Cerebral Palsy

Definition: Cerebral Palsy (CP) is defined by the Rosenbaum (2005) consensus: "A group of permanent disorders of the development of movement and posture, causing activity limitation, that are attributed to non-progressive disturbances that occurred in the developing fetal or infant brain. The motor disorders are often accompanied by disturbances of sensation, perception, cognition, communication, and behavior, by epilepsy, and by secondary musculoskeletal problems."

Epidemiology:

• Incidence: 2-2.5 per 1000 live births (Stable despite obstetric advances, due to survival of extreme preterms).
• Risk Factors: Prematurity (strongest), Low Birth Weight, Multiple gestation, Infection (Chorioamnionitis).
• Asphyxia: Intrapartum asphyxia accounts for only 10% of cases.

Primary Prevention:

• Magnesium Sulfate: Given to mothers in threatened very preterm labour for fetal neuroprotection. Pooled meta-analysis (Cochrane) shows roughly a one-third relative reduction in CP; individual trials were under-powered for CP alone (see Evidence Base).
• Cooling (Therapeutic Hypothermia): Standard of care for term infants with HIE. Reduces mortality and severe disability.
• Corticosteroids: Antenatal steroids for lung maturity also reduce IVH risk.

Brain Lesions:

1. Periventricular Leukomalacia (PVL): Necrosis of white matter near lateral ventricles. Affects medial fibres of the corticospinal tract (legs affected more than arms). Classic cause of Spastic Diplegia in premature infants.
2. Intraventricular Hemorrhage (IVH): Common in preterms.
3. HIE (Hypoxic Ischemic Encephalopathy): Global injury. Often leads to Quadriplegia or Dyskinetic CP.
4. Stroke (MCA Infarct): Cause of Hemiplegia.

Musculoskeletal Pathology: The brain lesion is static, but the MSK issues are progressive.

• Primary: Loss of selective motor control, spasticity, balance loss.
• Secondary: Muscle contracture (myostatic contracture), lever arm dysfunction (torsion).
• Tertiary: Bony deformity (hip dislocation, scoliosis), joint degeneration.

Lever Arm Dysfunction: Skeletal deformities reduce the efficiency of muscles.

• Femoral Anteversion: Intoeing. Glutes lose abduction power.
• Tibial Torsion: External. Foot pressure axis lateral.
• Pes Valgus: Midfoot break. Gastroc power lost (lever arm shortens).

History:

• Birth history (Gestation, ICU stay).
• Milestones (Sit by 2? Walk by ?).
• Communication/Feeding status.

Physical Examination:

• Tone: Modified Ashworth Scale (0-4). Tardieu Scale (R1/R2).
  • R1: Angle of first catch (velocity dependent).
  • R2: Angle of Max passive range (static length).
  • R2-R1: Dynamic component (Spasticity).
• Selective Motor Control (SMC): Ability to isolate joint movement.
• Rotational Profile: Anteversion, Tibial Torsion.
• Spine: Scoliosis check.
• Hips: Abduction range (Risk of dislocation if less than 45).
• Spine: Scoliosis check. Sitting balance. Pelvic obliquity.

Selective Motor Control (SMC): This is the ability to isolate joint movement.

• Test: Ask patient to dorsiflex ankle without flexing hip/knee.
• Significance: Poor SMC predicts poor outcome from tendon transfers. If SMC is absent, transfer will not work "in phase" (but may act as a tenodesis).

Gait Analysis (Observational):

• Sagittal Plane: Look for the "Gait Deviations".
  • True Equinus: Hips extended, Knee extended, Ankle plantarflexed.
  • Jump Gait: Hip flexed, Knee flexed, Ankle plantarflexed.
  • Apparent Equinus: Hip flexed, Knee flexed, Ankle neutral (but looks equinus due to knee flexion).
  • Crouch Gait: Hip flexed, Knee flexed (greater than 30 deg), Ankle dorsiflexed (Calcaneus).
• Coronal Plane:
  • Scissoring: Adductor spasticity.
  • Trendelenburg: Abductor weakness.
• Transverse Plane:
  • Intoeing: Femoral anteversion vs Internal Tibial Torsion.
  • Outtoeing: External Tibial Torsion (often iatrogenic or compensatory).

Anesthetic Considerations:

• Respiratory: High risk of aspiration (swallow dysfunction) and post-op pneumonia.
• Seizures: Ensure anticonvulsants are continued.
• Latex Allergy: Higher prevalence in CP/Spina Bifida.
• Positioning: Contractures make positioning on the table difficult. Pad purely bony prominences.
• Pain Assessment: FLACC scale for non-verbal children. High risk of under-treatment.

1. Hip Surveillance (X-rays):

• Why?: To prevent dislocation. Dislocation leads to pain, scoliosis, and hygiene issues in GMFCS V.
• Metric: Reimer's Migration Percentage (MP).
  • Calculation: Percentage of the femoral head lateral to Perkins' line (Lateral edge of acetabulum).
  • Normal: Less than 10% in normal children. Less than 30% acceptable in CP.
  • Risk: Greater than 30% ("Hip at Risk"). Often "Silent" (Pain free).
  • Dislocated: Greater than 100%. The head is completely lateral to the acetabulum.

2. Gait Analysis (3D Motion Lab):

• Gold Standard for surgical planning in walkers (GMFCS I-III).
• Kinematics: Joint angles.
• Kinetics: Forces/Moments (Joint powers).
• EMG: Muscle firing timing (rectus spasticity in swing?).
• Pedobarography: Foot pressure. 3. Gait Velocity and Oxygen Cost:
• Children with CP use 3-5x more energy to walk than peers.
• Oxygen Cost: measured in mL/kg/m.
• Goal of Surgery: Improve efficiency (Lower Oxygen cost).

4. GDI (Gait Deviation Index):

• A single number representing gait pathology.
• 100: Normal.
• Every 10 points below 100: One standard deviation from normal.
• Typical CP: GDI 60-70.
• Post-SEMLS: Expect increase of 5-10 points (Clinically significant).

5. Functional Assessment Tools:

• GMFM (Gross Motor Function Measure): Even more detailed than GMFCS. Used to track change over time (e.g. pre/post SDR).
  • GMFM-88: Validated for CP and Down Syndrome. Includes lying/rolling.
  • GMFM-66: Rasch-scaled version. Only for CP.
• FMS (Functional Mobility Scale): Rates mobility at 3 distances (Home, School, Community).
  • 5 meters: Home.
  • 50 meters: School.
  • 500 meters: Community.
  • Rating: 1 (Crawler) to 6 (Independent on all surfaces).
• CP-CHILD: Caregiver-reported Quality of Life measure (Comfort, Positioning).

Baclofen Pump Failure:

• Overdose: Coma, Respiratory depression, Hypotension. Support airway. Physostigmine (controversial).
• Withdrawal: Itchy, Agitated, Rigid, Seizures, Hyperthermia. Life threatening. Restore Baclofen (oral/intrathecal) immediately.

Pain management is critical, especially in Spastic CP where pain triggers spasm, which triggers more pain.

• Spasm Protocols: Benzodiazepines (Diazepam) + Gabapentin.
• Immobilization: Petrie Casts (Broomstick) or Spica for hips.
• Rehab: Intensive inpatient rehab for 6-12 weeks post-SEMLS.

• Walking: GMFCS I/II walk well. III walk with aids. IV/V do not walk.
• Employment: Competitive employment rates are low (GMFCS dependent).
• Pain: Over 50% of adults with CP report chronic musculoskeletal pain.
• Life Expectancy: Reduced in GMFCS V (respiratory issues). Near normal in I-III.

Hamstring Surgery Outcomes

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• SDR vs intrathecal baclofen vs SEMLS: For ambulant spastic diplegia there is no high-quality head-to-head RCT. Long-term cohorts (Tedroff) show SDR durably reduces tone but does not prevent later orthopaedic surgery or contracture — challenging the idea that early tone reduction alone changes natural history.
• Does SEMLS truly change long-term function? Gait-lab kinematics (GDI) improve, but functional/participation gains and durability are debated, and the evidence base lacks RCTs (McGinley).
• Optimal hip surveillance threshold for intervention: Migration percentage thresholds (30% vs 40% vs trend/velocity) and whether soft-tissue release alone suffices vary between programmes; reoperation rates remain high (Kiapekos).
• Magnesium sulfate magnitude of effect: Individual trials (including ACTOMgSO4/Crowther) were under-powered for CP as a sole endpoint; the neuroprotective recommendation rests on pooled meta-analysis, and optimal dosing/timing still varies.
• Single-event vs staged surgery: "Birthday syndrome" is condemned, yet very large single events carry higher perioperative and rehabilitation burden — the ideal bundling remains individualised.
• Botulinum toxin and muscle morphology: Concern that repeated BTX-A injections may cause long-term muscle atrophy/fibrosis in the developing muscle, tempering enthusiasm for high-frequency dosing.

Global Epidemiology:

• Prevalence: ~2.0-2.5 per 1000 live births in high-income settings; higher in low- and middle-income countries (LMICs) where prevalence may exceed 3 per 1000, with a higher proportion of severe, GMFCS IV-V and post-neonatally acquired CP (infection, kernicterus, birth asphyxia).
• Trend: Prevalence has plateaued or fallen modestly in high-income countries despite improved survival of extreme preterms, attributed to antenatal magnesium sulfate, antenatal steroids, and therapeutic hypothermia.
• Distribution: Spastic subtype ~80%; spastic diplegia/hemiplegia predominate; bilateral GMFCS IV-V drive the orthopaedic burden (hip, spine).

Registries & Surveillance Networks:

• CPUP (Sweden/Norway/Denmark/Scotland): The reference hip and spine surveillance registry; demonstrated near-elimination of hip dislocation.
• SCPE (Surveillance of Cerebral Palsy in Europe): Harmonised CP definitions and population prevalence data across European centres.
• CPIPS / UK national CP integrated pathway and Australian CP Register: National-scale GMFCS-based surveillance and outcome tracking.

High- vs Limited-Resource Practice Variation:

• High-resource: Routine GMFCS-based radiographic hip surveillance, 3D gait labs for SEMLS planning, intrathecal baclofen, SDR programmes, neonatal neuroprotection bundles.
• Limited-resource: Later presentation with established dislocation/contracture; emphasis on physiotherapy, low-cost orthoses, and salvage rather than preventive surgery; gait labs and SDR rarely available. Prevention of kernicterus and birth-asphyxia CP is a major public-health priority.