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R Iansek

Publications and source records attributed to R Iansek.

At least 19 recordsLinked to original sources
PubMed2006

Defining spatial parameters for non-linear walking.

Current definitions of the spatial and temporal parameters of gait have been based on the premise that walking occurs in a straight line. When the direction of progression (DoP) is not consistent and walking is non-linear, these definitions do not provide meaningful information. An alternative method based on the changing direction of each stride is presented. This method is easy to understand and use, and requires no expensive technology. A comparison of the spatial parameters of the footstep pattern during linear trials and trials incorporating a 60 degrees turn was performed, using output derived from the old and the new definitions. The two methods produced very different results. Spatial output from the old definitions was merely dictated by the change of direction. Output calculated relative to the changing stride direction however, provided useful information about the footstep adjustments made for turning and how these would act to improve stability. This method of establishing spatial parameters during non-linear walking should form a useful tool for further investigation of functional locomotion.

Biomechanical Phenomena↗
PubMed2006

Neuropsychological function and driving ability in people with Parkinson's disease.

In this study the association between cognitive symptoms of PD and driving performance was investigated by examining the correlation between neuropsychological test performance and driving simulator behavior. Eighteen participants with PD and 18 healthy participants in a matched comparison group completed a range of neuropsychological measures. These data were correlated with driving simulator performance results from an earlier study. Significant correlations were found between several measures of neuropsychological test performance and driving behavior in participants with PD. In contrast, few significant correlations were obtained in the comparison group. Results suggest that executive difficulties in people with PD such as working memory, planning and set shifting are associated with reduced tactical level driving performance such as speed adaptation and complex curve navigation. Impaired information processing, visual attention and visual perception in people with PD appears associated with reduced operational level driving performance, such as reacting to road obstacles and maintaining constant lane position. Few correlations were found between measures of physical mobility and psychomotor speed with driving measures. Overall, this study highlights the important role of cognitive function in driving performance within the PD population. Comprehensive assessment of cognitive function should be included when assessing driving competency in people with PD.

Aged↗
PubMed2001

Movement-related potentials in Huntington's disease: movement preparation and execution.

Movement-related potentials (MRPs) reflect increasing cortical activity related to the preparation and execution of voluntary movement. Execution and preparatory components may be separated by comparing MRPs recorded from actual and imagined movement. Imagined movement initiates preparatory processes, but not motor execution activity. MRPs are maximal over the supplementary motor area (SMA), an area of the cortex involved in the planning and preparation of movement. The SMA receives input from the basal ganglia, which are affected in Huntington's disease (HD), a hyperkinetic movement disorder. In order to further elucidate the effects of the disorder upon the cortical activity relating to movement, MRPs were recorded from ten HD patients, and ten age-matched controls, whilst they performed and imagined performing a sequential button-pressing task. HD patients produced MRPs of significantly reduced size both for performed and imagined movement. The component relating to movement execution was obtained by subtracting the MRP for imagined movement from the MRP for performed movement, and was found to be normal in HD. The movement preparation component was found by subtracting the MRP found for a control condition of watching the visual cues from the MRP for imagined movement. This preparation component in HD was reduced in early slope, peak amplitude, and post-peak slope. This study therefore reported abnormal MRPs in HD, particularly in terms of the components relating to movement preparation, and this finding may further explain the movement deficits reported in the disease.

Adult↗
PubMed2001

The biomechanics and motor control of gait in Parkinson disease.

Parkinson disease is a progressive neurological condition characterised by hypokinesia (reduced movement), akinesia (absent movement), tremor, rigidity and postural instability. These movement disorders are associated with a slow short-stepped, shuffling gait pattern. Analysis of the biomechanics of gait in response to medication, visual cues, attentional strategies and neurosurgery provides insight into the nature of the motor control deficit in Parkinson disease and the efficacy of current therapeutic interventions. In this article we supplement a critical evaluation of the Parkinson disease gait literature with two case examples. The first case describes the kinematic gait response of an individual with Parkinson disease to visual cues in the "off" phase of the levodopa medication cycle. The second case investigates the biomechanics and motor control of turning during walking in a patient with Parkinson disease compared with elderly and young control subjects. The results are interpreted in light of the need for gait analysis to investigate complex functional walking tasks rather than confining assessment to straight line walking, which has been the trend to date.

Biomechanical Phenomena↗
PubMed2001

Reliability of measurements obtained with the Timed "Up & Go" test in people with Parkinson disease.

BACKGROUND AND PURPOSE: The Timed "Up & Go" Test (TUG) is used to measure the ability of patients to perform sequential locomotor tasks that incorporate walking and turning. This study investigated the retest reliability, interrater reliability, and sensitivity of scores obtained with the TUG in detecting changes in mobility in subjects with idiopathic Parkinson disease (PD). SUBJECTS: The performance of 12 people with PD was compared with that of 12 age-matched comparison subjects without PD. METHODS: The subjects with PD completed 5 trials of the TUG after withdrawal of levodopa for 12 hours ("off" phase of the medication cycle) as well as an additional 5 trials 1 hour after levodopa was administered ("on" phase of the medication cycle). They were scored on the Modified Webster Scale at both sessions. The comparison subjects also performed 5 TUG trials. All trials were videotaped and timed by 2 experienced raters. The videotape was later rated by 3 experienced clinicians and 3 inexperienced clinicians. RESULTS: For the subjects with PD, within-session performance was highly consistent, with correlations (r) ranging from.80 to.98 for the "off" phase and from.73 to.99 for the "on" phase. The performance of the comparison subjects across the 5 trials was also highly consistent (r=.90-.97). Comparisons showed differences between trials 1 and 2 on the TUG for both groups. Removal of data for trial 1 (the practice trial) further enhanced retest reliability. There was close agreement in TUG scores among raters despite different levels of experience (intraclass correlation coefficient [3,1]=.87-.99). Mean TUG scores were different between the "on" and "off" phases of the levodopa cycle and between subjects with PD and comparison subjects during the "on" phase. CONCLUSION AND DISCUSSION: Retest reliability and interrater reliability of the TUG measurements were high, and the measurements reflected changes in performance according to levodopa use. The TUG can also be used to detect differences in performance between people with PD and elderly people without PD.

Activities of Daily Living↗
PubMed2000

Bimanual co-ordination in Huntington's disease.

The ability of Huntington's disease patients to co-ordinate their two hands with and without external cueing was investigated. Twelve Huntington's disease patients and sex- and age-matched controls performed a bimanual cranking task at two speeds (0.5 Hz, 1.5 Hz) and phase relationships (in-phase, anti-phase), with and without an external metronome cue. Data were sampled at 200 Hz, and raw displacement data for each hand, mean and standard deviation measures of the relative positions of the two hands and their velocities were then calculated. All participants could perform the in-phase movement, at both speeds; however. the Huntington's disease patients were more variable and less accurate than the control participants, particularly at the fast speed. While controls could perform the anti-phase movement, in which rotation of the cranks differed by 180 degrees at both speeds, Huntington's disease patients were unable to do so at either speed, reverting to the in-phase movement at the slow speed. An external metronome cue did not improve the performance of the Huntington's disease patients, which differentiated this group from patients suffering from Parkinson's disease. The Huntington's disease patients' inability to perform the anti-phase movement may be due to damage to the basal ganglia and its output regions.

Adult↗
PubMed2000

Postural instability in Parkinson's disease: a comparison with and without a concurrent task.

The purpose of this investigation was to determine the effects of dual task performance on postural instability in subjects with idiopathic Parkinson's disease (PD) compared with healthy elderly people. In particular, we aimed to divert attention to a secondary task so the full extent of balance disturbance could be revealed without compensation by attentional mechanisms. Forty-five subjects were tested: 15 PD subjects with a past history of falls; 15 PD subjects with no history of falls; and 15 unimpaired individuals. Groups were matched for age and sex and subjects with PD were tested at peak dose in the levodopa medication cycle. Each subject was tested on their ability to maintain stability in three conditions: (1) steady standing (feet apart, feet together, step stance, tandem stance, single leg stance); (2) in response to perturbations generated by self-initiated movements (arm raise test, step test); and (3) in response to an unexpected external perturbation in upright stance, the shoulder tug test. The concurrent task was verbal-cognitive and required subjects to recite the days of the week backwards. The concurrent task produced a significant deterioration in performance for the arm raise test in all groups, the step test for the PD fallers and controls and for tandem stance in the PD fallers. Ceiling effects were evident for timed tests with feet apart and feet together resulting in poor discriminative validity for these tests. The external perturbation test showed differences between the three groups for both unitask and concurrent task conditions, yet similar rates of change from unitask to dual task conditions. Because PD fallers had a more severe initial deficit than controls, deterioration placed them in that part of the balance continuum at high risk of losing equilibrium.

Accidental Falls↗
PubMed2000

Physiological localisation in functional neurosurgery for movement disorders: a simple approach.

Controversy exists between anatomical methods and single cell recording as the preferred approach in target localisation in functional neurosurgery for movement disorders. The controversy centres on accuracy as compared to practicality. We describe a mapping technique of semi-microstimulation utilising threshold measurements which has been used in 66 procedures in 50 subjects. We compared the accuracy of anatomical localisation with the final chosen target using the above technique. We also compared the benefit, the side effects and the surgical complication rate with published data on single cell recording and anatomical localisation. The mean difference in 3-dimensional space between the anatomical target and the physiological target was 6.85 mm (P < 0.0001). A good response was obtained in 80% of procedures. Mortality was 1.5%. The surgical complication rate was 1.5%. Mild side effects, serious side effects, transient side effects and permanent side effects were evident in 4.5%, 10.6%, 6.1% and 9.1% of procedures. These figures compared better than anatomical studies and similar to single cell recording studies. It is concluded that this approach provides both accuracy and simplicity and is recommended as a compromise to the currently available methods.

Adolescent↗
PubMed1999

Movement-related potentials in Parkinson's disease: external cues and attentional strategies.

Hypokinetic movement can be greatly improved in Parkinson's disease patients by the provision of external cues to guide movement. It has recently been reported, however, that movement performance in parkinsonian patients can be similarly improved in the absence of external cues by using attentional strategies, whereby patients are instructed to consciously attend to particular aspects of the movement which would normally be controlled automatically. To study the neurophysiological basis of such improvements in performance associated with the use of attentional strategies, movement-related cortical potentials were examined in Parkinson's disease and control subjects using a reaction time paradigm. One group of subjects were explicitly instructed to concentrate on internally timed responses to anticipate the presentation of a predictably timed go signal. Other subjects were given no such instruction regarding attentional strategies. Early-stage premovement activity of movement-related potentials was significantly increased in amplitude and reaction times were significantly faster for Parkinson's disease subjects when instructed to direct their attention toward internally generating responses rather than relying on external cues. It is therefore suggested that the use of attentional strategies may allow movement to be mediated by less automatic and more conscious attentional motor control processes which may be less impaired by basal ganglia dysfunction, and thereby improve movement performance in Parkinson's disease.

Aged↗
PubMed1999

Gait consistency over a 7-day interval in people with Parkinson's disease.

OBJECTIVE: To evaluate the consistency of temporal and spatial parameters of the walking pattern in subjects with idiopathic Parkinson's disease (PD) over a 7-day interval during the "on" phase of the levodopa medication cycle. SETTING: Walking patterns were measured on a 12-meter walkway at the Kingston Gait Laboratory, Cheltenham, using a computerized stride analyzer. SUBJECTS: Sixteen subjects (7 women, 9 men) with PD recruited from the Movement Disorders Clinic at Kingston Centre. MAIN OUTCOME MEASURES: Speed of walking, stride length, cadence, and the percentage of the walking cycle spent in the double limb support phase of gait were measured, together with the level of disability as indexed by the modified Webster scale. RESULTS AND CONCLUSIONS: Product-moment correlation coefficients and intraclass correlation coefficients (ICC 2,1) for repeat measures over a 7-day interval were high for speed (r = .90; ICC = .93), cadence (r = .90; ICC = .86), and stride length (r = 1.00; ICC = .97) and moderate for double limb support duration after removal of outliers (r = .75; ICC = .73); 95% confidence intervals for the change scores were within clinically acceptable limits for all variables. The mean modified Webster score was 11.4 on the first day and 10.1 7 days later. The gait pattern and level of disability in subjects with PD without severe motor fluctuations remained stable over a 1-week period when optimal medication prevailed.

Aged↗
PubMed1999

Speech volume regulation in Parkinson's disease: effects of implicit cues and explicit instructions.

This study examined the regulation of speech volume in hypophonic subjects with Parkinson's disease (PD) and age- and gender-matched controls. The first two experiments investigated the ability of subjects with PD to automatically regulate speech volume in response to two types of implicit cue: (i) background noise (BGN) and (ii) instantaneous auditory feedback (IAF). Control subjects demonstrated the Lombard effect by automatically speaking louder when competing against increasing levels of background noise. They also showed the reverse effect, decreasing speech volume when increasing levels of facilitative instantaneous auditory feedback were provided. Subjects with PD demonstrated decreased overall speech volume; they were less able than controls to appropriately increase volume as background noise increased, and to decrease volume as IAF increased. Thus, subjects with PD demonstrated over-constancy of speech volume and failed to respond to the implicit cues integral to volumetric scaling. A further experiment (3) was carried out to contrast the regulation of volume in response to implicit cue with an explicit attention-driven cue (i.e. instructions regarding volume level). As in Experiments 1 and 2, subjects with PD exhibited reduced speech volume. Under explicit volume instructions, the ability of subjects with PD to regulate volume was normalised. These findings suggest that subjects with PD have the capacity to speak with normal volume provided they consciously attend to speaking loudly. In subjects with PD, overall speech volume was always lower than for control subjects, suggesting a reduction of cortical motor set in the articulatory system similar to that demonstrated by the reduced amplitude of limb movements (hypokinesia) in the motor system.

Aged↗
PubMed1999

Does old age or Parkinson's disease cause bradyphrenia?

BACKGROUND: Age-related declines in intellectual functioning have been linked to slower processing of information. However, any slowness with advancing age could simply reflect slower movement rather than impaired cognition. To assess any age-related decline in cognitive speed, we used an accuracy-based task that does not require a speeded motor response and that measures the time required to acquire information (inspection time). To identify possible biological mechanisms of cognitive slowing, this task was also applied to patients with Parkinson's disease, a basal ganglia disorder that reportedly causes bradyphrenia (slower thought processes). METHODS: In one experiment, 16 young (mean age 22.4 years) and 16 older adults (mean age 71.6 years) matched for intelligence and education completed an inspection time task. The task required judgments as to order of onset of two lights, where the interval between onsets ranged from 20-250 msec. A second experiment compared 16 patients diagnosed with idiopathic Parkinson's disease and 16 age-matched controls upon the same task. RESULTS: Older adults demonstrated significant cognitive slowing compared to younger adults. Medicated nondemented Parkinsonian patients were not impaired on this task compared to age-matched controls. CONCLUSIONS: Clinical and empirical impressions of bradyphrenia in Parkinson's disease may instead reflect advancing age or slower movement, because the effects of age may be greater in some cases than the effects of basal ganglia disease once motor dysfunction has been allowed for.

Adult↗
PubMed1999

Regulation of parkinsonian speech volume: the effect of interlocuter distance.

This study examined the automatic regulation of speech volume over distance in hypophonic patients with Parkinson's disease and age and sex matched controls. There were two speech settings; conversation, and the recitation of sequential material (for example, counting). The perception of interlocuter speech volume by patients with Parkinson's disease and controls over varying distances was also examined, and found to be slightly discrepant. For speech production, it was found that controls significantly increased overall speech volume for conversation relative to that for sequential material. Patients with Parkinson's disease were unable to achieve this overall increase for conversation, and consistently spoke at a softer volume than controls at all distances (intercept reduction). However, patients were still able to increase volume for greater distances in a similar way to controls for conversation and sequential material, thus showing a normal pattern of volume regulation (slope similarity). It is suggested that speech volume regulation is intact in Parkinson's disease, but rather the gain is reduced. These findings are reminiscent of skeletal motor control studies in Parkinson's disease, in which the amplitude of movement is diminished but the relation with another factor is preserved (stride length increases as cadence-that is, stepping rate, increases).

Aged↗
PubMed1999

Interdisciplinary rehabilitation in Parkinson's disease.

The use of a multidisciplinary team in managing end-stage PD was described, emphasizing the use of a specifically designed rehabilitation program based on current concepts of basal ganglia function and malfunction in PD as a means of unifying the team members, providing them with a common knowledge base and enabling the team members to speak to the patients with a common language. This approach has enabled the multidisciplinary team to function in an interdisciplinary and intradisciplinary manner.

Humans↗
PubMed1999

Key points in the management of Parkinson's disease.

BACKGROUND: Parkinson's disease is a multidimensional disease that results in an accumulation of problems over time due to lack of cure, the progressive nature of the illness and diffuse pathology. This disease debt impacts on movement, cognition and mood, resulting in disruption of many normal daily activities for the patients and an increasing burden of care on the spouse and family. OBJECTIVE: The purpose of this article is to provide the busy general practitioner with key points in the management of Parkinson's disease which are of relevance to the patient and the career. DISCUSSION: All health care professionals who are involved in the management of Parkinson's disease need to be aware of the expectations of people with this disease and aim to meet these. Due to the multidimensional nature of this condition these patients are ideally managed in a team environment incorporating a medical practitioner, a psychiatrist, nurse, physiotherapist, occupational therapist, speech therapist, neuropsychologist, social worker and dietician.

Aged↗