• Nitin Purandare, Sarah Welsh, Susanne Hutchinson, Graham Riding, Alistair Burns, and Charles McCollum.
• University of Manchester, School of Psychiatry and Behavioural Sciences, Education and Research Centre, Wythenshawe Hospital, Wythenshawe, Manchester M23 9LT, UK. nitin.purandare@man.ac.uk
• Int J Geriatr Psychiatry. 2005 Jan 1; 20 (1): 12-6.

BackgroundThe causes of the common dementias remain unknown. Paradoxical embolisation of the cerebral circulation by venous thrombi passing through venous to arterial shunts (v-aCS) in the heart or pulmonary circulation is known to occur in cryptogenic stroke and post-operative confusion following hip replacement.ObjectivesTo explore the role of paradoxical embolisation in dementia by investigating for cerebral emboli, venous to arterial circulation shunt (v-aCS) and carotid artery disease.MethodsForty-one patients with dementia (24 Alzheimer's AD and 17 vascular VaD) diagnosed using DSM-IV criteria and 16 controls underwent transcranial Doppler (TCD) detection of spontaneous cerebral emboli in both middle cerebral arteries. A v-aCS was detected by intravenous injection of an air/saline ultrasound contrast at rest and after provocation by coughing and Valsalva's manoeuvre. Carotid artery disease was assessed by duplex imaging.ResultsCerebral emboli were detected in 11 (27.5%) dementia patients compared with one (7%) control (p = 0.15) with emboli being most frequent in VaD (41%) compared to controls [OR (95% CI): 10.5 (1.1, 98.9), p = 0.04]. A v-aCS was detected in 25 (61%) patients and seven (44%) controls (p = 0.24). In dementia patients with cerebral emboli; v-aCS was detected in seven (64%) and moderate to severe carotid stenosis was present in three (30%).ConclusionCerebral emboli and v-aCS may be more frequent in patients with both VaD and AD than in controls, which suggest paradoxical embolisation as a potential mechanism for cerebral damage. This pilot study justifies a definitive case-control study.

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