Objective: To describe a unique case of Alzheimer’s Disease in which olanzapine use resulted in unmasking an underlying corticobasal syndrome

Background: Corticobasal Syndrome is a rare, progressive syndrome whose core features are insidious progressive asymmetric rigidity and apraxia, accompanied by symptoms and signs of cortical and extrapyramidal dysfunction. Extrapyramidal involvement includes dystonia and levodopa nonresponsive Parkinsonism. Alzheimer’s Disease-Corticobasal Syndrome subtype (AD-CBS), is a clinicopathological subtype of AD with an atypical distribution of Alzheimer-type tau pathology. Greater neuronal loss in the substantia nigra may contribute to Parkinsonism which is not a feature of typical AD. AD-CBS has prominent motor problems, including limb apraxia, myoclonus, and gait disorders.

Method: 69 y.o. female with history of AD was referred for evaluation of dystonia. She had progressive shuffling gait and a stooped posture for few years. She developed a tendency to lean to the left around 6 months prior, and semi-flexion of left elbow and wrist starting around 5 months prior to this clinical visit. She was hospitalized for a UTI 4 months prior and during this time, her left elbow and wrist flexion became more prominent. She also developed torticollis and resting tremors in the lower extremities. It was noted that she had been on olanzapine for a few months prior to hospitalization. Following discontinuation of olanzapine, the torticollis resolved but other motor symptoms persisted.

Results: CT brain showed right parietotemporo atrophy greater than the left. No MRI imaging was available for review as patient could not tolerate this. The characteristic examination findings and progressive symptom development met criteria for probable CBS using criteria of Armstrong et al. We diagnosed AD-CBS subtype likely exacerbated by initiation of Olanzapine, though acknowledging the limitations of a diagnosis without MRI evidence.

Conclusion: AD-CBS is quite rare and has only been explored through case reports and series over the last 10 years. Olanzapine is an antipsychotic which is commonly used to manage psychosis and delirium in people with AD; however, given the possibility of AD-CBS in this population, we would suggest being judicious with its use. Furthermore, we seek to increase awareness of this unique subtype to advance clinical research in hopes of developing treatment catered towards this disease.

References: https://pmc.ncbi.nlm.nih.gov/articles/PMC3232678/#:~:text=This%20rare%20clinical%20syndrome%20is,produce%20agrammatic%20aphasia%20%5B17%5D.
https://pubmed.ncbi.nlm.nih.gov/31399334/
https://pmc.ncbi.nlm.nih.gov/articles/PMC3232678/
https://pubmed.ncbi.nlm.nih.gov/31399334/
https://alz-journals.onlinelibrary.wiley.com/doi/10.1016/j.jalz.2019.04.011
https://www.bcm.edu/healthcare/specialties/neurology/parkinsons-disease-and-movement-disorders/corticobasal-syndrome
https://www.uofmhealth.org/conditions-treatments/corticobasal-syndrome
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MDS Abstracts - https://www.mdsabstracts.org/abstract/subacute-unmasking-of-ad-cbs-subtype/