Hyponatremic seizures are a frightening entity. Anticonvulsants don't work well, and will likely cause apnea well before they halt the seizure. Hypertonic saline carries with it the fear of inducing central pontine myelinolysis (CPM) with overly rapid correction of the hyponatremia.
However:
CPM usually occurs at sodium level corrections of >8 mEq/L/day
Hyponatremic seizures are usually stopped with a correction of only 3-5 mEq/L
So, you can safely correct hyponatremia rapidly in the setting of seizures. Do it like this:
Give 2-3 mL/kg of 3% NaCl in rapid sequential boluses, until seizures stop. A theoretical maximum dose is 100mL/kg, but recall that only a relatively small correction is required to stop the seizure.
After you've stopped the seizure, correct the hyponatremia slowly, as you would otherwise.
References
Berg C, Schumann H. An Evidence-Based Approach to Pediatric Seizures in the Emergency Department. Pediatric Emergency Medicine Practice. Feb 2009. Vol 6, Number 2.
Moritz ML, AyusJC. New aspects in the pathogenesis, prevention, and treatment of hyponatremic encephalopathy in children. PediatrNephrol. 2010 Jul;25(7):1225-38. Epub 2009 Nov 6.
Sarnaik AP, Meert K, Hackbarth R, Fleischmann L. Management of hyponatremic seizures in children with hypertonic saline: a safe and effective strategy. Crit Care Med. 1991 Jun;19(6):758-62.
