Objective:

This case series poses combined immunotherapy as an alternative treatment approach for refractory epilepsy in the setting of anti-GABA-B-receptor encephalitis. It also challenges the necessity for further testing when initial cancer screening is unrevealing. 

Background:

Anti-γ-amino-butyric-acid-B-receptor (anti-GABA-B-R) encephalitis is a rare autoimmune-mediated inflammatory process affecting the brain parenchyma. Clinical manifestations include seizures, limbic dysfunction with cognitive dysfunction, and psychiatric manifestations. Treatment often involves immunotherapy, chemotherapy, or plasmapheresis alongside anti-seizure medications. Current protocols suggest CT chest followed by FDG-PET to screen for small cell lung carcinoma (SCLC) due to its strong association with anti-GABA-B-R encephalitis, although it currently isn’t clear whether further screening for other malignancies is indicated. 

Design/Methods:

NA

Results:

Case 1: A 53-year-old female presented with a new-onset headache, seizures, and progressive encephalopathy. Following diagnosis of anti-GABA-B-receptor encephalitis, cancer screening included an initial chest CT that was negative and then FDG-PET which revealed increased uptake in two cervical lymph nodes, however two subsequent biopsies were negative for malignancy. Continued monitoring for occult malignancy with routine CT chest scans are negative to date. 

Case 2: A 49-year-old female presented with confusion, dizziness, and seizures. Following diagnosis of anti-GABA-B-receptor encephalitis, her seizures were refractory to anti-seizure medications, methylprednisolone, and plasmapheresis, but an excellent response and recovery were seen after concurrent use of methylprednisolone and IVIG. Ongoing SCLC screening has been negative to date.

Conclusions:

While not typically the first-line approach, a combination of corticosteroids with IVIG or PLEX may be a promising option for refractory cases of anti-GABA-B-R encephalitis. It also isn’t clear whether malignancies other than SCLC are strongly associated, and screening outside of an initial CT chest is currently controversial. This article opens the question for further studies to evaluate the option of combined immunotherapy and the association of other malignancies to anti-GABA-B-R encephalitis.