B-082 Diagnostic and Clinical Characteristics of Neuroimmune Markers in a Tertiary Care Hospital
Authors: Das B , Mandani M , Bhatt M , Mani J , Aggarwal A , Raut T 
Published: September 2023

Abstract

Background
Neuroimmune disorders are a complex group of inflammatory conditions of the nervous system and remarkable discoveries over the last two decades have elucidated the autoimmune basis of several, previously poorly understood, neurological disorders. Autoimmune Encephalitis has been linked to a wide variety of neuronal autoantibodies targeting both intracellular and plasma membrane antigens. Paraneoplastic encephalitis syndromes are often associated with antibodies against intracellular neuronal proteins like anti-Hu, anti-Ri, anti-GAD65 and others and the encephalitis associated with antibodies against neuronal cell surface/synaptic proteins like NMDA and VGKC is referred to as “autoimmune encephalitis.” The diagnosis of these neuroimmune disorders can be challenging due to the wide spectrum of clinical presentations, frequent absence of diagnostic abnormalities on conventional brain MR-imaging and non-specific findings on EEG testing. The importance of early diagnosis and appropriate treatment is paramount. The objective of this study is to examine the diagnostic and clinical characteristics of these disorders with the goals of assisting clinicians in differential diagnosis.

Methods
This study took place from January 2016 to January 2023, at Kokilaben Dhirubhai Ambani Hospital and Research Centre, Mumbai, Maharashtra. We reviewed the laboratory records in our hospital to identify patients diagnosed with positive anti-NMDA receptor antibody, VGKC antibodies like LG1, CASPR2, GABBAR B1/B2, AMPA1, and AMPA2, positive NMO and MOG antibodies and also for antibodies against intracellular antigens like anti-Ri, anti-Hu. Inclusion criteria were adults and adolescents (aged 12–90 years) and pediatric population was excluded. The cohort was categorized into four groups according to different antibodies: NMDA group, VGKC group, NMO-MOG and paraneoplastic groups. Each cohort was further divided into two groups : Group I (positive patients) and Group II (negative patients) and their clinical characteristics were compared.

Results
A total of 650 patients aged from 12–90 years for whom NMDA, VGKC, NMO-MOG and paraneoplastic antibody testing was requested were identified for this retrospective study. Prominent differences became apparent when comparing the basic demographic variables, age and gender. Positive rate for autoimmune encephalitis was found to be 6.82% and for NMO-MOG antibodies, it was found to be 11.11 %. Most common synaptic autoimmune encephalitis was associated with LG1 (55%), followed by NMDA (27 %). Most common onco-neuronal paraneoplastic encephalitis series were GAD65, Yo and Zic. Clinical features, MRI and EEG findings have been evaluated in all groups.

Conclusion
Neuroimmune disorders are a complex group of inflammatory conditions and the clinical presentations and features are highly diverse and largely dependent on the particular neuronal antibodies. Focal seizures were the common symptom associated with anti-NMDA and anti-VGKC positive patients, whereas difficulty walking and lower limb weakness was the most common presentation associated with paraneoplastic antibodies. Autonomic stability and neoplastic etiologies were not noted in synaptic autoimmune encephalitis but were seen in paraneoplastic encephalitis. Patients with MOG antibodies also were found to have neoplastic etiologies and blurring of vision was the most prevalent symptom noted. Earlier recognition and treatment of these disorders can lead to improved outcomes and reduced disability.