Lower Extremity Passive Range of Motion in Community-Ambulating Stroke Survivors

Background: Physical therapists may prescribe stretching exercises for individuals with stroke to improve joint integrity and to reduce the risk of secondary musculoskeletal impairment. While deficits in passive range of motion (PROM) exist in stroke survivors with severe hemiparesis and spasticity, the extent to which impaired lower extremity PROM occurs in community-ambulating stroke survivors remains unclear. This study compared lower extremity PROM in able-bodied individuals and independent community-ambulatory stroke survivors with residual stroke-related neuromuscular impairments. Our hypothesis was that the stroke group would show decreased lower extremity PROM in the paretic but not the nonparetic side and that decreased PROM would be associated with increased muscle stiffness and decreased muscle length. Methods: Individuals with chronic poststroke hemiparesis who reported the ability to ambulate independently in the community (n = 17) and age-matched control subjects (n = 15) participated. PROM during slow (5 degrees/sec) hip extension, hip flexion, and ankle dorsiflexion was examined bilaterally using a dynamometer that measured joint position and torque. The maximum angular position of the joint (ANGmax), torque required to achieve ANGmax (Tmax), and mean joint stiffness (K) were measured. Comparisons were made between able-bodied and paretic and able-bodied and nonparetic limbs. Results: Contrary to our expectations, between-group differences in ANGmax were observed only during hip extension in which ANGmax was greater bilaterally in people post-stroke compared to control subjects (P ≤ 0.05; stroke = 13 degrees, able-bodied = −1 degree). Tmax, but not K, was also significantly higher during passive hip extension in paretic and nonparetic limbs compared to control limbs (P ≤ 0.05; stroke = 40 Nm, able-bodied = 29 Nm). Compared to the control group, Tmax was increased during hip flexion in the paretic and nonparetic limbs of post-stroke subjects (P ≤ 0.05, stroke = 25 Nm, able-bodied = 18 Nm). K in the nonparetic leg was also increased during hip flexion (P ≤ 0.05, nonparetic = 0.52 Nm/degree, able-bodied = 0.37 Nm/degree.) Conclusion: This study demonstrates that community-ambulating stroke survivors with residual neuromuscular impairments do not have decreased lower extremity PROM caused by increased muscle stiffness or decreased muscle length. In fact, the population of stroke survivors examined here appears to have more hip extension PROM than age-matched able-bodied individuals. The clinical implications of these data are important and suggest that lower extremity PROM may not interfere with mobility in community-ambulating stroke survivors. Hence, physical therapists may choose to recommend activities other than stretching exercises for stroke survivors who are or will become independent community ambulators

Correlating Behavior-based Assessment of Visual Testing with Functional Neuroimaging of the Human Visual Cortex

The overall goal of this project is to develop a functional magnetic resonance imaging (fMRI) application for the assessment of brain-related visual pathology in humans. Brain-related pathologies such as tumors, trauma, stroke, arteriovenous malformations (AVM\u27s) that affect the visual cortex may lead to visual impairments such as complete or partial blindness. In virtually all cases we lack a comprehensive understanding of the relationships between pathology, cortical dysfunction and sensory impairment. Patients with visual cortex maladies may experience partial blindness as restricted scotomata (isolated areas of diminished vision) within the field of view where contrast sensitivity may be reduced or absent. These zones of reduced sensitivity may be recoverable, so accurately detecting them may be important. In addition, preservation of intact cortical function is important in planning invasive treatment of tumors and operable pathologies. Psychophysical / behavioral techniques have been successful in diagnosing diseases that cause visual impairment, but they are of limited use for pre-surgical planning since they do not identify specific brain tissue that may be at risk. Thus, establishing methods that link behavior with fMRI activation in the brain potentially can be of great assistance in neurosurgery and clinical diagnosis. The aim of this study is to establish an fMRI correlate of impaired visual sensitivity in cases of brain pathology. We will be using functional magnetic resonance imaging (fMRI) to evaluate the relationship between perception and cortical activity. The long range goal of our lab is to assess the effect of brain-related pathologies on the brain mechanisms underlying visual sensitivity

Pedaling alters the excitability and modulation of vastus medialis H-reflexes after stroke

Objective Individuals post-stroke display abnormal Group Ia reflex excitability. Pedaling has been shown to reduce Group Ia reflexes and to normalize the relationship between EMG and reflex amplitude in the paretic soleus (SO). The purpose of this study was to determine whether these changes extend to the paretic quadriceps. Methods H-reflexes were used to examine Group Ia reflex excitability of the vastus medialis (VM). H-reflexes were elicited in paretic (n = 13) and neurologically intact (n = 13) individuals at 11 positions in the pedaling cycle and during static knee extension at comparable limb positions and levels of VM EMG. Results VM H-reflexes were abnormally elevated in the paretic limb of stroke survivors. During static muscle activation, H-reflex amplitude did not change with the level of background VM activity. Pedaling reduced the amplitude of paretic VM H-reflexes and restored the normal relationship between VM EMG and H-reflex amplitude. Conclusions Pedaling-induced changes in Group Ia reflex excitability that have been reported for the paretic SO are evident in the paretic VM. Pedaling may have a generalized effect on lower extremity Group Ia reflexes post-stroke. Significance Pedaling may be therapeutic for reducing Group Ia reflexes after stroke