Evaluating the Child with Cerebral Palsy

Original Editor - Kim Jackson as part of ICRC Cerebral Palsy Content Development Project

Top Contributors - Naomi O'Reilly, Kim Jackson, Admin, 127.0.0.1, WikiSysop, Simisola Ajeyalemi, Aminat Abolade, Wendy Walker, Rucha Gadgil and Jess Bell  

Introduction

Cerebral Palsy (CP) is a neurodevelopmental disorder marked by non-progressive motor function impairment originating from damage to the developing brain. The complexity of this condition necessitates an integrated rehabilitation approach, encompassing multiple professionals in the field. Knowledge of cerebral palsy and experience of managing neurological is necessary to ensure that treatable causes are identified. The team usually includes physiotherapists, occupational therapists, speech therapists, nutritionists, paediatricians, orthopaedic surgeons, and neurologists, each playing a distinct yet collaborative role in managing the unique challenges presented by CP.

The manifestations of CP often become clearer over time, meaning that a diagnosis may not be confirmed until several months to a year after birth, or even later in cases with milder symptoms. During this time, the child's growth and development are closely monitored, their medical history is reviewed, and physical examinations are conducted.

Clinical Assessment

The evaluation of a child with CP requires a comprehensive, multidimensional approach to accurately identify and address the individual's specific deficits and needs. The assessment process includes a thorough medical history, physical examination, functional assessment, and often, specialized evaluations. Importantly, the assessment extends beyond the child to incorporate the family, evaluating their needs and resources, as successful management often relies on family-centered care. 

Observing the child’s movements is the initial and a crucial part of the examination. Observe before you touch. If the child is young, apprehensive or tearful, let them stay on mother’s lap while you watch and talk to the mother. As the child adapts to the environment, slowly place them on the examination table or on the floor still close to the mother/carer and watch them move around. If the child cries a lot and does not cooperate, continue while they are in their mother’s lap. Tools required for the examination are very simple: toys, small wooden/different shaped blocks, and objects with different textures.

A comprehensive physical and biomechanical evaluation is paramount for a child with cerebral palsy (CP) who is ambulant, as it informs targeted interventions at specific joints and segment levels. Essential components of the clinical examination should include:

1. Postural Evaluation: This involves assessing the child's posture in various positions, such as prone lying, supine lying, sitting, standing, and walking. Variations in these postures may provide insights into underlying musculoskeletal imbalances or functional limitations.
2. Muscle Tone Assessment: This entails the evaluation of muscle tone in the extremities, trunk, and neck, along with deep tendon reflexes. CP often presents with muscle tone abnormalities, necessitating thorough and regular tone evaluations. Dystonia, characterised by involuntary intermittent muscle contractions leading to twisting movements or abnormal postures, can manifest in cases of hypertonia arising from an extrapyramidal brain lesion. Conversely, hypertonia associated with a pyramidal brain lesion often presents as spasticity, which is the defining motor disorder in approximately 80% of paediatric CP cases. Spasticity is typified by a velocity-dependent increase in tonic stretch reflexes (muscle tone) with exaggerated tendon jerks, resulting from stretch reflex hyperexcitability, a component of the upper motor neuron syndrome .
3. Muscle Strength Evaluation: Accurate muscle strength assessment is critical, given its profound influence on the functional abilities of the child.
4. Joint Range of Motion (ROM) Assessment: ROM should be evaluated at the hip, knee, ankle, sub-talar, and mid-tarsal joints. Joint angles identified during ROM testing, performed at slow, medium, and fast velocities, inform the position of the anatomical joint in any potential orthotic intervention. It further assists in identifying if mechanical joints should be included in the orthotic design and, if so, the specific type.

The identification and quantification of spasticity remain crucial in determining appropriate orthotic intervention, thereby necessitating detailed evaluations of muscle tone and ROM during clinical assessments.

Tone 

In the clinical assessment of children with CP, a comprehensive understanding of muscle tone and strength is paramount. Notably, these children frequently exhibit muscle tone alterations, which often coincide with signs of underlying muscle weakness. Muscle tone can vary substantially in this population, and its accurate evaluation guides the overall clinical intervention strategy. To reliably assess muscle tone and spasticity, clinicians use well-established tools such as the Tardieu Scale (TS), the Modified Tardieu Scale (MTS), and the Ashworth Scale (AS). Each tool adopts unique methodologies for this purpose, although potential sources of error should be considered, including individual variability, measurement tool inaccuracies, and variability in the attributes being measured.

Specifically, spasticity is a velocity-dependent increase in muscle tone, necessitating the application of tools that accommodate this aspect, such as the Tardieu Scale. The Tardieu Scale uniquely caters to this by incorporating passive muscle stretches at three different speeds, thereby providing a more comprehensive assessment of spasticity. Whereas the Ashworth Scale measures passive resistance to movement at just one speed.

The TS and MTS have displayed high intra and inter-rater reliability with adequate training, while the AS has shown inconsistent reliability (Fosang et al., 2003). Notably, the TS and MTS capture the velocity-dependent nature of spasticity, making them more suitable for accurately assessing this condition. Conversely, the AS measures passive resistance at a single speed, potentially leading to inaccuracies when identifying spasticity, particularly in the presence of muscle contracture.

Tardieu Scale

The Tardieu Scale (TS) measures spasticity (velocity-dependent) by passively moving the joints at three specified speeds - slow, under gravity, and fast. The muscle's reaction to stretch (X) is rated on a 6-point scale and the joint angle (Y) recorded at the point where the muscle reaction is first felt (Boyd & Graham, 1999).

Scoring

The scoring is done as follows

Quality of Muscle Reaction

0	No resistance throughout passive movement
1	Slight resistance throughout,with no clear catch at a precise angle
2	Clear catch at a precise angle followed by release
3	Fatiguable Clonus (< 10 secs) occurring at a precise angleFatiguable Clonus (< 10 secs) occurring at a precise angle
4	Unfatiguable Clonus (> 10 secs) occurring at a precise angle
5	Joint immobile

Velocity to Stretch

V1	As slow as possible
V2	Speed of the limb segment falling (with gravitational pull)
V3	At a fast rate (>gravitational pull)

Spasticity Angle

R1	Angle of catch seen at Velocity V2 or V3
R2	Full range of motion achieved when muscle is at rest and tested at V1 velocity

However, the TS's extensive nature often makes it time-consuming to perform. This led to the development of a more time-efficient variant - the Modified Tardieu Scale (MTS).

Modified Tardieu Scale (MTS)

This scale is an abbreviated version of the TS, focusing only on joint angles at fast and slow velocities. It takes into account the angle of muscle 'catch' at the highest velocity (R1) and the joint angle when the muscle length is at its maximum (R2), gauged by slow passive movement through full Range of Motion (ROM) (Patrick & Ada, 2006). The difference in degrees between R2 and R1, known as the dynamic component of spasticity, helps estimate the relative contribution of spasticity compared to muscle contracture.

Ashworth Scale

The Ashworth Scale (AS) is used to grade the intensity of muscle tone through joint ROM on a five-point scale at one non-specified speed. Despite the widespread use of the AS and its ability to identify general hypertonia, it is recommended that this tool no longer be used and that the TS or MTS be used to evaluate the muscle tone in ambulant children with Cerebral Palsy.  The Modified Ashworth Scale (MAS), a derivative of the AS, includes a 6-point grading scale and severity grading of muscle tone at an unspecified 'fast' speed.

Scoring

The scoring is done as follows

0	No increase in tone
1	Slight increase in tone giving a catch when slight increase in muscle tone, manifested by the limb was moved in flexion or extension
1+	Slight increase in muscle tone, manifested by a catch followed by minimal resistance throughout (ROM )
2	More marked increase in tone but more marked increased in muscle tone through most limb easily flexed
3	Considerable increase in tone, passive movement difficult
4	Limb rigid in flexion or extension

Thus, the evaluation of lower limb muscle strength is an essential part of the clinical picture in ambulant children with CP. Muscle strength has a direct bearing on a child's motor function, walking speed, energy expenditure, and gait characteristics.

Strength 

The presence of muscle weakness leads to muscle imbalance across other joints. This muscle imbalance is thought to be a factor in the development of muscle shortening, contributes towards rotational deformities and further affects the motor function of a child.   Hence, when performing the orthotic assessment of a child with Cerebral Palsy, a full muscle strength profile of the lower limbs is vital. The Medical Research Council Scale (MRCS) for manual muscle testing is the widely accepted clinical evaluation tool used to grade the muscle strength a child with Cerebral Palsy.  (TABLE 3) During the assessment it is important to note if the child does not cooperate, is unable to isolate the muscle being tested or comprehend what is being asked of them. If further quantification of muscle strength is required, a hand held dynamometer may be used.  

Grade	Description
0	No movement is observed
1	Only a flicker or trace of muscle movement is seen or felt in the muscle or fasiculations are observed in the muscle
2	Muscle can only move if the resistance of gravity is removed
3	Muscle strength is further reduced such that the joint can be moved only against gravity with the examiner’s resistance completely removed
4	Muscle strength is reduced but muscle contraction can still move the joint against resistance
5	Muscle contracts normally against full resistance

TABLE 3: The Medical Research Council Scale (MRCS) for muscle strength evaluation 

Range of Movement 

Muscle contracture and bony deformities are the commonly observed secondary musculoskeletal problems that children with Cerebral Palsy may develop. These secondary musculoskeletal problems cause a decrease in the child’s available lower limb joint
ROM. Therefore, evaluation and quantification of the passive and dynamic lower limb joint ROM is a crucial part of the orthotic assessment of any ambulant child with Cerebral Palsy. The findings assist with the prescription of orthoses, evaluation of the intervention and the monitoring of change due to growth. 

The hip joint should be assessed for the amount of available passive and dynamic ROM in flexion, extension, abduction and adduction. Hip flexion contractures are a frequent presentation in a child with a predominantly spastic presentation of Cerebral Palsy. A primary hip flexion contracture adversely affects the kinematics of a child’s gait by: 

• Restricting heel contact at initial contact;

• Altering the position of the body’s weight line during stance phase;

• Changing the degree of inclination of the femur and the tibia during stance phase;

• Reducing the amount of hip extension possible, causing an interruption of transfer through the second and third rockers of stance phase.

The knee joint needs to be assessed for flexion and extension in both passive and dynamic ROM. It is also important to assess the joint range of motion of the passive, active and velocity specific knee extension with the child supine and the hip flexed to approximately 30°. This position replicates the degree of the hip flexion that occurs at initial contact during gait and establishes the degree of knee extension that is possible during early stance phase.

To establish the ROM of plantar and dorsi flexion at the ankle joint, it is important the sub-talar joint is maintained in a neutral alignment and the tests are best carried out with a child in a supine position. Movement of the sub-talar joint into either eversion or inversion while dorsi flexing the ankle affects the length of the gastrocnemius muscle and may produce erroneous findings of the available dorsiflexion ROM.  A plantar extensor pattern generally exists in the lower limbs of a child with a spastic presentation of Cerebral Palsy. This often causes either the gastrocnemius or soleus muscles to be affected by increases in muscle tone. The gastrocnemius is a bi-articular muscle, originating proximal to the femoral condyles and inserting at the base of the calcaneus. Flexing the hip and knee to 90° and then dorsi flexing the ankle eliminates the effects of the gastrocnemius muscle on the foot and ankle and makes it possible to check the available ROM and muscle tone specifically attributed to the soleus muscle. (FIGURE 1A) 

A	B

FIGURE 1: Physical evaluation of the ROM of the ankle joint due to the Soleus Muscle (A) and the Gastrocnemius Muscle (B) 

Alternatively, positioning the hip in 30° of flexion, the knee in the maximum attainable extension, the sub-talar joint in a neutral alignment and then dorsi flexing the foot establishes the ROM of ankle dorsiflexion that is attributable to either changes in muscle tone or contracture of the gastrocnemius muscle. (FIGURE 1B) Assessing the ankle ROM due to gastrocnemius length ascertains the child’s plantar flexion-knee extension couple. This is used during the prescription of an AFO to determine the Angle of the Ankle in the AFO (AAAFO) and is the degree of ankle dorsi or plantar flexion the ankle is positioned within the AFO. It is defined as the angle of the foot relative to the tibial shank when viewed in the sagittal plane. 

Torsional deformities in ambulant children with Cerebral Palsy occur when there are muscle imbalances and abnormal loading and growth of bones due to increased tone or weakness.  Therefore it is important to include a rotational assessment of the joints of the lower limbs. The particular areas to assess are hip internal/external rotation, femoral ante/retro version, degree of tibial torsion, sub-talar inversion/eversion and mid-tarsal ab/adduction. Establishing the torsional profile of a child’s lower limbs aids orthotic prescription by identifying if a torsional lever arm deficiency is present. 

Goniometric measures are the most widely used technique to assess either passive or velocity dependent lower limb joint ROM in a child with Cerebral Palsy.  Factors such as the number of assessors, patient compliance and the method used for measuring can affect the reliability and repeatability of measures. Several studies involving children with spastic Cerebral Palsy found that goniometric measurements display high levels of inter and intra reliability and repeatability for observers who are trained and experienced.     This is provided a strict measuring protocol is adhered to.

 

Resources

Hambisela_Module_2_Evaluating_Your_Child   In: Getting to Know Cerebral Palsy: A learning resource for facilitators, parents, caregivers, and persons with cerebral palsy