Children with transient loss of consciousness: Clinical characteristics and the effectiveness of diagnostic tests

Relationship between syncopal symptoms and head-up tilt test modes

OBJECTIVE

Head-up tilt test (HUTT) is an important tool in the diagnosis of pediatric vasovagal syncope. This research will explore the relationship between syncopal symptoms and HUTT modes in pediatric vasovagal syncope.

METHODS

A retrospective analysis was performed on the clinical data of 2513 children aged 3-18 years, who were diagnosed with vasovagal syncope, from Jan. 2001 to Dec. 2021 due to unexplained syncope or pre-syncope. The average age was 11.76 ± 2.83 years, including 1124 males and 1389 females. The patients were divided into the basic head-up tilt test (BHUT) group (596 patients) and the sublingual nitroglycerine head-up tilt test (SNHUT) group (1917 patients) according to the mode of positive HUTT at the time of confirmed pediatric vasovagal syncope.

RESULTS

(1) Baseline characteristics: Age, height, weight, heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), and composition ratio of syncope at baseline status were higher in the BHUT group than in the SNHUT group (all P < 0.05). (2) Univariate analysis: Age, height, weight, HR, SBP, DBP, and syncope were potential risk factors for BHUT positive (all P < 0.05). (3) Multivariate analysis: syncope was an independent risk factor for BHUT positive, with a probability increase of 121% compared to pre-syncope (P<0.001).

CONCLUSION

The probability of BHUT positivity was significantly higher than SNHUT in pediatric vasovagal syncope with previous syncopal episodes.

Brain MRI and EEG overemployment in patients with vasovagal syncope: results from a tertiary syncope unit

BACKGROUND

The diagnosis of vasovagal syncope (VVS) is mainly based on history-taking and physical examination. However, brain Magnetic Resonance Imaging (MRI) and Electroencephalogram (EEG) are commonly used in the diagnostic course of VVS, despite not being indicated in the guidelines. This study aims to find the possible associated factors with the administration of brain MRI and EEG in patients with VVS.

METHODS

Patients with a diagnosis of VVS from 2017 to 2022 were included. Several demographic and syncope features were recorded. The association of these was assessed with undergoing MRI, EEG, and either MRI or EEG. Univariate and multivariable logistic regression models were also used to calculate odds ratios (OR) and 95% confidence intervals (CI).

RESULTS

A total of 1882 patients with VVS were analyzed, among which 810 underwent MRI (43.04%), 985 underwent EEG (52.34%), and 1166 underwent MRI or EEG (61.96%). Head trauma (OR 1.38, 95% CI 1.06 to 1.80), previous neurologist visit (OR 6.28, 95% CI 4.24 to 9.64), and gaze disturbance during syncope (OR 1.75, 95% CI 1.13 to 2.78) were all positively associated to the performance of brain MRI/EEG. Similar results were found for urinary incontinence (OR 2.415, 95% CI 1.494 to 4.055), amnesia (OR 1.421, 95% CI 1.053 to 1.930), headache after syncope (OR 1.321, 95% CI 1.046 to 1.672), and tonic-clonic movements in head-up tilt table test (OR 1.501, 95% CI 1.087 to 2.093). However, male sex (OR 0.655, 95% CI 0.535 to 0.800) and chest pain before syncope (OR 0.628, 95% CI 0.459 to 0.860) had significant negative associations with performing brain MRI/EEG.

CONCLUSION

Based on our findings, performing MRI or EEG was common among VVS patients while it is not indicated in the majority of cases. This should be taken into consideration to prevent inappropriate MRI/EEG when there is a typical history compatible with VVS.

Clinical and Autonomic Profile, and Modified Calgary Score for Children and Adolescents with Presumed Vasovagal Syncope Submitted to the Tilt Test

BACKGROUND

In the pediatric population, syncope is mainly from vasovagal (VVS) origin. Its evaluation must be done by clinical methods, and the tilt test (TT) can contribute to the diagnosis.

OBJECTIVES

To analyze the clinical profile, Calgary and modified Calgary scores, response to TT and heart rate variability (HRV) of patients aged ≤ 18 years with presumed VVS. To compare the variables between patients with positive and negative responses to TT.

METHOD

Observational and prospective study, with 73 patients aged between 6 and 18 years, submitted to clinical evaluation and calculation of scores without previous knowledge of the TT. It was done at 70º under monitoring for HRV analysis. P-value < 0.05 was the statistical significance criterion.

RESULTS

Median age was 14.0 years; 52% of participants were female, 72 had Calgary ≥ -2 (mean 1.80), and 69 had modified Calgary ≥ -3 (mean 1.38). Prodromes were observed in 59 patients, recurrence in 50 and trauma in 19. The response to TT was positive in 54 participants (49 vasovagal, with 39 vasodepressor responses), with an increase in the low frequency (LF) component and a decrease in the high frequency (HF) component (p < 0,0001). In the supine position, LF was 33.6 in females and 47.4 in normalized units for males (p = 0.02). When applying the operating characteristic curve for positive TT, there was no statistical significance for HRV and scores.

CONCLUSION

Most children and adolescents with a presumed diagnosis of VVS presented a typical clinical scenario, with a Calgary score ≥ -2, and a predominant vasodepressor response to TT. Greater sympathetic activation was observed in the supine position in males. Calgary scores and sympathetic activation did not predict the response to TT.

The value of QT interval in differentiating vasovagal syncope from epilepsy in children

BACKGROUND

Both vasovagal syncope (VVS) and epilepsy present with transient loss of consciousness and are often difficult to identify. Hence this study aimed to explore the value of QT interval in the differentiation of VVS and epilepsy in children.

METHODS

One hundred thirteen children with unexplained transient loss of consciousness were selected. 56 children with VVS (VVS group), including 37 males and 19 females, the average age is 9.88 ± 2.55 years old. 57 children with epilepsy (epilepsy group), including 36 males and 21 females, the average age is 8.96 ± 2.67 years old. At the same time, the 60 healthy individuals (control group) were examined according to age and sex. The QT interval of 12-lead electrocardiogram in a basal state of three groups was measured and statistically analyzed by SPSS 24.0 software.

RESULTS

Compared with the control group, (1) QTcmax, QTcmin and QTcd were significantly longer in VVS group (P < 0.05), QTmax and QTmin were significantly shorter in VVS group (P < 0.05), and there were no significant differences in QTd between the two groups (P > 0.05). (2) The QTmax and QTmin were significantly shorter in epilepsy group (P < 0.05), and there were no significant differences in QTd, QTcmax, QTcmin, QTcd between the two groups (P > 0.05). Compared with the epilepsy group, The QTcmax, QTcmin, QTcd were significantly longer in VVS group (P < 0.05), and there were no significant differences in QTd, QTmax, QTmin between the two groups (P > 0.05). When QTcmax > 479.84 ms, QTcmin > 398.90 ms and QTcd > 53.56 ms, the sensitivity and specificity of diagnosing VVS were 62.5% and 77.19%, 82.14% and 50.88%, 82.14% and 38.60% respectively.

CONCLUSION

QTcmax, QTcmin and QTcd have certain value in differentiating VVS from epilepsy in children.

Neurally Mediated Syncope in Children and Adolescents: An Updated Narrative Review

Syncope presents a proportion of up to 25% among children and adolescents and accounts for 0.9% of emergency room visits. Its most frequent aetiology is neurally mediated syncope, which includes vasovagal syncope and orthostatic hypotension. Up to 70% of the paediatric population with reflex syncope is female. There are usually precipitating factors and prodromes. This mini-review will discuss the particularities of the clinical presentation, diagnosis, modified Calgary score, indications and accuracy of the head-up tilt test, classification, and pathophysiology in four sequential phases. Prognostic data and the non-pharmacological and pharmacological approaches will also be reviewed and differences regarding reflex syncope in adults will be discussed.