Sonoelastographic evaluation of medial gastrocnemius muscles intrinsic stiffness after rehabilitation therapy with botulinum toxin a injection in spastic cerebral palsy.

OBJECTIVE

To investigate intrinsic stiffness changes using real-time sonoelastography (RTS) in the medial gastrocnemius muscle (GCM) after rehabilitation therapy with botulinum toxin type A (BTA) injection in spastic cerebral palsy (CP).

DESIGN

Prospective study using ultrasonography and RTS.

SETTING

An inpatient rehabilitation clinic.

PARTICIPANTS

Children (N=17) with spastic CP (mean age, 57±22y, age range, 26-110mo).

INTERVENTION

Rehabilitation therapy and intramuscular injection of BTA in both medial and lateral GCMs.

MAIN OUTCOME MEASURES

RTS was obtained on the medial GCM, and the elastic pattern of the medial GCM was graded from RTS 1 (purple to green: soft) to RTS 4 (red: stiff) on the basis of color-scaled RTS. RTS score, color histogram, Modified Ashworth Scale (MAS) score of the ankle plantar flexor muscles, and Gross Motor Function Measure (GMFM) score were obtained before intervention and 4 weeks after intervention. The correlations among RTS score, GMFM, and MAS score were determined. Intrarater reliability was also evaluated.

RESULTS

Before and at 4 weeks after intervention, the mean RTS score decreased from 3.4 to 1.5 (P<.05), median red pixel intensity decreased from 112.5 to 101.3 (P<.05), median blue pixel intensity increased from 82.6 to 90.4 (P<.05), mean MAS score of the ankle decreased from 2.7 to 1.3 (P<.05), and mean GMFM score increased from 54.55% to 62.32%. Significant correlations were observed between the RTS score and the MAS score. Intrarater reliability was high.

CONCLUSIONS

Our results suggest that more information about the change of spastic muscle in CP after rehabilitation treatment with BTA may be gained by estimating muscle stiffness using RTS combined with clinical scale measurements.