Kevin J. Daly

Cerebral emboli as a potential cause of Alzheimer's disease and vascular dementia: Case-control study

Abstract Objective To compare the occurrence of spontaneous cerebral emboli and venous to arterial circulation shunts in patients with Alzheimers disease or vascular dementia and controls without dementia. Design Cross sectional case-control study. Setting Secondary care old age psychiatry services, Manchester. Participants 170 patients with dementia (85 with Alzheimers disease, 85 with vascular dementia) and 150 age and sex matched controls. Patients on anticoagulant treatment, patients with severe dementia, and controls with marked cognitive impairment were excluded. Main outcome measures Frequencies of detection of spontaneous cerebral emboli during one hour monitoring of the middle cerebral arteries with transcranial Doppler and venous to arterial circulation shunts by a transcranial Doppler technique using intravenous microbubbles as an ultrasound contrast. Results Spontaneous cerebral emboli were detected in 32 (40%) of patients with Alzheimers disease and 31 (37%) of those with vascular dementia compared with just 12 each (15% and 14%) of their controls, giving significant odds ratios adjusted for vascular risk factors of 2.70 (95% confidence interval 1.18 to 6.21) for Alzheimers disease and 5.36 (1.24 to 23.18) for vascular dementia. These spontaneous cerebral emboli were not caused by carotid disease, which was equally frequent in dementia patients and their controls. A venous to arterial circulation shunt indicative of patent foramen ovale was found in 27 (32%) Alzheimers disease patients and 25 (29%) vascular dementia patients compared with 19 (22%) and 17 (20%) controls, giving non-significant odds ratios of 1.57 (0.80 to 3.07) and 1.67 (0.81 to 3.41). Conclusion Spontaneous cerebral emboli were significantly associated with both Alzheimers disease and vascular dementia. They may represent a potentially preventable or treatable cause of dementia.

Re: Clinical and Imaging Findings in Cryptogenic Stroke Patients With and Without Patent Foramen Ovale

Background and Purpose— Patent foramen ovale (PFO) has been identified as a potential risk factor for stroke, but the mechanisms of PFO-associated stroke remain unsettled. The aim of our study was to evaluate possible differences in stroke risk factors and stroke patterns between patients with and without PFO that may give clues to the mechanism of PFO-associated stroke. Methods— This prospective, multicentric study involved 581 young cryptogenic stroke patients. The presence of PFO and atrial septal aneurysm was assessed by transesophageal echocardiography and reviewed independently by 2 experienced sonographers. Clinical, brain, and vascular imaging findings were reviewed by 2 neurologists and 2 neuroradiologists. Results— Of the 581 stroke patients, 267 (45.9%) had PFO. Patients with PFO were younger (OR, 0.95; 95% CI, 0.93 to 0.97) and less likely to have traditional risk factors such as hypertension (OR, 0.49; 95% CI, 0.28 to 0.85), hypercholesterolemia (OR, 0.56; 95% CI, 0.34 to 0.93), or current sm...

Transcranial Doppler detection of venous-to-arterial circulation shunts: Criteria for patent foramen ovale

As paradoxical embolism is associated with stroke in young adults, migraine, and decompression sickness, the detection of venous‐to‐arterial circulation shunt (v‐aCS), such as patent foramen ovale (PFO), is increasingly important. We compared a rigorous transcranial Doppler (TCD) protocol with transesophageal echocardiography (TEE) to develop criteria for PFO.

Can a Peripheral Artery Be Used to Detect Venous to Arterial Circulation Shunts

Background: Transcranial Doppler is a sensitive test for patent foramen ovale (PFO), but an absent temporal window precludes this in 12–15% of patients. We investigated whether the brachial (BrA), common carotid (CCA) or common femoral (CFA) artery provided reliable alternatives. Methods: Patients underwent simultaneous insonation of a middle cerebral artery (MCA, n = 66) and either (a) the BrA (n = 22), (b) CCA (n = 20) or (c) CFA (n = 24) with a 2-MHz transcranial Doppler probe. Results: The correlation between microbubble emboli counts in the MCA and the peripheral arteries was (a) r = 0.67 (95% CI 0.53–0.77) for the BrA, (b) r = 0.80 (95% CI 0.71–0.87) for the CCA and (c) r = 0.92 (95% CI 0.89–0.95) for the CFA. The agreement for detection of PFO was best using the CFA with a kappa of 0.95 (95% CI 0.66–1.0). Conclusion: The CFA is a simple and reliable alternative to the MCA, but the criteria for diagnosis of a PFO are different.

Screening, Diagnosis and Advances in Aortic Aneurysm Surgery

Background: Aortic aneurysms are common in the elderly and a frequent cause of sudden death. As elective aneurysm repair has a mortality drastically lower than that associated with rupture, the emphasis must be on early detection and repair free from complications. Recent advances include ultrasound screening for asymptomatic abdominal aortic aneurysm (AAA) and clinical trials on the size of AAA that require repair. Pre-operative assessment, management of cardiac risk, autologous blood transfusion strategies, and endovascular stent graft technology to avoid major open surgery are all issues to be addressed. Methods: Following a computerized Medline search for publications on the detection and treatment of abdominal and thoracic aortic aneurysm, the publications identified were then read and the references within those publications examined for further publications on this topic. We have reviewed these publications without attempting a meta-analysis. Results: Randomized population studies have addressed ultrasound screening for AAA. Attendance for screening was good and AAA detection inexpensive. Screening men from 65 years reduces the mortality from rupture and is cost-effective. Open thoracic and abdominal aneurysm repair has a mortality of around 8%, with myocardial infarction being a frequent cause of death. Pre-operative reduction of cardiac risk by cardiac investigations and β-blockade may reduce this mortality. Autologous transfusion techniques such as acute normovolaemic haemodilution and interoperative cell salvage reduce the need for allogeneic blood and the complications associated with open surgery. Minimally invasive endovascular repair is now possible for 40% of the AAA and an increasing proportion of thoracic aneurysms. Conclusions: The combination of screening, reduced pre-operative risk, and new minimally invasive techniques extends aortic aneurysm treatment into an increasingly elderly population. The combination of these techniques will reduce mortality from ruptured aortic aneurysm in the elderly and also reduce the stress associated with aneurysm surgery.

Vascular complications of prosthetic inter-vertebral discs.

Five consecutive cases of prosthetic inter-vertebral disc displacement with severe vascular complications on revisional surgery are described. The objective of this case report is to warn spinal surgeons that major vascular complications are likely with anterior displacement of inter-vertebral discs. We have not been able to find a previous report on vascular complications associated with anterior displacement of prosthetic inter-vertebral discs. In all five patients the prosthetic disc had eroded into the bifurcation of the inferior vena cava and the left common iliac vein. In three cases the aortic bifurcation was also involved. The fibrosis was so severe that dissecting out the arteries and veins to provide access to the relevant disc proved impossible. Formal division of the left common iliac vein and artery with subsequent repair was our solution. Anterior inter-vertebral disc displacement was associated with severe vascular injury. Preventing anterior disc displacement is essential in disc design. In the event of anterior displacement, disc removal should be planned with a Vascular Surgeon.