# From Congenital Torticollis to Leigh Syndrome: A Case Report of Diagnostic Evolution in an Infant

## TL;DR

An infant initially thought to have a neck condition was later diagnosed with a rare mitochondrial disorder, highlighting the importance of early assessments for subtle symptoms.

## Contribution

This case report highlights the atypical presentation of Leigh syndrome with systemic rather than neurological features in an infant.

## Key findings

- Leigh syndrome can present with feeding difficulties and developmental delay rather than early severe neurological symptoms.
- Early neurological and feeding assessments can detect subtle dysfunction before overt symptoms appear.
- Genomic testing and neuroimaging are essential for timely diagnosis of Leigh syndrome in infants.

## Abstract

What are the main findings?

An infant referred for suspected congenital torticollis was ultimately diagnosed with MT-ATP6-related Leigh syndrome.

The case demonstrated subtle systemic features—feeding difficulties, recurrent vomiting, and failure to thrive—rather than early severe neurological symptoms.

What are the implications of the main findings?

Early application of standardized infant assessment tools, including movement assessment and structured feeding evaluation, can detect subtle neurological dysfunction before overt symptoms appear.

Careful follow-up with neuroimaging and genomic testing is essential for timely recognition and management of Leigh syndrome.

Leigh syndrome is a rare, progressive mitochondrial disorder of childhood. Early diagnosis is often challenging due to nonspecific clinical manifestations. We report a 1-month-old male infant initially referred for suspected congenital muscular torticollis who ultimately received a diagnosis of Leigh syndrome. Despite unremarkable perinatal history, he subsequently developed persistent feeding difficulties, recurrent vomiting, failure to thrive, and global developmental delay. Early neurological assessment revealed poor repertoire patterns on General Movement Assessment. The Neonatal Oral-Motor Assessment Scale (NOMAS) demonstrated dysfunctional oral-motor control, whereas the video fluoroscopic swallowing study (VFSS) revealed aspiration during swallowing. Brain MRI revealed symmetric basal ganglia lesions. Expanded whole-exome sequencing identified a pathogenic MT-ATP6 m.8993T>G variant with high heteroplasmy level (>90% in blood), confirming the diagnosis of Leigh syndrome. The variant was maternally inherited, although neither the mother nor the older sibling exhibited clinical features of mitochondrial disease. Leigh syndrome can initially manifest with subtle systemic features rather than overt neurological features. Persistent feeding difficulties and growth delay in infancy warrant thorough evaluation, including neuroimaging and comprehensive genomic testing, to enable timely diagnosis and optimize clinical management.