False negativity in towel test for elbow flexion assessment in brachial plexus birth palsy. Can we attribute to handedness?

Abstract

Objectives: The towel test is considered as a reliable clinical examination finding to test the elbow flexion in Brachial plexus birth palsy. A mature central nervous system makes this test positive at 6 months’ time and those who failed the test require microsurgical exploration and nerve repair/transfers for upper limb functions. Not all infants pass in this test. Majority of the children develop a clear hand preference at 6 months of age. We hypothesize the validity of the towel test in brachial plexus birth palsy children between 6 and 9 months of age and the possibility of mother and infant handedness in the false-negative tests. Materials and Methods: A retrospective analysis conducted between 2015 and 2019 about the utility of “towel test” involving 12 boys and 11 girls was analyzed and interpreted. The side involved in these infants and the mother’s handedness was also noted. Based on the age, side, gender, and mother-handedness, the results of towel tests were statistically interpreted. Results: The mean age of the infants involved was 6.6 months (range 6–9 months). Twenty children (87%) had positive tests. Three (13%) infants (male = 2; female = 1) had false-negative test. There was no action on the normal side to remove the towel but weak movements in the affected upper limb persisted to try and remove the towel. The left-hand mother’s infant had false-negative towel test, which was found statistically significant (P < 0.01). Conclusion: Clinicians should know that false negativity may coexist while using the towel test and handedness could be a possibility in them. In such conditions, additional tests can be used to assess the ongoing motor recovery in brachial plexus birth palsy children between 6 and 9 months of age.