A case report of Morvan syndrome, the unique clinical pattern of a rare disease

Abstract

Morvan syndrome is a rare autoimmune disorder mediated by antibodies against voltage-gated potassium channels (VGKC) and characterized by the involvement of both the peripheral and central nervous system. We report a case of Morvan syndrome. The patient presented with peripheral nerve hyperexcitability, dysautonomia and neuropsychiatric symptoms. The diagnosis was based on the unique clinical presentation that was highly suggestive of Morvan syndrome and confirmed by positive VGKC antibodies. In this paper we try to highlight the importance of clinical skills in the diagnosis and decision-making concerning the treatment process.

A Rare Phenomenon of Isaacs Syndrome: A Case Report

“…IS can be paraneoplastic; it is most commonly associated with thymomas and small-cell lung cancers [ 9 , 15 ]. In one study, 20% of patients classified with neuromyotonia according to doublet, triplet, or multiplet EMG discharges had thymoma, while 10% had lung cancer.…”

“…These findings provide further implicit evidence for the shared mechanisms between different manifestations of peripheral nerve hyperexcitability and underscore the need to screen patients with this constellation of symptoms thoroughly to rule out underlying neoplasia. While there is no fixed guideline in this regard, whole-body magnetic resonance imaging (MRI) may be considered an aggressive screening measure [ 9 ]. Chest CT and chest MRI should also be strongly considered in high-risk patients such as elderly smokers with late-onset disease [ 5 ].…”

“…The overlap of antibody targets with several other conditions like Morvan syndrome indicates other targets may be involved in IS etiology. The VGKC transmembrane channel, which is central to the pathology of a large number of cases of Morvan syndrome and IS, complexes with CASPR2, LGI1, and contactin-2 proteins [ 2 , 4 , 9 ], with CASPR2 being the most commonly targeted protein [ 9 ]. The widespread localization of LGI1 and CASPR2 in the central nervous system has implications on the pathophysiology of Morvan syndrome as well as the CNS effects seen in some cases of IS; the proteins are very commonly found in the neurons of the thalamus, hypothalamic, locus coeruleus, and the raphe nuclei [ 9 ].…”

“…The VGKC transmembrane channel, which is central to the pathology of a large number of cases of Morvan syndrome and IS, complexes with CASPR2, LGI1, and contactin-2 proteins [ 2 , 4 , 9 ], with CASPR2 being the most commonly targeted protein [ 9 ]. The widespread localization of LGI1 and CASPR2 in the central nervous system has implications on the pathophysiology of Morvan syndrome as well as the CNS effects seen in some cases of IS; the proteins are very commonly found in the neurons of the thalamus, hypothalamic, locus coeruleus, and the raphe nuclei [ 9 ]. The hypothalamic orexin neurons and the locus coeruleus are both involved in the control of arousal, wakefulness, and the sleep cycle; dysregulation of these pathways could explain the insomnia commonly observed in patients [ 9 ].…”

“…The widespread localization of LGI1 and CASPR2 in the central nervous system has implications on the pathophysiology of Morvan syndrome as well as the CNS effects seen in some cases of IS; the proteins are very commonly found in the neurons of the thalamus, hypothalamic, locus coeruleus, and the raphe nuclei [ 9 ]. The hypothalamic orexin neurons and the locus coeruleus are both involved in the control of arousal, wakefulness, and the sleep cycle; dysregulation of these pathways could explain the insomnia commonly observed in patients [ 9 ]. As the locus coeruleus is the synthetic site of norepinephrine, dysregulation in this area could account for the dysautonomia (i.e.…”