Caspr2 Antibody-Mediated Ataxia, Parkinsonism, and Epilepsy: A Case for Escalating Immunotherapy.
Objective:
To report a rare presentation of anti-Caspr2 syndrome treated successfully with rituximab.
Background:
Anti-Caspr2 syndrome has a variety of clinical phenotypes including encephalopathy, seizure, psychiatric disturbances, respiratory failure, dysautonomia, peripheral nerve dysfunction, as well as ataxia of a constant or episodic nature.1 In many of the cases with ataxia, there is associated limbic encephalitis.2 Anti-Caspr2 syndrome with ataxia, parkinsonism and seizure has only been reported once in the literature.3 This symptomatology can be easily mistaken for an atypical parkinsonism like cerebellar multiple systems atrophy, or spinocerebellar ataxia type 2 but this treatable cause is an important consideration.
Design/Methods:
To report a case of anti-Caspr2 syndrome presenting with pure ataxia, then progressing to parkinsonism, and epilepsy; its successful treatment; and accompanying video examinations.
Results:
A 71 year-old man was referred for 8 months of progressive, generalized ataxia and dysarthria. Immune-mediated ataxia was considered given the subacute course with rapid progression. He was found to have a Caspr2 antibody titer of 1:100. Evaluation for malignancy was unremarkable. Lumbar puncture revealed Caspr2 antibody positivity. The patient was treated with 4 days of intravenous steroids and immunoglobulins with significant improvement.
He relapsed four months later with lower extremity weakness and ataxia. Despite maintenance intravenous immunoglobulin, his ataxia continued to progress. He then developed focal seizures with impaired awareness and left sided parkinsonism. He was started on rituximab immunotherapy for ongoing disease activity. His ataxia and parkinsonism significantly improved to near-baseline with continued stability 6 months later.
Conclusions:
This case illustrates an example of an autoimmune-mediated cerebellar ataxia of subacute onset with progression to parkinsonism and epilepsy. Special consideration for anti-Caspr2 syndrome should be taken in cases of progressive ataxia with accompanying neurologic features of parkinsonism and seizure. Escalation to rituximab can be considered for patients who continue to progress despite preliminary immunotherapy.