Obligatory bimanual associated movements: Report of a non-familial case in an otherwise normal left-handed boy

Abstract

Amongst the abnormal synkinesias, bilateral and obligatory associated movements affecting predominantly the hands comprise a group of movement disorders which we have divided into: (1) those occurring as an autosomal dominant hereditary condition; (2) those occurring in the presence of disease of the central nervous system, including congenital abnormalities of the cervical region; and (3) rare, sporadic cases in otherwise healthy individuals. A left-handed patient falling into the last group is reported, in whom detailed neuropsychological assessment was also undertaken. Recalling the normal bimanual synkinesias of childhood, some of the mechanisms implicated in the production of pathological bimanual synkinesias are discussed: the effect of structural lesions within the central nervous system, defects in motor inhibition and the role of sensory afferent information, the part played by the commissures and abnormal motor pathways, the question of handedness, the relationship to mirror writing, and cerebral dominance have all been considered relevant, but from increasing evidence available from experimental work on primates the possible role of direct corticomotoneuronal connections is emphasised.