A multimodal approach to understanding motor impairment and disability after stroke.

Many different measures have been found to be related to behavioral outcome after stroke. Preclinical studies emphasize the importance of brain injury and neural function. However, the measures most important to human outcomes remain uncertain, in part because studies often examine one measure at a time or enroll only mildly impaired patients. The current study addressed this by performing multimodal evaluation in a heterogeneous population. Patients (n = 36) with stable arm paresis 3-6 months post-stroke were assessed across 6 categories of measures related to stroke outcome: demographics/medical history, cognitive/mood status, genetics, neurophysiology, brain injury, and cortical function. Multivariate modeling identified measures independently related to an impairment-based outcome (arm Fugl-Meyer motor score). Analyses were repeated (1) identifying measures related to disability (modified Rankin Scale score), describing independence in daily functions and (2) using only patients with mild deficits. Across patients, greater impairment was related to measures of injury (reduced corticospinal tract integrity) and neurophysiology (absence of motor evoked potential). In contrast, (1) greater disability was related to greater injury and poorer cognitive status (MMSE score) and (2) among patients with mild deficits, greater impairment was related to cortical function (greater contralesional motor/premotor cortex activation). Impairment after stroke is most related to injury and neurophysiology, consistent with preclinical studies. These relationships vary according to the patient subgroup or the behavioral endpoint studied. One potential implication of these results is that choice of biomarker or stratifying variable in a clinical stroke study might vary according to patient characteristics.

Striatal hypertrophy and its cognitive effects in new-onset benign epilepsy with centrotemporal spikes.

PURPOSE: Benign epilepsy with centrotemporal spikes (BECTS), the most common childhood epilepsy syndrome, is a neurodevelopmental disorder with a genetic influence. Despite its signature electroencephalographic pattern and distinct focal motor seizure semiology, little is known about the underlying brain anatomic alteration and the corresponding cognitive consequences. Given the motor manifestations of seizures in BECTS, we hypothesize that anatomic networks in BECTS involve a distributed corticostriatal circuit. METHODS: We investigated volumetric differences and shape deformities of caudate, putamen, pallidum, and thalamus in a group of children with new- and recent-onset BECTS (N = 3) compared to healthy controls (N = 54). We correlated specific subcortical volumes in BECTS that were significantly different from those in healthy controls with performances in executive function. KEY FINDINGS: Children with BECTS demonstrated significantly hypertrophied putamen, which was selective among the subcortical regions examined. Shape analysis showed dorsoventral elongation of the left caudate and bilateral putamen, with subnuclei expansion in ventral and dorsal striatum. Larger putamen volumes were linked to better cognitive performances on two complementary executive function tests. SIGNIFICANCE: Children with BECTS showed aberrant volume and shape in subcortical regions that are critical for both motor processing and executive function. It is of importance to note that the hypertrophy appears to be cognitively adaptive, as enlargement was associated with improved cognitive performances. The anatomic abnormalities and their cognitive effects are evident in a group of children with new- and recent-onset epilepsy, suggesting that the structural brain anomalies occurred before the diagnosis of epilepsy.

Anatomy of stroke injury predicts gains from therapy.

BACKGROUND AND PURPOSE: Many therapies are emerging that aim to improve motor function in people with stroke. Identifying key biological substrates needed for treatment gains would help to predict treatment effects and to maximize treatment impact. The current study addressed the hypothesis that behavioral gains from therapy targeting distal upper extremity are predicted by the structural integrity of key motor system white matter tracts. METHODS: Twenty-three subjects with chronic left-sided stroke underwent robotic therapy targeting the distal right upper extremity. MRI was obtained at baseline and used to outline the infarct. For each subject, the degree to which stroke injured each of 4 descending white matter tracts (from the primary motor cortex, supplementary motor area, dorsal premotor cortex, and ventral premotor cortex, respectively) was determined. Correlations between tract-specific injury and behavioral gains from therapy were then examined. RESULTS: Numerous examples were found whereby tract-specific injury predicted treatment gains. The strongest correlations pertained to stroke injury to tracts descending from the primary motor cortex and dorsal premotor cortex. Infarct volume and baseline behavior were weak predictors of treatment gains. CONCLUSIONS: Extent of injury to specific motor tracts predicts behavioral gains from treatment in subjects with chronic stroke. This supports a role for these tracts in mediating treatment effects and reinforces the importance of lesion location in stroke. Tract-specific injury was stronger than infarct volume or baseline clinical status at predicting gains, identifies subjects with sufficient biological substrate to improve from therapy, and so might be useful as an entry criterion in repair-based trials.

Neuroplasticity and brain repair after stroke.

PURPOSE OF REVIEW: This review considers recent insights into the neurobiology of repair after stroke in animals and humans, the range of emerging therapies to promote repair and recovery after the acute phase of stroke, and issues related to optimizing trials of such therapies. RECENT FINDINGS: Animal studies continue to shed light on the molecular, vascular, glial, neuronal, behavioral, and environmental events that are important to the spontaneous behavioral recovery that is observed during the weeks after a stroke. Animal and human studies are examining a wide range of potential interventions that may favorably modify outcome, including small molecules, growth factors, cell-based approaches, electromagnetic stimulation, a range of devices and robots, and intense physiotherapy methods, including constraint-induced movement therapy. Optimal prescription of these restorative therapies in human patients with stroke requires further study, including defining potential roles for functional neuroimaging. SUMMARY: A wide range of therapies shows promise for improving poststroke brain repair. Insights into the neurobiology of brain repair after stroke in animals and in humans continue to accrue. This information might prove useful in designing and implementing clinical trials that aim to measure the clinical effects of restorative therapies after stroke.