A multimodal approach to understanding motor impairment and disability after stroke

Abstract

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.

PREP2: A biomarker‐based algorithm for predicting upper limb function after stroke

“…The template corticospinal and sensorimotor tracts were then nonlinearly registered to each patient's T1‐weighted image. A stroke lesion mask was hand‐drawn on each patient's T1‐weighted image and the percentage of tract voxels that overlapped the stroke lesion was calculated 16, 19…”

Increased Brain Sensorimotor Network Activation after Incomplete Spinal Cord Injury

“…This constellation of findings lends further credence to ankle dorsiflexion paradigm as a valid probe of locomotor function. 15,23,24,34,54,55 Time is also a major covariate for understanding the effects of SCI on the CNS, 56 but to date few studies have examined its impact on activation of brain motor networks during attempts to move voluntarily. Time post-injury is a key distinguishing factor in relation to locomotor function after incomplete SCI, 47,57 which likely reflects many of the changes that evolve during the years post-SCI, such as altered cardiac function, bone density, muscle changes, and changes in autonomic nervous system function.…”

Validity of Robot-Based Assessments of Upper Extremity Function

“…Subjects were examined by licensed therapists with established inter-rater reliability (JS, LD, and AM) via clinical measures as well as robot-based assessments 19 . The primary clinical measure for current analyses was the total FMA scale 25, 33, 41 , a measure of upper extremity impairment. Five secondary clinical measures also were examined: (1) the hand/wrist subsection of the FMA; (2) Action Research Arm Test (ARAT) 34, 35 ; (3) Box & Blocks test (B/B) 36 , a second measure of upper extremity function with different psychometric qualities that lends itself to implementation in a robotic setting; (4) hand motor subscale of Stroke Impact Scale-2 (SIS) 37 , a patient-reported measure of hand usage; and (5) the Barthel Index (BI) 38 .…”

“…Infarct volume was outlined, binarized, then transformed into Montreal Neurologic Institute (MNI) stereotaxic space. The extent of injury to the hand region of the primary motor cortex (M1) injury was determined by measuring the degree of overlap that each infarct mask had with an MNI-space map of the hand region of M1 41 . The percent injury to the corticospinal tract (CST) was determined as described previously 3041 .…”