Morvan's syndrome

Morvan's syndrome
Specialty	Neurology
Symptoms	Morvan's fibrillary chorea

Morvan's syndrome is a rare, life-threatening autoimmune disease named after the nineteenth century French physician Augustin Marie Morvan. "La chorée fibrillaire" was first coined by Morvan in 1890 when describing patients with multiple, irregular contractions of the long muscles, cramping, weakness, pruritus, hyperhidrosis, insomnia and delirium.^[1] It normally presents with a slow insidious onset over months to years.^[2] Approximately 90% of cases spontaneously go into remission, while the other 10% of cases lead to death.^[3]

In 1890, Morvan described a patient with myokymia (muscle twitching) associated with muscle pain, excessive sweating, and disordered sleep.^[4] This rare disorder is characterized by severe insomnia, amounting to no less than complete lack of sleep (agrypnia) for weeks or months in a row, and associated with autonomic alterations consisting of profuse perspiration with characteristic skin miliaria (also known as sweat rash), tachycardia, increased body temperature, and hypertension. Patients display a remarkable hallucinatory behavior, and peculiar motor disturbances, which Morvan reported under the term “fibrillary chorea” but which are best described in modern terms as neuromyotonic discharges.^[5]

The association of the disease with thymoma, tumour, autoimmune diseases, and autoantibodies suggests an autoimmune or paraneoplastic aetiology.^[1] Besides an immune-mediated etiology, it is also believed to occur in gold, mercury, or manganese poisoning.^[6]