Acute-onset paralytic strabismus may be an early sign of late-infantile metachromatic leukodystrophy (MLD), according to research published in the European Journal of Paediatric Neurology.

Researchers reviewed records of 204 confirmed MLD patients (63 with late-infantile MLD). They evaluated gross motor deterioration of patients with strabismus using the Gross Motor Function Classification in MLD (GMFC-MLD), classified white matter abnormalities on the brain with a MLD Loes score, and calculated the median interval between strabismus onset and gross motor deterioration.

Investigators noted strabismus was an early symptom in 27% (n=17) of patients with late-infantile MLD, and it developed before gross motor symptoms in 71% (n=12) of those 17 reported cases. Median interval between strabismus onset and gross motor deterioration was 6 months, and 7 patients did not achieve independent walking. White matter abnormalities were absent (n=6) or mild (n=7) on brain magnetic resonance imaging (MRI) in the 13 patients with MRI data close to strabismus onset. 


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MLD presented as acute-onset paralytic esotropia before age 28 months in all participants, and was accompanied by other eye movement disorders such as nystagmus and ptosis (n=3 and n=4, respectively) in 41% of patients. 

Researchers stress the importance of referring toddlers who present with paralytic strabismus to an appropriate neurological specialist and state, “Presentation of paralytic strabismus in toddlers younger than 2.5 years, especially when characterized by an acute onset esotropia or when accompanied by abnormal motor development or other eye movement disorders, could be an early or presenting clinical sign of MLD, even if brain white matter abnormalities are still absent.” 

Limitations of the study included possible confounding variables as causes of strabismus and possible underreporting of strabismus cases in MLD patients. 

Reference

Beerepoot S, Wolf NI, Wehner K, et al. Acute-onset paralytic strabismus in toddlers is important to consider as a potential early sign of late-infantile metachromatic leukodystrophy. Eur J Paediatr Neurol. Published online February 2, 2022. doi:10.1016/j.ejpn.2022.01.020