Clinical autonomic research : official journal of the Clinical Autonomic Research Society
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Individuals with spinal cord injury (SCI) have an increased risk of cardiac arrhythmias, particularly during autonomic dysreflexia (acute hypertensive episodes). This may be partly due to impaired autonomic control of the heart after SCI. The interval between the peak and end of the T-wave of the electrocardiograph (ECG) provides an index of transmural dispersion of repolarisation, a factor underlying the development of ventricular arrhythmias. Another ECG-based risk factor for ventricular arrhythmias is variability in the QT segment, the QT variability index (QTVI). Similarly, P-wave variability may be correlated with risk for atrial arrhythmias. We aimed to: (1) determine whether there are abnormalities in these parameters at rest in those with SCI; (2) determine correlations between these ECG parameters and severity of autonomic impairment after SCI. ⋯ The higher T(peak)-T(end) variability, QTVI and P-wave variability in individuals with SCI could be markers of severity of injury to cardiac autonomic (sympathetic) pathways after SCI, and may represent new risk assessment parameters for predisposition to cardiac arrhythmias in this population.
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Hemorrhage is accompanied by baroreflex-mediated tachycardia and vasoconstriction. The difference between baseline and maximum responses is defined as the heart rate (HR) and vasoconstrictor 'reserve'. ⋯ Our data support the hypothesis that greater physiological reserve capacity for tachycardia and vasoconstriction related to high tolerance to central hypovolemia is associated with greater reserves for sympathoexcitation and cardiac vagal withdrawal.
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Review Meta Analysis
MIBG scintigraphy in differential diagnosis of Parkinsonism: a meta-analysis.
Differential diagnosis between Parkinson's disease (PD) and other Parkinsonism using clinical criteria or imaging methods is often difficult. The purpose of this study is to systematically review and meta-analyze published data about the diagnostic performance of myocardial innervation imaging using (123)I-metaiodobenzylguanidine (MIBG) scintigraphy in differential diagnosis between PD and other Parkinsonism. ⋯ In patients with clinically suspected PD, myocardial innervation imaging demonstrated high sensitivity and specificity. MIBG scintigraphy is an accurate test in this setting. Nevertheless, possible causes of false-negative and false-positive results should be kept in mind when interpreting the scintigraphic results.
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Cognitive deficits are reported in 10-60% of individuals with SCI, the primary etiology of these deficits is believed to be concomitant traumatic brain injury (TBI). We recently documented diminished memory and marginally deficient attention and processing speed in individuals with SCI discordant for hypotension but matched for TBI. ⋯ Asymptomatic hypotension relates to cognitive performance in persons with tetraplegia; therefore, BP normalization should be considered. The inappropriate cerebral vascular response to cognitive testing and poor test performance should be investigated in persons with paraplegia.
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Used in the diagnosis of Horner's syndrome, apraclonidine 1% dilatates the involved eye due to denervation supersensitivity. Recent literature suggests that in healthy volunteers, apraclonidine provokes a mild miotic effect. Since the comparison of both the pathologic and the non-pathologic eye is important, we wanted to further investigate the effect of apraclonidine on the healthy eye. By measuring the effect on the pupil intermittently over a few hours, we tried to determine the best moment for evaluation after instillation with apraclonidine. Therefore, the effect of apraclonidine on pupillary parameters was investigated in 14 healthy volunteers. ⋯ Instillation of apraclonidine 1% in healthy subjects causes relative miosis, which is most pronounced after 30-60 min. The amplitude of constriction to light also differs significantly. The relative miotic effect of apraclonidine could be explained by the α-2 receptor agonistic effect which is more pronounced than the α-1 agonistic effect in healthy subjects. In patients with Horner's syndrome, the α-1 agonistic effect will dominate because of the supersensitivity of the α-1 receptors, resulting in relative mydriasis. These findings stress the necessity to instill the unaffected eye in diagnosing a suspected Horner's pupil.