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Biomedical subjects

P G Bain

Publications and source records attributed to P G Bain.

At least 19 recordsLinked to original sources
PubMed2005

A randomly assigned double-blind cross-over study examining the relative anti-parkinsonian tremor effects of pramipexole and pergolide.

This study examined the relative anti-Parkinson's disease (PD) tremor potencies of pergolide and pramipexole in people with PD, using a 3-month double-blind cross-over design. Patients were randomly assigned to receive either pergolide and then pramipexole (n=9) or vice versa (n=8). The dose of the respective dopamine agonist was increased according to a titration schedule up to a maximum 1.5 mg t.d.s., with cross-over at 10 weeks. Assessments were performed at baseline, 4, 8 and 12 weeks. The primary outcome measures were the differences in the clinical (rest and postural) tremor scores on pergolide versus pramipexole. Seventeen PD patients (11 females and six males) with a mean age 68.4 years (range: 55-84 years) and a mean disease duration of 3.9 years (range: 2 months to 13 years) participated in the study. Twelve of the patients were taking other anti-parkinsonian medications. Two patients dropped out of the study whilst on pergolide. Fifteen of 16 patients were able to cross-over from one dopamine agonist to the other, without major retitration. There were no significant differences between the effects of the two drugs on the primary outcome measures, suggesting that the anti-PD tremor efficacies of dopaminergic medications are not dependent on differential affinities for dopamine receptor types.

Aged↗
PubMed2004

Cannabis for dyskinesia in Parkinson disease: a randomized double-blind crossover study.

BACKGROUND: The long-term treatment of Parkinson disease (PD) may be complicated by the development of levodopa-induced dyskinesia. Clinical and animal model data support the view that modulation of cannabinoid function may exert an antidyskinetic effect. The authors conducted a randomized, double-blind, placebo-controlled crossover trial to examine the hypothesis that cannabis may have a beneficial effect on dyskinesia in PD. METHODS: A 4-week dose escalation study was performed to assess the safety and tolerability of cannabis in six PD patients with levodopa-induced dyskinesia. Then a randomized placebo-controlled crossover study (RCT) was performed, in which 19 PD patients were randomized to receive oral cannabis extract followed by placebo or vice versa. Each treatment phase lasted for 4 weeks with an intervening 2-week washout phase. The primary outcome measure was a change in Unified Parkinson's Disease Rating Scale (UPDRS) (items 32 to 34) dyskinesia score. Secondary outcome measures included the Rush scale, Bain scale, tablet arm drawing task, and total UPDRS score following a levodopa challenge, as well as patient-completed measures of a dyskinesia activities of daily living (ADL) scale, the PDQ-39, on-off diaries, and a range of category rating scales. RESULTS: Seventeen patients completed the RCT. Cannabis was well tolerated, and had no pro- or antiparkinsonian action. There was no evidence for a treatment effect on levodopa-induced dyskinesia as assessed by the UPDRS, or any of the secondary outcome measures. CONCLUSIONS: Orally administered cannabis extract resulted in no objective or subjective improvement in dyskinesias or parkinsonism.

Aged↗
PubMed2004

Electron microscopy of tissue adherent to explanted electrodes in dystonia and Parkinson's disease.

Deep brain stimulation (DBS) is used to treat a variety of severe medically intractable movement disorders, including Parkinson's disease, tremor and dystonia. There have been few studies examining the effect of chronic DBS on the brains of Parkinson's disease patients. Most of these post mortem studies concluded that chronic DBS caused mild gliosis around the lead track and did not damage brain tissue. There have been no similar histopathological studies on brains from dystonic patients who have undergone DBS. In this study, our objective was to discover whether tissue would be attached to DBS electrodes removed from patients for routine clinical reasons. We hoped that by examining explanted DBS electrodes using scanning (SEM) and/or transmission (TEM) electron microscopy we might visualize any attached tissue and thus understand the electrode-human brain tissue interaction more accurately. Initially, SEM was performed on one control DBS electrode that had not been implanted. Then 21 (one subthalamic nucleus and 20 globus pallidus internus) explanted DBS electrodes were prepared, after fixation in 3% glutaraldehyde, for SEM (n = 9) or TEM (n = 10), or both (n = 2), according to departmental protocol. The electrodes were sourced from two patients with Parkinson's disease, one with myoclonic dystonia, two with cervical dystonia and five with primary generalized dystonia, and had been in situ for 11 and 31 months (Parkinson's disease), 16 months (myoclonic dystonia), 14 and 24 months (cervical dystonia) and 3-24 months (primary generalized dystonia). Our results showed that a foreign body multinucleate giant cell-type reaction was present in all TEM samples and in SEM samples, prewashed to remove surface blood and fibrin, regardless of the diagnosis. Some of the giant cells were >100 microm in diameter and might have originated from either fusion of parenchymal microglia, resident perivascular macrophage precursors and/or monocytes/macrophages invading from the blood stream. The presence of mononuclear macrophages containing lysosomes and sometimes having conspicuous filopodia was detected by TEM. Both types of cell contained highly electron-dense inclusions, which probably represent phagocytosed material. Similar material, the exact nature of which is unknown, was also seen in the vicinity of these cells. This reaction was present irrespective of the duration of implantation and may be a response to the polyurethane component of the electrodes' surface coat. These findings may be relevant to our understanding of the time course of the clinical response to DBS in Parkinson's disease and various forms of dystonia, as well as contributing to the design characteristics of future DBS electrodes.

Adult↗
PubMed2004

The effect of cannabis on tremor in patients with multiple sclerosis.

BACKGROUND: Disabling tremor is common in patients with multiple sclerosis (MS). Data from animal model experiments and subjective and small objective studies involving patients suggest that cannabis may be an effective treatment for tremor associated with MS. To our knowledge, there are no published double-blind randomized controlled trials of cannabis as a treatment for tremor in MS patients. METHODS: The authors conducted a randomized double-blind placebo-controlled crossover trial to examine the effect of oral cannador (cannabis extract) on 14 patients with MS with upper limb tremors. There were eight women and six men, with a mean age of 45 years and mean Expanded Disability Status Scale score of 6.25. Patients were randomly assigned to receive each treatment and the doses escalated over a 2-week period before each assessment. The primary outcome was change on a tremor index, measured using a validated tremor rating scale. The study was powered to detect a functionally significant 50% improvement in the tremor index. Secondary outcomes included accelerometry, an ataxia scale, spiral drawing, finger tapping, and nine-hole pegboard test performance. RESULTS: Analysis of the data showed no significant improvement in any of the objective measures of upper limb tremor with cannabis extract compared to placebo. Finger tapping was faster on placebo compared to cannabis extract (p < 0.02). However, there was a nonsignificant trend for patients to experience more subjective relief from their tremors while on cannabis extract compared to placebo. CONCLUSIONS: Cannabis extract does not produce a functionally significant improvement in MS-associated tremor.

Administration, Oral↗
PubMed2003

Post-operative progress of dystonia patients following globus pallidus internus deep brain stimulation.

In the current era of functional surgery for movement disorders, deep brain stimulation (DBS) of the globus pallidus internus (GPi) is emerging as the favoured intervention for patients with dystonia. Here we report our results in 20 patients with medically intractable dystonia treated with GPi stimulation. The series comprised 14 patients with generalized dystonia and six with spasmodic torticollis. Although comparisons were limited by differences in their respective neurological rating scales, chronic DBS clearly benefited both patient groups. Data conveying the rate of change in neurological function following intervention are also presented, demonstrating the gradual but progressive and sustained nature of improvement following stimulation of the GPi in dystonic patients.

Adult↗
PubMed2003

Target board test for the quantification of ataxia in tremulous patients.

OBJECTIVE: The objective was to develop and assess the validity and reliability of a target board test (TBT) for quantifying ataxia and measuring dysmetria in the presence of tremor. DESIGN: Each subject was instructed to reach out and mark a target placed at arm's length with a pen (10 times with each hand). Ten patients performed the test twice. SETTING: A hospital-based multiple sclerosis (MS) unit. SUBJECTS: Fifty-three patients with MS and upper limb tremor/ataxia and 20 healthy control subjects. The MS patients were classified into four subgroups: MS control group (n = 13), MS tremor group (n = 9), MS dysmetria group (n = 6), MS mixed (tremor and dysmetria) group (n = 25). MAIN OUTCOME MEASURES: The main outcome measures were the average radial distance away from the target (mean R) and the mean directional error (mean V) of the 10 contact points from the target. From these a dysmetria tremor index (DTI) was calculated by dividing mean V by mean R. Also used were a dysmetria scale, a dysdiadochokinesia scale and a finger-tapping test. RESULTS: Mean R correlated significantly with dysmetria, dysdiadochokinesia, kinetic tremor and (inversely) with the finger-tapping test (all p < 0.005). The median difference between two measurements of mean R for all 10 contact points was 11.3% and 19.0% and for mean V48.3% and 63.4% and DTI 57.2% and 50.5% for the right- and left-hand sides respectively, indicating the considerable directional variability within ataxia. CONCLUSION: The TBT provides simple quantitative objective measurements of upper limb ataxia.

Adolescent↗
PubMed2001

A study of tremor in multiple sclerosis.

One hundred patients with definite multiple sclerosis, who were randomly selected from a multiple sclerosis unit in London, were examined in order to study the prevalence, subtypes, clinical features and associated disability of tremor in this population. There were 35 males and 65 females with an average age of 47 years and an average disease duration of 18.8 years. The mean tremor duration was 13 years, with a median latency of 11 years from disease onset to appearance of tremor. Tremor was reported in 37 patients but was detected in 58. Tremor affected the arms (56%), legs (10%), head (9%) and trunk (7%). There were no examples of face, tongue or jaw tremor. All the patients had action tremor, either postural or kinetic (including intention). Rest, Holmes' ('rubral') and primary orthostatic tremors were not encountered. Tremor severity ranged from minimal in 27%, to mild in 16% and moderate or severe in 15% of cases. Tremor severity correlated with the degree of dysarthria, dysmetria and dysdiadochokinesia but not with grip strength. In order to determine the clinical characteristics of these tremors, the action tremors of the upper limbs were subclassified according to the predominant site and state of tremulous activity. Of the 50 patients with tremor in the right arm, 32% had distal postural tremor, 36% had distal postural and kinetic tremor, 16% had proximal postural and kinetic tremor; 4% had proximal and distal postural and kinetic tremor and 12% isolated intention tremor. Twenty-seven percent of the overall study population had tremor-related disability and 10% had incapacitating tremor. Patients with abnormal tremor (severity grade >1/10) were more likely than those without tremor to be wheelchair dependent and have a worse Expanded Disability Systems Score, but Barthel activities of daily living indices and cognitive scores were comparable in the two groups.

Activities of Daily Living↗
PubMed2001

Stereotactic lesional surgery for the treatment of tremor in multiple sclerosis: a prospective case-controlled study.

The effect of stereotactic lesional surgery for the treatment of tremor in multiple sclerosis was examined in a prospective case-controlled study. Surgery was not undertaken in 33 patients (72% of 46 cases referred for stereotactic surgery), two of whom died within 4 months of referral. Twenty-four multiple sclerosis patients were included in the study; 13 underwent surgery and were matched against 11 controls on the basis of age, sex, expanded disability system scores (EDSS) and disease duration. Assessments were carried out at baseline/preoperatively, and then 3 and 12 months later; these included accelerometric and clinical ratings of tremor, spirography, handwriting, a finger-tapping test, nine-hole peg test, tremor-related disability, general neurological examination, Barthel Activities of Daily Living (ADL) Index of general disability, EDSS, a 0-4 ataxia scale, Mini-Mental State (MMS) examination, speech and swallowing assessments and grip strength. Postoperative MRI scans demonstrated that tremor could be attenuated by lesions centred on the thalamus in seven cases, on the zona incerta in five cases and in the subthalamic nucleus in one case. Two patients developed hemiparesis and in two cases epilepsy recurred. Two surgical patients and one control patient died between the 3 and 6 months assessments. Both groups had a significant deterioration in EDSS but not Barthel ADL Index scores at 1 year, but the difference between the groups was not significant. Similarly, no differences between the groups' rates of deterioration of speech or swallowing or MMS were found. Significant improvements in contralateral upper limb postural (P2) and kinetic tremors, spiral scores and head tremor were detected at 3 and 12 months after surgery (but not handwriting or nine-hole peg test performance). Tremor-related disability and finger-tapping speed were also significantly better 12 months after surgery, the latter having significantly worsened for the control group. A 3 Hz 'filter' for postural (P2) upper limb tremor was detected by accelerometry/spectral analysis above which tremor was always abolished and at or below which some residual tremor invariably remained. Criteria for selecting multiple sclerosis patients for this form of surgery are discussed.

Activities of Daily Living↗
PubMed2000

Evaluation of three different ways of assessing tremor in multiple sclerosis.

OBJECTIVES: To examine the comparative reliability and validity of three simple ways of rating upper limb tremor in patients with multiple sclerosis. METHODS: Three examiners independently rated severity of upper limb tremor in patients with multiple sclerosis on a 0-10 scale by studying videotape recordings of patients' examinations, spiral drawings, and handwriting samples. The correlations of the tremor severity scores with scores from arm dexterity tests and a tremor related disability scale were also assessed. RESULTS: Rating tremor on posture had a good intrarater and interrater reliability. However, these reliabilities decreased when kinetic tremor was assessed, in part because dysmetria was a confounding factor. The intrarater reliabilities of rating tremor from spirals and handwriting were also good but the interrater reliabilities were only fair to moderate. Tremor severity scored by all three methods correlated highly with scores obtained from the nine hole peg test, finger tapping test, and a tremor related activities of daily living (ADL) questionnaire, indicating that all three methods were valid ways of assessing tremor in multiple sclerosis. CONCLUSION: Multiple sclerosis tremors in posture can be scored using a clinical rating scale in a valid and reliable way, and from spirals and handwriting samples if the ratings are carried out by the same examiner. However, scoring kinetic tremor was less reliable. In addition, the nine hole peg and finger tapping tests provide useful objective assessments of upper limb function in tremulous patients with multiple sclerosis.

Activities of Daily Living↗
PubMed2000

Frequency analysis of involuntary movements during wrist tracking: a way to identify ms patients with tremor who benefit from thalamotomy.

To identify those multiple sclerosis (MS) patients with disabling tremor who will benefit most from thalamotomy, measurements of frequency spectra of involuntary movements during visually guided wrist tracking were carried out in 11 consecutive patients with MS before and after ventrolateral thalamotomy. Thalamotomy was significantly more effective if patients had disruptive action tremor which appeared as a single peak in the frequency spectra. Such patients showed an average reduction of nearly 80% in tremor magnitude after thalamotomy. In comparison, surgery produced an average reduction of only 30% in 3 other patients who had action tremor but showed multiple peaks in the frequency spectra. Frequency analysis of involuntary movements identifies those MS patients with disabling tremor who benefited most from thalamotomy.

Adult↗
PubMed2000

Tremor assessment and quality of life measurements.

Essential tremor (ET) can be measured objectively by physiological techniques, simple tests of the tremor's impact on function, or subjective use of clinical rating scales. The methods of measuring ET and its influence on patients are reviewed. Multidimensional evaluations are recommended for the assessment of the severity of ET in clinical trials. The term "detractor" describes the relationships between ET and the disability and handicap that it produces.

Diagnosis, Differential↗
PubMed1999

Classification of normal and pathological tremors using a multidimensional electromagnetic system.

A new multidimensional movement analysis system was used to record limb tremor over six degrees-of-freedom, and signal processing techniques were explored to develop a suitable classification method to distinguish between different types of tremor. The specific aims were to investigate the ability of the system to screen for differences between normal subjects and a group of neurological patients, and then to differentiate between three diagnostic groups of patients. Postural tremor at the hand was recorded in normal subjects (n=24) and patients with essential tremor (n=21), multiple sclerosis (n=17) and parkinsonism (n=19). Data were collected using a 3Space Fastrak((R)) (Polhemus, Inc.) over six degrees-of-freedom (three translational directions and three rotations). Spectral estimates produced measures of tremor frequency and amplitude. Mathematical models of the data, using autoregressive modelling and K-nearest neighbour classification, produced parameters used to classify, (1) the normal subjects and 24 patients (using the three rotational movements), and (2) the three patient groups (using all six movement directions). Results were given in terms of the probability of each subject belonging to the groups being classified. 70%). The diagnostic classification produced clear differences between the patient groups (60% for essential tremor, 80% for multiple sclerosis and 60% for parkinsonism). The ability of this assessment technique to distinguish between postural tremor in normal subjects and neurological patients suggests that it could be developed as a screening tool. Classification of tremors between the patients groups, with a high degree of sensitivity, indicates the potential for further development of the system as a diagnostic aid.

Adult↗
PubMed1998

A comparison of fast Fourier transform (FFT) and autoregressive (AR) spectral estimation techniques for the analysis of tremor data.

This review outlines the theory of spectral estimation techniques based on the fast Fourier transform (FFT) and autoregressive (AR) model and their application to the analysis of human tremor data. Two FFT-based spectral estimation techniques are presented, the Blackman-Tukey and periodogram methods. Factors that influence the quality of spectral estimates are discussed including the choice of windowing function. The theory of parametric modelling is introduced and AR modelling identified as the technique best suited to the analysis of tremor data. The processes of parameter estimation and model order selection are described. The theory of AR spectral estimation is outlined and differences between the AR and FFT-based spectral estimates are summarised. A brief guide to the implementation of FFT-based and AR spectral estimation techniques is given concentrating on data analysis packages that require little or no programming expertise. This review concludes that the AR modelling approach can produce tremor spectra that are superior to those from FFT-based methods for short data sequences. Although the spectral estimates are improved, the benefits of AR modelling for providing information about the physiological mechanisms of tremor generation are not yet clear.

Algorithms↗