P2.215: Diagnostic Dilemmas: A Case of MRI Negative, GFAP Positive Autoimmune Encephalitis

Introduction: Autoimmune encephalitis is a conglomerate of immune-mediated, non-infectious disorders resulting in inflammation of the brain with myriad neurologic and psychiatric symptoms. It can be a diagnostic challenge with a variable response to treatment and can be anxiety provoking for family members given the drastic change to behaviors. We present a case of GFAP autoimmune encephalitis complicated by an inciting mycoplasma infection, MRI negative findings, slower response to treatment, and initial negative CSF antibody panel. Additional social barriers existed as the family spoke a specific dialect of Arabic that was difficult to access with virtual translators. Collaboration and effective communication allowed for a positive outcome and final unifying diagnosis.

Case Description: An 8-year-old female presented with 1 week of cough, fevers, and emesis. She was diagnosed with Mycoplasma pneumonia and started on azithromycin, but developed odd behaviors and periods of encephalopathy. An MRI brain and spine were unremarkable and LP studies and EEG were normal. She was transferred to our institution for further evaluation and work up. IV levofloxacin was started for possible Mycoplasma encephalitis without improvement. Work-up for nausea was positive for H pylori and treatment was initiated. An autoimmune encephalopathy panel was sent on her CSF. Repeat MRI brain was normal, EEG revealed only minor slowing, and infectious workup returned negative. Her behavior ranged from periods of hypoactivity to agitation and crying. The patient had minimal improvement to high dose steroids. She had a slow, but noticeable response to IVIG. CSF autoimmune panel returned negative, but she had good clinical response to treatment. She returned closer to baseline and became conversational again with family. She was discharged home with follow up with neurology. After discharge a serum autoimmune panel returned positive for GFAP and GAD65 antibodies further supporting a diagnosis of autoimmune encephalitis.

Discussion: This case posed several diagnostic challenges. The patient had recently immigrated from Yemen and family spoke a dialect of Arabic that made finding an interpreter challenging. GFAP autoimmune encephalitis is typically characterized by MRI changes, which were not seen in this case. CSF and Serum panels for autoimmune antibodies were needed to identify the autoantibodies and use of multiple panels may be indicated if clinical suspicion is high. Identification of antibodies can also be important as different forms of autoimmune encephalitis are associated with paraneoplastic syndromes and may require additional screening for possible malignancy.

Conclusion: Autoimmune encephalitis can be an elusive diagnosis that is very distressing to the patient and their family. This case demonstrates an interesting case of MRI negative, GFAP and GAD65 positive, autoimmune encephalitis. Consistent communication amongst multiple specialties and the patient’s family allowed for a comprehensive work up with a successful diagnosis and treatment for autoimmune encephalitis.