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Biomedical subjects

K Lyons

Publications and source records attributed to K Lyons.

At least 19 recordsLinked to original sources
PubMed1999

Neuropsychological and quality of life outcome after thalamic stimulation for essential tremor.

OBJECTIVE: To evaluate short-term effects of unilateral thalamic deep brain stimulation (DBS) on cognition, mood state, and quality of life in patients with essential tremor (ET). BACKGROUND: Unilateral thalamotomy and thalamic DBS are effective in alleviating refractory tremor contralateral to the side of surgery. Thalamotomy can lead to cognitive morbidity, and DBS might be a preferable surgical intervention given potential avoidance or reversibility of such morbidity. Although unilateral thalamic DBS is cognitively safe and leads to quality of life improvement in PD, its neurobehavioral effects in ET are unknown. METHODS: Forty patients with ET were administered a broad neuropsychological test battery, measures of mood state, and generic and disease-specific quality of life measures approximately 1 month before and 3 months after surgery (left hemisphere, 38 patients). RESULTS: Unilateral thalamic DBS was associated with significant improvements in tremor and dominant-hand fine visuomotor coordination. Statistically significant but clinically modest gains were observed on tasks of visuoperceptual and constructional ability, visual attention, delayed word list recognition, and prose recall. Only lexical verbal fluency declined significantly after surgery. Patients rated themselves as less anxious after surgery, and they perceived their quality of life as improved significantly. In particular, patients reported improved quality of life with respect to activities of daily living, stigma, emotional well-being, and communication. CONCLUSIONS: Unilateral thalamic DBS for ET is cognitively safe and associated with improvements in anxiety and quality of life in the near term and in the absence of operative complications. Patients were better able to carry out activities of daily living after surgery, and they reported improvement in several psychosocial domains of quality of life.

Aged↗
PubMed1999

Abnormal performance on the PD test battery by asymptomatic first-degree relatives.

OBJECTIVE: To determine whether a sensitive and specific battery of tests (PD Battery) could identify a subset of asymptomatic first-degree relatives (FDRs) of PD patients who were significantly more impaired than age-matched normal control (NC) subjects. The PD Battery incorporates tests of motor function, olfaction, and mood. In previous studies, it has shown high specificity and sensitivity in distinguishing mildly affected PD patients from NC subjects. METHODS: The PD Battery and regression analysis-derived scoring equations were applied to asymptomatic FDRs. RESULTS: Eighty FDRs and 100 NC subjects were tested. Of the FDRs, 22.5% scored in the abnormal range, and 9% of NC subjects had abnormal scores. This difference was statistically significant. Further analysis demonstrated that FDRs with abnormal scores on the PD Battery differed on all three components of the test battery from FDRs who had normal scores. Among the sons and daughters whose scores were abnormal, there was a much higher prevalence of the affected parent being the father. CONCLUSIONS: The proportion of FDRs who demonstrated abnormal performance on the PD Battery was greater than that of NC subjects. Thus, the PD Battery may detect the asymptomatic carrier state or risk for PD. Sons and daughters whose scores were in the abnormal range were more likely to have fathers with PD.

Adult↗
PubMed1999

Integrating qualitative and quantitative liquid chromatography/tandem mass spectrometric analysis to support drug discovery.

During the early phase of a drug discovery process, in order to facilitate the selection of drug candidates from a discovery research program, a liquid chromatography tandem mass spectrometry (LC/MS/MS) strategy has been developed to assess the preliminary pharmacokinetics and metabolism of new drug entities. For pharmacokinetic studies using multiple reaction monitoring (MRM), the parent drug concentration and its 'suspected' (predictable) metabolites were monitored in the biological samples simultaneously. For metabolic identification, the general methodologies most frequently used to search for metabolites include full scan, precursor-ion scan, product-ion scan and neutral-loss scan. However, when the metabolites do not produce intense signals for tandem mass spectrometry, a more sensitive and selective assay has to be developed, and MRM would be the method of choice. Likewise, an intelligent guess as to which MRM transitions ought to be used for the metabolites will be considered, based on the product ion mass spectrum of the parent drug.

Acetonitriles↗
PubMed1999

The National Breast Referral Guidelines have cut down inappropriate referrals in the under 50s.

AIMS: When the National Breast Referral Guidelines were applied to our local GPs letters immediately prior to their release in January 1996, it was shown that on the basis of the GPs own conclusions that 29% of symptomatic women could have been managed initially by their own GP without missing any carcinomas. We conducted this study at the Rapid Access Breast Clinic at the University Hospital of Wales to determine if the breast referral practices of local GPs have altered due to the breast referral guidelines. METHODS: We studied 2332 referrals from the inception of the Rapid Access Clinic in May 1995 to the issue of the guidelines, and 2421 referrals from May 1996 to the end of the year. Random samples of 600 patients were drawn from each year and the referral letters were scored as within or outside the guidelines. Family history patients were excluded. RESULTS: There was an 11% fall in referrals outside the guidelines in the under 50s (chi-squared=<0.001) but the 7% fall in the over 50s was not significant. CONCLUSIONS: The Breast Referral Guidelines seem to have been effective in reducing the higher level of inappropriate referrals in younger patients at less risk of carcinoma.

Age Factors↗
PubMed1999

Adenosine challenge and boost protocols: new tools for myocardial perfusion imaging.

The validity of pharmacologic stress testing and subsequent myocardial perfusion imaging is uncertain in those patients who may have taken caffeine within the 24 hours before testing. For such patients, two new challenge tests have been developed. An intravenous bolus dose of adenosine is given at a dose of 6 mg in a period of 1 or 2 seconds. A physiologic response qualifies the patient to proceed with the scheduled stress test. In the occasional patient who exhibits no pharmacologic symptoms during an infusion test, a similar bolus dose of 6 mg adenosine can validate perfusion tests. These two applications are successful regardless of whether adenosine or dipyridamole infusions are performed. Based on this multicenter experience over 4 years, the authors estimate that 5% to 10% of patients undergoing pharmacologic testing are appropriate candidates for a challenge test.

Adenosine↗
PubMed1998

Double-blind controlled trial of gabapentin in essential tremor.

Gabapentin has been reported to be effective for essential tremor (ET) based on open-label trials. We studied gabapentin (1800 mg/day) and placebo in a double-blind crossover design in 20 ET patients. Eighteen patients completed the study and two patients dropped out as a result of adverse effects which resolved when the medication was discontinued. Tremor was assessed at baseline and after 2 weeks of gabapentin and placebo treatment. One patient was mildly improved and another was moderately improved with placebo. Similarly, one patient reported mild improvement and another patient had marked improvement with gabapentin. All the remaining patients either reported no change or were worse with both treatment arms. There was no significant difference for total tremor score, hand tremor score, handwriting scores, or pouring scores. Sickness Impact Profile scores were no different between placebo and gabapentin. Our results suggest that as an adjuvant therapy in ET, gabapentin has limited benefit.

Acetates↗
PubMed1998

Magnetic resonance imaging of acute intraosseous disc herniation.

Schmorl's nodes, the result of previous intraosseous disc herniation (IODH), are a common incidental finding on plain radiographs, computed tomography (CT) and magnetic resonance imaging (MRI). Acute IODH can, however, cause severe back pain, and the radiological features may also lead to inappropriate suspicion of malignancy or infection. We present eight cases of acute IODH in order to illustrate how the correct diagnosis can be made by MRI. In six cases isotope bone scintigraphy had been performed, demonstrating focal increased activity at the site of IODH. MRI can reinforce the concern about serious underlying pathology by the demonstration of marrow oedema, which may be localized around the disc herniation or extensive, extending throughout the vertebral body and into the pedicles. The key to the correct diagnosis is the recognition of the endplate defect and disc herniation. In three cases the diagnosis may have been possible from plain radiographs in which disc calcification visible on previous radiographs had migrated into an intraosseous location.

Acute Disease↗
PubMed1998

Cricothyroid joint injury.

Cricothyroid joint injuries may result in severe voice dysfunction and may be associated with laryngeal pain. Otolaryngologists and radiologists should be familiar with this rarely recognized injury.

Adult↗
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↗