French angles: a simple aid to neurodevelopmental examination

Area of Science:

• Pediatric Neurology
• Developmental Pediatrics
• Biomedical Engineering

Background:

• Passive tone, a measure of muscle lengthening capacity, is crucial for assessing infant neurodevelopment.
• Existing methods for assessing passive tone can be subjective and lack quantitative precision.
• The "French angles" offer a potential objective measure of passive movement and muscle extensibility.

Purpose of the Study:

• To establish normative data for "French angles" in healthy infants aged 1-52 weeks.
• To evaluate the reliability and simplicity of using a goniometer for measuring "French angles" by non-expert examiners.
• To explore the utility of "French angles" as a screening tool for infant neuromuscular disorders.

Main Methods:

• Fifty healthy infants (1-52 weeks) had passive joint range of motion measured using a plastic goniometer to determine "French angles."
• Measurements were taken by non-expert examiners to assess practical application.
• Three infants with known neuromuscular disorders (cerebral palsy, Werdnig Hoffman syndrome) were included for comparison.

Main Results:

• "French angles" increased linearly and predictably from birth to one year, except for ankle dorsiflexion, indicating gradual relaxation of passive tone.
• Infants with cerebral palsy exhibited reduced adductor angles, consistent with adductor spasm.
• The infant with Werdnig Hoffman syndrome showed an increased adductor angle, suggesting increased extensibility.

Conclusions:

• "French angles" provide a quantitative, reliable, and simple method for assessing neurological maturation in infants.
• The measurement complements routine neurodevelopmental assessments and shows potential as a screening tool for neuromuscular conditions.
• Normative data suggest a gradual decrease in passive muscle tone during the first year of life.