Objective: Describe two corticobasal syndrome (CBS) cases presenting with levodopa-induced dyskinesia (LID), one with motor fluctuations (MFs).

Background: CBS is a rare neurodegenerative syndrome characterized by asymmetrical parkinsonism, apraxia, cortical sensory deficits, and poor response to dopaminergic therapy. LID and MFs are uncommon in CBS.

Method: Report of two patients.

Results: Case 1: A 60-year-old woman with a two-year history of progressive speech apraxia, right arm agraphestesia, rigidity, bradykinesia, myoclonic tremor, and severe aphasia. Brain MRI revealed asymmetrical frontoparietal cortical atrophy, and DAT-SPECT demonstrated asymmetrically reduced uptake. Levodopa initially improved parkinsonism but not cortical symptoms. After two years, when she was taking levodopa 200 mg tid, she developed MF with wearing-off one hour before each intake consisting of parkinsonism, whereas during on periods she featured peak-dose choreic dyskinesia including orolingual movements and moderate-to-severe limb involvement. Levodopa was progressively increased to a total daily dose of 1300 mg, requiring administration every 2–3 hours to keep her in ON state. This drug scheme was maintained two years when it was gradually reduced to 700 mg/day due to progressive deterioration and lack of efficacy although amantadine 200 mg/day was needed to control dyskinesia. The disease progressed with typical CBS milestones and death occurred 11 years after onset.

Case 2: A 59-year-old woman with CBS characterized by asymmetric left-predominant apraxia, parkinsonism, and dystonia, later accompanied by cortical sensory deficits. Brain MRI revealed asymmetric frontoparietal cortical atrophy, and DAT-SPECT showed absent uptake in the putamen and right caudate, with reduced uptake in the left caudate. Seven years later and after 33 months under levodopa, she developed right lower limb dyskinesia progressing later to the left and trunk, without MFs.

Conclusion: LID and MFs, although uncommon, may occur in CBS. Dyskinesias may appear in the more affected or relatively preserved hemibody and can influence treatment decisions. Relative preservation of post-synaptic structures (i.e., globus pallidus internus) could be involved in pathophysiology. Recognition of this phenotype may help refine clinical characterization and therapeutic management of CBS

References: 1- Medina Escobar A, Rossi M, Richer M, Gautreau S, Lang AE. Chorea and levodopa-induced dyskinesia in corticobasal syndrome: Two case reports with pathological insights and literature review. Mov Disord Clin Pract. 2025. doi:10.1002/mdc3.70420. PMID: 41190461.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/levodopa-induced-peak-dyskinesia-and-motor-fluctuations-in-corticobasal-syndrome/