Objective: We report two patients with spinal myoclonus and Contactin-associated protein-2 (Caspr-2)-antibodies, idiopathic in one and paraneoplastic in the other.

Background: Caspr-2-antibodies have classically been associated with limbic encephalitis, cerebellar dysfunction, neuromyotonia and Morvan’s syndrome. Caspr-2 antibodies are often associated with underlying malignancy. There has only been one previous report of Caspr-2 associated spinal myoclonus [1].

Method: Patient 1 is a 68-year-old gentleman who presented with gradually worsening, predominantly flexion, truncal jerks, consistent with propriospinal myoclonus over 5 years, initially present only when supine. The myoclonus became continuous over months. Additionally, his cognition deteriorated. There was no history of malignancy.

Patient 2 is a 65-year-old gentleman who presented with marked gait deterioration secondary to an acute on chronic subdural haematoma, on a background of cerebellar ataxia and a recent diagnosis of oesophageal cancer. Shortly following presentation, he developed truncal and abdominal jerks, consistent with propriospinal myoclonus.

In both, the jerks were irregular, variable in amplitude and severity and in patient 1, initially even distractible, consistent with psychogenic jerks.

Results: Patient 1 had positive Caspr-2-antibodies in his serum and CSF. Investigations revealed no evidence of malignancy. Clonazepam resulted in moderate improvement. He is due to commence immunotherapy.

Patient 2 had positive Caspr-2-antibodies in serum and CSF. Clonazepam, levetiracetam and methylprednisolone resulted in marked improvement. He underwent chemoradiotherapy and local resection of oesophageal cancer.

Conclusion: Our patients provide further evidence of an association between Caspr2 antibodies and spinal myoclonus. Differentiation from psychogenic myoclonus may be difficult. Diagnosis should trigger a search for underlying malignancy. 

This abstract has been submitted, but not yet accepted, to be presented at the ANZAN Annual Meeting 2020.

References: 1. Hines, H., et al., Video NeuroImages: Paraneoplastic spinal myoclonus associated with Caspr2 antibodies. Neurology, 2018. 90(14): p. 660-661.

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