Video NeuroImages: Paraneoplastic spinal myoclonus associated with Caspr2 antibodies

Abstract

A 42-year-old man with thymoma-associated myasthenia gravis presented with 6 weeks of abnormal leg movements. Examination revealed myoclonus in the legs bilaterally (video, [links.lww.com/WNL/A322][1]). Chest CT showed recurrence of metastatic thymoma. MRI spine revealed nonspecific hemosiderin deposition at the T9 level without metastases or vascular malformation. EMG demonstrated right leg and rectus abdominus myoclonus up to T6, most prominently at T9-L1 (figure). Serum anti-contactin-associated protein-like 2 (Caspr2) antibodies were positive. Chemotherapy led to resolution of the myoclonus. Caspr2 antibodies have been associated with limbic encephalitis and neuromyotonia,1,2 but our patient showed unusual Caspr2-associated spinal myoclonus. [1]: http://links.lww.com/WNL/A322