Objective: To describe an unusual initial presentation of corticobasal syndrome manifesting as writer’s cramp, a task-specific focal dystonia, and to discuss its compatibility with the clinical diagnosis of probable corticobasal degeneration.

Background: Corticobasal degeneration is a rare neurodegenerative tauopathy characterized by asymmetric parkinsonism, dystonia, myoclonus, and cortical signs. Its clinical presentation is heterogeneous, and diagnosis during life relies primarily on clinical criteria. Corticobasal syndrome is the most common clinical phenotype associated with this pathology. Although dystonia is frequently reported in corticobasal syndrome, task-specific focal dystonia such as writer’s cramp is rarely described as an initial manifestation.

Method: Clinical data were obtained from the patient’s medical records after written informed consent. A literature review was conducted in the PubMed and SciELO databases using the terms “corticobasal degeneration,” “corticobasal syndrome,” “writer’s cramp,” “focal dystonia,” and “task-specific dystonia.”

Results: We report the case of a 64-year-old woman whose initial symptom was writer’s cramp affecting the right hand, with progressive difficulty writing due to abnormal posturing and cramps in the fourth and fifth fingers. Over the following months, the patient developed fixed dystonia, marked asymmetric rigidity and bradykinesia, myoclonus, pyramidal signs, and cortical features including apraxia, astereognosia, and agraphesthesia predominantly on the right side. There was no sustained benefit with levodopa, and dose escalation was limited by adverse effects. Botulinum toxin injections provided partial functional improvement. Brain magnetic resonance imaging demonstrated asymmetric cortical atrophy predominantly involving the left frontoparietal and temporal regions with relative preservation of the brainstem. The clinical picture fulfilled criteria for probable corticobasal degeneration.

Conclusion: This case highlights writer’s cramp as a rare initial manifestation of corticobasal syndrome. Task-specific focal dystonia may precede more typical features such as asymmetric parkinsonism and cortical signs. Recognition of these atypical presentations may facilitate earlier diagnostic suspicion of underlying neurodegenerative disease.

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References: Jellinger KA. Pathomechanisms of cognitive and behavioral impairment in corticobasal degeneration. J Neural Transm. 2023;130(12):1509–1522.
Révész T, Lees AJ, Morris HR. Corticobasal degeneration: an update. Ideggyogy Sz. 2024;77(11–12):379–394.
Armstrong MJ, Litvan I, Lang AE, et al. Criteria for the diagnosis of corticobasal degeneration. Neurology. 2013;80(5):496–503.
Stocco A, et al. Best practices in the clinical management of corticobasal syndrome and progressive supranuclear palsy: consensus statement of the Cure PSP Centers of Care. Front Neurol. 2021;12:694872.
Vale TC, et al. Síndrome corticobasal: aspectos clínicos, diagnósticos e terapêuticos. Arq Neuropsiquiatr. 2020;78(6):358–366.
Koga S, Josephs KA, Aiba I, Yoshida M, Dickson DW. Neuropathology and emerging biomarkers in corticobasal syndrome. J Neurol Neurosurg Psychiatry. 2022;93(4):448–458.
Aiba I, McGeachan A, King J, et al. Clinical course of pathologically confirmed corticobasal degeneration and corticobasal syndrome. Brain Commun. 2023;5(6):fcad296.
Idrissi S, Erro R, Mascia MM, et al. Phenotypic comparison between combined dystonia-parkinsonism and idiopathic adult-onset dystonia. J Neural Transm. 2025;132(2):205–214.
Graff-Radford J, Yong KXX, Apostolova LG, et al. New insights into atypical Alzheimer’s disease in the era of biomarkers. Lancet Neurol. 2021;20(10):838–850.
Nouh CD, et al. Diagnosis and management of progressive corticobasal syndrome. Curr Treat Options Neurol. 2024;26(7):319–338.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/probable-corticobasal-syndrome-presenting-as-writers-cramp-a-case-report/