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Biomedical subjects

P J Tyrrell

Publications and source records attributed to P J Tyrrell.

18 recordsLinked to original sources
PubMed2006

Deglutitive laryngeal closure in stroke patients.

BACKGROUND: Dysphagia has been reported in up to 70% of patients with stroke, predisposing them to aspiration and pneumonia. Despite this, the mechanism for aspiration remains unclear. AIMS: To determine the relationship between bolus flow and laryngeal closure during swallowing in patients with stroke and to examine the sensorimotor mechanisms leading to aspiration. METHODS: Measures of swallowing and bolus flow were taken from digital videofluoroscopic images in 90 patients with stroke and 50 healthy adults, after repeated volitional swallows of controlled volumes of thin liquid. Aspiration was assessed using a validated Penetration-Aspiration Scale. Oral sensation was also measured by electrical stimulation at the faucial pillars. RESULTS: After stroke, laryngeal ascent was delayed (mean (standard deviation (SD)) 0.31 (0.06) s, p<0.001), resulting in prolongation of pharyngeal transit time (1.17 (0.07) s, p<0.001) without a concomitant increase in laryngeal closure duration (0.84 (0.04) s, p = 0.9). The delay in laryngeal elevation correlated with both the severity of aspiration (r = 0.5, p<0.001) and oral sensation (r = 0.5, p<0.001). CONCLUSIONS: After stroke, duration of laryngeal delay and degree of sensory deficit are associated with the severity of aspiration. These findings indicate a role for sensorimotor interactions in control of swallowing and have implications for the assessment and management of dysphagia after stroke.

Adult↗
PubMed2005

A randomised phase II study of interleukin-1 receptor antagonist in acute stroke patients.

OBJECTIVES: The cytokine interleukin (IL)-1 mediates ischaemic brain damage in rodents. The endogenous, highly selective, IL-1 receptor antagonist (IL-1ra) protects against ischaemic cerebral injury in a range of experimental settings, and IL-1ra causes a marked reduction of cell death when administered peripherally or at a delay in transient cerebral ischaemia. We report here the first randomised, double blind, placebo controlled trial of recombinant human IL-1ra (rhIL-1ra) in patients with acute stroke. METHODS: Patients within 6 hours of the onset of symptoms of acute stroke were randomised to rhIL-1ra or matching placebo. Test treatment was administered intravenously by a 100 mg loading dose over 60 seconds, followed by a 2 mg/kg/h infusion over 72 h. Adverse events and serious adverse events were recorded for up to 3 months, serial blood samples were collected for biological markers up to 3 months, and 5-7 day brain infarct volume was measured by computed tomography. RESULTS: No adverse events were attributed to study treatment among 34 patients randomised. Markers of biological activity, including neutrophil and total white cell counts, C reactive protein, and IL-6 concentrations, were lower in rhIL-1ra treated patients. Among patients with cortical infarcts, clinical outcomes at 3 months in the rhIL-1ra treated group were better than in placebo treated. CONCLUSIONS: These data suggest that rhIL-1ra is safe and well tolerated in acute stroke. In addition, rhIL-1ra exhibited biological activity that is relevant to the pathophysiology and clinical outcome of ischaemic stroke. Our findings identify rhIL-1ra as a potential new therapeutic agent for acute stroke.

Acute Disease↗
PubMed2001

Dementia with Lewy bodies studied with positron emission tomography.

OBJECTIVE: To report a case initially fulfilling the clinical criteria for probable Alzheimer disease, although later clinical features suggested dementia with Lewy bodies. Oxygen 15-labeled positron emission tomograms revealed a pattern of hypometabolism characteristic of Alzheimer disease. At post mortem, there was no evidence of the pathological features of Alzheimer disease, but diffuse cortical Lewy bodies were seen in the pigmented brainstem nuclei and cerebral cortex. DESIGN: A case report. SETTING: Tertiary referral center. PATIENT: A 65-year-old white man presented with a 3-year history of memory loss and language difficulties. RESULTS: Oxygen 15-labeled positron emission tomograms revealed hypometabolism in the frontal, temporal, and parietal lobes, more severe on the left than right. Metabolism in the left caudate was just outside the 95% reference range. Occipital metabolism was normal. CONCLUSIONS: Positron emission tomographic studies have been reported to show occipital hypometabolism in dementia with Lewy bodies, in addition to the characteristic posterior bitemporal biparietal pattern of Alzheimer disease. We suggest that although this finding may favor a diagnosis of dementia with Lewy bodies, it is not necessary for diagnosis.

Aged↗
PubMed2000

Post stroke shoulder pain: more common than previously realized.

Stroke is a common disease often requiring rehabilitation, which may be prolonged by shoulder pain. The true incidence of post stroke shoulder pain has not been fully evaluated. In order to establish this, we undertook a prospective study of 123 consecutive patients with a diagnosis of acute stroke during a 6-month period. Patients were assessed by interview, full rheumatological and neurological examination, 14 days post stroke, for a history of shoulder pain according to predetermined criteria. In addition, Barthel Index, HAD score and pain scores were also recorded. Twenty-five percent of patients developed shoulder pain within 2 weeks of their stroke. There was a statistically significant association with ipsilateral sensory impairment (p < 0.005), abnormal rheumatological examination (p < 0.001) and depression score (p < 0.005). We conclude that post stroke shoulder pain is more common than previously realized and in addition to abnormal shoulder joint examination may also be associated with upper limb sensory impairment. Thorough neurological examination is required to detect sensory loss and hence establish patients at risk. This is probably best done by a structured proforma.

Aged↗
PubMed2000

The unreliability of clinical measures of muscle tone: implications for stroke therapy.

BACKGROUND: the central tenet of the neurofacilitatory approach to stroke therapy is that muscle tone needs to be normal before normal movement can occur. A reliable clinical measure of the full spectrum of muscle tone is needed to test: (i) the purported relationship between muscle tone, other motor impairments and disability, and (ii) the effectiveness of stroke therapy to restore movement. AIM: the purpose of the study was to test the inter-rater reliability of clinical categorization of muscle tone (spastic/normal/flaccid) and also a visual analogue scale with anchor points of 'lowest tone possible' (score 0) and 'highest tone possible' (score 100). METHODS: four independent raters assessed tone of elbow flexors and knee extensors of 14 stroke rehabilitation inpatients using the categorical scale. Six independent raters assessed tone of elbow flexors and knee extensors of 25 chronic stroke patients and two healthy volunteers using the visual analogue scale. All assessment orders were randomized. RESULTS: both scales were unreliable, with K coefficients for the categorical scale ranging from -0.046 to 0.56 for the categorical scale, and intra-class correlation coefficients for the visual analogue scale of 0.595 for elbow flexors and 0.451 for knee extensors. Assessment order effects for the visual analogue scale were non-significant for elbow flexors (P= 0.545) and knee extensors (P= 0.911). CONCLUSIONS: these results, and those of earlier studies, suggest that clinical measures of muscle tone are consistently unreliable. Systematic investigation of the therapy rationale for planning and evaluating treatment is required before relevant clinical measures can be developed.

Humans↗
PubMed1999

Progressive frontal gait disturbance with atypical Alzheimer's disease and corticobasal degeneration.

OBJECTIVES: The clinical neuropsychological, neuroradiological, and neuropathological description of two patients presenting with a frontal gait disturbance. METHODS: Clinical case note review, neuropsychological assessment, functional imaging with (15)O(2) and (18)F-fluorodopa PET, and neuropathology. RESULTS: Both patients presented with frontal gait impairment and only later developed more widespread cognitive impairment. In both cases (15)O(2) PET disclosed focal hypometabolism in the medial frontal lobes and in one patient (18)F-fluorodopa uptake into the caudate and putamen was normal. The neuropathological examination in one patient showed Alzheimer's histopathology together with large swollen eosinophilic neurons characteristic of corticobasal degeneration, which were particularly prominent in the medial frontal lobes. CONCLUSION: Focal degeneration of the medial frontal lobes may present as an isolated gait disturbance and should be considered in the differential diagnosis of patients who present without an obvious structural abnormality on neuroimaging.

Aged↗
PubMed1991

Progressive loss of speech output and orofacial dyspraxia associated with frontal lobe hypometabolism.

Three patients are described with slowly progressive loss of speech and dysarthria associated with orofacial dyspraxia, initially with intact written language, who subsequently developed more widespread cognitive abnormalities. Positron emission tomography (PET) revealed bifrontal hypometabolism in all of the patients, most marked in the inferior and lateral portions of both frontal lobes, with some extension into the parietal and temporal cortices in one case. These patients may represent a further example of focal progressive cortical degeneration.

Aged↗
PubMed1990

Clinical and positron emission tomographic studies in the 'extrapyramidal syndrome' of dementia of the Alzheimer type.

Extrapyramidal signs, particularly rigidity and tremor, have been reported in a proportion of patients with dementia of the Alzheimer type. To test the hypothesis that these extrapyramidal signs are similar clinically and neurochemically to the extrapyramidal signs of Parkinson's disease, a group of 20 patients satisfying clinical criteria for probable Alzheimer's disease were studied and assessed clinically for the presence of rigidity, tremor, and bradykinesia. In those patients with extrapyramidal signs, qualitative differences were observed between the signs in these patients and in subjects with Parkinson's disease. Fifteen of 20 patients underwent fluoro-18-dopa scans, which showed no significant difference in fluoro-18-dopa uptake into the caudate and putamen between normal subjects and the rigid and nonrigid patients with Alzheimer's disease, in contrast to the marked reduction in fluoro-18-dopa uptake into the putamen that is observed in Parkinson's disease. This provides clinical and in vivo neurochemical support for the hypothesis that extranigral factors may be involved in the pathogenesis of rigidity in Alzheimer's disease.

Adult↗
PubMed1990

Heterogeneity in progressive aphasia due to focal cortical atrophy. A clinical and PET study.

Six patients with a slowly progressive aphasic disorder due to degenerative cortical disease are reported. The length of history varied from 18 months to 6 years. In 5 patients, there was a naming deficit, associated in 4 of these with some abnormalities in comprehension. One patient had a progressive history of reduced speech output, which was associated with an orofacial dyspraxia. All patients were studied neuropsychologically, and in addition regional cerebral metabolism was measured using position emission tomography. A localized left hemisphere deficit was found in all patients except 1, who had the longest history and the most profound clinical deficit, and who also had right hemisphere hypometabolism. The major brunt of the deficit was in the anterior portion of the left temporal lobe in all but 1 case, the patient with poor speech output who had a more severe left posterior frontal deficit. These findings suggest that in progressive aphasia due to focal cortical atrophy there is heterogeneity in the clinical presentation and anatomical site of the deficit, with possible implications for the underlying aetiology.

Adult↗
PubMed1990

Progressive degeneration of the right temporal lobe studied with positron emission tomography.

A 79 year old man with a twelve year progressive history of prosopagnosia and recent naming difficulty, in whom other intellectual skills were preserved, is described. Positron emission tomography (PET) revealed an area of right temporal lobe hypometabolism, with an additional area of less severe hypometabolism at the left temporal pole. This may represent an example of progressive focal cortical degeneration similar to that associated with primary progressive dysphasia, but affecting the right temporal lobe.

Aged↗
PubMed1986

A microprocessor-controlled gas mixing device.

This paper describes the use of solenoid valves for the production of binary gas mixtures. The system is controlled by a microprocessor and is capable of delivering accurate flows and concentrations of gases over the ranges commonly used in anaesthesia. Since the flow produced by the valves is pulsatile, a system for mixing the gases and smoothing the pulses is described. A back pressure regulator is fitted downstream of each of two mixing/damping chambers and a method of using this as a flow transducer is described. The advantages of this system over conventional rotameters are discussed.

Anesthesia, Inhalation↗