Pediatric Triad: Craniofacial Fibrous Dysplasia, Chiari I Malformation, and Syringomyelia
Overview
This case study describes a 16-year-old girl presenting with craniofacial fibrous dysplasia (CFD), Chiari malformation type I (CM1), and syringomyelia (SM). Surgical decompression led to significant symptomatic improvement and near-complete resolution of syringomyelia within six months.
Background
Fibrous dysplasia (FD) is a rare benign bone disorder characterized by replacement of normal bone with fibrous tissue, often causing deformities and neurovascular compression. When FD affects craniofacial bones (CFD), it can alter skull base anatomy, predisposing to Chiari malformation type I, defined by cerebellar tonsillar herniation below the foramen magnum. CM1 is frequently associated with syringomyelia, a fluid-filled cavity within the spinal cord that can cause neurological deficits. The coexistence of CFD, CM1, and SM is extremely rare, especially in pediatric patients.
Data Highlights
Parameter
Value
Reference Range
Alkaline Phosphatase (ALP)
3167.5 U/L
35.0–135.0 U/L
Human Growth Hormone (HGH)
2.42 μg/L
1–5 μg/L
Cerebellar Tonsillar Herniation
14.8 mm below foramen magnum
≥ 5 mm defines CM1
Preoperative ASIA Score
D
N/A
Postoperative ASIA Score (6 months)
E
N/A
Key Findings
The patient exhibited diffuse craniofacial bone thickening with a characteristic ground-glass appearance on imaging, consistent with fibrous dysplasia.
Cervical MRI showed cerebellar tonsillar herniation of 14.8 mm and syringomyelia extending below T5.
Genetic testing identified the Gsα-R201H mutation in the GNAS gene, confirming the molecular basis of FD.
Suboccipital decompression including removal of occipital bone and posterior arch of atlas relieved CSF obstruction at the foramen magnum and foramen of Magendie.
Postoperative imaging demonstrated significant reduction in tonsillar herniation and near-complete resolution of syringomyelia by 6 months.
Neurological function improved from ASIA score D preoperatively to E postoperatively, enabling return to normal activities.
Clinical Implications
In pediatric patients with craniofacial fibrous dysplasia presenting with neurological symptoms, evaluation for Chiari malformation and syringomyelia is warranted due to potential skull base deformities causing CSF flow obstruction. Surgical decompression targeting the foramen magnum and upper cervical spine can effectively relieve symptoms and reverse syringomyelia. Early diagnosis and multidisciplinary management are critical to optimize neurological outcomes.
Conclusion
This rare pediatric triad of CFD, CM1, and SM highlights the complex interplay between craniofacial bone pathology and hindbrain herniation. Surgical intervention can achieve significant clinical and radiological improvement, underscoring the importance of recognizing this association.
References
Fibrous Dysplasia and Craniofacial Involvement -- Clinical and Genetic Insights
Chiari Malformation Type I and Syringomyelia -- Pathophysiology and Management
Case Report: Pediatric Triad of CFD, CM1, and SM -- Surgical Outcomes
