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Biomedical subjects

P R Humphrey

Publications and source records attributed to P R Humphrey.

At least 19 recordsLinked to original sources
PubMed1998

Hyperekplexia and trismus due to brainstem encephalopathy.

The brainstem is said to be the generator of pathological startle responses due to reticular reflex myoclonus or hyperekplexia. A patient with facial weakness, nystagmus, and pyramidal tract signs had generalised reflex spasms in response to auditory, visual and tactile stimuli which clinically and neurophysiologically resembled hyperekplexia. The case is unusual because as well as hyperekplexia, the patient's initial presentation was with an equally rare manifestation of brainstem pathology-brainstem mediated trismus. The causes of brainstem trismus and exaggerated startle responses are discussed with respect to their underlying mechanisms.

Brain Diseases↗
PubMed1997

Overdiagnosis of TIA and minor stroke: experience at a regional neurovascular clinic.

We compared the referral diagnoses of TIAs and minor strokes made by non-specialists with those of two consultant neurologists, in 565 consecutive cerebrovascular clinic patients, of whom 508 (90%) were referred with a diagnosis of any TIA or stroke. In 373 (73%), the neurologists felt the diagnosis of a cerebrovascular event to be correct. Agreement with the vascular syndrome (CVA vs. TIA) was significantly higher for patients with a referral diagnosis of stroke (136/176) (77%) than it was for patients with a referral diagnosis of TIA (200/332) (60%) (difference in proportions 17%, 95% CI 9-25). In 37 patients (7%) the neurologists confirmed the diagnosis of cerebrovascular disease but not the specific TIA/stroke diagnosis. Vascular surgeons were more likely to be correct in their referral diagnosis of carotid territory cerebrovascular disease (88% correct) than all other sources combined (63% correct) (difference in proportions 25%, 95% CI 11-39), but there was no significant variation in diagnostic accuracy between other individual groups. In 135/508 patients (27%) referred as any TIA or stroke, the diagnosis of cerebrovascular disease was undone. Alternative diagnoses included migraine (3%), epilepsy (1%), hyperventilation (1%), multiple sclerosis (1%) and a case of idiopathic Parkinson's disease, but many symptoms (8%) were unclassifiable. A strict comparison of diagnostic accuracy would have required assessment of patients not referred for specialist opinion, to estimate false-negative as well as false-positive diagnoses. However, in this patient group (which reflects current local practice) TIAs and strokes seem overdiagnosed.

Adult↗
PubMed1997

Causes of ischaemic stroke in the young.

The causes of ischaemic stroke in young adults are many and diverse. Such patients usually require more extensive investigations in order to find an underlying cause than more elderly patients. It is important that a comprehensive search is made since many of the underlying disorders are treatable. Principal causes are extracranial arterial dissection, cardioembolism, premature atherosclerosis, haematological and immunological disorders and migraine. Drug abuse is becoming increasingly important but the risk of stroke in pregnancy remains unclear. Isolated angiitis of the central nervous system, heritable disorders of connective tissue and other genetically determined disorders (mitochondrial cytopathies, CA-DASIL) account for a small proportion of ischaemic strokes in the young. Management is probably best undertaken by a physician with a specialist interest and, if full investigation fails to elucidate a definite cause, the risk of future stoke is low.

Adolescent↗
PubMed1996

Observer variation in the interpretation of intra-arterial angiograms and the risk of inappropriate decisions about carotid endarterectomy.

OBJECTIVE: To determine how often observer variation in the interpretation of intra-arterial angiograms might alter the decision whether or not to refer patients for carotid surgery. METHODS: A prospective study was carried out in a consecutive series of 99 patients with transient ischaemic attacks and minor strokes. Interpretable angiographic films were available for 179 carotid artery bifurcations. Stenosis of the internal carotid artery was measured using mm scales, independently by three different radiologists (A, B, and C), using the European Carotid Surgery Trial method. RESULTS: An analysis of the grouped data showed good to moderate agreement by kappa statistics for radiologists A v B, B v C, and A v C of 0.68, 0.60, and 0.70 respectively. The mean absolute difference in the estimate of stenosis by each of the different radiologists (interobserver variation) was 9.5% and for each radiologist on two separate occasions (intraobserver variation) 8.4%. The degree of observer error was smallest among severely stenosed arteries. Although the absolute differences were small, "clinically important" differences which could change the treatment recommended from surgery to no surgery (or vice versa) occurred between radiologists A and B, B and C, and A and C in: seven (3.9%), six (3.4%), and 11 (6.1%) vessels respectively. CONCLUSIONS: Because observer variation affects all of the imaging methods (Doppler, duplex, contrast arteriography, and MR angiography) used to select patients with transient ischaemic attack and stroke, these findings are likely to be widely relevant. Any centre assessing patients with cerebrovascular disease will need to implement strict quality control measures in the interpretation of angiograms (and other vascular imaging procedures) to minimise observer error and thereby reduce the number of inappropriate decisions made to refer for carotid artery surgery or not.

Carotid Artery Diseases↗
PubMed1996

Variability in measurement of extracranial internal carotid artery stenosis as displayed by both digital subtraction and magnetic resonance angiography: an assessment of three caliper techniques and visual impression of stenosis.

BACKGROUND AND PURPOSE: The degree of stenosis in the extracranial internal carotid artery helps predict the risk of an individual suffering subsequent cerebrovascular ischemic events. Different techniques have evolved to measure stenosis from angiograms, leading to some confusion and a call for the adoption of a single technique. To help choose the most reliable technique, this study assessed observer variability in reporting carotid stenosis for four different techniques, from both digital subtraction (DSA) and MR angiograms (MRA). Three of the techniques used caliper measurements; the fourth was the visual impression of stenosis. METHODS: From a total of 137 angiograms, caliper measurements were possible on 105 DSAs and 74 MRAs. Measurements from these angiograms were made by two independent observers on two separate occasions to assess interobserver and intraobserver variation in reporting. RESULTS: For DSA, the variability in reporting and the number of clinically significant differences arising as a result were similar for each of the four techniques. While the typical measurement errors for each of the techniques studied were on the order of +/- 5%, each technique produced some sizable individual differences for the same angiogram, with resultant wide 95% limits of agreement. Observer variability for reporting MRA was generally a little greater than for DSA. Compared with the caliper techniques, the visual impression of stenosis technique performed well, particularly for MRA. CONCLUSIONS: Although observer variability in reporting can be considerable, no important differences were found among the different techniques widely used for measuring carotid stenosis.

Angiography, Digital Subtraction↗
PubMed1995

Management of transient ischaemic attacks and stroke.

The management of stroke and transient ischaemic attacks (TIAs) has changed greatly in the last two decades. The importance of good blood pressure control is the hallmark of stroke prevention. Large multicentre trials have proven beyond doubt the value of aspirin in TIAs, warfarin in patients with atrial fibrillation and embolic cerebrovascular symptoms, and carotid endarterectomy in patients with carotid TIAs. There seems little doubt that patients managed in acute stroke units are more likely to be independent at six months than those managed in a general medical ward. This article emphasizes the importance of basing clinical management on simple history taking and examination and appropriate investigation. This, combined with knowledge of the natural history risk of TIA and stroke and the results of randomised trials, allows individuals to be managed in the most appropriate manner. This review is designed to be a practical guide, useful in the day to day management of patients with cerebrovascular disease.

Cerebrovascular Disorders↗
PubMed1994

Comparison of magnetic resonance angiography, duplex ultrasound, and digital subtraction angiography in assessment of extracranial internal carotid artery stenosis.

The results of a prospective study comparing ultrasound, intra-arterial digital subtraction angiography, and magnetic resonance angiography in the assessment of the degree of extracranial internal carotid artery stenosis are reported in patients with symptoms of recent carotid territory ischaemia. A total of 70 patients and 137 vessels were examined by all three techniques. The results obtained by each technique were reported blind. The mean difference (SD) for the comparison of magnetic resonance angiography and digital subtraction angiography was -0.7 (14)%, for ultrasound and digital subtraction angiography 3.1 (15)%, and for magnetic resonance angiography and ultrasound -3.8 (15)%. The level of agreement was greater for the more tightly stenosed vessels. With the assumption that the results of the digital subtraction angiogram reflect the true situation, the sensitivity and specificity in the detection of > or = 30% stenoses were 93% and 82% with ultrasound and 89% and 82% with magnetic resonance angiography; for stenoses > or = 70% 93% and 92% with ultrasound and 90% and 95% with magnetic resonance angiography; and for stenoses of 70-99% 89% and 93% with ultrasound and 86% and 93% with magnetic resonance angiography. For occlusion the values were 93% and 99% with ultrasound and 80% and 99% with magnetic resonance angiography. Increased sensitivity and specificity were obtained when analysis was confined to those vessels in which ultrasound and magnetic resonance angiography were in agreement over classification. It is thus possible to accurately categorize the degree of stenosis of the extracranial internal carotid artery from a combination of ultrasound and magnetic resonance angiography. The adoption of this combination for the investigation of patients before carotid endarterectomy removes the risk associated with conventional angiography and represents an important advance in the management of carotid stenosis.

Adult↗
PubMed1994

Do carotid bruits predict disease of the internal carotid arteries?

A carotid bruit is often thought of as a reliable sign of extracranial carotid artery disease. In addition finding a bruit may precipitate a referral to hospital. Carotid endarterectomy has now been shown to be beneficial in patients with symptomatic carotid territory ischaemia and 70-99% stenosis of the relevant carotid artery, therefore it is important that such patients are detected and referred. In this study of 331 consecutive patients referred to a specialist cerebrovascular clinic we examined the practical value of a carotid bruit mentioned by the referring practitioner. All patients underwent clinical assessment, evaluation of risk factors and Doppler duplex scanning of the carotid arteries. A bruit was stated in the referral letter of 110 (33%) patients. Moderate (30-69%) or severe (70-99%) stenosis was present in 37% of patients with, and 17% of those without a carotid bruit (P < 0.001). We found a carotid bruit was a poor predictor of such disease (positive predictive value, 37%). The false negative rate for severe disease was 43%. Normal carotid arteries were found in 32% of patients with a bruit. We therefore suggest that all patients with suspected carotid territory ischaemia should be referred for assessment whether there is a bruit present or not.

Adult↗
PubMed1993

Complications of cerebral angiography in patients with symptomatic carotid territory ischaemia screened by carotid ultrasound.

After nearly 40 years, carotid endarterectomy has been shown to be of benefit to patients with symptomatic carotid territory ischaemia and greater than 70% stenosis of the relevant internal carotid artery. Cerebral angiography is performed before surgery and is not without risk. These risks must be added to those of surgery before recommending the procedure to patients. The study evaluated the local, systemic and neurological complications following digital subtraction angiography with selective catheterisation of the carotid arteries in 200 patients presenting to a cerebrovascular clinic for assessment of cerebral ischaemia. All patients had carotid ultrasound screening before angiography to screen out those with normal arteries or mild disease (less than 30% stenosis of symptomatic internal carotid artery). Complications occurred in 28 patients. There were six (3%) local, two (1%) systemic and 20 (10%) neurological complications. Seventeen neurological complications occurred within 24 hours and there were three late complications (24-72 hours). Neurological complications occurred more frequently when angiography was performed by a trainee rather than a consultant neuroradiologist (p < 0.01). The neurological complications were transient (resolved within 24 hours) in 10/200 (5%), reversible (resolved within seven days) in two (1%) and permanent in 8/200 (4%). Two patients died after a stroke and two other patients suffered a disabling stroke. At 24 hours post angiography the permanent (persisting beyond seven days) neurological complication rate was 2.5%. The incidence of total neurological complications and post angiographic strokes was higher in patients with greater than 90% stenosis of the symptomatic internal carotid artery (p < 0.001). The increased use of non-invasive Doppler duplex screening will reduced the absolute number of patients put at risk of angiography, yet the rate of post angiographic complications is likely to increase as patients with severe stenosis of the symptomatic internal carotid artery are probably most at risk of complications and have most to gain from carotid endarterectomy.

Adult↗
PubMed1991

Extracranial vertebral artery dissection following tonic clonic seizure.

A 34 year old woman developed cerebral infarction, following a tonic-clonic seizure. A vertebral artery dissection was demonstrated and may have been caused by arterial trauma during the seizure. This cause of morbidity following convulsive seizures may have been overlooked in the past and needs to be recognised in view of the potential benefits of anticoagulation.

Adult↗