Title : Prospective observational study on hyponatremia in Acute Encephalitis Syndrome (AES) in children: it's occurrence and effect on outcome
Hyponatremia has been reported in various central nervous system infections like tuberculous meningitis and found to be associated with poor outcome. So far, no study has been conducted on hyponatremia in acute encephalitis syndrome (AES) in children. This study was planned to study proportion of hyponatremia in acute encephalitis syndrome (AES) in children, its association with clinical and lab parameters and effect on outcome.
This was a prospective observational study done at tertiary care teaching hospital. Institutional ethical clearance and informed consent from parents was taken. Patients between 6 months and 12yrs of age who presented with acute onset (7 days) of fever and neurological manifestation that included new onset seizures and/ or change in mental status (duration of altered sensorium >12 hrs) were included. A detailed history and examination was conducted, blood and CSF investigations and serum electrolytes were done in all AES cases, neuroimaging was done in a few cases. Hyponatremia was the main outcome variable of interest, defined as serum sodium of less than 135 mmol/L. Clinical, lab parameters and mortality were compared between hyponatremic and non hyponatremic patients. 200 children were enrolled over 18 months duration. Hyponatremia (serum sodium of less than 135 mmol/L) was found in 24.5% cases. Mild hyponatremia (130- 134 mmol/l) was seen in 69.5% cases, moderate hyponatremia (120- 129 mmol/l) in 26.5% cases and severe hyponatremia (<120 mmol/l) in 4% cases. Mortality was significantly higher in children with hyponatremia (24.5%) in comparison to non hyponatremic patients (9.3%), p=0.02. No significant association was observed with the occurrence of fever, seizures, focal deficits, altered consciousness. Hepatomegaly was seen more (36.7%) in children with hyponatremia, p value- 0.012. No significant association was seen with GCS at admission, meningeal signs and CNS examination. Hypocalcemia (p value- 0.002) and hypoalbuminemia (p value 0.007) were seen more in children with hyponatremia. Uraemia ( p value- 0.03) was seen more in children without hyponatremia. CBC, LFT and CSF examination didn't show any significant association. The most common etiology was scrub typhus, positive in 12.2% children with hyponatremia, 8.6% children without hyponatremia, followed by dengue, JE, chikungunya and malaria, no significant association seen. On multivariate analysis, past admission in hospital (p value- 0.026, OR- 0.423, 95% CI, lower 0.198, upper 0.904) and hepatomegaly (p value- 0.045, OR-2.221, 95% CI, lower 1.019, upper 4.844) were found to be predictors of hyponatremia. Severity of hyponatremia had significant association with duration of seizures (p value- 0.016), hepatomegaly (p value- 0.042), deranged urea levels (p value- 0.043) and deranged transaminases, SGOT (p value- 0.015) and SGPT (p value- 0.002). Etiology was not known in the majority of cases. The most common etiology was scrub typhus, no significant association was seen. In the outcome, 20.59% of children in the mild hyponatremic group and 26.67% of children in the moderate and severe hyponatremic group expired, no significant association was seen.
Hyponatremia was found in one fourth cases and was associated with significantly higher mortality in AES.
Audience Take Away
- This is the first study conducted in the pediatric population in India to determine the percentage of hyponatremia in children with AES and to study its clinical and biochemical implications and its effect on outcome
- The study has shown that if hyponatremia is documented in a child with acute encephalitis syndrome, we predict a higher mortality rate. We must take this as a warning sign and be extra vigilant to deal with the sodium imbalance both to prevent mortality and adverse neurological outcomes
- Pediatricians at all tertiary and peripheral centers and elsewhere should also be in a position to immediately identify the imbalance and take immediate and necessary steps for further management