Paraneoplastic nerve hyperexcitability

Objectives: To provide an overview of paraneoplastic nerve hyperexcitability syndromes. Methods: An extensive review of the literature on nerve hyperexcitability was performed. Particular attention was paid to Isaacs’ syndrome and Morvan’s syndrome, as well as their relationship to neoplasia. Results: An overview of the history, clinical manifestations (including neurophysiologic findings), pathophysiology, and management is presented. Clinical differences between the exclusively peripheral nervous system involving Isaacs’ syndrome and Morvan’s syndrome, which also involves the central nervous system (CNS) are detailed. The role of immune-mediated dysfunction of specific components of the voltage-gated potassium channel (VGKC) complex in the pathophysiology of these syndromes is explained. Finally, the limited data on management of these syndromes, including the use of antiepileptic and immunomodulatory therapies are discussed. Conclusion: Nerve hyperexcitability syndrome represents a spectrum of neuroimmunologic diseases, which are often paraneoplastic in etiology.