Variability in the location of high frequency oscillations during prolonged intracranial EEG recordings.

The rate of interictal high frequency oscillations (HFOs) is a promising biomarker of the seizure onset zone, though little is known about its consistency over hours to days. Here we test whether the highest HFO-rate channels are consistent across different 10-min segments of EEG during sleep. An automated HFO detector and blind source separation are applied to nearly 3000 total hours of data from 121 subjects, including 12 control subjects without epilepsy. Although interictal HFOs are significantly correlated with the seizure onset zone, the precise localization is consistent in only 22% of patients. The remaining patients either have one intermittent source (16%), different sources varying over time (45%), or insufficient HFOs (17%). Multiple HFO networks are found in patients with both one and multiple seizure foci. These results indicate that robust HFO interpretation requires prolonged analysis in context with other clinical data, rather than isolated review of short data segments.

Tolerance of esophageal pressure monitoring during polysomnography in children.

OBJECTIVES: To assess tolerance of esophageal pressure monitoring (EPM) among 5- to 13-year-old children during research polysomnography at study entry and again 1 year later. DESIGN: Prospective, observational study. SETTING: University-based sleep laboratory. PARTICIPANTS: Children scheduled for adenotonsillectomy or hernia repair. INTERVENTIONS: None; all operations were performed for clinical indications only. RESULTS: Forty-two of 336 families approached about the study declined to participate mainly to avoid EPM. The EPM was usually the main concern for the 47 adenotonsillectomy and 7 hernia-repair patients and families who did participate. Among 54 enrolled subjects, 51 allowed attempts at insertion of the esophageal catheter, and insertion was successful in all cases; 38 tolerated EPM for at least 2 hours; 33 maintained EPM for the entire night; and 36 had repeat EPM 1 year later for at least 2 hours. Reasons for EPM failure included crying at insertion, vomiting, pain, and inadvertent catheter removal during sleep. The children who tolerated EPM for at least 2 hours did not differ from other subjects based on age, sex, presence of a disruptive behavior disorder, anxiety, tonsil size, history of tonsillitis, or body mass index (all P > .05). CONCLUSIONS: The EPM was well tolerated in most school-aged volunteers, but many families did not volunteer, and some children were not able to endure EPM for at least 2 hours. Although better success might be achieved in clinical settings if EPM is medically indicated and not part of voluntary research, EPM is still likely to create significant concern, for children and parents, that must be weighed against anticipated benefits.