Upper limb neurodynamic mobilization disperses intraneural fluid in cervical nerve roots: A human cadaveric investigation.

BACKGROUND: Cervical radiculopathy is a common cause of neck pain with resultant intraneural edema and impaired nerve function. One strategy to treat radiculopathy is neurodynamic mobilization (NDM); however, little is known about the effect of this treatment on nerve tissue fluid dynamics. OBJECTIVE: Investigate the impact of upper limb, median nerve-biased NDM on longitudinal intraneural fluid dispersion in the C5,C6,C7 nerve roots in un-embalmed cadavers. DESIGN: In situ repeated measures. METHODS: Human cadavers (n = 8) were dissected to expose and inject C5,C6,C7 cervical nerve roots with a dying agent. Initial longitudinal dye spread was recorded after dye spread stabilization. Cadavers were taken through 150 repetitions of upper limb, median nerve-biased NDM followed by dye spread re-measurement. Paired-samples t-tests with Bonferroni correction (α = 0.017) were used to compare pre-vs post-NDM dye spread measurements at C5,C6,C7 nerve roots; a one-way repeated measures ANOVA (α = 0.05) was used to examine differences between change scores for C5,C6,C7 nerve roots. RESULTS: Median nerve-biased NDM resulted in significant intraneural longitudinal dye spread at C5 and C6 nerve roots of 0.6 ± 0.6 mm and 3.4 ± 3.9 mm, respectively (p < 0.014). Dye spread was not significant at C7 nerve root (0.4 ± 0.7 mm). There was no between root difference in change of longitudinal dye spread between C5, C6, and C7 nerve roots. CONCLUSIONS: The results of this study show median nerve-biased NDM produced internal fluid movement within C5 and C6 cervical nerve roots. Results provide insight regarding possible mechanism of action and feasibility of NDM in treatment of patients with cervical radiculopathy.

Adaptation in motor strategies for postural control associated with sensory reweighting.

The purpose of this study was to identify and differentiate the motor strategies associated with sensory reweighting adapted during specific sensory integration tasks by healthy young adults. Thirty-six subjects (age range: 21-33 years) performed standing computerized dynamic posturography balance tasks across progressively increasing amplitudes of visual (VIS), somatosensory (SOM) and both (VIS+SOM) systems perturbation conditions. Adaptation in the motor strategy was measured as changes in electromyographic (EMG) activities and joint angles. The contribution of the perturbed sensory input in maintaining postural stability was calculated to determine the sensory reweighting. A multivariate design was used to model a linear combination of motor adaptation variables that discriminates specific sensory integration tasks. Results showed a significant progressive decrease in postural sway per unit amplitude of sensory perturbation in each condition, indicating dynamic sensory reweighting. Linear discriminant function analysis indicated that the adaptation in motor strategy during the VIS condition was associated with increased activity of EMG and joint angles in the upper body compared to the lower body. Conversely, during the SOM and VIS+SOM conditions, the adaptation in motor strategy was associated with decreased activity of EMG and joint angles in the lower body compared to the upper body. Therefore, the adaptation in motor strategies associated with sensory reweighting were different for different sensory integration tasks.

Exploration of arm weight effects on hemiparetic stroke participants' gait performance.

BACKGROUND: This study explores the potential benefits of an arm weight intervention for improving gait performance in stroke survivors. Consistent with an interlimb neural coupling mechanism, the investigators hypothesized that arm weight would improve gait performance. METHODS: Nine stroke and nine healthy participants (1 female; age: 58.0 ± 6.8 years) participated. Participants walked over-ground at their preferred speed in four conditions: no weight (C1), non-hemiparetic (healthy: dominant) side weights (C2), hemiparetic (non-dominant) side weights (C3), and bilateral weights (C4). Statistical analyses included repeated analysis of variance (ANOVA) and paired t-test planned comparisons to explore the effects of added weight on gait speed, step width, step length, cadence, and arm swing amplitude. Single-subject analyses used randomization tests to delineate further the weight's effect on gait speed. FINDINGS: The stroke group walked significantly faster with arm weight (p = 0.048), exhibiting large ANOVA (η2p = 0.28) and C1 vs. C4 planned comparison (p = 0.021; dD = 0.95) effect sizes. Four of nine stroke participants significantly increased gait speed in at least one condition, and seven of nine exhibited large effect size increases (d = 0.85-4.71). The stroke group's hemiparetic-side step length and cadence significantly (p = 0.008) increased in C4 compared to C1, exhibiting large effect size increases (rb = 0.96). Four of nine healthy participants significantly increased gait speed in at least one condition, with five of nine exhibiting large effect size increases (d = 0.80-6.63). INTERPRETATION: This study's exploratory results demonstrate arm weight's potential for improving higher-functioning stroke survivors' gait performance. Arm weight addition merits further investigation as a possible rehabilitation intervention in the stroke population.