Morvan's syndrome-is a pathogen behind the curtain?

Clinicopathological Features in Morvan's Syndrome: An Autopsy Case Study

Morvan's syndrome is a rare, complex autoimmune syndrome comprising peripheral nerve hyperexcitability, dysautonomia, insomnia, and encephalopathy. In this case report, we highlight the clinical and pathological findings of an elderly gentleman who presented to us with clinical features of Morvan's syndrome associated with anti-contactin-associated protein 2 (CASPR-2) antibodies. Histopathology [Figure 3] revealed cortical atrophy with gliosis and mild microglial proliferation. Microglial activation and gliosis were observed in the hippocampus, hypothalamus, and thalamus. Brainstem showed multifocal inflammation. Mild inflammation was observed in the leptomeninges. Morvan's syndrome is an autoimmune disease with antibodies targeted against CASPR within the voltage-gated potassium channel (VGKC) complex. Early diagnosis and treatment play a key role in the management of patients. Most patients show a good response when treated with plasmapheresis and steroids. This patient presented to us late into the illness and succumbed.

Occult bowel cancer presenting as Morvan syndrome

A man in his mid-60s presented with a 3-month history of progressive muscle twitching, agitation, cognitive impairment, insomnia, hyperhidrosis and lower limb pain. He had fasciculations, myokymia, myoclonus, exaggerated startle response and significant postural hypotension. Electrophysiological studies showed evidence of peripheral nerve hyperexcitability with neuromyotonia. Contactin-associated protein-like 2 antibodies (CASPR2) were strongly positive. A diagnosis of Morvan syndrome was made. CT of the chest, abdomen and pelvis was undertaken to identify any occult malignancy, and a large bowel carcinoma in situ was identified and resected. His central nervous system and autonomic symptoms significantly improved following surgery, but neuromyotonia persisted, and this was treated with intravenous immunoglobulins and steroids. Early detection of bowel cancer in this patient enabled curative treatment.

[Rare diseases in the differential diagnosis of myalgia]

Myalgia describes pain in the skeletal muscles. According to the current German clinical guidelines from 2020 (AWMF register number: 030/051), the initial diagnostic assessment consists of the anamnesis, clinical examination, electrophysiological examination and standard laboratory tests. Additional special examinations, such as molecular genetic investigations, special laboratory tests, medical imaging and muscle biopsy are only needed in certain cases. This article focuses on rare neurological diseases that are classically associated with myalgia. In this context etiologically different diseases are considered, whereby some genetically linked diseases (fascioscapulohumeral dystrophy, FSHD, dystrophia myotonica, McArdle's disease, Pompe's disease, limb girdle muscular dystrophy) are contrasted with diseases with an (auto)immune-related pathogenesis (stiff-person syndrome, Isaacs syndrome). The aspects relevant for the diagnosis are particularly highlighted. The therapeutic aspects of the diseases are not part of this article.

[Rare diseases in the differential diagnosis of myalgia]

Myalgia describes pain in the skeletal muscles. According to the current German clinical guidelines from 2020 (AWMF register number: 030/051), the initial diagnostic assessment consists of the anamnesis, clinical examination, electrophysiological examination and standard laboratory tests. Additional special examinations, such as molecular genetic investigations, special laboratory tests, medical imaging and muscle biopsy are only needed in certain cases. This article focuses on rare neurological diseases that are classically associated with myalgia. In this context etiologically different diseases are considered, whereby some genetically linked diseases (fascioscapulohumeral dystrophy, FSHD, dystrophia myotonica, McArdle's disease, Pompe's disease, limb girdle muscular dystrophy) are contrasted with diseases with an (auto)immune-related pathogenesis (stiff-person syndrome, Isaacs syndrome). The aspects relevant for the diagnosis are particularly highlighted. The therapeutic aspects of the diseases are not part of this article.

CASPR2-Related Morvan Syndrome: Autonomic, Polysomnographic, and Neuropsychological Observations

Objective

Morvan syndrome is characterized by central, autonomic, and peripheral hyperexcitability due to contactin-associated protein 2 (CASPR2) antibody. Our objective was to study the clinical spectrum, electrophysiologic, autonomic, polysomnographic, and neuropsychological profile in patients with CASPR2-related Morvan syndrome.

Methods

Serum and CSF samples that were CASPR2 antibody positive from 2016 to 2019 were assessed. Among them, patients with Morvan syndrome diagnosed based on clinical and electrophysiologic basis were included.

Results

Fourteen (M:F = 10:4) patients with Morvan syndrome were included with age at onset of 37.1 ± 17.5 years. The clinical features were muscle twitching (12), insomnia (12), pain (11), paresthesias (9), hyperhidrosis (7), hypersalivation (6), double incontinence (3), spastic speech (2), dysphagia (2), behavioral disturbances (2), seizures (1), and cold intolerance (1). Neurologic examination revealed myokymia (12), hyperactive tendon reflexes (10), and tremor (6). EMG revealed neuromyotonia (12) and increased spontaneous activity (7). Autonomic function tests conducted in 8 patients revealed definite autonomic dysfunction (4), orthostatic hypotension (2), early dysfunction (1), and postural orthostatic tachycardia syndrome (1). Polysomnography findings in 6 patients revealed insomnia (3), absence of deep sleep (1), high-frequency beta activity (1), REM behavior disorder (1), and periodic leg movements (1). Neuropsychological evaluation showed subtle involvement of the left frontal and temporal lobe. Malignancy workup was negative. All patients were treated with steroids. There was complete neurologic resolution in follow-up with persistent neuropathic pain in 5 patients.

Conclusions

This study has contributed to the growing knowledge on CASPR2-related Morvan syndrome. It is important for an increased awareness and early recognition as it is potentially treatable by immunotherapy.

Morvan syndrome associated with LGI1 antibody: a case report

Background

Morvan syndrome (MoS) is a rare autoimmune syndrome associated with antibodies against two kinds of potassium channel proteins, contactin associated protein-like 2 (CASPR2) and leucine-rich glioma inactivated protein 1 (LGI1). MoS patients with only LGI1-antibody seropositivity have rarely been reported. Here, we describe a 64-year-old male MoS patient with only LGI1-antibody seropositivity.

Case presentation

A 64-year-old male patient was referred to our hospital due to limb pain, widespread myokymia, insomnia, constipation, and hyperhidrosis for 1 month. The patient was diagnosed with MoS based on the clinical symptoms and positive LGI1-antibody in serum. He was treated with intravenous immunoglobulin (IVIG), intravenous methylprednisolone followed by oral prednisone, and other drugs for symptomatic relief. Several days later, myokymia and insomnia symptoms improved. After 60 days of follow-up, all the drugs had been stopped for 2 weeks, and the patient achieved complete remission without any medical side effects.

Conclusion

We report the clinical characteristics of a Chinese MoS patient with only LGI1-antibody seropositivity, and further support the view that non-neoplasm MoS patients respond well to immunotherapy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-021-02205-9.

A Patient with Double-Negative VGKC, Peripheral Nerve Hyperexcitability, and Central Nervous System Symptoms: A Postinfectious Autoimmune Disease

Research in the last few years has indicated that most voltage-gated potassium channel- (VGKC-) complex antibodies without leucine-rich glioma-inactivated protein 1 or contactin-associated protein-like 2 antibody specificity lack pathogenic potential and are not clear markers for autoimmune inflammation. Here we report on a patient with double-negative VGKC who developed severe peripheral nerve hyperexcitability, central nervous system symptoms with agitation and insomnia, dysautonomia, and systemic symptoms with weight loss, itch, and skin lesions. The disease started acutely one month after an episode of enteroviral pericarditis and responded well to immunotherapy. The patient is presumed to have developed a postinfectious immunotherapy-responsive autoimmune disease. In the setting of anti-VGKC positivity, it seems likely that anti-VGKC contributed to the pathogenesis of the patient's symptoms of nerve hyperexcitability and that the disease was caused by an acquired autoimmune effect on the neuronal kinetics of VGKC. It is still unknown whether or not there are unidentified extracellular molecular targets within the VGKC-complex, i.e., a novel surface antigen and a pathogenic antibody that can cause affected individuals to develop a peripheral nerve hyperexcitability syndrome. This case highlights the fact that less well-characterized autoimmune central and peripheral nervous system syndromes may have infectious triggers.

COVID-19 in India: Are Biological and Environmental Factors Helping to Stem the Incidence and Severity?

The ongoing Corona virus (COVID-19) pandemic has witnessed global political responses of unimaginable proportions. Many nations have implemented lockdowns that involve mandating citizens not to leave their residences for non-essential work. The Indian government has taken appropriate and commendable steps to curtail the community spread of COVID-19. While this may be extremely beneficial, this perspective discusses the other reasons why COVID-19 may have a lesser impact on India. We analyze the current pattern of SARS-CoV-2 transmission, testing, and mortality in India with an emphasis on the importance of mortality as a marker of the clinical relevance of COVID-19 disease. We also analyze the environmental and biological factors which may lessen the impact of COVID-19 in India. The importance of cross-immunity, innate immune responses, ACE polymorphism, and viral genetic mutations are discussed.

Efficacy of Tocilizumab in Limbic Encephalitis with Anti-CASPR2 Antibodies

We report the case of a 64-year-old man who presented with subacute memory, balance impairment, behavioral and mood changes, and epileptic seizures. Magnetic resonance imaging (MRI) showed bilateral hippocampal abnormalities. Brain [¹⁸F]-FDG fluorodeoxyglucose positron emission tomography (PET) revealed hypometabolism in both the temporal lobe as well as in the left insular and parietal regions. The clinical and neuroradiological picture and the detection of anti-CASPR2 antibodies in serum oriented the diagnosis towards autoimmune limbic encephalitis. Intravenous high-dose steroid and immunoglobulin treatments were ineffective. We did not use rituximab for the presence of antibodies to HbcAg positivity. Tocilizumab given intravenously 8 mg/kg once a month for six months and then subcutaneously 162 mg every week for six months resulted in clinical and neuroradiological improvement. These data support the efficacy of tocilizumab in autoimmune limbic encephalitis associated with anti-CASPR2 antibodies, which has been sporadically reported in the literature.

Morvan's syndrome treated successfully with rituximab and lacosamide

We describe a woman with both central and peripheral nervous system symptoms consistent with Morvan's syndrome who was successfully treated with immunosuppression including rituximab and the new antiepileptic drug lacosamide against peripheral nerve hyperexcitability. Despite being over 8 months in hospital and 4 months in an intensive care unit she recovered fully. It is also the first case where cerebrospinal fluid neurofilament-light (NfL) levels were followed during the disease course. The clinical course resembled that of anti-NMDA receptor encephalitis, where patients often recover surprisingly well despite severe symptoms and an extensive time in intensive care. A possible explanation is the comparatively low levels of NfL, indicating disease processes that are not characterised by extensive neuroaxonal degeneration.