Encephalitis with antibodies against the GABAB receptor: seizures as the most common presentation at admission.

OBJECTIVE

Autoimmune encephalitis associated with antibodies against gamma-aminobutyric-acid B receptor (GABABR) has not been described in detail in Chinese patients.

METHODS

Patients with anti-GABABR encephalitis treated between January 2013 and December 2015 were analyzed in terms of clinical characteristics, laboratory findings, tumor presence, autoantibody patterns, treatment response and outcomes.

RESULTS

Eleven patients were identified (male, N = 8; female, N = 3), with the median age of 51 years. All patients presented with seizures (N = 11; 100%), and they were given anti-epileptic drugs and first-line immunotherapy to address the disease. Seizures always accompanied by limbic manifestations (N = 10; 90.9%). Extralimbic manifestations were present in 4 patients (N = 4; 36.4%). MRI Brain abnormality with increased medio-temporal lobe T2/FLAIR signal were present in 2 patients (N = 2; 18.2%), and epileptiform epileptiform activity on electroencephalography were observed in 2 patients (N = 2; 18.2%). Small-cell lung cancer was histologically confirmed in 3 patients (N = 3; 27.3%). Seven patients showed good outcomes (mRS 1-2; N = 7; 63.6%), one patient showed poor neurological status with minimal changes (mRS 4; N = 1; 9.1%), and three patients died during follow-up (mRS = 6; N = 3; 27.3%). Outcomes were correlated with age-of-onset, and were worse among older patients (P = 0.0112).

CONCLUSION

Anti-GABABR encephalitis is a potentially treatable disorder involving seizures as the most predominant presentation at admission. It should be considered as a possible diagnosis in middle-aged and older patients with refractory new-onset epilepsy.