1.
Neuroimaging Applications in Restless Legs Syndrome.
Rizzo, G, Plazzi, G
International review of neurobiology. 2018;:31-64
Abstract
Neuroimaging studies provide information useful to understand the pathophysiology of restless legs syndrome. Molecular PET and SPECT imaging findings mainly supported dysfunction of dopaminergic pathways involving not only the nigrostriatal but also mesolimbic pathways. Magnetic resonance imaging (MRI) studies have used different techniques. Studies using iron-sensitive sequences supported the presence of a regionally variable low brain iron content, mainly at the level of substantia nigra and thalamus. The search for brain structural or microstructural abnormalities by voxel-based morphometry, diffusion tensor imaging or cortical thickness analysis has reported none or variable findings in restless legs syndrome patients, most of them in regions belonging to sensorimotor and limbic/nociceptive networks. Functional MRI studies have substantially demonstrated activation or connectivity changes in the same networks. Magnetic resonance spectroscopy studies showed metabolic changes in the thalamus, which is a hub of these networks. In summary, neuroimaging findings in restless legs syndrome support the presence of reduction of brain iron content, of dysfunction of mesolimbic and nigrostriatal dopaminergic pathways, and of abnormalities at level of limbic/nociceptive and sensorimotor networks.
2.
Reduced heart rate response to dipyridamole in patients undergoing myocardial perfusion SPECT.
Gorur, GD, Ciftci, EA, Kozdag, G, Isgoren, S, Oc, MA, Haksal, C, Gur, M, Demir, H
Annals of nuclear medicine. 2012;(8):609-15
Abstract
OBJECTIVE A mild decrease in blood pressure and increase in heart rate (HR) are considered normal hemodynamic responses to dipyridamole. In this study, we tried to investigate HR response to dipyridamole and its predictors in patients undergoing gated myocardial perfusion single photon emission computed tomography (SPECT). METHODS 201 consecutive patients undergoing dipyridamole stress Tc99m-MIBI or Tl-201 gated myocardial perfusion SPECT were prospectively enrolled. Dipyridamole was infused over 4 min and radiopharmaceutical was injected 3 min after the end of infusion. A reduced heart rate response to dipyridamole considered if the HR ratio (peak HR/rest HR) was 1.20 or less. Stress (sLVEF), rest (rLVEF) left ventricular ejection fractions, stress and rest motion (SMS, RMS) and thickening scores (STS, RTS) were derived automatically by QGS. Summed stress score (SSS), summed rest score (SRS), and summed difference score (SDS) for myocardial perfusion were calculated. Patients were grouped according to HR response and groups were compared. A logistic regression analysis was used to determine independent predictors of reduced HR response. RESULTS Reduced HR response was found in 78 % of patients. Patients with abnormal HR response were more frequently had a history of diabetes mellitus, chronic renal failure, and had lower high-density lipoprotein (HDL) levels. Peak HR, SSS, SRS, sLVEF and rLVEF were lower; rest HR, RTS, and the number of patients with ≤ 45 % sLVEF and rLVEF were higher in reduced HR response group (all p < 0.05). There was no difference between groups by means of gender, rest and peak systolic or diastolic tension, SDS, SMS, STS, RMS, history of hypertension, peripheral arterial disease, metabolic syndrome, coronary interventions, digoxin, calcium channel blocker or beta blocker usage. Multivariable logistic regression analysis demonstrated that the independent predictors of reduced HR response were HDL, rest HR and SSS. When HDL was removed from the model, chronic renal failure also emerged as an independent predictor. CONCLUSION Reduced HR response to dipyridamole is associated with ventricular dysfunction, cardiac autonomic neuropathy. Low HDL levels also seem to be related with reduced HR response.