FA) of the ipsilesional CST relative to the contralesional CST were measured. Results. Acute loss in CST AD correlated most strongly and significantly with subacute and chronic strength and dexterity and remained significant after adjusting for acute motor impairment or lesion volume. Subacute loss in CST FA correlated most strongly with chronic dexterity, whereas subacute behavioral measures of limb strength correlated most strongly with chronic strength measures. Conclusions. Loss in acute CST AD and subacute CST FA are strong prognostic indicators of future motor functions of the upper limb for stroke patients with substantial initial motor impairment. DTI-derived measure of CST injury early after stroke may have utility in health care planning and in design of acute stroke clinical trials.

Abstract T MP37: Fractional Anisotropy Changes in the Acute Stroke Phase Only Modestly Predict Motor Outcome at 3 Months

Background: A decrease in fractional anisotropy (FA) of the ipsilesional corticospinal tract (CST) distal to ischemic stroke lesions in chronic stroke patients has been associated with poor motor outcome, but in the acute phase no clear FA trends have been observed or used to make outcome predictions. Methods: This study followed 40 patients with first-ever ischemic stroke, measuring motor impairment with the Upper Extremity Fugl-Meyer (UE-FM) acutely and at 3 months. Images obtained <3 days after stroke, including FA, were overlaid with a probabilistic CST (blue in Figure 1) derived from healthy subjects to define a cerebral peduncle region of interest ROI and a “nearest slice” ROI (green line in Figure 1), the second slice downstream from the stroke lesion (red in Figure 1). Ipsilesional and contralesional CST FA values as well as Apparent Diffusion Coefficient (ADC) values of regions of interests were compared using a laterality index and related to 3-month motor outcome. Results: Asymmetry between ipsilesional and contralesional CST FA values was significant different between patients with bad motor outcome and good outcome, with lower FA of the ipsilesional CST in the bad outcome group. No such asymmetry was seen for the cerebral peduncle ROI using either FA or ADC values. The FA laterality index for the nearest slice ROI was a significant but modest predictor of 3-month motor outcome (R2=0.186, p=.02), with the best predictive value offered by the combination of this imaging variable and the initial motor impairment (R2=0.696, p=.01). Conclusion: FA changes of the CST can be detected near the ischemic lesion in the acute phase after stroke, but these changes offer only modest predictive value for eventual motor outcome.

Abstract 87: Neuroimaging, Not Clinical Assessment Predicts Post-Stroke Motor Outcome in Severely Impaired Stroke Patients

Background: Initial motor impairment by clinical assessment and neuroimaging measures of corticospinal tract injury have been shown to predict 3-month motor outcome in mild-to-moderately impaired stroke patients. Clinical assessment alone is good to predict outcome of more severely impaired patients. This study aims to compare clinical assessment with neuroimaging in severely impaired patients. Methods: This study followed 27 first-ever ischemic stroke patients who presented with severe motor impairment at baseline( between 2- 5 days after stroke) which is defined as Upper Extremity Fugl-Meyer (UE-FM) Scale was <=5. Patients will be assessed at 3 months (90 ±14 days) again with UE_FM. A weighted CST lesion load (wCST-LL) was calculated by overlaying each patient’s lesion map on MRI with a probabilistic CST constructed from healthy subjects. A regression analysis was applied to assess the predictive value of wCST-LL and initial motor impairment. Results: Initial motor impairment has no predictive value (p=0.25, R 2 =0.05) while wCST-LL has a strong prediction (p=0.002, R 2 =0.31) for post-stroke motor outcome in this severely impaired stroke group. If wCST is more than 7 cc, no patient recovers more than 20 on UE_FM at 3 months. Conclusion: Compared with clinical assessment, a neuroimaging measure of CST injury excels in post-stroke motor outcome prediction in a severely impaired subgroup.

Abstract 2856: Lesion load of Corticospinal Tract and Initial Motor Impairment in the Acute Stroke Phase Predict Motor Impairment 3 Months Post-Stroke

Background: We use lesion-mapping techniques in combination with diffusion tensor imaging to quantitatively test the hypothesis that motor impairment 3 months post- stroke is inversely related to the lesion load of the corticospinal tract (CST) in the acute stroke phase. Methods: We prospectively followed up a cohort of 32 patients who presented with their first-ever acute ischemic stroke with various degree of motor deficit , had a MRI during the hospitalization, and had follow-up motor assessments using the Fugl-Meyer Upper Extremity Scale (FM-UE) at 3 months (+/- 2 weeks) after stroke. We calculated a CST-lesion load for each patient by overlaying the patient’s lesion map from diffusion weighted image with a probabilistic DTI tract constructed from 12 age-matched healthy subjects . Both raw and weighted (which accounts for the narrowing of the CST as it descends from the motor cortex to the posterior limb of the internal capsule) were calculated; weighted lesion-loads were calculated by multiplying the lesion-tract overlap on each slice by the ratio of the maximum cross-sectional area of the tract to the cross-sectional area of the tract on that particular slice). A multiple regression is fit to assess the predicted value of CST lesion load (raw or weighted), along with other variables such age, gender, lesion size, initial impairment, days of therapy known to have an possible effect on motor outcome. Results: CST-lesion load and initial motor impairment are found to be significant predictors of upper extremity motor impairment at 3 months post-stroke. Age, gender, lesion size or days of therapy does not have predictive value in our cohort study. The adjusted R² is 0.63 with initial impairment and raw lesion load in the regression model, and is 0.66 with initial impairment and weighted lesion load. Conclusions: Our data shows the degree of motor impairment at 3 months after a first-ever ischemic stroke can be predicted by the overlap of the lesion with the canonical CST derived from age-matched healthy control subjects and the initial motor impairment measured in the acute phase.

Predictors of upper limb recovery after stroke: a systematic review and meta-analysis

Objective: To systematically review and summarize the current available literature on prognostic variables relating to upper limb recovery following stroke. To identify which, if any variables predict upper limb recovery following stroke. Data sources: We completed searches in MEDLINE, EMBASE, AMED, CINAHL and Cochrane CENTRAL databases. Searches were completed in November 2010. Review methods: Studies were included if predictor variables were measured at baseline and linked to an outcome of upper limb recovery at a future time point. Exclusion criteria included predictor variables relating to response to treatment and outcome measurements of very specific upper limb impairments such as spasticity or pain. Two independent reviewers completed data extraction and assessed study quality. Results: Fifty-eight studies met the inclusion criteria. Predictor variables which have been considered within these studies include; age, sex, lesion site, initial motor impairment, motor-evoked potentials andsomatosensory-evoked potentials. Initial measures of upper limb impairment and function were found to be the most significant predictors of upper limb recovery; odds ratio 14.84 (95% confidence intervals (CI) 9.08–24.25) and 38.62 (95% CI 8.40–177.53), respectively. Conclusions: Interpretation of these results is complicated by methodological factors including variations in study populations, upper limb motor outcome scales, timing of baseline and outcome assessments and predictors selected. The most important predictive factors for upper limb recovery following stroke appears to the initial severity of motor impairment or function.

The Role of the Contralesional Motor Cortex for Motor Recovery in the Early Days after Stroke Assessed with Longitudinal fMRI

Stroke may trigger a number of cellular and molecular events in perilesional and remote brain regions enabling cortical reorganization and recovery of function. We here investigated the pattern and time course of acute stroke-induced changes in motor system activity during motor recovery using functional magnetic resonance imaging. Hand movement-related neural activity was assessed in 11 acute stroke patients scanned 3 times during the first 2 weeks starting within 72 h after symptom onset. A motor recovery score was computed based on the action research arm test and the maximum grip force. Increases of activity in primary motor cortex, premotor cortex (dorsal and ventral), and supplementary motor area in both hemispheres significantly correlated with behavioral recovery. These longitudinal changes depended upon the degree of initial motor impairment: Patients with mild deficits did not differ from healthy subjects. In contrast, patients with severe deficits were characterized by a global reduction of task-related activity, followed by increases in ipsilesional as well as contralesional motor areas. The finding that the gradually increasing activity in contralesional primary motor and premotor cortex correlated with improved functional recovery in severely affected patients indicates early cortical reorganization supporting motor function of the affected hand.

Prise en charge des accidents de décompression médullaire en plongée sous-marine : actualités en 2010

The outcome of spinal cord decompression sickness after scuba diving is unpredictable during the 24 first hours with a high risk of incomplete recovery. The treatment is defined on first aid normobaric oxygen when neurological symptoms occur, rehydration and prompt recompression in hyperbaric chamber. The presence of initial motor impairment, the aggravation of symptoms during the transfer to the hyperbaric facility and the emergence of sphincter dysfunction are predictive of poor prognosis whatever the treatment undertaken.

Initial motor impairment influences activation pattern of motor recovery

Objectives: We investigated the functional magnetic resonance imaging (fMRI) activation pattern of a motor task in patients with acute subcortical lesions to examine the relationship between activation pattern and recovery of motor impairment.Methods: Five patients (one with subcortical infarction and four with thalamic hemorrhage) were examined using fMRI 1 month after the insult. Impairment was assessed by the Medical Research Council motor strength classification (MRC). One patient with severe motor deficits was also studied at 4 months when her motor deficits improved up to MRC grade 4.Results: Three patients with relatively mild deficits (MRC grade 3 or 4) at their onsets, improved fully up to grade 5 within 1 month. FMRI performed at 1 month showed activation in the contralateral primary motor cortex and supplementary motor area (SMA), but no significant activation was seen on the ipsilateral unaffected side. Two patients with severe motor impairment (MRC grade 1) improved up to 3 and 4 of MRC at 1 month or later. They showed activation of the ipsilateral premotor area as well as contralateral primary motor cortex and SMA. One of them, whose severe motor deficit improved at 4 month, also showed activation of the ipsilateral postcentral gyrus and the activated area expanded longitudinally corresponding with her functional recovery.Discussion: Our study demonstrates that the fMRI pattern varies according to functional recovery, suggesting the importance of the ipsilateral premotor area and postcentral gyrus especially for those patients with severe motor impairment initially.

Bi‐hemispheric contribution to functional motor recovery of the affected forelimb following focal ischemic brain injury in rats

In many recovering hemiparetic stroke patients, movement of the affected limb elicits ipsilateral activation of sensorimotor areas within the undamaged hemisphere, which is not observed in control subjects. Following middle cerebral artery occlusion, rats received intensive enriched-rehabilitation (ER) of the impaired forelimb for 4 weeks. Weekly assessments on a skilled reaching test demonstrated significant improvement in ischemic animals over 4 weeks of ER (P < 0.05). We hypothesized that if the undamaged forelimb motor cortex contributed to improved forelimb function, then inhibition of neural activity within this region should reinstate (at least some of) the initial motor impairment. After 3 and 4 weeks of ER, animals received a microinjection of lidocaine hydrochloride into the undamaged motor cortex and were re-assessed on reaching ability. The behavioral effect of lidocaine challenge was dependent on the size of the infarct: animals with large infarcts were rendered unable to retrieve any food pellets and had great difficulty even contacting a pellet with the affected forepaw. Small-infarct animals were only moderately affected (25% reduction in success) by lidocaine, an effect similar to that observed in control animals. Qualitative assessments of recovered reaching after 4 weeks of rehabilitation revealed that impairments in forelimb lift, advance and aim were exacerbated (P < 0.05) following lidocaine-inactivation of the undamaged motor cortex of animals with large ischemic infarcts. In animals with small infarcts, lidocaine challenge only impaired limb advance. Thus, recruitment of the undamaged hemisphere may depend on the functional integrity of the remaining sensorimotor system. These data suggest that, in the rat, the undamaged (ipsilateral) motor system may contribute to compensatory recovery of the affected forelimb.

Reorganization of remote cortical regions after ischemic brain injury: a potential substrate for stroke recovery.

Although recent neurological research has shed light on the brain's mechanisms of self-repair after stroke, the role that intact tissue plays in recovery is still obscure. To explore these mechanisms further, we used microelectrode stimulation techniques to examine functional remodeling in cerebral cortex after an ischemic infarct in the hand representation of primary motor cortex in five adult squirrel monkeys. Hand preference and the motor skill of both hands were assessed periodically on a pellet retrieval task for 3 mo postinfarct. Initial postinfarct motor impairment of the contralateral hand was evident in each animal, followed by a gradual improvement in performance over 1-3 mo. Intracortical microstimulation mapping at 12 wk after infarct revealed substantial enlargements of the hand representation in a remote cortical area, the ventral premotor cortex. Increases ranged from 7.2 to 53.8% relative to the preinfarct ventral premotor hand area, with a mean increase of 36.0 +/- 20.8%. This enlargement was proportional to the amount of hand representation destroyed in primary motor cortex. That is, greater sparing of the M1 hand area resulted in less expansion of the ventral premotor cortex hand area. These results suggest that neurophysiologic reorganization of remote cortical areas occurs in response to cortical injury and that the greater the damage to reciprocal intracortical pathways, the greater the plasticity in intact areas. Reorganization in intact tissue may provide a neural substrate for adaptive motor behavior and play a critical role in postinjury recovery of function.

Motor impairment as a predictor of functional recovery and guide to rehabilitation treatment after stroke.

This study tests three hypotheses relevant for the efficient use of rehabilitation services after stroke: (a) the severity of initial motor impairment after stroke predicts discharge motor impairment and self-care mobility scores; (b) identification of those unlikely to show improvement in motor impairment can focus rehabilitzation efforts on use of compensatory techniques and assist devices; and (c) improvement in self-care mobility scores without change in motor impairment, balance, or cognition is a quantitative estimate of the value of teaching compensatory techniques and use of assist devices. We studied 171 sequential patients previously independent in the community who were admitted for inpatient rehabilitation within 17 +/- 12 SD days of an initial, unilateral, hemispheric, ischemic stroke. Impairment was assessed using the Fugl-Meyer upper limb motor (ULM), lower limb motor (LLM), and upper plus lower limb total motor (TM) subscores. Disability was assessed using the Functional Independence Measure (FIM), FIM self-care (FIMS), FIM mobility (FIMM), and FIM self-care plus FIM mobility (FIMSM) subscores. Spearman correlation coefficients tested strength of association between dependent and independent variables, stepwise linear regression tested the effects of clinically relevant co-variables, and positive and negative predictive values (PPV, NPV) assessed the clinical relevance of outcome-prediction models. The highest correlations observed were between admission TM scores and the following discharge scores: TM (R = 0.92; p < 0.01), ULM (R = 0.91; p < 0.01), LLM (R = 0.82; p < 0.01), FIMSM (R = 0.67; p < 0.01), FIMM (R = 0.67; p < 0.001), FIM (R = 0.58; p < 0.0001). An admission TM score in the lowest quartile had a PPV of 0.74 for a discharge ULM score in the lowest quartile. An admission TM score in the highest quartile had a PPV of 0.86 for a discharge ULM score in the highest quartile. Similar but weaker PPVs were seen for admission TM scores and discharge LLM scores. Patients without significant change in TM scores (< or = 2 points) had a 17 +/- 9 SD improvement in FIMSM scores. Admission motor impairment scores (a) predict discharge impairment and activities of daily living mobility functional outcome; and (b) guide treatment toward improving motor impairment versus use of compensatory techniques and assistive devices. The use of compensatory techniques and assistive devices, without change in motor impairment, is associated with a 17 +/- 9 SD improvement in FIMSM score.

Assessment of Stroke Outcome Based on Initial Stroke Severity Measured on Different Stroke Severity Scales

Background: Stroke is the second most common cause of death globally and the major cause of disability. Thougha number of studies have been conducted on stroke outcome and recovery of walking function, the list and effectsof predictive factors are still a major challenge to stroke rehabilitation.Materials and methods: This was a randomized prospective study to evaluate whether initial stroke severityinfluences the stroke outcome. The patients were categorized after CT scan into two groups (group I- infarction typeand group II haemorrhagic type). Initial stroke severity was evaluated in Scandinavian Stroke Scale (SSS). Functionalstatus was evaluated after admission in Functional Independence Measure (FIM), Barthel Index (BI) and ShortForm- 36 (SF- 36).To see the outcome in relation to time patients were evaluated with FIM, BI and SF- 36 four weeksafter discharge.Results: Analysis of Scandinavian Stroke Scale indicated that the overall score was higher among the patients withcerebral infarct (mean score 29.25) compared to patients with cerebral hemorrhage (mean score 20.08) and themean difference was statistically significant (p&lt;0.001). Analysis of Barthel Index indicated that the percentage ofimprovement was significantly high among the patients with cerebral hemorrhage compared to cerebral infarct interms of transfers from bed to chair or vice versa (p&lt;0.001). However, improvement was also high among thepatients with cerebral hemorrhage as well as cerebral infarct, but the difference was not statistically significant(p&gt;0.05)Conclusion: This study indicates that initial motor, sensory and cognitive impairment can be good predictor inamount and time period of recovery of mobility function and other aspect in acute stroke patients, as data shows thatmilder the initial impairment faster and more is the recovery.Keywords: Stroke; cerebrovascular accident; outcome assessmentDOI: 10.3329/jom.v11i2.5460J MEDICINE 2010; 11 : 137-142