Anti-LGI1 Encephalitis Developing Immunoglobulin Responsive Orthostatic Hypotension after Remission

Abstract

Anti-leucine-rich glioma-inactivated 1 (LGI1) antibody is associated with limbic encephalitis. We herein report a patient with anti-LGI1 encephalitis who developed severe orthostatic hypotension (OH) responsive to immunoglobulin therapy five years after developing symptoms of encephalitis. A 71-year-old man presented with amnesia caused by limbic encephalitis. The symptoms of encephalitis improved partially without any immunotherapy. Five years later, he developed severe OH, and anti-LGI1 antibody was positive. The catecholamine dynamics indicated that the central autonomic nervous system was the lesion of his OH. Intravenous immunoglobulin therapy improved the OH. This case suggests that anti-LGI1 antibody can be associated with severe OH.

Keywords: autonomic dysfunction; leucine-rich glioma-inactivated 1 (LGI1); limbic encephalitis; orthostatic hypotension (OH); tilt test; voltage-gated potassium channel (VGKC).

Figure 1.

Brain imaging. Radiological findings of encephalitis (a, b) and five years after remission (c, d). During encephalitis, MRI showed FLAIR hyperintensity at the bilateral medial temporal lobes (a), and ¹²³IMP-SPECT showed an increase in blood flow at the left medial temporal lobe (b). MRI five years after remission showed diminished signal abnormality and slight atrophy of the affected area (c). No increased blood flow was observed on ¹²³IMP-SPECT (d). FLAIR: fluid-attenuated inversion recovery, ¹²³IMP-SPECT: N-isopropyl-p-[¹²³I] iodoamphetamine single photon emission computed tomography, MRI: magnetic resonance imaging

Figure 2.

The tilt test before and after intravenous immunoglobulin (IVIg) therapy. The patient was placed in the supine position for 15 min before the tilt test. The head side of the table was raised every 5 min to 15°, 30°, 45°, 60°, and 80°, and then restored to the horizontal position. To analyze NA and AVP, blood samples were obtained every 5 min just before changing positions and 10 min after restoring the flat position. In the resting position, the BP, NA, and AVP values were within normal limits. However, before treatment and while raising the head, his BP dropped remarkably, and he felt nauseous and nearly fainted; the NA and AVP levels increased as the BP decreased. When he returned to the flat position, rebound hypertension was observed. After treatment, his systolic BP did not decrease below 80 mmHg, and he did not feel nauseous. The increases in the NA and AVP levels were larger than those before treatment. AVP: arginine vasopressin, BP: blood pressure, HR: heart rate, IVIg: intravenous immunoglobulin, NA: noradrenaline