Cerebral Palsy (CP): Comprehensive Clinical Assessment, Tone, Strength, and Range of Motion

Cerebral palsy (CP) is a neurological developmental disorder characterized by non-progressive motor impairment resulting from injury to the developing brain¹.Because CP is complex, effective care requires a multidisciplinary rehabilitation team—physiotherapists, occupational therapists, speech and language therapists, dietitians, pediatricians, orthopedists, and neurologists—each with defined roles in assessment and treatment¹.

Clinical manifestations often become clearer over time; therefore, diagnosis is rarely made immediately after birth, especially in milder cases². Ongoing follow-up should include growth monitoring, detailed history, and systematic clinical examination.

Clinical Assessment

Holistic Evaluation

A thorough assessment is essential to identify functional limitations and guide interventions³. It should include:

• Detailed medical history

• Physical examination

• Functional assessment

• Specialized investigations when indicated³

Family involvement is always recommended—resources, needs, and goals should be integrated into planning because a family-centered approach improves outcomes³.

Observation of Movement

Observe before touching. Watch the child in natural surroundings—ideally on the caregiver’s lap—to avoid stress that may alter movement patterns⁴.Once comfortable, move to the plinth or floor near the caregiver for further observation. Use toys/blocks with different textures to elicit typical play and movement⁴.

Physical and Biomechanical Assessment

A detailed physical exam helps reveal both muscular and joint-related challenges in children with CP⁵.

Posture Evaluation

Assess posture in supine, sitting, standing, and during gait⁶. Deviations may indicate muscle imbalance or other functional limitations.

Muscle Tone

Assess tone systematically in limbs, trunk, and neck⁷. CP commonly features hypertonia (spasticity), especially with pyramidal lesions (~80% of cases)⁸. Spasticity is a velocity-dependent increase in muscle tone with exaggerated tendon reflexes—classic upper motor neuron signs⁸.With extrapyramidal involvement, dystonia may appear—characterized by involuntary twisting movements or abnormal postures⁹.

Muscle Strength

Systematic strength testing is important to determine functional capacity¹⁰.

Range of Motion (ROM)

Assess ROM in hip, knee, ankle, subtalar, and midtarsal joints¹¹. Use slow/medium/fast test speeds to determine mechanical joint angles and to inform orthosis needs¹². Combined spasticity + ROM evaluation is critical for correct orthotic prescription.

Tone Assessment Tools

Muscle tone varies widely in CP; careful assessment is key to planning¹³. Common tools include:

• Tardieu Scale (TS)

• Modified Tardieu Scale (MTS)

• Ashworth Scale (AS)¹³

TS/MTS are preferred because they capture velocity-dependent spasticity. AS measures passive resistance at one speed only and shows lower reliability¹⁴. With adequate training, TS/MTS demonstrate strong intra- and inter-rater reliability¹⁴.

Tardieu Scale (TS)

Passive movement tested at three velocities¹⁵:

• V1: Slow

• V2: Speed of gravity

• V3: Fast

Two parameters are recorded:

• Quality of muscle reaction (X), 0–5:0 = No resistance; 1 = Slight resistance, no clear stop; 2 = Clear catch at a precise angle;3 = Fatigable clonus (<10 s); 4 = Unfatigable clonus (>10 s); 5 = Immobilized joint¹⁵.

• Angle:R1: Angle at which the spastic reaction (“catch”) occursR2: Full passive range at V1 (rest)¹⁵

TS is detailed but time-consuming; many clinics therefore use MTS.

Modified Tardieu Scale (MTS)

A streamlined version for pediatric CP¹. Records:

• R1: “Catch” angle during fast movement

• R2: Full ROM during slow movement¹

R2–R1 estimates the dynamic spasticity component, helping distinguish spasticity from fixed contracture¹.

Ashworth / Modified Ashworth Scale (MAS)

AS grades tone with single-speed passive movement². Due to limited reliability and inability to separate spasticity from other hypertonias², TS/MTS are preferred today.MAS refines AS (0–4 plus 1+) at an unspecified fast speed²:

• 0 = No increase in tone

• 1 = Slight increase, “catch” then release

• 1+ = Catch then minimal resistance through <½ ROM

• 2 = Marked increase through most of ROM, easily moved

• 3 = Considerable increase, passive movement difficult

• 4 = Rigid in flexion or extension

Strength

Why Strength Matters

Weakness is central in CP and often leads to joint imbalance, muscle shortening, and rotational deformities³. These reduce motor function, gait speed, and energy efficiency³. A comprehensive lower-limb strength assessment is therefore essential during orthotic planning³.

Manual Muscle Testing

Use the Oxford/MRC Scale (0–5)⁴. Suggested muscle groups⁴:

• Wrist extension

• Elbow flexion

• Shoulder abduction

• Ankle dorsiflexion

• Knee extension

• Hip flexion

MRC grading: 0 = No contraction; 1 = Flicker; 2 = Movement not against gravity; 3 = Against gravity; 4 = Against resistance; 5 = Normal⁴.

Hand-Held Dynamometry

When objective quantification is needed, dynamometers provide more precise, reliable strength data⁵.

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Lower-Limb Range of Motion in CP

Introduction

Measuring and understanding ROM is crucial for both orthotic prescription and overall management¹. Secondary MSK changes—contractures and bony deformities—are common and can markedly reduce available ROM¹. Reduced mobility, spasticity/dystonia, age, sex, pain threshold, comorbidities, injury, and physical activity can all negatively affect ROM¹.Assess passive and dynamic ROM in the lower limbs to understand functional limitations.

Torsional Deformities

Often caused by muscle imbalance and abnormal bone growth secondary to increased tone or weakness². For ambulant children, include²:

• Hip internal/external rotation

• Degree of femoral anteversion/retroversion

• Tibial torsion, subtalar inversion/eversion

• Midtarsal adduction/abduction²

This torsion profile informs orthotic prescription by revealing torsional moment arms².

Hip

Assess passive/dynamic flexion, extension, abduction, adduction³. Hip flexion contracture is common in spastic CP and shifts the COM during stance³—reducing initial heel contact, altering femur/tibia alignment, and limiting hip extension, which disrupts normal transitions through stance phases³.

Knee

Assess passive/dynamic flexion and extension⁴. Also test knee extension in supine with ~30° hip flexion to simulate the hip position at initial contact during gait—this gives a functional view of early stance ROM⁴.

Ankle

Carefully assess dorsiflexion and plantarflexion, especially with spasticity⁵. Maintain the subtalar joint in neutral during testing to avoid measurement error from inversion/eversion influencing gastrocnemius length⁵.Spastic CP often shows a plantar extensor pattern affecting gastrocnemius/soleus⁶. To isolate soleus, flex hip and knee to 90° before measuring dorsiflexion⁶.

Passive goniometry (supine for standardization)⁶:

• Knee at 0° extension: gastrocnemius flexibility

• Knee at 45° flexion: soleus flexibility

Orthosis Planning

When prescribing an ankle–foot orthosis (AFO), evaluate gastrocnemius passive length with the knee extended⁷—this determines AFO ankle angle and heel-sole differential⁷. If the ankle sits in plantarflexion in the device, adjust to achieve vertical shank alignment⁷.

Integrated View

ROM and torsional assessment together provide a full picture of the child’s biomechanics. Limitations in ankle dorsiflexion/plantarflexion reflect not only muscle factors but also capsule, ligaments, and periarticular structures⁸.

Goniometry

The most common method to assess passive or velocity-dependent ROM in CP is goniometry⁹. Reliability depends on the number of trials, child cooperation, and measurement technique⁹.

Conclusion

A comprehensive evaluation of tone, strength, ROM, and torsional deformities is essential for functional profiling and sound clinical decision-making in children with CP. Use standardized tools (TS/MTS, MRC, goniometry), integrate family goals, and apply clinical expertise to ensure reliable measurements and targeted interventions.

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