Facial Asymmetry Present Only with Smiling is LESS Concerning Than Asymmetry at Rest
New progressive facial asymmetry in a child that is present only with smiling (dynamic asymmetry) is generally less concerning than asymmetry present at rest (static asymmetry), as the latter more strongly suggests serious neurological pathology requiring urgent evaluation. 1, 2, 3
Critical Distinction: Dynamic vs. Static Asymmetry
Asymmetry only with smiling typically indicates:
- Asymmetric crying facies (ACF) or congenital hypoplasia of the depressor anguli oris muscle, which is often benign 4
- Incomplete or mild facial nerve dysfunction (House-Brackmann grades 2-3) that becomes apparent only with voluntary facial movement 5
- Compensatory head posture from strabismus that becomes more evident during facial expression 1, 3
Asymmetry at rest is MORE concerning because it suggests:
- Complete or severe facial nerve paralysis (House-Brackmann grades 4-6) indicating more extensive nerve damage 5
- Intracranial mass or tumor affecting the facial nerve, which presents with static asymmetry even before movement 1, 2, 3
- Cerebrovascular event affecting the facial motor cortex 1, 3
- Progressive structural deformities like hemifacial microsomia, which show increasing asymmetry with growth 6
Immediate Evaluation Required for BOTH Presentations
Despite the distinction above, any new progressive facial asymmetry in a child without trauma should be considered potentially serious and requires prompt evaluation, as it may be the first sign of an intracranial process requiring urgent attention. 1, 2, 3
Essential Clinical Assessment:
Document the exact pattern:
- Onset timing and rate of progression 1, 2
- Whether asymmetry is present at rest or only with movement 5, 4
- Associated symptoms including weakness, sensory changes, vision problems, or developmental delays 2
Perform complete facial nerve assessment:
- Use the House-Brackmann scale to grade severity 5, 2
- Evaluate forehead movement (ability to wrinkle forehead), eye closure completeness, and mouth symmetry at rest and with movement 5
- Check for synkinesis, contracture, or hemifacial spasm 5
Complete cranial nerve examination beyond just facial nerve:
Ophthalmological assessment:
- Visual acuity testing, binocular alignment, extraocular muscle function 1, 3
- Evaluate for compensatory head posture from strabismus 1, 2, 3
- Fundoscopic examination 2, 3
Mandatory Diagnostic Workup
Obtain brain MRI with contrast as first-line imaging to evaluate for intracranial mass, tumor affecting facial nerve, or cerebrovascular pathology. 1, 2, 3
Immediate specialty referrals:
- Pediatric neurology for evaluation of possible intracranial or neurological causes 1, 2, 3
- Pediatric ophthalmology for comprehensive eye examination to rule out strabismus with compensatory head posture 1, 2, 3
Critical Pitfalls to Avoid
Do not assume benign structural asymmetry without neuroimaging, even if asymmetry is only present with smiling. New-onset progressive hemifacial asymmetry requires prompt evaluation regardless of when it appears. 2
Do not delay evaluation based on the assumption that dynamic-only asymmetry is benign, as facial asymmetry may be the first sign of an intracranial process. 2
Distinguish between true anatomical asymmetry and functional asymmetry from compensatory posturing, as strabismus with compensatory head posture can mimic structural facial asymmetry. 1, 2, 3
Do not overlook subtle neurological signs that might indicate serious underlying pathology, particularly in progressive cases. 1
Follow-Up Monitoring
Close monitoring of progression is essential, as conditions like hemifacial microsomia show increasing asymmetry with growth. 1, 2, 6 Repeat imaging may be necessary if symptoms progress or change. 1, 2
Families should understand that clinical changes including regression of motor skills, loss of strength, or any concerns with respiration or swallowing should prompt urgent reevaluation. 5