Aspects of hand function in children with unilateral impairments : caused by obstetric brachial plexus or hemiplegic cerebral palsy

Abstract

Unilateral arm/hand dysfunction caused by obstetric brachial plexus palsy (OBPP) or hemiplegic cerebral palsy (CP) is most often afflicted on a child in the pre- or perinatal period of life. Despite different origin of the impairments, the outcomes for both groups implicate one well functioning and one dysfunctioning hand, and the consequences for every day task performance are similar. In the present thesis different aspects of arm and hand function were studied for these two groups, both concerning sensory motor components, bimanual coordination and functional use.

Two hundred-fifty-eight 5-year old children with differing severity of OBPP were thoroughly assessed. The results revealed that the outcome in upper plexus lesions, mainly involving restricted shoulder movements, is more complex than commonly regarded. Hand function was indirectly affected, and grip strength was reduced. Children with total plexus lesions have a more severe disability always affecting grip-strength, dexterity and often sensibility. Bimanual use of the affected limb and performance of activities in daily life was influenced. mostly in children with total plexus lesions. The resulting outcome from nerve reconstructive surgery was studied. The shoulder range of motions in C5-6 palsies was better in the operated group. Otherwise there were no significant differences between children in the operated and the un-operated groups, although, the groups were not randomised and completely comparable. The time for operation, before or after age 6 months, did not influence the outcome.

In 25 children and adolescents with congenital hemiplegia and 19 controls, different tests of tactile sensibility were applied and their results compared. We found three tests to be useful; two-point discrimination, which was the most sensitive test, stereognosis of familiar objects and functional sensibility assessed through the Pick-up Test. Decreased tactile sensibility was found to affect dexterity but not bimanual performance.

The occurrence and features of mirror movements were investigated in 22 children and adolescents with hemiplegia and 17 controls. In subjects with CP, mirror activity was 15 times stronger than in controls, independent of age. 'Mirroring' was more prominent in the unaffected hand. The amount of mirror activity was not related to the degree of hemiparesis. The influences of increased mirror movements were found to negatively affect bimanual performance.

The lack of an instrument measuring how effectively the affected arm/hand actually is used in tasks requiring the both hands, was recognised in all the studies. Therefore, a test measuring the usefulness of the affected hand, the Assisting Hand Assessment (AHA), was developed with the use of the Rasch measurement model for analysis of data. The AHA is constructed of 22 items and is scored with a 4-point rating scale from observations of a play situation with selected toys. The analysis of 60 assessments suggests that the test rationale, the usefulness of the assisting hand, does indeed form a unidimensional construct and that the items represent the tested phenomenon well. The results show potential for the AHA to be a useful tool for both evaluation and treatment planning.