Unusual Cases of Syncope in the Pediatric Age Group

Serum Vitamin D Levels in Children and Adolescents with Vasovagal Syncope, Syncope Due to Orthostatic Hypotension, and Cardiac Syncope

OBJECTIVE

The study aimed to compare vitamin D levels between children and adolescents with vasovagal syncope, syncope due to orthostatic hypotension, cardiac syncope, and healthy individuals and to investigate the correlations of 25(OH)D with main clinical parameters of syncope.

MATERIALS AND METHODS

This study involved 83 children aged 8-17 years with syncope: 40 with vasovagal syncope, 24 with syncope due to orthostatic hypotension, and 19 with cardiac syncope. There were 24 healthy volunteers in the control group. Data concerning active standing test, electrocardiography, echocardiography, electroencephalography, and 24-hour Holter monitoring findings were collected. Serum vitamin D was evaluated by an enzyme-linked immunoassay technique test.

RESULTS

The mean levels of serum 25(OH)D were decreased in children with vasovagal syncope (18.8 ± 5.9 ng/mL), syncope due to orthostatic hypotension (19.9 ± 6.7 ng/mL), and cardiac syncope (20.6 ± 7.3 ng/mL) in comparing with the control group (30.9 ± 5.9 ng/mL; P < .001). In patients with syncope due to orthostatic hypotension, vitamin D deficiency was associated with a reduction in systolic blood pressure (r = 0.43) and diastolic blood pressure (r = 0.38) within the first minute, lower systolic blood pressure (r = 0.44) within the third minute of active orthostasis (P < .05). There were significant correlations of vitamin D deficiency with parameters of cardiac autonomic activity pNN50 (r = 0.49), total power (r = 0.39), and low frequency index (r = 0.35) in children with cardiac syncope (P < .05), while heart rate variability was not affected in patients with vasovagal syncope and syncope due to orthostatic hypotension (P > .05).

CONCLUSION

Children and adolescents with vasovagal syncope, syncope due to orthostatic hypotension, as well as cardiac syncope had higher frequency of vitamin D deficiency than healthy pediatric controls. This provides a new approach to syncope management in pediatric population, requiring further studies.

Clinical Discordance in Monozygotic Twins With Autism Spectrum Disorder

There is a significant concordance of autism spectrum disorder in monozygotic (MZ) twins, where behavioral manifestations are heavily influenced by genetic factors. We describe a case of male monozygotic twins with autism spectrum disorder (ASD), raised in the same household, that present with different clinical manifestations. One of the twins presents with intermittent frank syncopal episodes, sinus bradycardia, and elevated alkaline phosphatase (ALP), while the other has symptoms of attention-deficit/hyperactivity disorder (ADHD), normal cardiological findings, and normal ALP level. The clinical discordance in this pair of monozygotic twins may be due to any of the following: 1) neuroanatomic cerebellar differences, 2) variable expression of genotype, and 3) inconsistent neurotransmitter regulation.