Cerebral Dominance

Left or right hand dominance in children with cleft lip and palate

[Summary] (( S. L. A. Jeffery, J. G. Boorman. Left or right hand dominance in children with cleft lip and palate. British Journal of Plastic Surgery, 53(6), pp. 477-478. September 2000))
The relationship between unilateral cleft lip, bilateral cleft lip, palatal clefting and left-right hand dominance was studied in 337 patients with cleft lip and/or palate aged between 3 and 14 years. The study was carried out at the Queen Victoria Hospital, East Grinstead, West Sussex, UK.

There was no statistically significant difference in the laterality of handedness between different types of cleft nor between unilateral left and right sided cleft lip with or without cleft palate. neither was there any difference found in handedness between boys and girls.

Unilateral Cleft Lip with or without Cleft Palate and Handedness: Is There an Association?

[Original Abstract] (( J. Daskalogiannakis et al. Unilateral Cleft Lip with or without Cleft Palate and Handedness: Is There an Association? The Cleft Palate-Craniofacial Journal 35(1), pp. 46‚51, January 1998))
The purpose of this study was to investigate the possibility of a relationship between the side of occurrence of unilateral clefting of the lip and/or palate and handedness, also taking into account the type of the initial cleft condition, a factor that has not been adequately assessed in previous studies.

Subjects were 289 patients (176 males and 113 females) 9 years of age or older presenting with a history of unilateral clefts of the lip with or without the palate. Of these patients, 217 were recruited from the patient pool of the Orthodontic Clinic at the Hospital for Sick Children in Toronto. The remaining 72 were selected from the registry of the Cleft Lip and Palate Program of the Children’s Hospital in Winnipeg. Any syndromic cases were excluded from the sample.

Assessment of handedness was performed by asking the patients to fill out a multi-item questionnaire in which patients were asked to identify which hand they would use for different tasks. The side and type of the initial cleft condition were identified by reviewing each patient’s hospital chart and by cross-referencing with clinical examination. Statistical evaluation of the results was performed by using the chi-square test.

Results: There was a significantly larger number of left-sided clefts (198) in the sample than right-sided clefts (91), (p < .001). The proportion of left-sided clefts among left-handers (84.6%) was higher than that among right-handers (66.8%). However, the relationship between side of cleft and handedness was not statistically significant (p = .185). Clefts of the primary palate only seemed to occur on the left side 3.5 times more often than on the right, whereas the corresponding ratio of left:right manifestation for clefts of the primary and secondary palate was 1.8:1. The difference was statistically significant (p < .05).

Conclusion: The findings of this study confirm the affinity of unilateral clefts for the left side but suggest that there are differences between clefts of the primary palate only and clefts of the primary and secondary palate. Also, nonright-handed patients show a greater predilection for having a cleft on the left side than do right-handed patients.

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