Search or browse years of Parkinsn Email list messages
Mail converted by MHonArc 2.6.10
 
Site Hosting donated by
&
Grant from The Parkinson Alliance

Parkinsn Current Topics

TITLE: Physiological localisation in functional neurosurgery for movement disorders: a simple approach.
AUTHORS: Iansek R; Rosenfeld JV; Feniger H; Huxham F
AUTHOR AFFILIATION: Geriatric Neurology Service, Kingston Centre, Melbourne, Australia.
SOURCE: J Clin Neurosci 2000 Jan;7(1):29-33
CITATION IDS: PMID: 10847647 UI: 20304297
ABSTRACT: 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.

2000/07
2000/15 11:00


--------------------------------------------------------------------------------


TITLE: Speech volume regulation in Parkinson's disease: effects of implicit cues and explicit instructions.
AUTHORS: Ho AK; Bradshaw JL; Iansek R; Alfredson R
AUTHOR AFFILIATION: Psychology Department, Monash University, Clayton, Victoria, Australia. aileen.ho@sci.monash.edu.au
SOURCE: Neuropsychologia 1999 Dec;37(13):1453-60
CITATION IDS: PMID: 10617265 UI: 20083555
ABSTRACT: 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.

2000/01
2000/05 09:00


--------------------------------------------------------------------------------


TITLE: Key points in the management of Parkinson's disease.
AUTHORS: Iansek R
AUTHOR AFFILIATION: Monash University. Robert.Iansek@med.monash.edu.au
SOURCE: Aust Fam Physician 1999 Sep;28(9):897-901
CITATION IDS: PMID: 10561888 UI: 20024531
ABSTRACT: 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.

1999/11
1999/24 09:00

--------------------------------------------------------------------------------


TITLE: Does old age or Parkinson's disease cause bradyphrenia?
AUTHORS: Phillips JG; Schiffter T; Nicholls ME; Bradshaw JL; Iansek R; Saling LL
AUTHOR AFFILIATION: Department of Psychology, Monash University, Clayton, Vic, Australia. psy193g@alpha1.cc.monash.edu.au
SOURCE: J Gerontol A Biol Sci Med Sci 1999 Aug;54(8):M404-9
CITATION IDS: PMID: 10496546 UI: 99424865
ABSTRACT: 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.

1999/09
1999/25 09:00

--------------------------------------------------------------------------------


TITLE: Evolution of motor fluctuations in Parkinson's disease: a longitudinal study over 6 years.
AUTHORS: Reardon KA; Shiff M; Kempster PA
AUTHOR AFFILIATION: Department of Neurosciences, Monash Medical Centre, Clayton, Victoria, Australia.
SOURCE: Mov Disord 1999 Jul;14(4):605-11
CITATION IDS: PMID: 10435497 UI: 99361850
ABSTRACT: A prospective longitudinal 6-year study of 34 patients with Parkinson's disease from the time of initiation of drug treatment explored changes in the motor response to L-dopa over the early to mid disease course. Motor fluctuations developed in 41% after a mean L-dopa treatment interval of 25 months and dyskinesia developed in 53% after a mean of 15 months' treatment. Patients who developed fluctuations had a significantly better response to L-dopa than nonfluctuators. Nonfluctuators also had significantly greater "midline" motor disability affecting cranial and truncal muscles and gait. The development of motor fluctuations may simply reflect a retained capacity to respond to L-dopa as endogenous dopaminergic neurotransmission declines with progressive nigral cell loss. Many patients who show no sign of motor fluctuation 5 or 6 years into the disease course have a relatively blunted response to L-dopa. The proportion of such cases seems to correspond to the percentage that have coexisting striatal pathologic changes in postmortem studies.

1999/08
1999/06 10:00


--------------------------------------------------------------------------------


TITLE: Interdisciplinary rehabilitation in Parkinson's disease.
AUTHORS: Iansek R
AUTHOR AFFILIATION: Geriatric Research Unit, Kingston Centre, Cheltenham, Melbourne, Australia.
SOURCE: Adv Neurol 1999;80:555-9
CITATION IDS: PMID: 10410771 UI: 99338960
ABSTRACT: 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.

1999/07
1999/20 10:00


--------------------------------------------------------------------------------


TITLE: Regulation of parkinsonian speech volume: the effect of interlocuter distance.
AUTHORS: Ho AK; Iansek R; Bradshaw JL
AUTHOR AFFILIATION: Neuropsychology Research Unit, Psychology Department, Monash University, Clayton 3168, Victoria, Australia. Aileen.Ho@sci.monash.edu.au
SOURCE: J Neurol Neurosurg Psychiatry 1999 Aug;67(2):199-202
CITATION IDS: PMID: 10406989 UI: 99337756
ABSTRACT: 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).

1999/07
1999/17 10:00


--------------------------------------------------------------------------------


TITLE: Gait consistency over a 7-day interval in people with Parkinson's disease.
AUTHORS: Urquhart DM; Morris ME; Iansek R
AUTHOR AFFILIATION: Spinal Management Clinics of Victoria, Peninsula Sports Medicine Centre, and Peninsula Community Health Service, Mornington, Australia.
SOURCE: Arch Phys Med Rehabil 1999 Jun;80(6):696-701
CITATION IDS: PMID: 10378498 UI: 99304843
ABSTRACT: 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.

1999/06
1999/23 10:00


--------------------------------------------------------------------------------


TITLE: Movement-related potentials in Parkinson's disease: external cues and attentional strategies.
AUTHORS: Cunnington R; Iansek R; Bradshaw JL
AUTHOR AFFILIATION: Department of Psychology, Monash University, Clayton, Victoria, Australia.
SOURCE: Mov Disord 1999 Jan;14(1):63-8
CITATION IDS: PMID: 9918346 UI: 99114905
ABSTRACT: 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.

1999/01
1999/26 03:01

--------------------------------------------------------------------------------


TITLE: Performance on clinical tests of balance in Parkinson's disease.
AUTHORS: Smithson F; Morris ME; Iansek R
AUTHOR AFFILIATION: Research Unit, Kingston Centre, Cheltenham, Victoria, Australia.
SOURCE: Phys Ther 1998 Jun;78(6):577-92
CITATION IDS: PMID: 9626270 UI: 98289510
ABSTRACT: BACKGROUND AND PURPOSE: Due to the high incidence of falls in people with idiopathic Parkinson's disease (PD), the assessment of standing balance is a key component of physical therapist evaluation. This study investigated performance on clinical tests of standing balance in subjects with and without PD.

SUBJECTS: The subjects were 10 persons with PD who had a history of falls (age range = 60-80 years), 10 persons with PD who had no history of falls (age range = 63-79 years), and 10 persons with no known neurological impairment (age range = 60-78 years) who served as a comparison group.

METHODS: Subjects were tested on their ability to maintain stability in 3 conditions: (1) steady standing (feet apart, feet together, tandem stance, step stance, and single-limb stance), (2) in response to perturbations generated by self-initiated movements (arm raise, functional reach, bend-reach, and step tests), and (3) in response to an external perturbation to upright stance (shoulder tug). Balance was measured at peak dosage in the levodopa medication cycle (in the morning) and 7 days later.

RESULTS: The mean Hoehn and Yahr Disability Scale score was 3.0 for the fallers with PD and 2.5 for the nonfallers with PD. Performance on the tandem stance, single-limb stance, functional reach, and shoulder tug tests demonstrated differences between the subjects with PD and the comparison group and between the fallers and nonfallers with PD. The results of these tests were highly repeatable over 7 days (ICC = .61-.94).

CONCLUSION AND DISCUSSION: Although there was a small sample size, performance was highly consistent across 7 days when testing occurred during peak dosage of levodopa. A small battery of tests were sensitive enough to discriminate between people with PD who fall and those with no history of falls.

1998/06
1998/17 02:03

--------------------------------------------------------------------------------


TITLE: Bimanual co-ordination in Parkinson's disease.
AUTHORS: Johnson KA; Cunnington R; Bradshaw JL; Phillips JG; Iansek R; Rogers MA
AUTHOR AFFILIATION: Department of Psychology, Monash University, Clayton, Victoria, Australia.
SOURCE: Brain 1998 Apr;121 ( Pt 4):743-53
CITATION IDS: PMID: 9577398 UI: 98238259
ABSTRACT: The basal ganglia may be involved in bimanual co-ordination. Parkinson's disease (which impairs basal ganglia output) is clinically reported to cause difficulties in the performance of co-ordinated bimanual movements. Nevertheless, any bimanual co-ordination difficulties may be task specific, as experimental observations are equivocal. To infer the role of the basal ganglia in co-ordinating the two arms, this study investigated the bimanual co-ordination of patients with Parkinson's disease. Sixteen Parkinson's disease patients and matched control subjects performed a bimanual cranking task, at different speeds (1 and 2 Hz) and phase relationships. All subjects performed the required bimanual in-phase movement on a pair of cranks, at fast (2 Hz) and slow (1 Hz) speeds. However, the Parkinson's disease patients were unable to perform the asymmetrical anti-phase movement, in which rotation of the cranks differed by 180 degrees, at either speed; but instead reverted to the in-phase symmetrical movement. For Parkinson's disease patients, performance of the in-phase movement was more accurate and stable when an external timing cue was used; however, for anti-phase movement, the external cue accentuated the tendency for patients to revert to more symmetrical, in-phase movements.

1998/05
1998/13 02:02

--------------------------------------------------------------------------------


TITLE: Abnormalities in the stride length-cadence relation in parkinsonian gait.
AUTHORS: Morris M; Iansek R; Matyas T; Summers J
AUTHOR AFFILIATION: Kingston Centre, Cheltenham, Australia.
SOURCE: Mov Disord 1998 Jan;13(1):61-9
CITATION IDS: PMID: 9452328 UI: 98112707
ABSTRACT: The purpose of this investigation was to clarify abnormalities in the stride length-cadence relation in gait hypokinesia in Parkinson's disease (PD). A second aim was to investigate the effect of levodopa medication on the foot-step pattern. In the first experiment, 20 subjects with idiopathic PD and 20 age-, sex-, and height-matched controls performed a series of 10 m walking trials at cadence rates ranging from 40 steps/min to 180 steps/min. Cadence rates were set by an electronic metronome, and gait patterns were measured by using a footswitch stride-analyzer system. By instructing subjects to concentrate on walking in time to the metronome beat, the baseline stride length could be monitored for a range of velocities with the compensatory effects of cadence removed. Linear-regression analysis revealed that the mean slope for the regression of stride length against cadence was not different from normal in PD, although there was a statistically significant difference in mean intercept between the PD group (0.25) and the control group (0.59); [t (19) = -4.76; p = 0.0001]. The second experiment evaluated the effects of levodopa on stride-length regulation in 10 subjects with idiopathic PD on average 45 min before and after the first morning dose was administered. There was a statistically significant increase in stride length for all cadence rates from premedication to postmedication phases and the maximal stride length was achieved at higher cadence rates after medication. The slope of the regression of stride length against cadence did not alter according to medication status, although the mean intercept was significantly lower before levodopa (-0.06) compared with after levodopa (0.27); [t (9) = -3.83; p = 0.004]. These results suggest that defective scaling of stride length underlies gait disturbance in PD.

1998/02
1998/06 05:53



TITLE: Movement-related potentials in Parkinson's disease. Motor imagery and movement preparation.
AUTHORS: Cunnington R; Iansek R; Johnson KA; Bradshaw JL
AUTHOR AFFILIATION: Department of Psychology, Monash University, Clayton, Victoria, Australia.
SOURCE: Brain 1997 Aug;120 ( Pt 8):1339-53
CITATION IDS: PMID: 9278627 UI: 97424514
ABSTRACT: Movement-related potentials (MRPs) associated with voluntary movements reflect cortical activity associated with processes of movement preparation and movement execution. Early-stage pre-movement activity is reduced in amplitude in Parkinson's disease. However, it is unclear whether this neurophysiological deficit relates to preparatory or execution-related activity, since previous studies have not been able to separate different functional components of MRPs. Motor imagery is thought to involve mainly processes of movement preparation, with reduced involvement of end-stage movement execution-related processes. Therefore, MRP components relating to movement preparation and execution may be examined separately by comparing MRPs associated with imagined and actual movements. In this study, MRPs were recorded from 14 subjects with Parkinson's disease and 10 age-matched control subjects while they performed a sequential button-pressing task, and while they imagined performance of the same task. Early-stage pre-movement activity was present in both Parkinson's disease patients and control subjects when they imagined movement, but was reduced in amplitude compared with that for actual movement. Movement execution-related components, arising predominantly from the primary motor cortex, were relatively unaffected in Parkinson's disease subjects. However, motor preparatory processes, probably involving the supplementary motor area, were reduced in amplitude overall and abnormally prolonged, indicating impaired termination following the motor response. Further, this impaired termination of preparatory-phase activity was observed only in patients with more severe parkinsonian symptoms, and not in early-stage Parkinson's disease.

1997/08
1997/01 00:00


Return To Index of Current Parkinson's Topics