CASPR2 antibody-related movement disorders: case series

Introduction Contactin-associated protein 2 (CASPR2) antibodies are implicated in the development of a spectrum of neurological conditions where movement disorders constitute a substantial part of the clinical manifestations along with behavioral and cognitive impairment. Case report We report a case series of three patients presenting with a variety of clinical phenotypes associated with choreoathetoid movement disorder, camptocormia and myoclonus. All three patients, in addition to motor manifestations, exhibited a degree of cognitive impairment. One patient was severely debilitated with florid choreoathetoid movements and prominent behavioral disturbance impacting upon daily living. In the other two patients, worsening camptocormia and myoclonus resulted in the loss of ambulation. Their atypical clinical manifestations necessitated an extensive diagnostic workup with the exclusion of neurodegenerative and paraneoplastic causes. Not uncommonly, the possibility of a functional neurological disorder was also raised. The diagnosis was reached with the detection of CASPR2 antibodies in serum and CSF. The causative relationship between CASPR2-antibodies and the clinical manifestations was further substantiated by the good response to immunological therapies including steroid treatment, intravenous immunoglobulin and therapeutic plasma exchange. Conclusion The spectrum of CASPR2-associated movement disorders continues to rapidly expand. Increased awareness amongst clinicians is necessary for a timely diagnosis and treatment initiation.