Objective: The link between handedness and the prevalence of writer’s cramp has not been investigated yet. In this systematic review, the distribution of handedness was compared between the population of writer’s cramp patients and the general population.

Background: Writer’s cramp is the most common form of task-specific focal hand dystonia. It is characterised by an abnormally increased muscle tonus and involuntary muscle contractions, leading to movement-specific spasms of the hand or forearm. Earlier studies on focal hand dystonia revealed that both hemispheres are affected. Moreover, right-handers and males demonstrate a stronger motor lateralisation. The underlying pathophysiological mechanisms are still debated, and the role of handedness is unknown.

Method: A systematic literature search on the medical database PubMed was performed and resulted in 1159 articles on focal hand dystonia. The detected articles were screened and evaluated by two independent investigators. Studies containing original data on writer’s cramp were included, and epidemiological data (handedness, gender, age of onset, affected hand) was extracted. Chi-square-goodness-of-fit tests and cross tabulations were conducted in the statistical analysis to compare the patient population with the general population.

Results: Out of 243 included articles, a total of 2802 patients with writer’s cramp were analysed. Of these 96,1% (2693) were right-handed and 3,9% (109) non-right-handed, as compared to 89,4% and 10,6% in the general population (X²=147,59; df=1; p <0,01). The mean age of the patients was 46,4±10,9 years, and the mean age at disease onset was 36,6±10,4 years. A gender ratio of 1:1,36 (f:m) was found.

Conclusion: The lower proportion of left-handed writer’s cramp patients suggests that right-handedness may act as a promoting factor for the development of writer’s cramp. This could be due to the stronger lateralisation of motor functions in right-handers. This interpretation is also supported by the unequal gender distribution in the patient group, since a stronger motor lateralisation has also been reported for males.

This work was previously presented at the DGN-Congress in Berlin, Germany in November 2022.

« Back to 2023 International Congress

MDS Abstracts - https://www.mdsabstracts.org/abstract/the-link-between-handedness-and-prevalence-of-writers-cramp-a-systematic-literature-review/