%0 Journal Article
%T Acquired neuromyotonia in thymoma-associated myasthenia gravis: a clinical and serological study.
%A Gastaldi M
%A De Rosa A
%A Maestri M
%A Zardini E
%A Scaranzin S
%A Guida M
%A Borrelli P
%A Ferraro OE
%A Lampasona V
%A Furlan R
%A Irani SR
%A Waters P
%A Lang B
%A Vincent A
%A Marchioni E
%A Ricciardi R
%A Franciotta D
%J Eur J Neurol
%V 26
%N 7
%D 07 2019
%M 30714278
%F 6.288
%R 10.1111/ene.13922
%X Acquired neuromyotonia can occur in patients with thymoma, alone or in association with myasthenia gravis (MG), but the clinical prognostic significance of such comorbidity is largely unknown. The clinico-pathological features were investigated along with the occurrence of neuromyotonia as predictors of tumour recurrence in patients with thymoma-associated myasthenia.<BR>A total number of 268 patients with thymomatous MG were studied retrospectively. Patients with symptoms of spontaneous muscle overactivity were selected for autoantibody testing using immunohistology for neuronal cell-surface proteins and cell-based assays for contactin-associated protein 2 (CASPR2), leucine-rich glioma inactivated 1 (LGI1), glycine receptor and Netrin-1 receptor antibodies. Neuromyotonia was diagnosed according to the presence of typical electromyography abnormalities and/or autoantibodies against LGI1/CASPR2.<BR>Overall, 33/268 (12%) MG patients had a thymoma recurrence. Five/268 (2%) had neuromyotonia, four with typical autoantibodies, including LGI1 (n = 1), CASPR2 (n = 1) or both (n = 2). Three patients had Netrin-1 receptor antibodies, two with neuromyotonia and concomitant CASPR2+LGI1 antibodies and one with spontaneous muscle overactivity without electromyography evidence of neuromyotonia. Thymoma recurrence was more frequent in those with (4/5, 80%) than in those without (28/263, 10%, P < 0.001) neuromyotonia. Neuromyotonia preceded the recurrence in 4/5 patients. In univariate analysis, predictors of thymoma recurrence were age at thymectomy [odds ratio (OR) 0.95, 95% confidence interval (CI) 0.93-0.97], Masaoka stage ≥IIb (OR 10.73, 95% CI 2.38-48.36) and neuromyotonia (OR 41.78, 95% CI 4.71-370.58).<BR>De novo occurrence of neuromyotonia in MG patients with previous thymomas is a rare event and may herald tumour recurrence. Neuronal autoantibodies can be helpful to assess the diagnosis. These observations provide pragmatic risk stratification for tumour vigilance in patients with thymomatous MG.