Learning objectives
To know the main clinical manifestations of the acrofacial dysostosis or Nager syndrome.
To analize various CT imaging approaches and techniques for the evaluation of these midface anomalies.
To standardize a radiological report with all the items clinicians need to know to make an appropiate diagnosis,
determine the extent of disease and plan an appropriate management.
Background
- TERMINOLOGY:
Acrofacial dysostosis,
also known as Nager syndrome,
is a rare congenital syndrome primarily characterised by facial and skeletal anomalies.
- PATHOLOGY:
The prevalence of Nager syndrome is unknown,
however it's a very rare syndrome.
Most cases appear to be sporadic,
although autosomal dominant inheritance has been reported.
The occurrence of affected siblings with normal parents suggests an additional autosomal recessive form and adds further genetic heterogeneity.
Recently,
exome sequencing identified mutations in the SF3B4 gene (Splicing Factor 3B,
subunit 4) as a major...
Findings and procedure details
The best imaging tool to diagnose the syndrome is the high-resolution bone CT (Protocol advice < 1 mm axial images,
multiplanar and 3D reformats),
in which the main imaging findings are:
A).
Bilateral ± symmetric MICROGNATHIA.
Fig. 1
B).
MALAR and ZYGOMATIC complex HYPOPLASIA.
Fig. 1
C).
HYPOPLASTIC muscles of MASTICATION.
Fig. 2
D).
TEMPORAL BONE findings:
- EAC: Stenosis/atresia,
small/absent tympanic plate.
- Middle ear space: Hypoplasia/atresia.
- Ossicles: Absent or malformed ± fixation. Fig. 3
- Oval window: Stenosis/atresia.
E).
LIMB ANOMALIES are...
Conclusion
Nager syndrome is a rare condition that includes a wide range of clinical and imaging findings which cause midface anomalies within the main are: Symmetric micrognathia,
zygomatic complex hipoplasia and external ear anomalies.
Limb anomalies are a cardinal sign and,
in combination with the characteristic craniofacial features,
are diagnostic.
High-resolution CT imaging have proved useful in evaluating the extent of these lesions to help pediatricians make an accurate diagnosis and plan an appropiate treatment.
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