Abstract Details

Title Peripheral Nerve Hyperexcitability Syndromes: a Single Center Experience.

Topic Autoimmune Neurology

Presentation(s) P2 - Poster Session 2 (5:30 PM-6:30 PM)

Poster/Presentation
Number 15-099

Objective To describe the clinical characteristics and associated antibodies in patients with acquired peripheral nerve hyperexcitability syndromes (aPNHSs).

Background aPNHSs include neuromyotonia (NMT) and cramp-fasciculation syndrome (CFS) and can be associated with central nervous system (CNS) involvement.

Design/Methods We reviewed patients with electrophysiologically confirmed aPNHSs seen in our Institution between 1998 and 2018. Serum samples from these patients were tested for Lgi1-IgG and Caspr2-IgG by cell-based assays (CBA). In addition, 12 samples were tested for neural autoantibodies (NAbs) by immunohistochemistry on mouse brain.

Results Our series includes 19 patients (six females, 32%) with age of onset ranging 22-75 years (median: 49.5). Eleven out of 19 (58%) patients were diagnosed with NMT. All these patients experienced widespread fasciculations and muscle cramps, 5/11 (45%) complained of hyperhidrosis, 4/11 (36%) had CNS involvement as limbic encephalitis (1), Morvan syndrome (1) and sleep disorders (2). Ten out of 11 patients (91%) were also affected by thymoma-associated myasthenia gravis (MG). Autoantibodies to Caspr2 were found in 2/11 (18%), two additional patients (18%) had Lgi1 and Caspr2 antibodies. Five out of 7 NMT patients negative on CBA were found positive for NAbs targeting unclassified antigens (UNCA) at immunohistochemistry.
Eight patients were diagnosed with CFS; seven (88%) complained of fasciculations and five (63%) of muscle cramps. These patients were all negative for Lgi1- and Caspr2-IgG; NAbs against UNCA were found by immunohistochemistry in a single case. Lung adenocarcinoma was present in two patients.
The detection rate of NAbs was significantly higher in NMT than CFS (p=0.0182), along with a higher frequency of thymoma, MG and CNS involvement.

Conclusions Our data confirms the low prevalence of NAbs in patients with CFS. On the other hand, in NMT antibody profiling contributes to clinical characterization, even though a substantial proportion of these patients harbor antibodies against antigens that need to be defined.

Authors/Disclosures
Gregorio Spagni PRESENTER	Gregorio Spagni has nothing to disclose.
Raffaele Iorio, MD (Catholic University)	Dr. Iorio has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Alexion. Dr. Iorio has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Argenx. Dr. Iorio has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for UCB. Dr. Iorio has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Dianthus Therapeutics. Dr. Iorio has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Johnson & Johnson. Dr. Iorio has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Amgen. Dr. Iorio has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Alexion. Dr. Iorio has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Argenx. Dr. Iorio has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Johnson&Johnson.
Valentina Damato (University of Florence)	Valentina Damato has nothing to disclose.
Amelia Evoli, MD (Catholic University, Neuroscience Dept)	No disclosure on file

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