From the Guidelines
Morvan's syndrome is a rare autoimmune disorder characterized by peripheral nerve hyperexcitability, encephalopathy, and autonomic dysfunction, often associated with CASPR2 antibodies, and requires prompt immunotherapy to improve outcomes. The condition typically presents with muscle twitching (myokymia), cramps, excessive sweating, insomnia, hallucinations, and confusion, as reported in a study published in the Journal of Neurology, Neurosurgery and Psychiatry 1. Key features of Morvan's syndrome include:
- Encephalopathy
- Peripheral nerve hyperexcitability
- Dysautonomia
- Association with thymoma
- Presence of CASPR2 antibodies Treatment usually involves immunotherapy, including corticosteroids, intravenous immunoglobulin (IVIG), and plasma exchange, as well as symptomatic treatment with anticonvulsants and benzodiazepines, as suggested by guidelines for recognition of neuronal surface antibody associated syndromes 1. It is essential to screen for underlying malignancies, particularly thymoma, upon diagnosis, and to consider long-term maintenance therapy to prevent relapse, as the pathophysiology involves antibodies disrupting potassium channel function, leading to neuronal hyperexcitability in both central and peripheral nervous systems. The prognosis is generally good with prompt treatment, but the condition can be severe and refractory in some cases, requiring additional therapies like rituximab or cyclophosphamide, as indicated by the study on central nervous system neuronal surface antibody associated syndromes 1.
From the Research
Definition and Characteristics of Morvan's Syndrome
- Morvan's syndrome is a rare autoimmune disorder characterized by peripherally innervated hyperexcitability, autonomic disturbances, and encephalopathic encephalopathy 2.
- It is marked by symptoms such as neuromyotonia, myotonia, neuropathic pain, hyperhidrosis, severe constipation, and severe sleep disturbances accompanied by dream reenactments, agrypnia agitation, and delusions 2.
- The syndrome is associated with autoantibodies to voltage-gated and potassium channel complexes, such as anti-contactin-associated protein-like 2 (Caspr2) antibody 2, 3 and leucine-rich glioma inactivated protein 1 (LGI1) antibody 4.
Clinical Presentation and Diagnosis
- Morvan's syndrome can present with multiple asynchronous fasciculations of the long muscles, weakness, pruritus, hyperhidrosis, insomnia, and delirium 5.
- The diagnosis is based on clinical symptoms and laboratory findings, including the presence of autoantibodies such as Caspr2 or LGI1 2, 3, 4.
- The syndrome can be associated with other conditions, such as myasthenia gravis 3 or B-cell lymphoma 5.
Treatment and Management
- Treatment options for Morvan's syndrome include immunologic therapies such as corticosteroids, intravenous immunoglobulins, plasma exchanges, azathioprine, cyclophosphamide, rituximab, or carbamazepine, gabapentin, and clonazepam 2.
- Therapeutic plasma exchange (TPE) has been found to be an effective mode of treatment for this disease 6.
- Traditional Chinese medicine (TCM) has also been used as a complementary and alternative medicine, with reported improvement in symptoms and quality of life 2.
- Immunotherapy has been shown to be effective in reducing symptoms and autoantibody levels in some patients 3, 4.