Adult-onset drug-refractory seizure disorder associated with anti-voltage-gated potassium-channel antibody

Abstract

Voltage-gated potassium channels are widely expressed throughout the entire nervous system. These channels play a critical role in establishing the resting membrane potential and generation of neuronal action potentials. There is mounting evidence that autoantibodies reactive to neuronal cell surface antigens, such as voltage-gated potassium channels, play a pathogenic role in a wide spectrum of central and peripheral nervous system disorders. We report a case of new-onset drug-refractory seizure disorder associated with the presence of high levels of serum anti-voltage-gated potassium channel antibodies that responded only to immunotherapy. As demonstrated by this case report, anti-voltage-gated potassium channel antibody associated drug-refractory seizure disorder, although rare, should be considered in patients with unexplained adult-onset seizure activity. Once the diagnosis has been established the initiation of immunotherapy should be undertaken without delay.

Figure 1

MR imaging of the medial temporal and frontal lobes of the brain three weeks after onset of seizure activity. A–C) Coronal FLAIR, axial FLAIR, and diffusion images demonstrates hyperintensity within the left hippocampus (arrows) without associated reduced diffusion. D–E) Axial FLAIR and diffusion images demonstrate hyperintensity within the bilateral frontal lobes with associated reduced diffusion (arrows).

Figure 2

EEG three weeks after initiation of seizure activity demonstrates complex partial seizure activity in the left temporal lobes with slowing in the left frontal regions.

Figure 3

Pre and post immunotherapy follow up MR imaging. A–C) Pre immunotherapy follow up coronal and axial FLAIR MR imaging eight weeks after initiation of seizure activity shows progression (from the initial MRI at three weeks) of hyperintensity and swelling within the left hippocampus (arrow), bilateral medial temporal lobes (arrow), and bilateral frontal lobes (arrow). D–F) Follow up coronal FLAIR and axial T2 fast spin echo MR images seven weeks after initiation of immunotherapy demonstrates improvement of hyperintensities within the hippocampus, medial temporal, and frontal lobes. Reduction of T2 hyperintensity may be most noticeable by comparing image B to E. Unfortunately, an axial FLAIR sequence was not acquired on post-immunotherapy follow-up MRI.