Stretching in Children and Adolescents With Spastic Cerebral Palsy

The primary aim of this study is to gain knowledge about both the effects of a single bout of static and proprioceptive neuromuscular facilitation (PNF) stretching and the effects of 8-week static and PNF stretching training on the calf muscle-tendon properties in children with spastic cerebral palsy (SCP). Furthermore, the effects on joint and muscle function, stretch reflexes, gait, and self-reported gait function and functional performance are examined to receive a comprehensive picture of potential changes. Further aims of this study are to identify which stretching technique might be more efficient by comparing the effects of both stretching interventions, and to gain information about the influence of foot flexibility on the stretch achieved by the spastic gastrocnemius muscle.

Background: Spastic cerebral palsy (SCP) is a non-progressive neuro-muscular disorder in children resulting from an injury in the central nervous system. Individuals with SCP present with impairments such as hyperreflexia, demonstrate impaired motor control and muscle growth. Manual stretching is an important approach in the physical therapy of individuals with SCP used to increase muscle extensibility and length, decrease muscle stiffness, and to improve functional abilities. However, there are only a few studies that have examined its acute and long-term effects in children with SCP and it is still not clear, if it may lead to the expected changes, and which method might be the most-effective one. Besides static stretching, proprioceptive neuromuscular facilitation (PNF) stretching has been used to aid the rehabilitation of, for example, stroke patients by either facilitating muscle elongation and/or improving muscle strength. Positive effects were found (e.g., increased dorsiflexion, improved gait function, altered tendon properties), which are also clinically relevant for individuals with SCP. However, there is no information about the impact of PNF in this population. Aims: The primary aim of this study is to gain knowledge about both the effects of a single bout of static and PNF stretching and the effects of 8-week static and PNF stretching training on the calf muscle-tendon properties in children with SCP. Furthermore, the effects on joint and muscle function, stretch reflexes, gait, and self-reported gait function and functional performance are examined to receive a comprehensive picture of potential changes. Further aims of this study are to identify which stretching technique might be more efficient by comparing the effects of both stretching interventions, and to gain information about the influence of foot flexibility on the stretch achieved by the spastic gastrocnemius muscle-tendon unit. Methods: A randomized controlled trial with a cross-over design will be performed. Prior to the measurements, a familiarization session takes place and both groups will further be examined in three separate measurement sessions. Based on a power calculation and in order to account for possible dropouts, 30 individuals with SCP (age range: 6 to 15 years) will be recruited. The participants will be randomly allocated to either the static stretching or PNF stretching intervention after the familiarization session. Passive muscle-tendon morphological properties will be examined. A manually controlled instrumented spasticity assessment will be performed to test for differences in the reflex responses. Information about the lengthening behavior of the tissues throughout the dorsiflexion rotations will also be collected by use of ultrasound. Isometric muscle strength and the active torque-angle relationship will be investigated using an isokinetic dynamometer. To assess the gait pattern of the children, a gait analysis will be performed by use of an 8-camera motion capture system. In addition, we will examine the participants' gait function and functional performance by use of the Gait Outcomes Assessment List questionnaire.

An 8-week home-based static stretching training for the calf muscles will be performed by group A. Altogether, 10 stretches are performed per leg 4 times a week.

While group A performs the 8-week static stretching training, group B acts as control group performing its daily life activities as usual.

After group A has finished the 8-week static stretching training, group B starts with the 8-week home-based proprioceptive neuromuscular facilitation stretching training. Altogether, 10 stretches are performed per leg 4 times a week.

While group B performs the 8-week proprioceptive neuromuscular facilitation stretching, group A is in its follow-up period performing its daily life activities as usual.

During the static stretching training for the calf muscles, the ankle joint is moved into maximal dorsiflexion until the point of discomfort is reached. The ankle joint is then held in this maximal position for 30 s followed by a rest period of 30 s. Afterwards, the procedure is repeated with the knee in flexed position to stretch the soleus muscle.

During the proprioceptive neuromuscular facilitation stretching, the ankle joint is moved into maximal dorsiflexion. While the foot is kept in this position, the child will perform a (sub-) maximal isometric contraction of the plantar flexors against the resistance of their parents. Afterwards, the ankle joint will be moved further into greater dorsiflexion and is held there for the remaining seconds followed by 30 s of rest. Subsequently, the stretch will be applied with the knee flexed.

Gastrocnemius medialis muscle morphology, muscle stiffness, tendon-aponeurosis length and stiffness, muscle-tendon unit length and stiffness, elongations of the tissues

familiarisation session (T0, 1-week before T1), post-measurement (T2, 8 weeks), follow-up measurement (T3, 16 weeks)

familiarisation session (T0, 1-week before T1), post-measurement (T2, 8 weeks), follow-up measurement (T3, 16 weeks)

Inclusion Criteria: spastic cerebral palsy ambulatory children and adolescents ability to accept and follow verbal instructions no severe contracture of the calf muscles (max. ankle dorsiflexion >= 0°, with knees extended) classified as GMFCS level I, II, or III aged between 6 and 5 years willingness to participate Exclusion Criteria: others than spastic forms of cerebral palsy severe mental retardation fixed muscle contractures (ankle equinus deformity = max. ankle dorsiflexion <= 0°, with knees extended) oral anti-spastic and/or muscle relaxation medication in the last 6 months orthopaedic surgery and/or Botulinum toxin type A application in the last 12 months

Lee WY, Park GY, Kwon DR. Comparison of treatment effects between children with spastic cerebral palsy under and over five years after botulinum toxin type a injection. Ann Rehabil Med. 2014 Apr;38(2):200-8. doi: 10.5535/arm.2014.38.2.200. Epub 2014 Apr 29.

Willerslev-Olsen M, Choe Lund M, Lorentzen J, Barber L, Kofoed-Hansen M, Nielsen JB. Impaired muscle growth precedes development of increased stiffness of the triceps surae musculotendinous unit in children with cerebral palsy. Dev Med Child Neurol. 2018 Jul;60(7):672-679. doi: 10.1111/dmcn.13729. Epub 2018 Mar 24.

Barber L, Barrett R, Lichtwark G. Medial gastrocnemius muscle fascicle active torque-length and Achilles tendon properties in young adults with spastic cerebral palsy. J Biomech. 2012 Oct 11;45(15):2526-30. doi: 10.1016/j.jbiomech.2012.07.018. Epub 2012 Aug 3.

Wiart L, Darrah J, Kembhavi G. Stretching with children with cerebral palsy: what do we know and where are we going? Pediatr Phys Ther. 2008 Summer;20(2):173-8. doi: 10.1097/PEP.0b013e3181728a8c.

Sharman MJ, Cresswell AG, Riek S. Proprioceptive neuromuscular facilitation stretching : mechanisms and clinical implications. Sports Med. 2006;36(11):929-39. doi: 10.2165/00007256-200636110-00002.

Zhou Z, Sun Y, Wang N, Gao F, Wei K, Wang Q. Robot-Assisted Rehabilitation of Ankle Plantar Flexors Spasticity: A 3-Month Study with Proprioceptive Neuromuscular Facilitation. Front Neurorobot. 2016 Nov 14;10:16. doi: 10.3389/fnbot.2016.00016. eCollection 2016.

Zhou Z, Zhou Y, Wang N, Gao F, Wang L, Wei K, Wang Q. Changes of Achilles tendon properties via 12-week PNF based robotic rehabilitation of ankle joints with spasticity and/or contracture. Annu Int Conf IEEE Eng Med Biol Soc. 2014;2014:1214-7. doi: 10.1109/EMBC.2014.6943815.