We aim to study the presentation of autoimmune encephalitis (AIE), focusing on diagnostic approach in customising treatment for individual patient. We also highlight the importance of advancements in neuroimmunology (biomarkers) and PET as a radiological marker for severity and prognosis.

Autoimmune encephalitis (AIE) is one of the most common causes of treatable non-infectious encephalitis, which can be acute or subacute onset. It can be triggered by tumours, infections, or it may be cryptogenic. There are myriad of clinical manifestations including behavioural and psychiatric symptoms, autonomic disturbances, movement disorders, and seizures. 

This is an observational study from a tertiary care hospital in India from September 2016 till April 2024.Our study includes seropositive and seronegative autoimmune encephalitis patients fulfilling Graus et al diagnostic criteria. Ancillary testing with MRI, EEG and PET was done for excluding other causes. Autoantibody testing in serum and CSF was done for diagnosis of AIE using cell-based assay and tissue indirect Immunofluorescence.

Total number of patients was 48 with 23 females and 25 males, with age range from 2 years till 80 years. Their clinical phenotypes included altered sensorium, headache, seizures, memory deficits, speech difficulty, movement disorder in the form of dyskinesias.  abnormal carinal MRI and EEG. All patients received immunotherapy treatment with variable response.

Autoimmune encephalitis has emerged as an important diagnosis in patients presenting with progressive neurological disorder.  Clinical suspicion of these disorders remains the cornerstone to their detection coupled with autoimmune biomarkers and imaging studies. The presence of several clinically recognisable syndromes today is described. Early recognition, treatment and escalation of immunotherapy in many of these syndromes can lead to improved outcomes. Present guidelines do not include 18F-FDG PET/CT in their algorithms, with MRI remaining the standard imaging modality. Higher isotope uptake in defined brain areas corresponding to clinical features support inflammatory aetiology.