Laterality in children: cerebellar dominance, handedness, footedness and hair whorl

The purpose of our study was to ascertain the degree of correlation between handedness and physiological neocerebellar extinction syndrome demonstrable on the side contra lateral to the dominant upper extremity. Using the Edinburgh questionnaire and other tests for “handedness”, we examined 221 healthy 9–11-year old schoolchildren for handuse preference. To test their handedness the following 6 mutually indistinguishable tests (p<0.001) were found the most reliable: writing, drawing, holding a knife, scissors, and spoon and striking a match. Congruent response or test outcomes were used for the definition of pure (100%) right-handers (n=166) and pure (100%) left-handers (n=13); the rest were rated as ambidexters (n=42). Cerebellar dominance was ascertained clinically by means of palpation and aspection; by the presence of physiological muscle hypotonia in the extremities contra lateral to the dominant upper extremity in right-handers and in left-handers. In addition to these signs of laterality, we have studied also other questions and tests (totally 34) of handedness and footedness, recorded the hair whorl form, ocular dominance and the direction of turning while standing or walking. Our findings: 1) Enhanced mirror movements in the non-dominant upper extremity while walking and greater passivity in the wrist, elbow, knee and ankle. 2) For one-foot skipping and for ball kicking the percentage of foot preference was approaching that of hand preference; half the pure right-handers used the left foot for take-off, half the pure left-handers used the right foot for take-off. 3) Physiological hypotonia was also found in the take-off foot for jump-over with what is known as crossed dominance of foot and hand (p < 0.05), thus proving that “neocerebellar dominance” manifests itself in accordance with hand dominance. 4) The ocular dominance depends on handedness (by eye preference at looking into a key-hole or a monoskope). 5) Trunk rotation to the left in right-handers and to the right in left-handers lacked statistical consistence. 6) The hair whorl direction was not in agreement with right-handedness or cerebellar dominance associated with it.