My 17‑month‑old child has trouble walking more than a few steps and his leg swings outward while walking; what could be causing this and what evaluation and treatment are recommended?

Evaluation of a 17-Month-Old with Difficulty Walking and Leg Swinging Outward

This child requires urgent evaluation for cerebral palsy, specifically spastic hemiplegia, given the unilateral leg swing pattern and inability to walk more than a few steps at 17 months—well past the expected 18-month milestone for independent walking. 1, 2

Immediate Clinical Assessment

Key History Elements

• Pregnancy and birth complications: Document prematurity, birth asphyxia, neonatal encephalopathy, intrauterine growth restriction, or genetic abnormalities, as these are major risk factors for cerebral palsy 2
• Developmental trajectory: Determine if the child achieved sitting independently by 9 months and assess for any loss of previously acquired motor skills, which would indicate progressive neurologic disease requiring urgent evaluation 1, 3
• Asymmetry onset: Early hand asymmetry before 12 months is a red flag for unilateral cerebral palsy 2, 4
• Family history: Screen for muscular dystrophy (particularly X-linked Duchenne on maternal side) or other neuromuscular disorders 4

Critical Physical Examination Findings

Observe spontaneous movement patterns while the child plays naturally, noting whether both legs move symmetrically or if one leg consistently swings outward (circumduction gait pattern typical of spastic hemiplegia) 3, 5

Neuromotor examination must include:

• Deep tendon reflexes: Brisk reflexes in the affected leg indicate upper motor neuron dysfunction, the hallmark of spastic cerebral palsy 2
• Muscle tone assessment: Increased tone (spasticity) in the affected leg versus the unaffected side 2
• Plantar reflex: Abnormal (upgoing) Babinski sign suggests upper motor neuron pathology 4
• Gower sign testing: Have the child rise from the floor; using arms to push up suggests muscle weakness and possible neuromuscular disease 3, 4
• Muscle bulk: Look for calf hypertrophy with weakness (suggests Duchenne muscular dystrophy) or asymmetric muscle development 4

Functional movement observation:

• Watch quality of transitions from sitting to standing 4
• Assess whether the child bears weight symmetrically when held upright 3
• Note if arm swing is asymmetric during attempted walking, as reduced arm swing on one side accompanies hemiplegic cerebral palsy 5

Diagnostic Workup

Mandatory Neuroimaging

Brain MRI is mandatory to identify characteristic cerebral palsy patterns including white matter injury, cortical/deep gray matter lesions, or brain maldevelopments, achieving >95% diagnostic accuracy when combined with clinical examination 2

Laboratory Screening

Obtain serum creatine phosphokinase (CK) to exclude Duchenne muscular dystrophy, which can present with weakness but typically shows diminished (not brisk) reflexes and delayed walking 2, 3, 4

Measure thyroid-stimulating hormone (TSH) to screen for hypothyroidism, which can cause motor delays with hypotonia 3, 4

Standardized Assessment Tools

Perform the Hammersmith Infant Neurological Examination (HINE), as scores <57 at 3 months have 96% predictive value for cerebral palsy; this can be adapted for older infants 2

Complete a standardized developmental screening tool to assess for delays across all domains (language, fine motor, social skills), as motor delays may be the first sign of global developmental disorder 1, 4

Most Likely Diagnosis: Spastic Hemiplegia

The unilateral leg swing pattern (circumduction) strongly suggests spastic hemiplegic cerebral palsy, which accounts for approximately 38% of all cerebral palsy cases and affects one side of the body 2

Key diagnostic features supporting this:

• Unilateral gait abnormality indicates possible upper motor neuron dysfunction 4
• Spastic cerebral palsy represents 85-91% of all cerebral palsy cases 2
• Asymmetric movements or persistent use of only one side requires urgent subspecialist referral 3

Differential Diagnosis Considerations

Cerebral palsy is non-progressive by definition; any acute neurological deterioration requires urgent neuroimaging to exclude stroke, hemorrhage, or spinal cord compression 2

Duchenne muscular dystrophy typically presents at 2-4 years with calf hypertrophy, waddling gait, and significantly elevated CK (>1000 U/L), but shows diminished reflexes rather than brisk reflexes 4

Idiopathic toe walking can occur but typically presents bilaterally and children achieve independent walking by 18 months with heel-toe gait pattern 4, 6

Immediate Management and Referral

Refer immediately to pediatric neurology for comprehensive neuromotor evaluation, even before completing the full diagnostic workup 3, 4

Initiate early intervention services immediately, not after subspecialist evaluation is complete, focusing on postural control, movement training, and parent education 2, 3

Early intervention before 6 months corrected age optimizes neuroplasticity and functional outcomes, though this child is older, immediate referral remains critical 2

Classification and Monitoring

Use the Gross Motor Function Classification System (GMFCS) to standardize severity assessment from Level I to Level V 2

Screen for common comorbidities:

• Epilepsy (35% prevalence in cerebral palsy) 2
• Vision and hearing impairments 2
• Hip displacement (28% prevalence) requiring monitoring 2
• Intellectual disability 2

Critical Pitfalls to Avoid

Do not wait for the child to "catch up"—inability to walk independently by 18 months is a clear developmental delay requiring immediate evaluation 1, 4

Do not dismiss unilateral findings—asymmetric gait or movements always warrant further investigation for focal neurologic lesions or unilateral cerebral palsy 3, 4

Do not delay referral pending complete workup—neurology referral and early intervention should begin immediately while diagnostic testing proceeds 3

Maintain high index of suspicion if symptoms persist beyond 48-72 hours or if any red flags are present 3