Insomnia and Dysautonomia with Contactin-Associated Protein 2 and Leucine-Rich Glioma Inactivated Protein 1 Antibodies: A “Forme Fruste” of Morvan Syndrome?

Abstract

Morvan syndrome (MoS) is typically characterized by neuromyotonia, sleep dysfunction, dysautonomia, and cognitive dysfunction. However, MoS patients with mild peripheral nerve hyperexcitability (PNH) or encephalopathy features have been described. A 46-year-old woman presented with a 2-month history of constipation, hyperhidrosis, and insomnia. Neurologic examination revealed muscle twitching and needle electromyography showed myokymic discharges in all limbs. No clinical or electrophysiological features of neuromyotonia were present. Although the patient denied any cognitive symptoms, neuropsychological assessment revealed executive dysfunction, while other cognitive domains were preserved. Cranial and spinal MRIs were unrevealing and tumor investigation proved negative. Polysomnography examination revealed total insomnia, which was partially reversed upon immune-modulatory therapy. Investigation of a broad panel of antibodies revealed serum leucine-rich glioma inactivated protein 1 and contactin-associated protein 2 antibodies. The features of this case indicate that the presentation of PNH syndromes may show significant variability and that MoS patients may not necessarily exhibit full-scale PNH and encephalopathy symptoms.

Morvan syndrome: Unravelling the engimatic neurological disorder and its immunomodulatory management

“…Peripheral nerve hyperexcitability is characterized by cramps, fasciculations, as well as neuromyotonic and myokymic discharges on needle electromyography. 3 There are several reports suggesting that Morvan syndrome may be closely associated with ayurvedic drug intake leading to heavy metal toxicity. 4 Mercury poisoning can present with a clinical picture similar to Morvan syndrome.…”