Treatment of Anti-GAD65 Autoimmune Encephalitis Presenting as NORSE with Intrathecal Dexamethasone
Karla Salazar1, Christina Massrey1, Alexander Ankar1, Jonathan Yarimi1, Manasa Sudheendra1, Jon Cokley2, Daniel Davila-Williams1, Kristen Fisher1
1Baylor College of Medicine, 2Texas Childrens Hospital
Background:
New-onset refractory status epilepticus (NORSE) is a devastating clinical condition that often leads to severe disability or even death. A pathologic antibody is often not identified. Anti-glutamic acid decarboxylase 65 (anti-GAD65) antibody encephalitis is an uncommon form of autoimmune encephalitis with a broad range of presentations including NORSE. Current guidelines for treatment of NORSE include systemic high dose intravenous methylprednisolone (IVMP), intravenous immunoglobulin (IVIg), and plasma exchange (PLEX). Clinical management of refractory status epilepticus requires high-dose anesthetic infusions, often with complicated medical courses.
Results:
An 11-year-old previously healthy female presented with five days of behavioral changes followed by refractory status epilepticus after a febrile illness. She required rapid escalation to continuous anesthetic infusions and initiation of ketogenic diet. Work-up showed elevated CSF WBC to 18 and a protein of 56. Anti-GAD65 antibodies were elevated in serum (49.9) and CSF (2.08). Immunotherapy included high-dose IVMP, IVIG, PLEX, Anakinra and Rituximab with minimal improvement in seizure burden. On hospital day 27, due to inability to wean anesthetic infusions, she received intrathecal dexamethasone (IT-DEX) weekly for 6 weeks. Initial CSF cytokines showed elevated interleukin 6, 8, and soluble interleukin-2 receptor. By the fourth dose of IT-DEX, there was near normalization of CSF cytokines and CSF pleocytosis, meanwhile seizure burden decreased from 4 minutes to 1 minute per hour. Patient was weaned off anesthetics and continued to exhibit a decrease in seizure burden. She eventually transferred to the transitional unit. No major adverse effects occurred from IT-DEX administration.
Conclusions:
Intrathecal dexamethasone is an effective and safe medication for treatment of NORSE. IT-DEX aided in the weaning of anesthetic infusions and dramatically decreased seizure burden in this patient. It also highlights the role of local inflammation in the central nervous system in the pathophysiology of NORSE.