Autoimmune encephalitis: Clinical diagnosis versus antibody confirmation

Autoimmune encephalitis is a heterogeneous disorder which is being diagnosed with increasing frequency. The diagnosis of these disorders is based on the detection of autoantibodies and characteristic clinical profiles.

We aimed to study the antibody profile in encephalitis patients with suspected autoimmune etiology presenting to a tertiary care center.

The subjects were selected by screening all patients with clinical profile suggesting autoimmune encephalitis admitted in the neuromedical intensive care unit (ICU) of a tertiary care center in South India.

Patients who fulfilled modified Zuliani et al.'s, criteria for autoimmune encephalitis were identified during the period December 2009-June 2013. Blood samples from these subjects were screened for six neuronal antibodies.

Chi-square test was applied to compare the antibody positive and negative patients.

Out of 1,227 patients screened, 39 subjects (14 males: 25 females) were identified with a mean age of 15.95 years and 19 cases were assessed in the acute and 20 in the convalescent phase of the illness. Seizure (87.8 %) was the most common presenting symptom; status epilepticus occurred in 23 (60.5%) patients during the course of the illness. Fourteen (35.9%) patients were N-methyl-D-aspartate receptor (NMDAR) antibody-positive and all were negative for the other antibodies tested.

One-third of patients presenting with acute noninfective encephalitis would be positive for NMDAR antibodies with the remaining two-thirds with clinically suspected autoimmune encephalitis being antibody-negative. There are few markers in the clinical and investigative profiles to distinguish antibody-positive and -negative patients.