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

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.

Autonomic nervous system involvement in autoimmune encephalitis and paraneoplastic neurological syndromes

In autoimmune neurological diseases, the autonomic nervous system can be the primary target of autoimmunity (e.g. autoimmune autonomic ganglionopathy), or, more frequently, be damaged together with other areas of the nervous system (e.g. Guillain-Barré syndrome). Patients with autoimmune encephalitis and paraneoplastic neurological syndromes (PNS) often develop dysautonomia; however, the frequency and spectrum of autonomic signs and symptoms remain ill defined except for those scenarios in which dysautonomia is a core feature of the disease. Such is the case of Lambert-Eaton myasthenic syndrome, Morvan syndrome or anti-NMDAR encephalitis; in the latter, patients with dysautonomia have been reported to carry a more severe disease and to retain higher disability than those without autonomic dysfunction. Likewise, the presence of autonomic involvement indicates a higher risk of death due to neurological cause in patients with anti-Hu PNS. However, in anti-Hu and other PNS, as well as in the context of immune checkpoint inhibitors' toxicities, the characterization of autonomic involvement is frequently overshadowed by the severity of other neurological symptoms and signs. When evaluated with tests specific for autonomic function, patients with autoimmune encephalitis or PNS usually show a more widespread autonomic involvement than clinically suggested, which may reflect a potential gap of care when it comes to diagnosing dysautonomia. This review aims to revise the autonomic involvement in patients with autoimmune encephalitis and PNS, using for that purpose an antibody-based approach. We also discuss and provide general recommendations for the evaluation and management of dysautonomia in these patients.

Anti-contactin-associated protein-like 2 antibody autoimmune encephalitis with rapidly progressive parkinsonism: a case report and literature review

OBJECTIVE

Anti-contactin-associated protein-like 2 (CASPR2) antibody encephalitis is a rare autoimmune encephalitis (AE) that often presents with epilepsy, cognitive dysfunction, peripheral neuropathy, autonomic nerve damage, and ataxia. Parkinsonism is often observed in neurodegenerative diseases but progresses slowly, and rapidly progressive parkinsonism is rare. Given that it is a curable parkinsonism, identifying and providing early immunotherapy is crucial.

METHODS

We reported a patient initially presenting with anxiety and depression, whose symptoms were relieved following mood regulation treatment. After discontinuation of the mood-regulating drugs, mood disorders recurred, accompanied by parkinsonism. The onset of parkinsonism was subacute (< 3-month disease course), and progression was rapid. After immunotherapy, all symptoms disappeared completely. We reviewed all relevant literature on anti-CASPR2 antibody encephalitis with parkinsonism.

RESULTS

Our literature review revealed three cases (including our patient): two male and one female, ranging in age from 48 to 72 years. All patients had parkinsonism, generalized tonic-clonic seizures, and hyponatremia. Three patients had anti-CASPR2 antibody positivity in the serum, and one patient had anti-CASPR2 antibody positivity in the CSF. All three patients were treated with anti-epileptic drugs and intravenous steroid pulse therapy, followed by oral steroid therapy, symptoms improved.

CONCLUSION

Parkinsonism can be easily misdiagnosed as a neurodegenerative disease, especially during the early stages. In patients with parkinsonism, treatable diseases should be considered in addition to neurodegenerative diseases. In clinical practice, anti-CASPR2 antibody encephalitis should be considered if rapidly progressing parkinsonism is encountered after ruling out common etiologies.

Distinct phenotypes in a cohort of anti-CASPR2 associated neurological syndromes

INTRODUCTION

Anti-contactin-associated protein-like 2 (CASPR2) is classically associated with limbic encephalitis (LE), Morvan syndrome and peripheral nerve hyperexcitability (PNH). Additional clinical features have been previously recognized.

OBJECTIVE

To describe a cohort of patients with anti-CASPR2-associated neurological syndromes from a tertiary referral centre.

METHODS

Retrospective analysis of patients with positive serum anti-CASPR2 antibodies in the period between 2014 and 2021.

RESULTS

Nineteen patients were identified, 11 (57.9%) male, with a median age at symptom onset of 49.0 (31.3-63.0) years and a median time to diagnosis of 1.0 (0.0-1.8) years. The most common clinical syndromes were LE (7 cases, 36.8%), Morvan syndrome (4, 21.1%) and PNH (2, 10.5%). Six patients presented with atypical phenotypes (31.6%), comprising dysautonomia (orthostatic hypotension and Adie's Pupil), motor tics/stereotypies, obsessive-compulsive disorder, and brainstem involvement. The most common presenting symptoms were seizures (31.6%), PNH (21.1%) and cognitive dysfunction (15.8%). One LE patient had a disease duration of 2,5 years and was initially diagnosed with dementia. CSF was normal in most cases. Brain MRI showed temporal lobe hyperintensities in 4 LE cases (57.1%). All PNH cases had myokymic discharges of fasciculations in the electromyography. Two patients had associated thymoma and 1 had lung adenocarcinoma. Eight patients (42.1%) received treatment during the acute phase and 26.3% maintenance treatment. Approximately half of the treated cases improved or stabilised, with 4 (21.1%) deaths in the whole cohort.

CONCLUSION

Anti-CASPR2-associated neurological disorders may present with isolated atypical phenotypes, a slowly progressive clinical course, and with normal CSF or imaging findings.

Contactin-associated protein-like 2 antibody-associated autoimmune encephalitis in children: case reports and systematic review of literature

OBJECTIVES

To ascertain the clinical characteristics of pediatric patients with contactin-associated protein-like 2 (CASPR2) antibody-associated autoimmune encephalitis (AEs).

METHODS

Two cases of CASPR2 antibody-associated AEs have been reported. In addition, a systematic search of literature published between January 2010 and March 2022 through six online databases was conducted to identify the pediatric patients with CASPR2 antibody-associated AEs. Data on demographics, clinical symptoms, laboratory examinations, imaging, treatment, and outcome were collected.

RESULTS

Our updated literature search yielded 1,837 publications, of which 21 were selected, and 40 patients in this study met the diagnostic criteria for AE. There were 25 males and 15 females with a mean age of 9.2 years. The most common presenting symptoms are psychiatric symptoms (72.5%), sleep changes (62.5%), and movement disorders (60%). The psychiatric symptoms included mood changes (39.1%), behavior changes (25%), and hallucination (7.5%). In total, 23 cases (57.5%) combined with autonomic dysfunction, such as gastrointestinal dysmotility, cardiovascular-related symptoms, and sweating. No tumors were observed in children. Thirty-eight patients received first-line immunotherapy, and eight received first-line and second-line immunotherapy. All patients had a good clinical response to immune therapy. Mean mRS at onset was 3.4; It was 0.88 at the last follow-up. There was no recurrence during follow-up.

CONCLUSION

Psychiatric symptoms, sleep disorders, movement disorders, and cardiovascular-related symptoms are the most common presentation in pediatric patients with CASPR2 antibody-associated AEs. Tumor, particularly with thymoma, is uncommon in children diagnosed with CASPR2 antibody-associated AEs. In addition, prompt diagnosis and immunotherapy can relieve symptoms and improve the prognosis.

An Unusual Presentation of Dermatomyositis With Muscle Hypertrophy

Peripheral nerve hyperexcitability is a rare disorder characterized by spontaneous motor unit activity. Although peripheral nerve hyperexcitability is seen in multiple immune-mediated neurological conditions, an association with dermatomyositis has rarely been reported. We present a 65-year-old woman with serological and muscle biopsy features of dermatomyositis who also developed marked muscle hypertrophy, stiffness, and delayed relaxation along with electrodiagnostic features of peripheral nerve hyperexcitability such as that seen in Isaacs syndrome.

Autoimmune neuromyotonia

PURPOSE OF REVIEW

Autoimmune neuromyotonia encompasses a group of rare immune-mediated neurological disorders frequently associated with anti-contactin-associated protein-like 2 (CASPR2) antibodies and featuring clinical and electrical signs of peripheral nerve hyperexcitability (PNH). We aim to summarize the current knowledge on immune-mediated neuromyotonia, focusing on clinical presentations, pathophysiology, and management.

RECENT FINDINGS

Neuromyotonia is a major feature of several autoimmune neurological syndromes characterized by PNH with or without central neurological system involvement. Experimental and clinical evidence suggest that anti-CASPR2 antibodies are directly pathogenic in autoimmune neuromyotonia patients.

SUMMARY

Neuromyotonia, a form of PNH, is a major feature in several syndromes associated with anti-CASPR2 antibodies, including cramp-fasciculation syndrome, Isaacs syndrome, Morvan syndrome, and autoimmune limbic encephalitis. Diagnosis relies on the identification of motor, sensory, and autonomic signs of PNH along with other neurological symptoms, anti-CASPR2 antibody-positivity, and of characteristic electroneuromyographic abnormalities. Paraneoplastic associations with thymoma are possible, especially in Morvan syndrome. Patients usually respond to immune-active treatments, including steroids, intravenous immunoglobulins, plasma exchanges, and rituximab.

Neural autoantibodies in delirium

BACKGROUND

Delirium in hospitalized and intensive care unit patients is an emerging condition due to its rapid-onset requiring fast action to mitigate a worse clinical outcome. Although several causes and conditions are known, the association between delirium and neural autoantibodies has often been neglected in cohort studies and reviews as causing delirium. The aim of our review is to delineate the occurrence and type of neural autoantibodies and to depict other biological markers of autoimmunity in relationship to delirium.

METHODS

For this narrative review Pubmed research was done to select articles about delirium and neural autoantibodies.

RESULTS

We can report on several cell-surface autoantibodies such as anti-α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors, anti-contactin associated protein 2, anti-Leucin rich glioma inactivated protein 1, anti-dipeptidyl-peptidase-like 6 protein, anti-glycine receptor and anti-myelin autoantibodies, as well as intracellular autoantibodies such as anti-glutamic acid decarboxylase 65 (GAD65), anti-CV2 and anti-Hu associated with delirium in patients. Our case reports and case series screening revealed that 20 of 63 patients with delirium presented neural autoantibodies, thus revealing a 32% frequency of autoantibody-associated delirium in delirium patients. Our main finding is that delirium's hyperactive form is associated with neural autoantibodies. Diagnosing delirium differentially is difficult, as in patients with delirium and GAD65 autoantibodies, as it must be distinguished from other psychopathological excitation states such as mania. We also describe autoimmune delirium's potential pathophysiologic pathways.

CONCLUSIONS

The existence of neural autoantibodies in delirious patients is scientifically and clinically highly relevant in its diagnosis, therapy, and pathogenesis. More large-scale studies should be conducted to evaluate their significance and prevalence in delirium.