Biomedical subjects

Kathleen E Norman

Publications and source records attributed to Kathleen E Norman.

5 recordsLinked to original sources

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↗

PubMed2006

Effects of visual and auditory cues on gait initiation in people with Parkinson's disease.

OBJECTIVE: To evaluate the effects of auditory and visual cues on gait initiation in people with Parkinson's disease. SUBJECTS: Fourteen subjects with Parkinson's disease were recruited from community support groups, seven of whom reported having experienced freezing when walking. DESIGN AND SETTING: This study was a repeated measures analysis of gait initiation performance during a single visit to a university-based motion laboratory. Following baseline trials, auditory and visual cue conditions were presented in random order. The auditory cues were rhythmic sounds with an interval matching the subject's average step time. The visual cues were high-contrast transverse lines on the floor adjusted for the subject's first step length and overall height. MAIN MEASURES: Kinematic recordings enabled calculation of the timing and length of steps as well as overall velocity. The timing and magnitude of weight shift and push-off force were obtained from a force platform. RESULTS: The magnitudes of first and second step lengths, of push-off force and of overall gait velocity were significantly greater in the visual cue condition than in the baseline condition, whereas there was no significant effect of auditory cue on these measures. Neither cue had any significant effect on the timing of key events in gait initiation. CONCLUSIONS: Transverse line visual cues enable people with Parkinson's disease to begin walking with longer steps, greater push-off force and higher velocity. Auditory cues that others have shown to improve aspects of gait in people with Parkinson's disease do not appear to have any systematic effect on the first two steps of gait initiation.

Aged↗

PubMed2003

Computational approaches to motor control and their potential role for interpreting motor dysfunction.

PURPOSE OF REVIEW: Computational frameworks, notably internal models and optimal control theory, have led to rapid advances in our understanding of how the brain plans and controls movement. The purpose of this review is to provide an overview of these theoretical ideas, how they have been used to interpret motor control, as well as their potential role for interpreting motor dysfunction. RECENT FINDINGS: There are two general types of internal models, neural processes that mimic the mechanical properties of the limb (and environment). Forward internal models parallel the normal causal flow of the motor periphery and estimate limb motion from motor commands. Inverse internal models perform the reverse process by estimating motor commands from signals related to intended limb motion and/or spatial targets. This framework has led to several important behavioural observations on motor planning, control and learning, and has also been influential for interpreting neural activity in awake, behaving non-human primates. A more recent framework for interpreting motor function is optimal control theory, which recognizes that noise or errors are an inherent feature of the motor system and may influence strategies to plan and control movement. SUMMARY: Internal models and optimal feedback control both provide frameworks for interpreting motor performance, and may be of value for interpreting many motor dysfunctions associated with neurological injuries. Advanced technologies such as robots that have played a key role in these frameworks may be also of considerable value for motor assessment and rehabilitation.

Animals↗

PubMed2002

A randomized controlled trial of the effects of weights on amplitude and frequency of postural hand tremor in people with Parkinson's disease.

OBJECTIVE: To evaluate the effects of weights on postural hand tremor related to self-feeding in subjects with Parkinson's disease (PD). DESIGN: In a repeated-measures design, postural hand tremor was recorded three times in each of three weight conditions in a single session for each subject. The order of all recording conditions was randomized. SETTING: Intervention was applied and measurement was conducted in a university-based motor performance laboratory. SUBJECTS: Fourteen men and two women diagnosed with PD and having hand tremor participated (mean age 67.1 years, mean duration of PD 4.6 years). All were community-dwelling. INTERVENTION: The control condition consisted of holding a built-up spoon (108 g). There were two experimental conditions: holding a weighted spoon (248 g); and holding the built-up spoon while wearing a weighted wrist cuff (470 g). MAIN OUTCOME MEASURES: Three measures of tremor amplitude and two measures of tremor frequency were calculated from recordings of displacement of the spoon obtained from laser displacement sensors. RESULTS: Repeated-measures analyses of variance revealed no significant differences across conditions in any measure of tremor amplitude or in either measure of tremor frequency. Correlational and Mann-Whitney U-test analyses revealed that none of age, disease duration or medication intake had any significant relationship with tremor amplitude in the control condition or with whether amplitude was altered by weights. CONCLUSIONS: The findings suggest that there is no support for the clinical recommendation of using weighted utensils or weighted wrist cuffs to alleviate postural hand tremor in PD.

Activities of Daily Living↗