Objective: To identify the thickness of gastrocnemius muscles (GCM) in normal children and children with spastic cerebral palsy using ultrasonography and to determine the influencing factors in order to increase the accuracy of intramuscular injection of botulinum toxin A. Method: Fifty-six children with spastic cerebral palsy (Group A) with no fixed contractures or operation history were involved in this study and they were compared with normal children (Group B). Children lay prone and one examiner measured the thickness of medial and lateral GCM using ultrasonography. Relationship between GCM thickness and clinical variables (age, height, weight, body mass index (BMI), calf circumference, Gross Motor Function Classification System (GMFCS) level, spasticity, number of botulinum toxin injections) were determined with Pearson’s correlation. Results: The thickness of medial and lateral GCM were 78.06±14.66 mm, 66.90±12.23 mm respectively, in Group A, and 103.44±12.04 mm, 79.95±9.76 mm respectively, in Group B. Medial GCM were thicker than lateral GCM in both groups. The age, height, weight, BMI, calf circumference and the thickness of GCM were higher in Group B. In group A, weight, BMI, calf circumference showed positive correlations with the thickness of medial GCM and GMFCS showed negative correlation with the thickness of medial GCM. Conclusion: To increase the accuracy of intramuscular injection of botulinum toxin A, we should keep in mind that the thickness of GCM may be influenced by several factors. Further controlled study including larger group is needed.

Objective: To identify the thickness of gastrocnemius muscles (GCM) in normal children and children with spastic cerebral palsy using ultrasonography and to determine the influencing factors in order to increase the accuracy of intramuscular injection of botulinum toxin A. Method: Fifty-six children with spastic cerebral palsy (Group A) with no fixed contractures or operation history were involved in this study and they were compared with normal children (Group B). Children lay prone and one examiner measured the thickness of medial and lateral GCM using ultrasonography. Relationship between GCM thickness and clinical variables (age, height, weight, body mass index (BMI), calf circumference, Gross Motor Function Classification System (GMFCS) level, spasticity, number of botulinum toxin injections) were determined with Pearson’s correlation. Results: The thickness of medial and lateral GCM were 78.06±14.66 mm, 66.90±12.23 mm respectively, in Group A, and 103.44±12.04 mm, 79.95±9.76 mm respectively, in Group B. Medial GCM were thicker than lateral GCM in both groups. The age, height, weight, BMI, calf circumference and the thickness of GCM were higher in Group B. In group A, weight, BMI, calf circumference showed positive correlations with the thickness of medial GCM and GMFCS showed negative correlation with the thickness of medial GCM. Conclusion: To increase the accuracy of intramuscular injection of botulinum toxin A, we should keep in mind that the thickness of GCM may be influenced by several factors. Further controlled study including larger group is needed.