An Unusual Case of Refractory Seizures

A 54-year-old female presented with recurrent episodes of altered sensorium. The episodes lasted 4-6 minutes with snoring and unresponsiveness, and confusion during resolution. She was found to have recurrent hyponatremia and hypoglycemia. The hyponatremia was hypo-osmotic with raised urinary sodium excretion managed with hypertonic saline and oral extra salt. Electroencephalogram (EEG) showed epileptiform discharges. The recurrent seizure episodes persisted in spite of antiepileptic drugs. Cerebrospinal fluid (CSF) examination showed: glucose 174.7 mg/dL, protein 60.4 mg/dL, total leukocyte count (TLC) 5. acid-fast bacilli (AFB), Gram stain-no organism, culture sensitivity sterile, Cryptococcus antigen, cobwebbing absent, BioFire CSF meningitis/encephalitis panel was negative. Serum autoimmune encephalitis panel was positive for leucine-rich glioma-inactivated 1 (LGI1) antibody (2+) (titer 1:10). The patient was initially treated with IV immunoglobulin 170 gm over 5 days. The nonconvulsive seizure activity reduced but remained persistent. The patient was further treated for syndrome of inappropriate antidiuretic hormone secretion (SIADH)-induced hyponatremia with fluid restriction and desmopressin. In view of persistent hyponatremia and altered sensorium, and positive autoimmune encephalitis panel, rituximab infusion was given on 2 occasions, 2 weeks apart. The sensorium showed a gradual but significant improvement with cessation of seizure activity and improved activities of daily living. Our patient presented with nonconvulsive seizure activity and persistent hyponatremia and recurrent hypoglycemia. The anti-leucine-rich glioma inactivated 1 (LGI1 antibody) is a rarely found entity first described in 2010. It is associated with electrolyte abnormalities, namely hyponatremia and hypoglycemia. A PubMed search revealed very few cases reported of LGI1 antibody encephalitis in association with nonconvulsive seizure activity. The electrolyte abnormalities associated with the entity make the management difficult. The recommended immunosuppressive regimen consists of IV pulsed steroids, which was precluded in our patient due to poorly controlled diabetes. Inadequate response seen after IVIg infusion prompted further immunosuppression with rituximab. Satisfactory control of the seizure activity was attained after the second rituximab dose.