Morvan Syndrome

Excerpt

Morvan syndrome or Morvan’s fibrillary chorea (MFC) is a rare constellation of neurological symptoms, consisting of peripheral nerve hyperexcitability, autonomic instability, and encephalopathy often associated with autoantibodies to voltage-gated potassium channel complexes (VGKCs).

On 12 April 1890, the French physician, Dr. Augustine Marie Morvan first published a novel description of this neurological syndrome in La Gazette Hebdomadaire de Medecine et de Chirurgie. He called it “la choree fibrillaire,” which we now know as Morvan syndrome. There have been approximately 60 cases published in the French and other literature but only a few in English literature since then. See table 1 in media section at the end of this script for a review and comparison of the varied clinical features and clinical outcomes in 20 such cases reported in English literature. As per table 1, Morvan syndrome is predominantly a male-dominant entity with a male to female ratio of 19 to 1. The only female case was a rheumatoid arthritis patient on gold therapy who developed mild Morvan syndrome features, and whose condition reverted once treatment was discontinued. Insomnia, hyperhidrosis, dysautonomia, and myokymia were consistent findings noted in 100% (all 20) of the patients. Whereas, hallucinations were seen in 75% (15) of the patients and anti-voltage-gated potassium channel antibodies (VGKC) were observed in 45% (9) of the patients. Another very consistent finding was the conspicuous absence of seizures in 100% (all 20) of the cases and benign findings on MRI in 100% (all 20) in contrast to Limbic encephalitis where seizures and temporal lobe structural abnormalities on MRI are classic findings. Myokymia was seen in 100% (all 20) of the patients, and it was confirmed in most 80%(16) cases with EMG studies which showed spontaneous, either repetitive or continuous muscle activity in the form of fasciculations which were a combination doublet, triplet, multiplet, or neuromyotonic discharges. Other sporadic findings were elevated manganese levels in 5% (1), oligoclonal bands in cerebrospinal fluid (CSF) in 15% (3), thymoma in 40% (8), Acetylcholine receptor (AchR) antibodies in 30% (6) of patients. However, AchR antibodies in association with myasthenic features were seen in only 10% (2) of the patients. Twenty percent (4) of the patients had AchR antibodies without myasthenic features. Treatment modalities tried with varied effectiveness were thymectomy in 25% (5), anticonvulsant therapy in 45% (9), immunosuppression in 50% (10), and IVIG in 20% (4) of the patients. The most effective treatment was plasma exchange which was tried in 55% (11) of the patients, all of whom except one patient showed dramatic improvement. Treatment effectiveness was even more significant when immunosuppression and plasma exchange was tried together. Death was the outcome in only 20% (4) of the patients.