Autoantibody-induced encephalitis

Abstract

Neurologists often encounter encephalitis caused by unknown agents. Autoantibody-induced encephalitis is a new and exciting group of disorders that must be considered in the differential diagnosis as they are reversible if treated early in the course of the disease, but fatal if unrecognized. We describe the first report from the Indian subcontinent of three rare cases of different autoantibody-induced disorders, which were successfully managed with immunosuppressive therapy resulting in a good clinical outcome. Case 1 was a young woman with anti-N-methyl-D-aspartate (NMDA) receptor encephalitis, not associated with tumor, who showed significant improvement with Rituximab. NMDA receptor encephalitis occurs typically in young females with psychiatric features, followed by an altered level of consciousness, dysautonomia, hyperkinetic movement disorder, seizures, and hypoventilation. Rituximab, which aims to suppress antibody production is an effective treatment modality. Anti-voltage-gated potassium channel antibodies (anti-VGKC-Ab) cause hyperexcitability of the peripheral nerve and central nervous system. Case 2 was a patient of limbic encephalitis presenting with complex partial seizures responding dramatically to steroids. Anti-VGKC-Ab-associated limbic encephalopathy is considered to be an autoimmune, non-paraneoplastic, potentially treatable encephalitis. The clinical features of anti-VGKC-Ab-associated limbic encephalitis are: Subacute onset of episodic memory impairment, disorientation, and agitation. Case 3 presented with Morvan's fibrillary chorea. Peripheral nerve hyperexcitability is the chief manifestation of the Morvan syndrome or cramp-fascilulation syndrome. The Morvan syndrome is characterized by neuromyotonia with autonomic and central nervous syndrome (CNS) involvement. Both VGKC-Ab-associated limbic encephalitis and Morvan syndrome can be successfully treated. Therefore, when these diseases are suspected, it is important to measure the anti-VGKC-Ab level.