Neuropsychiatric and seizure outcomes in nonparaneoplastic autoimmune limbic encephalitis.

INTRODUCTION: Autoimmune limbic encephalitis is an inflammatory condition often associated with an underlying neoplasm. However, a subset of patients does not have an underlying tumor and have a nonparaneoplastic form of this condition. The focus in the literature has been on the acute phase of this illness, but long-term follow-up is lacking.

METHODS: A retrospective chart review, over a period of 15 years, of patients carrying a diagnosis of encephalitis was performed. Inclusion criteria included a clinical presentation consistent with limbic encephalitis (subacute behavioral change, seizures, or anterograde memory decline) and an identifiable autoantibody, inflammatory CSF (>5 white blood cells/mm(3)), or limbic hyperintensities on MRI. Readmission rates and long-term psychiatric, psychosocial, and seizure outcomes were evaluated.

RESULTS: A total of 16 patients were identified. Clinical presentation included new-onset seizures in 14 (88%), behavioral changes in 7 (44%), and memory decline in 5 (31%). Four (25%) patients presented with status epilepticus. Five patients had antibodies against NMDAR (N-methyl-D-aspartate receptor) and four against VGKC (voltage gated potassium channel) complex. An inflammatory CSF was noted in 7 (44%) and MRI changes in 9 (56%). Four were readmitted during the follow-up period. Around half the patients continued to have medically drug/treatment-refractory seizures, while 7 (44%) had a new psychiatric diagnosis (mood disorder, anxiety disorder, or impulse control disorder). The majority of the patients continued to reside at home, while 43% of previously employed patients lost employment.

CONCLUSION: Nonparaneoplastic autoimmune limbic encephalitis is a neuropsychiatric condition presenting with a combination of seizures (sometimes status epilepticus), behavioral changes, and memory decline. After the acute phase, patients are at risk of readmissions, medically refractory seizures, chronic mood and anxiety disorders, and loss of employment.