Paul Guerin1, Syed Shah1, Ariel Gallanosa2, Ahmad El Kouzi3
1Southern Illinois University School of Medicine, 2Southern Illinois University, 3SIU School of Medicine
Background:
Anti-GABA-BR encephalitis is clinically characterized by symptoms of limbic dysfunction including cognitive decline, behavioral changes, and seizures. Although cases are limited, there is a strong connection with underlying malignancy. We present a case of seropositive encephalitis in a patient without malignancy.
Results:
We examined a 75-year-old man for new onset seizures and a 5-week history of cognitive and personality changes. His PMH is significant for alcohol use disorder, chronic tobacco smoking, hyperlipidemia, and hypertension. A CT head obtained in the ED demonstrated a left mesial temporal hypodensity. Further investigation with MRI revealed left mesial temporal hyperintensity with avid contrast uptake suggesting infectious versus neoplastic or paraneoplastic disease. CT chest/abd/pelvis obtained to evaluate for occult malignancy and was negative. CSF analysis revealed elevated protein, normal glucose, normal WBC, increased IgG synthesis, and increased myelin basic protein. HSV PCR was negative. Broad spectrum antibiotics and antivirals were discontinued when infectious causes were ruled out. Serum autoimmune encephalitis panel demonstrated positive GABA-B Receptor antibodies at titer of 1:160. CSF autoimmune panel demonstrated GABA-B receptor antibodies at titer of 1:20. He was started on a 5-day course of IV steroids with little benefit on his symptoms. He was then treated with 5-day course of IVIG. Seizures were controlled with levetiracetam. Patient improved clinically and was discharged to extended care facility.
Our patient is unique in the fact that he had a classic GABA-BR encephalitis presentation with seizures, cognitive and behavioral changes but lacked any evidence of systemic malignancy. The fact that he is a chronic smoker puts him at higher risk of malignancy, and we plan to continue to screen him for a neoplastic illness during follow-up.
Conclusions:
GABA-B receptor encephalitis can present without signs of systemic malignancy. Patients with high risk for malignancy must be continuously screened on follow-ups.