title: Carotid sinus syndrome is common in dementia with Lewy bodies and correlates with deep white matter lesions.
abstract: BACKGROUND
  Carotid sinus syndrome (CSS) is a common cause of syncope in older persons. There appears to be a high prevalence of carotid sinus hypersensitivity (CSH) in patients with dementia with Lewy bodies (DLB) but not in Alzheimer's disease.
  
  
  OBJECTIVE
  To compare the prevalence of CSH in DLB and Alzheimer's disease, and to determine whether there is an association between CSH induced hypotension and brain white matter hyperintensities on magnetic resonance imaging (MRI).
  
  
  METHODS
  Prevalence of CSH was compared in 38 patients with DLB (mean (SD) age, 76 (7) years), 52 with Alzheimer's disease (80 (6) years), and 31 case controls (73 (5) years) during right sided supine carotid sinus massage (CSM). CSH was defined as cardioinhibitory (CICSH; >3 s asystole) or vasodepressor (VDCSH; >30 mm Hg fall in systolic blood pressure (SBP)). T2 weighted brain MRI was done in 45 patients (23 DLB, 22 Alzheimer). Hyperintensities were rated by the Scheltens scale.
  
  
  RESULTS
  Overall heart rate response to CSM was slower (RR interval = 3370 ms (640 to 9400)) and the proportion of patients with CICSH greater (32%) in DLB than in Alzheimer's disease (1570 (720 to 7800); 11.1%) or controls (1600 (720 to 3300); 3.2%) (p<0.01)). The strongest predictor of heart rate slowing and CSH was a diagnosis of DLB (Wald 8.0, p<0.005). The fall in SBP during carotid sinus massage was greater with DLB (40 (22) mm Hg) than with Alzheimer's disease (30 (19) mm Hg) or controls (24 (19) mm Hg) (both p<0.02). Deep white matter hyperintensities were present in 29 patients (64%). In DLB, there was a correlation between magnitude of fall in SBP during CSM and severity of deep white matter changes (R = 0.58, p = 0.005).
  
  
  CONCLUSIONS
  Heart rate responses to CSM are prolonged in patients with DLB, causing hypotension. Deep white matter changes from microvascular disease correlated with the fall in SBP. Microvascular pathology is a key substrate of cognitive impairment and could be reversible in DLB where there are exaggerated heart rate responses to carotid sinus stimulation.
authors.affiliation: MRC Institute for Ageing and Health, University of Newcastle upon Tyne, UK. anne.harrison@ncl.ac.uk
authors.forename: R A
authors.initials: RA
authors.lastname: Kenny
authors.forename: F E
authors.initials: FE
authors.lastname: Shaw
authors.forename: J T
authors.initials: JT
authors.lastname: O'Brien
authors.forename: P H
authors.initials: PH
authors.lastname: Scheltens
authors.forename: R
authors.initials: R
authors.lastname: Kalaria
authors.forename: C
authors.initials: C
authors.lastname: Ballard
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000453:epidemiology* / Q000473:pathology*; D001921:Brain / Q000473:pathology*; D015897:Comorbidity; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D020961:Lewy Body Disease / Q000453:epidemiology* / Q000473:pathology*; D016015:Logistic Models; D008279:Magnetic Resonance Imaging; D008297:Male; D015995:Prevalence; D013575:Syncope / Q000453:epidemiology* / Q000503:physiopathology