What this study looked at
Metachromatic leukodystrophy (MLD) is a fatal lysosomal storage disease in which the nervous system progressively loses its protective myelin, and diagnosing it quickly matters as new treatments emerge. Squinting (strabismus) had only been noted anecdotally in MLD, so researchers reviewed the records of 204 patients across two national cohorts to find out how common it was and when it appeared. They also examined how the onset of strabismus related to declining movement and to changes seen on brain scans.
Key takeaways
- Strabismus was an early sign specifically in the late-infantile form of MLD, occurring in 27% of those patients.
- In most cases the strabismus came first — preceding declining movement in 71% of cases and brain white matter changes in 46%.
- A telling pattern was a sudden-onset paralytic inward squint, sometimes with other eye movement problems and enhancement of the cranial nerves on contrast MRI.
Why it matters
A sudden paralytic squint in a toddler could be an early clue to late-infantile MLD, and a brain MRI with contrast may help clinicians reach the diagnosis sooner.
