Children hospitalized for flu at risk of seizures, encephalopathy

Neurologic complications are not uncommon among children hospitalized with influenza infections, according to a study. The most common complication is seizure, which may be prolonged or recurrent.

“Previous underlying conditions pose the greatest risk to a neurologic event and that those neurologic events increase disease severity and seem to play an important role in morbidity associated to the infection,” the researchers said.

This retrospective cohort study included 245 hospitalized patients (median age, 21 months; interquartile range [IQR], 6–57) with microbiologic confirmation of influenza disease over four epidemic seasons, focusing on neurologic complications. The researchers recorded demographic, laboratory, and clinical data, as well as patient history. They also performed descriptive and analytic statistical study using SPSS and R statistical software.

Of the hospitalized children, 47.8 percent had a previous underlying condition and 86 percent received oseltamivir. Median hospitalization was 4 days (IQR, 3–6), while the admission rate in the paediatric intensive care unit (PICU) was 8.9 percent. [Pediatr Infect Dis J 2020;39:789-793]

Neurologic events developed in 29 patients (11.8 percent), with febrile seizures being the most frequent, followed by nonfebrile seizures and encephalopathy. Four children had status epilepticus, and 69.6 percent of seizures recurred.

“Febrile seizures are believed to be caused by a temperature-induced dynamic reduction of mutant surface gamma-aminobutyric acid receptors, whereas influenza-related seizures can be caused by infection of brain tissue which causes cellular damage and inflammatory cytokine cascades,” according to the researchers. [J Neurosci 2006;26:2590-2597; Vaccine 2008;26:D59-D66; Neuroscience 2010;168:613-623]

A previous underlying condition correlated with a higher risk of developing neurologic complications (odds ratio [OR], 4.55, 95 percent confidence interval [CI], 1.23–16.81). In addition, admission to PICU was associated with  male sex (OR, 3.21, 95 percent CI, 1.22–8.33), influenza B virus (OR, 2.82, 95 percent CI, 1.14–7.14), and neurologic events (OR, 3.34, 95 percent CI, 1.10–10.19).

Several studies also reported a prevalence of neurologic complications in influenza-related hospitalizations, ranging from 7 percent to 11 percent. [Clin Infect Dis 2017;65:653-660; Ann Neurol 2010;68:762-766; J Pediatr 2007;150:306-310]

“Our study found a similar but slightly higher prevalence (12 percent) which may be explained by the high rate of underlying chronic conditions in our cohort (49.8 percent), which [is] one of the risk factors associated with complications,” the researchers said.

The finding that chronic conditions correlated with neurologic complications in multivariate models also supports the recommendation of generalized influenza vaccination in these patients and stresses the importance of an active approach to vaccination in chronic patients whose caregivers lack information regarding such high risk. [Pediatrics 2018;142:e20182367; Vaccine 2015;33:2322-2327]

The present study was limited by its retrospective design and the absence of a control group with healthy patients. In addition, selection and information bias might have been present.

“Thus, more studies are needed, especially prospective and controlled, to support recommendations and highlight the significance and consequences of those neurologic events,” the researchers said.