Introduction: IEM though heterogenous are not uncommon. Neurologic manifestations predominate¹. Lack of universal newborn screening, awareness and resources delay diagnosis. Early treatment ameliorates neuromorbidity. Hence this study to understand presentation, diagnostic clues and outcome.

Methodology:  Thirty-four children(post-neonatal) received a diagnosis of small molecule IEM between 2008 and 2018 in a tertiary care hospital. Clinical and laboratory data were retrospectively retrieved and analyzed.

Results: Average age was 18.6 months​ ​at symptom onset (M:F ratio 1.1). Average delay in diagnosis was 11.2 months. Organic- acidurias(OA) were diagnosed in 18/34 (52.9%), urea-cycle disorders(UCED) in 9/34 (26.5%), aminoacidopathies (AA) in 4/34 (11.7%) and fatty acid oxidation disorders(FAOD) in 3/34 (8.8%). Mode of presentation was chronic encephalopathy in 21 (61.8%) with regression in 7, acute encephalopathy 8 (23.5%), metabolic myopathy 1; 4 diagnosed on newborn screen, 2 with affected sibs. Developmental delay (38.2%), seizures (32.4%), tone abnormalities (61.8%), movement disorder and ataxia (14.7%) each, failure to thrive (20.6%) were noted. Positive family history in 11/34 (32.4%). Tandem mass spectrometry(TMS) was done in 29, diagnostic/suggestive in 26 and normal in 3. In 11 children, MRI helped clinch the diagnosis. Normal neuro-developmental outcome was seen in 9 (26.5%), mild neurodeficit in 12 (35.3%), severe neurodeficits in 5 (14.7%) with 2 deaths (5.9%); follow-up unavailable in 6 (17.6%). Conclusion: Chronic encephalopathy is common presentation of late-onset IEM. Neuroimaging and TMS are useful in etiologic diagnosis.

References:

1. Christopher R. Ann Indian Acad Neurol 2008 Apr;11(2):68-81.