Short communicationReduplicative paramnesia in Morvan's syndrome
Introduction
Voltage gated potassium channel antibody (VGKC ab)-associated disorders present with a variety of clinical manifestations, including cognitive disturbances with or without signs of peripheral nervous system hyperexcitability (myokymia and neuromyotonia). Morvan's syndrome refers to peripheral nervous system hyperexcitability, subacute encephalopathy, hallucinations, sleep disturbance, and dysautonomia [1], [2], [3]. Non-paraneoplastic limbic encephalitis associated with VGKC ab without peripheral nervous system hyperexcitability has also been described, and usually presents with seizures, encephalopathy, and hyponatremia [1], [2], [4]. Unlike paraneoplastic limbic encephalitis, which usually has a poor prognosis, VGKC ab-related syndromes are potentially responsive to immunomodulatory therapies; corticosteroids, intravenous immunoglobulin (IVIG), and plasmapheresis have resulted in improved cognitive function [1], [2], [4], [5].
Reduplicative paramnesia (RP), a delusional misidentification syndrome characterized by the belief that a place has been reduplicated and the replica exists at another site [6], [7], [8], [9], [10], [11], has not been described with VGKC ab disorders. We describe a man with RP in the setting of VGKC-ab positive Morvan's syndrome.
Section snippets
Case report
A 64-year-old man presented with the belief his home had been reduplicated, confusion, diffusely abnormal muscle movements, parasomnia with vivid dreams, limb parathesias, and 35-pound weight loss. He specifically denied hyperhydrosis although he felt increasingly intolerant of cold and noted frequent subjective fever. He described eight years of muscle cramping that had started in his feet and calves. Three months before presentation, he had an acute ill-defined episode of joint pain and
Comment
We describe a patient with immunotherapy-responsive RP in the setting of VGKC-ab positive Morvan's syndrome. VGKC abs have been implicated in both peripheral and central nervous system disturbances [1], [2], [18]. VGKC ab-associated encephalopathy with or without peripheral nerve hyperexcitibility produces a range of cognitive and behavioral disturbances [1], [3], [4], [19], [20], [21], [22], [23], [24], [25], [26] (Table 2), but RP has not been reported.
The lesion localization responsible for
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