A case study: Therapeutic plasma exchange in voltage-gated potassium channel autoimmune encephalitis.

INTRODUCTION: Neurological syndromes associated with voltage-gated potassium channels (VGKC) affect the nerve and muscle physiology. Presence of antibodies to VGKC are associated with three main neurologic syndromes namely neuromyotonia (NMT), limbic encephalitis (LE) and Morvan's syndrome(MVS) LE is a variably treatable neurologic syndrome associated with high levels of antibodies to the voltage-gated potassium channel (VGKC) complex. These antibodies are directed against protein antigens that bind to the VGKC complex. These antigens are usually leucine-rich, glioma inactivated 1 (LGI1), and contactin associated protein-like 2 (CASPR2).

CASE DESCRIPTION: A 58-year-old female and with a known case of auto immune encephalitis (voltage gated potassium channel) and steroid induced diabetes mellitus presented with progressive worsening of vertigo, recurrent myoclonic jerks and post ictal confusion for last 7 days. She had memory impairment since last few months. She was on treatment with steroids which were gradually tapered off 11 months back. CSF was tested for presence of VGKC antibodies and the test was positive for LGI (leucine-rich glioma inactivated 1) antibody. Therapeutic plasma exchange (TPE) was scheduled every day for 6 consecutive days based upon the recommendations from the ASFA guidelines for the treatment of neurologic syndromes.

CONCLUSION: TPE done every day in patient diagnosed LE with VGKC antibodies had shown rapid improvement in controlling the symptoms.