What are the concerns and management options for a 5-week-old baby with an overriding unilateral coronal suture, potentially indicating craniosynostosis (premature fusion of the skull bones)?

Overriding Unilateral Coronal Suture in a 5-Week-Old Baby

An overriding unilateral coronal suture at 5 weeks of age requires urgent clinical evaluation to distinguish true craniosynostosis from benign overriding sutures, with immediate referral to pediatric neurosurgery if craniosynostosis is confirmed or highly suspected, as clinical examination alone is sufficient for diagnosis in most cases. 1, 2

Immediate Clinical Assessment

Perform a focused physical examination looking for these specific findings:

• Palpate the coronal suture for a rigid, bony ridge indicating true fusion versus a mobile, overlapping edge suggesting benign overriding 1, 3
• Assess skull asymmetry pattern: unilateral coronal synostosis produces anterior plagiocephaly with ipsilateral frontal flattening, contralateral frontal bossing, and ipsilateral orbital elevation (the "harlequin eye" deformity) 4, 5
• Measure and track head circumference serially, as insufficient increase suggests craniosynostosis 6, 2
• Perform fundoscopic examination to evaluate for papilledema indicating increased intracranial pressure 1, 6, 2
• Complete basic neurological examination assessing for developmental delays and signs of intracranial hypertension 1, 2

Critical Distinction: True Synostosis vs. Benign Overriding

Benign overriding sutures are common in newborns and typically resolve spontaneously within the first few months of life, whereas craniosynostosis presents with a rigid, immobile suture and progressive skull deformity. 3 At 5 weeks, overriding sutures from birth molding should be improving, not worsening. If the suture feels mobile and the skull shape is normalizing, observation is appropriate. If the suture is rigid with progressive asymmetry, craniosynostosis is likely. 3

Imaging Strategy

Reserve imaging for specific scenarios only:

• Clinical examination is sufficient for diagnosis in most cases; imaging should only be pursued when clinical findings are equivocal 1, 2
• If imaging is needed, ultrasound of the suspect suture is the first-line modality when clinical examination cannot definitively exclude craniosynostosis 1, 2
• CT or MRI should be reserved for confirmed craniosynostosis requiring surgical planning, not for initial diagnosis 1, 2
• Avoid routine CT scanning due to radiation risks in developing children 1

Urgent Referral Criteria

Refer immediately to pediatric neurosurgery if:

• Craniosynostosis is confirmed or highly suspected clinically based on rigid suture palpation and characteristic skull deformity 1, 6
• Signs of increased intracranial pressure are present (papilledema, bulging fontanelle, developmental delays) 1, 6
• Syndromic features are identified (facial dysmorphism, limb abnormalities, other congenital anomalies), which requires referral to nationally designated craniofacial centers 1, 6

Syndromic Considerations

Screen for syndromic craniosynostosis, as unilateral coronal synostosis can be associated with genetic syndromes:

• Muenke syndrome and Saethre-Chotzen syndrome commonly present with isolated coronal suture involvement 7
• One-third of coronal synostosis patients have detectable single gene mutations 7
• Syndromic cases require multidisciplinary craniofacial team management with genetics, ophthalmology, and other specialists 6

Timing of Intervention

If craniosynostosis is confirmed, surgical intervention is ideally performed before 6 months of age to allow for minimally invasive options and optimize outcomes. 3, 5 At 5 weeks, this patient is within the optimal window for intervention if surgery is indicated. Early recognition and timely referral are imperative to minimize potential neurologic impairments. 4

Common Pitfalls to Avoid

• Do not dismiss overriding sutures at 5 weeks as purely positional without careful examination, as true synostosis requires urgent intervention 3
• Do not order routine X-rays or CT scans when clinical examination is diagnostic 1
• Do not miss syndromic features that would necessitate referral to specialized craniofacial centers rather than general neurosurgical centers 1, 6
• Do not delay referral if craniosynostosis is suspected, as the window for minimally invasive surgery closes rapidly after 6 months 3