Variable cerebral dysfunction during tilt induced vasovagal syncope

Sub-Scalp Implantable Telemetric EEG (SITE) for the Management of Neurological and Behavioral Disorders beyond Epilepsy

Sub-scalp Implantable Telemetric EEG (SITE) devices are under development for the treatment of epilepsy. However, beyond epilepsy, continuous EEG analysis could revolutionize the management of patients suffering from all types of brain disorders. This article reviews decades of foundational EEG research, collected from short-term routine EEG studies of common neurological and behavioral disorders, that may guide future SITE management and research. Established quantitative EEG methods, like spectral EEG power density calculation combined with state-of-the-art machine learning techniques applied to SITE data, can identify new EEG biomarkers of neurological disease. From distinguishing syncopal events from seizures to predicting the risk of dementia, SITE-derived EEG biomarkers can provide clinicians with real-time information about diagnosis, treatment response, and disease progression.

Orthostatic Headache in Children Including Postural Tachycardia Syndrome and Orthostatic Hypotension: A Near-Infrared Spectroscopy Study

Background and aim: Although head and/or neck pain attributed to orthostatic hypotension is included in international guidelines, its mechanisms and relevance remain unknown. This study examined the term’s relevance and aimed to elucidate the associated clinical features. Methods: An active stand test was performed to evaluate fluctuations in systemic and cerebral circulation in children and adolescents reporting complaints in the absence of a confirmed organic disorder. The subjects were categorized based on orthostatic headache presence/absence, and their characteristics and test results were compared. Results: Postural tachycardia syndrome was observed in 50.0% of children with, and 55.1% without, orthostatic headache. For orthostatic hypotension, the respective values were 31.3% and 30.6%. A history of migraine was more prevalent in children with orthostatic headaches (64.1% vs. 28.6%; p < 0.01). The observed decrease in the cerebral oxygenated hemoglobin level was larger in children with orthostatic headaches (Left: 6.3 (3.2–9.4) vs. 4.1 (0.8–6.1); p < 0.01, Right: 5.3 (3.1–8.6) vs. 4.0 (0.8–5.9); p < 0.01). Conclusion: Fluctuations in cerebral blood flow were associated with orthostatic headaches in children, suggesting that the headaches are due to impaired intracranial homeostasis. As orthostatic headache can have multiple causes, the term “head and/or neck pain attributed to orthostatic (postural) hypotension” should be replaced with a more inclusive term.

Data fusion for paroxysmal events' classification from EEG

BACKGROUND

Spatiotemporal analysis of electroencephalography is commonly used for classification of events since it allows capturing dependencies across channels. The significant increase of feature vector dimensionality however introduce noise and thus it does not allow the classification models to be trained using a limited number of samples usually available in clinical studies.

NEW METHOD

Thus, we investigate the classification of epileptic and non-epileptic events based on temporal and spectral analysis through the application of three different fusion schemes for the combination of information across channels. We compare the commonly used early-integration (EI) scheme - in which features are fused from all channels prior to classification - with two late-integration (LI) schemes performing per channel classification when: (i) the temporal context varies significantly across channels, thus local spatial training models are required, and (ii) the spatial variations are negligible in comparison to the inter-subject variation, thus only the temporal variation is modeled using a single global spatial training model. Furthermore, we perform dimensionality reduction either by feature selection or by principal component analysis.

RESULTS

The framework is applied on events that manifest across most channels, as generalized epileptic seizures, psychogenic non-epileptic seizures and vasovagal syncope. The three classification architectures were evaluated on EEG epochs from 11 subjects.

COMPARISON WITH EXISTING METHODS

Although direct comparison with other studies is difficult due to the different characteristics of each dataset, the achieved recognition accuracy of the LI fusion schemes outperforms the performance reported in the literature.

CONCLUSIONS

The best scheme was the LI with global model which achieved 97% accuracy.

Overuse of EEG in the evaluation of common neurologic conditions

The objective of the present study was to analyze the diagnostic indications that most often prompt the referral of children and adolescents in the outpatient clinical pediatric practice for electroencephalographic evaluation and to check its utility in these clinical conditions. The electroencephalographic records of 547 consecutive children and adolescents (5-16 years of age) referred to a single community laboratory for the evaluation of various neurologic disorders were prospectively read by a single blinded investigator. Common diagnostic indications included the following: clinical seizures (42%), attention-deficit-hyperactivity disorder (23%), headaches (10.4%), syncope (9.9%), and tic disorder (4.9%). Overall, 76% of records were normal. Slowing of electroencephalographic activity was noted in 1% (attention-deficit-hyperactivity disorder) to 26% (probable epilepsy), and epileptiform activity in 53% of the probable and 29% of the clinically possible epileptics. Epileptiform activity was rarely found in the nonepileptic patients. The results of the present study demonstrate that standard interictal electroencephalogram is being overused during evaluation of various neurologic disorders in children and adolescents, suggesting that its use should be reserved for supporting the diagnosis in those cases in which epilepsy is a reasonable clinical possibility.