Search PubMed⌕ Search

Biomedical subjects

K Lyons

Publications and source records attributed to K Lyons.

At least 55 records · Page 3Linked to original sources
PubMed1998

Power Doppler in breast tumours: a comparison with conventional colour Doppler imaging.

OBJECTIVE: Tumour vascularity can be assessed in-vivo using Doppler ultrasound. The purpose of this study was to determine whether Power Doppler imaging (PDI) better differentiates benign from malignant breast masses than conventional colour doppler imaging (CDI) on the basis of assessment of tumour vascularity. METHODS: One-hundred women with solid breast lumps (51 malignant lesions, 49 benign lesions) were investigated using a Toshiba SSA-270A ultrasound machine with a 5.0 MHz (3.75 MHz Doppler reference frequency) or a 7. 5 MHz (5.0 MHz Doppler reference frequency) linear array probe. The vascularity within or at the periphery of the mass was subjectively assessed from the CDI and Power Doppler images by two independent observers. It was assumed that the absence of vascularity indicated benignity and the presence of flow malignancy. RESULTS: CDI showed sensitivities of 62 and 42% and specificities of 62 and 62% using the 5 and 7.5 MHz probes respectively. PDI showed sensitivities of 76 and 51% and specificities of 56 and 48% using the 5 and 7.5 MHz probes respectively. A comparison of images of the 59 lesions investigated with both probes on both CDI and PDI concluded that the 5 MHz (3.75 MHz DRF) probe displayed equal vascularity to the 7.5 MHz (5.0 MHz DRF) probe in 76% of cases and greater vascularity in 24% of cases on CDI, and 68 and 31% of cases respectively on PDI. CONCLUSION: Power Doppler imaging with a 5 MHz (3.75 MHz DRF) probe increases the sensitivity of Doppler ultrasound to malignant breast tumours but the sensitivity achieved is not high enough to propose it as a screening investigation.

Adult↗
PubMed1998

Comparative magnetic resonance image-based evaluation of thalamotomy and pallidotomy lesion volumes.

Acute thalamotomy and pallidotomy lesion volumes based on magnetic resonance (MR) images were measured in 22 patients (11 thalamotomy and 11 pallidotomy patients). Thalamotomy inner lesion volumes (0.06 +/- 0.04 ml; thermocoagulative zone) were smaller than pallidotomy inner lesion volumes (0.14 +/- 0.08 ml) as determined using T(1)-weighted 3D-MPRAGE (1.5-mm slice spacing). Similar results were found using T(1)-weighted (6-mm slice spacing) image sets (0.09 +/- 0.05 ml, thalamotomy; 0.13 +/- 0.05 ml, pallidotomy). No differences were found when comparing thalamic or pallidal inner lesion volumes when the comparison was based on T(2) weighted images. Thalamotomy total lesion volumes (thermocoagulative and surrounding edematous zones) were less than pallidotomy total lesion volumes independent of the MR protocol. The difference in thalamotomy and pallidotomy lesion volumes is most likely based on the distance between each discrete lesion placed along the lesioning tracts. In 7 of 11 thalamotomies, this distance was 1 mm with the remaining having 2 mm between each discrete lesion. All pallidotomy discrete lesions were 2 mm apart. More overlap between discrete lesioning sites for thalamotomies is likely to produce reduced lesion volumes.

Adult↗
PubMed1998

Lesion volume and clinical outcome in stereotactic pallidotomy and thalamotomy.

Postoperative lesion volume and clinical outcome were assessed in 19 Parkinson's disease (PD) patients who received posteroventral pallidotomy, and in 14 essential tremor (ET) patients who received ventrolateral thalamotomy. Before and after surgery, PD patients were evaluated using the Unified PD Rating Scale (UPDRS), and ET patients were evaluated using the Fahn-Tolosa-Marin (FTM) tremor rating scale. Inner and total lesion volumes were determined with postoperative MR imaging and three-dimensional data segmentation. Lesion volumes were compared to percent improvement in UPDRS and FTM scores, using Spearman's rank-order correlation test. No rank-order correlations were found between lesion volume and clinical improvement in either the PD or the ET patients. In performing stereotactic surgery for movement disorders, any lesion volume within a prescribed range may be equally effective in relieving symptoms associated with PD or ET.

Aged↗
PubMed1998

Nightguard vital bleaching: a review and clinical study.

Based on current clinical experience and research, dentist-prescribed home bleaching, also referred to as nightguard vital bleaching, is a safe and effective technique for whitening teeth when a carbamide peroxide material (up to 10 percent) is used. The bleaching material should be produced by a recognised and reputable manufacturer and must be used under a dentist's supervision over a relatively short time. Mild thermal sensitivity is a common side effect; however, no long-term pulpal effects have been shown. The reduction in the bond strength of resin to freshly bleached enamel and dentine has been shown to be transient, and no clinically significant changes in surface morphology or physical properties have been shown to occur to teeth or dental restorative materials as a result of vital bleaching. As a consequence, vital bleaching has gained favour with patients and dentists alike. Significant benefit was obtained in 12 subjects using two nightguard bleaching systems which were equally effective.

Carbamide Peroxide↗
PubMed1997

Effects of thalamic deep brain stimulation based on tremor type and diagnosis.

It has been suggested that deep brain stimulation (DBS) is less effective in alleviating proximal than distal postural arm tremor reduction is said to be less in essential tremor (ET) than in Parkinson's disease (PD). We analyzed blinded rater's tremor scores and subjects' disability ratings at 3-month follow-up to examine the effects of DBS based on tremor type (rest, kinetic, distal postural, proximal postural) and diagnosis (ET, PD). An independent examiner provided tremor scores using randomized videotaped footage of 19 ET and 10 PD subjects at baseline and at follow-up with DBS "on." Subjects provided self-ratings of disability at baseline and at follow-up. Comparisons of baseline and follow-up tremor scores and disability ratings were made using the Mann-Whitney U and Wilcoxon rank sum W test; correlation analyses were performed using Spearman rank order correlation test. There were significant and essentially equal improvements in tremor scores of test, kinetic, distal postural, and proximal postural tremor at follow-up. Only one subject had no improvement in tremor. Tremor improved significantly and to the same extent in ET and PD subjects in each position except "at rest," which was most improved in PD (p = 0.0003). ET and PD subjects did not differ in the extent of disability improvement. Improved disability correlated only with improved postural tremor scores; proximal postural and distal postural (r = 0.41, p = 0.03; r = 0.47, p = 0.01). DBS is effective in alleviating tremor and disability in both ET and PD. Resting, kinetic, distal postural, and proximal postural tremor can be reduced to an equal degree. However, DBS produces the greatest improvement in disability in association with improved postural tremor in both ET and PD.

Adolescent↗
PubMed1997

Comparison of standard carbidopa-levodopa and sustained-release carbidopa-levodopa in Parkinson's disease: pharmacokinetic and quality-of-life measures.

We compared clinical, pharmacokinetic, and quality-of-life measures in patients with Parkinson's disease (PD) who were on standard carbidopa-levodopa (Std-L) and after conversion to sustained-release carbidopa-levodopa 50/200 (L-CR). A total of 20 PD patients with motor fluctuations participated in the study and 18 completed it. There were 10 women and eight men, with a mean age of 67.5 years and a mean disease duration of 9.9 years. All patients underwent 10-h pharmacokinetic and clinical evaluations while on Std-L and again while on L-CR. The patients maintained diaries for 2 days before the 10-h evaluations and completed a sickness impact profile (SIP) while on Std-L and again while on L-CR. The total daily levodopa intake was significantly greater with L-CR because of the reduced bioavailability of the L-CR. The mean daily levodopa dosage was 569 mg for Std-L compared with 751 mg for L-CR. The patients performed better in walking time, Unified Parkinson's Disease Rating Scale (motor score), and tapping total with L-CR, although the improvement was not statistically significant. There was no significant difference in dyskinesias between the two preparations. The plasma levodopa levels and the areas under the curve were significantly greater with L-CR. "On" time as measured by patient diaries was significantly greater for L-CR. There was no significant difference in the total SIP scores for patients on the two preparations, but patients had significantly better home management and mobility while on L-CR. In conclusion, L-CR resulted in more "on" time with greater plasma levodopa levels, which resulted in better home management and mobility.

Activities of Daily Living↗
PubMed1997

Clinical expression of essential tremor: effects of gender and age.

Essential tremor (ET) is considered to be a monosymptomatic disorder consisting primarily of postural hand tremor. Nevertheless, clinical expression can vary based on the body region affected by tremor and the coexistence of other neurologic signs, such as tandem gait disturbance. We conducted a two-part study to test the hypothesis that variability in ET clinical expression is influenced by gender and age. In part 1, we examined a large ET clinical database (n = 450), comparing ratings of postural hand and head/voice tremor based on gender. Head/voice tremor was significantly more frequent and more severe among female ET patients; men had more severe postural hand tremor. In part 2, ET patients (n = 40) had significantly more missteps when tandem walking in comparison to age-matched controls. Poor tandem walk in ET cases was associated with more advanced age, but not gender, disease duration, or ratings of postural hand or head/voice tremor. We conclude that gender influences the body region most affected by ET possibly through the effects of the sex chromosomes or hormones. Ataxia (tandem gait difficulty) is common in ET and may be an accentuation of cerebellar dysfunction due to aging.

Age Distribution↗
PubMed1997

Grammatical abilities in Parkinson's disease: evidence from written sentences.

This study examined the grammatical content of written sentences elicited from 96 Parkinson's patients, 30 Parkinson's with dementia patients and 167 control subjects. Parkinson's patients without dementia or with mild dementia presented no impairments in sentence length, syntactic complexity or amount of information content. Moderately demented Parkinson's patients showed reduced sentence length and information content but normal syntactic complexity. This pattern of results provides evidence that lexical-semantic content is more susceptible to decline than syntactic structure with the progression of dementia in Parkinson's disease.

Aged↗
PubMed1997

Evaluation of general practitioner referrals to a specialist breast clinic according to the UK national guidelines.

The recently published national guidelines to general practitioners for the referral of patients with breast problems were retrospectively applied to letters of all patients attending the Rapid Access Breast Clinic at the University Hospital of Wales. The patients have all had diagnostic investigations performed at the initial visit with a multidisciplinary review of results and provision of a management plan prior to the subsequent visit. Since its inception in May 1995 until the end of the year when the guidelines were published, 2332 new patients had been seen. Overall, 29% of patients with benign breast disease would not have been referred if the guidelines had been strictly followed. Of the 147 symptomatic carcinomas diagnosed from general practitioner referrals (6.3% of total referrals), no invasive cancers would have been missed. One patient with incidental detection of ductal carcinoma in situ (DCIS) in the asymptomatic contralateral breast would not have been referred. Referral for pain without a discrete lump constituted 63% of the patients with a benign diagnosis who fell outside the guidelines. The guidelines also include comprehensive algorithms for the initial management of benign breast symptoms that do not require immediate referral by the general practitioners. Our general practitioners were significantly better at referring patients over 50 years old but the proportion of appropriate referrals were not related to the number referred by each practice. The present guidelines adequately cover referral for the diagnosis of malignant breast disease to a specialist, and may reduce the benign workload of breast clinics.

Ambulatory Care Facilities↗
PubMed1997

Sentence comprehension in Alzheimer's disease: effects of grammatical complexity, speech rate, and repetition.

Caregivers of patients diagnosed with Alzheimer's disease (AD) are often advised to modify their speech to facilitate the patients' sentence comprehension. Three common recommendations are to (a) speak in simple sentences, (b) speak slowly, and (c) repeat one's utterance, using the same words. These three speech modifications were experimentally manipulated in order to investigate their individual and combined effects on sentence comprehension in AD. Fifteen patients with mild to moderate AD and 20 healthy older persons were tested on a sentence comprehension task with sentences varying in terms of (a) degree of grammatical complexity, (b) rate of presentation (normal vs. slow), and (c) form of repetition (verbatim vs. paraphrase). The results indicated a significant decline in sentence comprehension for the AD group. Sentence comprehension improved, however, after the sentence was repeated in either verbatim or parapharsed form. However, the patients' comprehension did not improve for sentences presented at the slow speech rate. This pattern of results is explained via-à-vis the patients' working memory loss. The findings challenge the appropriateness of several clinical recommendations.

Aged↗
PubMed1997

Motor complications of chronic levodopa therapy in Parkinson's disease.

We report on motor complications of chronic levodopa therapy among 811 levodopa-responsive patients with idiopathic Parkinson's disease (PD), stratified by duration after diagnosis. Predictable "offs" were noted in 20.2% of patients in the first 5 years, in 58.3% after 15 years. Unpredictable or sudden offs and early morning dystonia were less common. Longer duration was associated with greater percentages of patients with off periods or dyskinesias (up to 70% after 15 years), although patients with 6-15 years' duration saw relatively little increase in frequency of those complications, and a minority of patients (approximately 30%) with duration into the second decade did not experience off periods or dyskinesia. Across groups, mean Hoehn and Yahr stage and daily levodopa dosage progressively increase (and mean Schwab and England disability ratings decrease), but more conservatively than in prior reports in the postlevodopa era. We note that with advancing PD duration, levodopa complications are more common, but in many cases there appear to be relatively stable periods in terms of levodopa dosage and disease severity, and a minority of patients will be relatively free of motor complications into the second decade of their disease.

Adult↗
PubMed1997

High-frequency stimulation of the globus pallidus for the treatment of Parkinson's disease.

Long-term treatment of Parkinson's disease (PD) with levodopa is complicated by the development of motor fluctuations and dyskinesias. Posteroventral pallidotomy can improve tremor, bradykinesia, rigidity, and dyskinesias in PD. We performed chronic stimulation of the globus pallidus (CSGP) to duplicate the positive results of pallidotomy with reduced risk of permanent neurologic deficit in patients with advanced PD. The lead for CSGP was stereotactically implanted with the aid of microelectrode recordings in the globus pallidus pars interna. An electrical pulse generator was implanted in the subclavicular region. Stimulation settings were adjusted by computer. Five PD patients (four men, one woman) with disabling symptoms were enrolled. Three of the patients had bilateral implants. At 3 months following the last implant, four patients rated themselves as markedly improved, and one patient was moderately improved. The amount of time in the "on" state increased from 21% at baseline to 65% at 3-month follow-up (p < 0.05). There was a significant improvement in all subscales of the UPDRS (p < 0.05). One patient had an asymptomatic intracranial bleed, one patient had transient hemiparesis during surgery with stimulation, and one patient required surgical repositioning of the lead. Adverse effects caused by stimulation were minimal. CSGP is a safe and effective procedure in PD patients with motor fluctuations and dyskinesias.

Aged↗
PubMed1997

Alternatives to amalgam.

The use of amalgam as a restorative material is again under review following a decision by the German and Swedish Governments to limit its use. This paper reviews the use of direct and indirect composite resins, ceramics, and glass ionomer cements as options to amalgam as a restorative material. None of these restorative materials offers the case of use, technique-forgiveness, cost-effectiveness and, in many situations, the durability of amalgam. Further development of these materials and the techniques involved in their use are required before any can be considered an ideal alternative to amalgam.

Ceramics↗
PubMed1996

Pharmacokinetic comparison of Sinemet and Atamet (generic carbidopa/levodopa): a single-dose study.

We compared the pharmacokinetic and motor responses of Sinemet and Atamet (generic carbidopa/levodopa) in patients with Parkinson's disease. Thirty Parkinson's disease patients (10 previously untreated, 10 with early disease, and 10 with motor fluctuations/dyskinesia) participated in a single-dose double-blind study. Following administration of an equivalent oral dose of Sinemet and Atamet on two separate days, we compared the peak plasma concentration, time to peak plasma concentration, area under the curve, total motor score, tapping score, and walking time. The mean time to peak plasma concentrations was 49 min with Sinemet and 47 min with Atamet, the mean peak plasma concentration was 1,273 ng/ml with Sinemet and 1,153 ng/ml with Atamet, and the mean area under the curve was 2,295 micrograms/ml/h with Sinemet and 2,330 micrograms/ml/h with Atamet. Similarly, there was no significant difference between total motor score, tapping score, or walking time. In this single-dose study, there were no significant differences in pharmacokinetic and motor responses between Sinemet and Atamet.

Administration, Oral↗
PubMed1996

Early morning akinesia in Parkinson's disease: effect of standard carbidopa/levodopa and sustained-release carbidopa/levodopa.

We examined the effects of supplemental standard carbidopa/levodopa (Std-L) on early morning akinesia in patients with Parkinson's disease (PD) who were being treated with sustained-release carbidopa/levodopa (L-CR). We compared plasma dopa levels and clinical response in 15 PD patients after a dose of Std-L and L-CR (2 hours later) and after a dose of L-CR and placebo in a double-blind, placebo-controlled, crossover study. Plasma dopa levels, total motor score, walking time, and finger tapping time were assessed every 15 minutes for the first 2 hours and then every 30 minutes for the next 3 hours. The time of onset in clinical benefit was significantly earlier with Std-L (47 minutes, range 15 to 75 minutes) as the first dose as compared with L-CR (58 minutes, range 30 to 105 minutes). Similarly, there was a significant difference in the peak plasma dopa levels (Cmax) and the time to reach peak plasma dopa levels (Tmax) with administration of Std-L (Tmax 36 minutes; Cmax 1,501 micrograms/ml) as compared with L-CR (Tmax 111 minutes, Cmax 1,260 micrograms/ml). There was no significant difference in dyskinesias between the two treatment arms. An initial morning dose of Std-L alleviates the problem of delayed-onset clinical response that commonly occurs with L-CR.

Aged↗
PubMed1996

Deep brain stimulation for essential tremor.

We examined the effects and safety of deep brain stimulation (DBS) as a treatment for essential tremor (ET). Ten ET patients with disabling medication-refractory tremor underwent stereotactic implantation of a DBS lead in the left Vim thalamic nucleus and completed a 6-month follow-up. The Clinical Tremor Rating Scale and disability assessments were performed at baseline, 1-, 3-, and 6-month follow-up. There were significant improvements in dressing, drinking, eating, bathing, and handwriting as reported by the subjects. Tremor severity, writing, pouring, and spiral and line drawing were significantly improved as rated by the examiner. Improvements persisted through the 6-month follow-up period. Although global disability significantly lessened in the group as a whole, one subject with hand-finger tremor accentuated by writing had no change in disability status. In this 6-month open-label study, DBS was effective and safe in reducing tremor and functional disability in ET.

Aged↗