Botulinum toxin type A for spasticity in cerebral palsy patients: which impact on popliteal angle to hamstring length? A proof-of-concept study

BACKGROUND: Cerebral palsy (CP) is the most common physical disability in childhood. It is a heterogeneous condition in terms of etiology, motor type and severity of impairments. Clinical impairments, such as increased muscle tone (spasticity), muscle weakness and joint stiffness contribute to the abnormal development of functional activities, including gait. OBJECTIVE: The objective of this study was to investigate the popliteal angle to hamstring length after ultrasound guided Incobotulinum toxin A injections for spasticity in CP patients. METHODS: In this proof-of-concept study, we included outpatients with CP and crouch gait correlated to hamstrings spasticity referred to the Pediatric Rehabilitation outpatient clinic of Umberto I University Hospital, Sapienza University of Rome, in the period between February and October 2018. METHODS: Modified Ashworth Scale (MAS) of hamstring muscles, Popliteal Angle and Modified Popliteal Angle, Passive Knee Extension and 10 Meter Walk Test (10MWT) were assessed at baseline (T0) and three weeks after ultrasound guided injection (T1) of Incobotulinum Toxin A (dose weight and site dependent). RESULTS: Thirteen patients (5 male and 8 female), mean aged 9.91 ± 3.59, were included. The clinical evaluation at T0 showed hamstring muscles spasticity, with MAS of 2.4 ± 0.6, popliteal angle -51.7± 11.0 modified popliteal angle of -39.5 ± 11.0 , passive knee extension of -14.0 ± 8.7 and 10MWT of 14.3 ± 4.6 seconds. At T1, hamstring muscles MAS mean value was 1.7 ± 0.6 (p< 0.01), popliteal angle 41.3 ± 7.0 (p< 0.001), modified popliteal angle -32.9 ± 10.4 (p< 0.001), passive knee extension -4.0 ± 4.2 (p< 0.05) and 10MWT 12.6 ± 4.8 seconds (p< 0.05). None of the treated patients reported any adverse event related to Incobotulinum Toxin A injection. CONCLUSION: Incobotulinum toxin A treatment has been proven to be safe and effective for hamstring muscles spasticity management in CP patients. Further studies with larger samples and longer follow-up are warranted to assess the efficacy of this treatment on the popliteal angle.