Sophia M. Buitenhuis, Willem Pondaag, Ron Wolterbeek, Martijn J.A. Malessy
Department of Neurosurgery, Leiden University Medical Center, Voorburg, The Netherlands. E-mail: s.m.buitenhuis@lumc.nl
DOI: 10.2340/16501977-2855

Objective: To assess gripforce in children with a C5 and C6 neonatal brachial plexus palsy, as it may affect hand use. Applying classic innervation patterns, gripforce should not be affected, as hand function is not innervated by C5 or C6. This study compares gripforce in children with a neonatal brachial plexus palsy with that in a healthy control group, and assesses correlations with hand sensibility, bimanual use and external rotation.
Methods: A total of 50 children with neonatal brachial plexus palsy (mean age 9. 8 years) and 25 controls (mean age 9. 6 years) were investigated. Nerve surgery had been performed in 30 children, and 20 children had been treated conservatively. Gripforce of both hands was assessed using a Jamar dynamometer. Sensibility of the hands was assessed with 2-point discrimination and Semmes-Weinstein monofilaments. External rotation was assessed using the Mallet score. Bimanual use was measured by using 1 of 3 dexterity items of the Movement Assessment Battery for Children-2. The affected side of the neonatal brachial plexus palsy group was compared with the non-dominant hand of the control group using 1-way analysis of variance (ANOVA), χ2 and Mann–Whitney tests.
Results: The mean gripforce of the affected non-dominant hand of children with neonatal brachial plexus palsy was reduced compared with healthy controls (95 N and 123 N, respectively, with p = 0. 001). The mean gripforce of the non-dominant hand in the control group was 92% of that of the dominant hand, while it was only 76% in the neonatal brachial plexus palsy group (p = 0. 04). There was no relationship between gripforce reduction and sensibility, bimanual use or shoulder external rotation.
Discussion: The gripforce in neonatal brachial plexus palsy infants with a C5 and C6 lesion is lower than that of healthy controls, although classic interpretation of upper limb innervation excludes this finding. The reduction in gripforce in upper neonatal brachial plexus palsy lesions is not widely appreciated as a factor inherently compromising hand use. The reduction in gripforce should be taken into consideration in planning the type of rehabilitation and future activities.

Children with a shoulder nerve lesion caused at birth, use the hand at that side in a limited way. This is odd, as hand function is not controlled by nerves of the shoulder plexus. To get more information about the hand use, we investigated the gripforce and compared this with healthy children. This objective comparison has not been carried out before. Fifty children with comparable shoulder nerve lesion and twenty five controls were investigated. Gripforce of the affected hand was 23 % lower than the gripforce of the hand of the controls. This finding contradict previous research. Also the often limited external rotation of the shoulder in the group with nerve lesion could not be correlated with the diminished gripforce. Diminished gripforce is not widely appreciated as a factor compromising hand use. This reduction should be taken into consideration in planning the type of rehabilitation and future activities.