Radiological and Genetic Evaluation in Hypotonic Infants.

Objective: To investigate the importance and diagnostic yield of genetic and radiological evaluations in children with hypotonia.

Study design: Comparative observational study. Place and Duration of the Study: Department of Pediatrics Neurology, Namik Kemal University, Tekirdag, Turkey, between 2019 and 2022.

Methodology: Patients' medical histories, laboratory results, radiological examinations, and genetic tests, if any, were obtained retrospectively from the patients' clinic files. Children with hypotonia detected since the infantile period and who were on regular follow-up were included in the study. Patients who lost the follow-up were excluded.

Results: Out of one hundred and seventy patients, 61.8% (n=105) were boys and 38.2% (n=65) were girls. The admission age of the patients ranged from 1 to 121 months; the mean age at presentation was 13.52±17.35 months. Hypotonia was central in 85.3% (n=145), peripheral in 12.4% (n=21), and mixed in 2.3% (n=4). Cerebral palsy was the predominant, non-genetic clinical cause of hypotonia (n=66, 39%). Brain magnetic resonance imaging (MRI) was normal in 48.2% (n=82). The most common MRI abnormality was periventricular leukomalacia in 15.9% (n=27). Sixty-five (38.2%) patients were diagnosed genetically. More than half of the patients with a genetic diagnosis were diagnosed by whole exome sequencing (WES).

Conclusion: Brain MRI is the first choice for the patients with central hypotonia. Patients who cannot be diagnosed with clinical findings and brain MRI should undergo WES. This is helpful for the long-term prognosis and management.

Key words: Hypotonia, Whole exome sequencing, Magnetic resonance, Spinal muscular atrophy, Cerebral palsy.