Objective: To characterize the clinical and demographic profile of patients with writer’s cramp treated at the botulinum toxin outpatient clinic of the Instituto de Assistência Médica ao Servidor Público Estadual de São Paulo (IAMSPE).
Background: Writer’s cramp is a task-specific focal hand dystonia characterized by involuntary muscle contractions during writing. It has an insidious onset, with altered pen grip and abrupt hand movements as hallmark clinical features. It may be classified as simple, progressive, or complex. Botulinum toxin type A (BoNT-A) is the treatment of choice, with reported efficacy ranging from 73–76%. Treatment requires individualized selection of target muscles and dosing in order to reduce spasms while preserving functional strength.
Method: This was a retrospective study based on medical record review. Patients with writer’s cramp who received botulinum toxin injections between January 2024 and January 2026 were included. Data regarding clinical characteristics, injected muscles, and toxin doses were collected. Statistical analysis included measures of central tendency and dispersion.
Results: Nine patients were included (mean age 61 years; 77.8% female). The mean disease duration was 13.8 years. The mean dose of abobotulinumtoxin A (Dysport®) per patient was 231 U. Approximately 33% of treatment sessions involved injections into only two muscles. The most frequently selected muscles were the flexor carpi radialis, flexor digitorum superficialis, flexor carpi ulnaris, and palmaris longus. The flexor digitorum profundus received the highest mean dose (90 U).
Conclusion: The treatment approach adopted at IAMSPE is consistent with current evidence, prioritizing forearm flexor muscles with an individualized strategy. Larger multicenter studies and standardized functional outcome assessments are needed to optimize dosing strategies and injection techniques.
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2.Kaplan, E. H., Vecchio, M., & Simpson, D. M. (2025). Review: Botulinum Toxin for Treatment of Focal Limb Dystonia. Toxins, 17(3), 122.
3.Zakin, E., & Simpson, D. M. (2021). Botulinum Toxin Therapy in Writer’s Cramp and Musician’s Dystonia. Toxins, 13(12), 899.
4.Albanese, A., Bhatia, K. P., Fung, V. S. C., Hallett, M., Jankovic, J., Klein, C., Krauss, J. K., Lang, A. E., Mink, J. W., Pandey, S., Teller, J. K., Tijssen, M. A. J., Vidailhet, M., & Jinnah, H. A. (2025). Definition and Classification of Dystonia. Movement disorders : official journal of the Movement Disorder Society, 40(7), 1248–1259.
To cite this abstract in AMA style:
K. Alves, T. Gonçalves, B. Dias, R. Pinto, E. Souto, D. Faria, S. Gomes. A Therapeutic Approach to Writer’s Cramp-Type Focal Dystonia Using Botulinum Toxin: Experience of the Neurology/Movement Disorders Department of the Hospital do Servidor Público de São Paulo [abstract]. Mov Disord. 2026; 41 (suppl 1). https://www.mdsabstracts.org/abstract/a-therapeutic-approach-to-writers-cramp-type-focal-dystonia-using-botulinum-toxin-experience-of-the-neurology-movement-disorders-department-of-the-hospital-do-servidor-publico-de-sao-paulo/. Accessed October 1, 2026.« Back to 2026 International Congress
MDS Abstracts - https://www.mdsabstracts.org/abstract/a-therapeutic-approach-to-writers-cramp-type-focal-dystonia-using-botulinum-toxin-experience-of-the-neurology-movement-disorders-department-of-the-hospital-do-servidor-publico-de-sao-paulo/