Biomedical subjects

Martin E Héroux

Publications and source records attributed to Martin E Héroux.

4 recordsLinked to original sources

PubMed2006

Corticomotor excitability associated with unilateral knee dysfunction secondary to anterior cruciate ligament injury.

In the present report, we investigated changes in corticomotor excitability associated with unilateral knee dysfunction secondary to anterior cruciate ligament (ACL) injury. Ten participants, each with a previous history of unilateral ACL injury (median time post-injury 22 months) and eight healthy controls underwent transcranial magnetic stimulation (TMS) to assess excitability of the lower limb motor representation. Resting motor thresholds (RMTs) and stimulus response curves were measured at rest, while amplitude of motor evoked potentials and silent period duration were measured during active contraction. Correlations between these indices of excitability and three clinical measures of knee function were identified. Paired comparisons of indices by hemisphere revealed an asymmetry only in RMTs, which were significantly reduced on the side of injury in the ACL group. Correlations with clinical measures showed that the extent of quadriceps motor representation, as reflected by the steepness of SR curves, was strongly associated with quadriceps strength (r 2=0.71) on the injured side. The RMT asymmetry reported here in the context of ACL injury is consistent with other recent reports describing enhanced excitability of corticomotor projections targeting muscles adjacent to an immobilized or a painful joint. In such conditions, alterations in the quantity and quality of sensory feedback from the affected limb may underlie the rise in cortical excitability.

Adult↗

PubMed2006

Upper-extremity disability in essential tremor.

OBJECTIVE: To determine the extent of disability in subjects with essential tremor (ET) using time-based, standardized measures of upper-extremity function. DESIGN: Descriptive case series. SETTING: Motor performance research laboratory. PARTICIPANTS: Thirty subjects with ET (mean age, 58.3+/-13.7 y) and 28 healthy controls (mean age, 58.4+/-12.4 y). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: We assessed upper-extremity function using the Box and Block Test, Purdue Pegboard Test (PPT), and Test Evaluant la performance des Membres supérieurs des Personnes Agées (TEMPA). We measured tremor severity with laser displacement sensors. RESULTS: Subjects with ET-type tremor in 1 or both hands performed significantly worse than controls on all unilateral and bilateral tasks (P range, .038-.001) except on the PPT for the dominant side. ET subjects without ET-type tremor in the dominant hand also performed significantly worse than controls on the TEMPA unilateral tasks (P=.043). Performance on the 3 functional measures correlated moderately with tremor severity for the nondominant hand. CONCLUSIONS: Subjects with ET show measurable disability on time-based measures of upper-extremity function. However, our findings are consistent with other reports that tremor severity does not correlate well with disability, especially with regard to the dominant upper extremity.

Adult↗

PubMed2006

Functional mobility and postural control in essential tremor.

OBJECTIVE: To evaluate functional mobility and postural control in participants with essential tremor (ET). DESIGN: Cross-sectional cohort study. SETTING: Motor performance research laboratory. PARTICIPANTS: Sixteen participants with ET including head tremor (age, 59.4+/-12.0 y), 14 participants with ET and no head tremor (age, 57.1+/-15.9 y), and 28 healthy controls (age, 58.4+/-12.4 y). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: We assessed the Timed Up & Go, time to ascend and descend stairs, Dynamic Gait Index, and Berg Balance Scale (BBS). Participants completed the Activities-specific Balance Confidence Scale and the Human Activity Profile. We assessed postural control using center-of-pressure measures from force platform recordings of quiet standing in 5 conditions. RESULTS: Participants with ET including head tremor performed worse than controls on all functional mobility performance and self-report measures (P<.05) except the BBS and stair descent time. Mean performance of ET participants without head tremor was intermediate between the other 2 groups. Sway speed measures of postural control showed similar patterns, but no significant group differences in post hoc analysis. There were no statistically significant or clinically important correlations between measures of tremor status and functional mobility status. CONCLUSIONS: Participants with ET show reduced functional mobility, especially those with head tremor.

Cohort Studies↗

PubMed2005

Weight discrimination after anterior cruciate ligament injury: a pilot study.

OBJECTIVE: To determine whether the ability to discriminate weights remained accurate after anterior cruciate ligament (ACL) injury. DESIGN: Descriptive case series. SETTING: Outpatient physical therapy. PARTICIPANTS: Convenience sample of 10 participants with unilateral ACL injuries (age, 27.1+/-8.2 y) and 8 healthy controls (age, 22.6+/-2.8 y). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Weber fractions, expressed as percentage differences from the standard weight (3.00 kg) that could be reliably detected (75% correct level), were derived from each leg to provide an index of proprioceptive acuity for weight discrimination. Subjective ratings of knee function (Activities of Daily Living Scale of the Knee Outcome Survey) and measurements of quadriceps strength (peak isometric torque). RESULTS: The ACL group exhibited a reduced acuity to detect differences in weight on the injured, as compared with the uninjured, side as reflected in the increase in Weber fractions (mean, 6.7%+/-2.3% vs 4.8%+/-1.1%, respectively; P = .043). No such difference in acuity between legs was detected in healthy controls (mean right and left, 5.4%+/-1.4% vs 5.7%+/-1.3%, respectively, P = .99). CONCLUSIONS: Proprioceptive acuity for weight discrimination was significantly reduced after an ACL injury, possibly reflecting deficits in the ability to properly calibrate force signals generated while muscles are actively contracting, as a result of a loss in ligamentous sensory innervation.

Activities of Daily Living↗