Hemichorea Associated with CASPR2 Antibody

Abstract

pronounced CT-PET-findings and the history of excessive smoking led us to suspect a smoking-associated lung cancer. However, a histological tissue diagnosis was refused by the patient, as was subsequent oncologic therapy. Second, the isolated pattern of CASPR2 autoantibody positivity is interesting. Only one case of autoimmune chorea with a positive CASPR2 antibody has been reported, and it was an idiopathic case. This is according to a study on autoimmune chorea in adults, 4 in which the case of Ramdhani and Frucht1 can also be grouped. In the paraneoplastic group of autoimmune chorea, CASPR2 has not yet been reported. 4 On the other hand, CASPR2 is more often associated with neuromyotonia and Morvan syndrome and occurs more often in thymoma, 6 though these clinical findings were not present in our patient. However, it is informative that LGI1 (the antibody detected in the patients of Ramdhani and Frucht1 and of Toranis et al. 3) and CASPR2 are taken together as voltage-gated potassium channel (VGKC) complex autoantibodies and thus share substantial similarity. 7,8 To conclude, autoimmune processes must be considered in the differential diagnosis of adult-onset chorea. Besides laboratory and cerebrospinal fluid analysis, 9,10 a serum panel of autoantibodies, including LGI1 and CASPR2, may contribute to the diagnosis.

Eyelid Tremor in a Patient with Anti-Caspr2 Antibody-Related Encephalitis

“…Despite such a broadened clinical spectrum, a recent large clinicoserologic study demonstrated that extrapyramidal signs, including tremor, parkinsonism, and chorea, were not common in this disease as they were observed in only 1 patient (about 3%) [ 8 ]. Nonetheless, the eyelid tremor, masked face, and rigidity found in our patient may support the extrapyramidal involvement, which may be further supported by a very recent case report describing hemichorea in a patient with anti-Caspr2 antibody [ 9 ]. Since clinical details of this disease have been reported infrequently, their accumulation might identify susceptible central nervous system regions and help the correct diagnosis.…”

A case of immunotherapy‐responsive autoimmune hemichorea

“…The presence of antiphospholipid antibodies is the most well‐known cause of autoinflammatory chorea and hemichorea in adults 9–11 . Among antibody‐mediated encephalitides anti‐CRMP‐5 is best known for causing generalized or unilateral chorea, 12 though chorea has also been described in cases of anti‐NMDA, anti‐CASPR2, anti‐LGI1, anti‐PDE10A, anti‐IgLON5, anti‐Yo, and anti‐MOG 2,13–17 . Comprehensive neuronal autoantibody testing should be performed from serum and CSF in patients for whom an autoimmune mechanism is under consideration, and may be repeated if initial testing is negative.…”

Isolated unilateral chorea: a diagnostic challenge

“…There are only a few reported cases of isolated unilateral chorea of paraneoplastic etiology. [1,3,4] Our patient started with chorea several months before the definitive diagnosis of lung cancer was made and manifested respiratory symptoms only a couple months after the beginning of chemotherapy. The most frequently associated antibodies were excluded in serum and we were unable to pursue the investigation because of patient refusal.…”

“…It was reported an association with CV2/CRMP5, Anti-Hu/ANNA, CASPR2 and Yo antibodies, which are detectable in serum in most cases, isolated or in association. [1][2][3][4] However, in a minority of cases an autoantibody cannot be detected. [1] The antibody most frequently associated with paraneoplastic chorea is CV2/CRMP5, followed by Anti-Hu/ANNA.…”