Abnormal Vertebral Column



Abnormal Vertebral Column


Anne Kennedy, MD



DIFFERENTIAL DIAGNOSIS


Common



  • Spina Bifida


  • Segmentation and Fusion Anomalies


Less Common



  • Caudal Regression Sequence


  • VACTERL Association


  • Skeletal Dysplasias



    • Achondrogenesis


    • Thanatophoric Dysplasia


Rare but Important



  • Iniencephaly


  • Chiari III Malformation


ESSENTIAL INFORMATION


Key Differential Diagnosis Issues



  • Are all vertebral bodies present?



    • Take care to assess all segments systematically


    • Caudal regression may be quite subtle when mild


    • Coronal views useful to see tapering sacral segments, look for hemivertebrae


  • Are all posterior elements closed?



    • Axial views essential to avoid missing spinal dysraphism


    • Look for intracranial findings of Chiari II malformation if suspect neural tube defect


  • Is spine orientation normal?



    • Does orientation change with fetal movement?


    • Is odd position/alignment due to crowding/amniotic cavity distortion?


  • Is fluid volume normal?



    • Polyhydramnios: Skeletal dysplasias, tracheoesophageal fistula, maternal diabetes (macrosomia)


    • Oligohydramnios: Significant renal anomalies, maternal diabetes (microvascular disease)


Helpful Clues for Common Diagnoses



  • Spina Bifida



    • Associated with elevated maternal serum alpha fetoprotein


    • Associated with brain findings of Chiari II malformation


    • Spinal laminae parallel or divergent



      • Normally converge to form a “teepee”


    • Look for associated myelomeningocele



      • Interrupted skin echo


      • Fine membranous sac ± contained neural elements


    • Look for associated myeloschisis



      • Interrupted skin echo with rolled edges, no sac


  • Segmentation and Fusion Anomalies



    • Result from aberrant vertebral column formation



      • Block vertebra: Segmentation failure of two or more vertebral somites


      • Posterior neural arch anomalies: Dysraphism ± unilateral pedicle aplasia/hypoplasia


      • Partial or complete failure of formation: Vertebral aplasia, hemivertebra, butterfly vertebra


      • Partial duplication: Supernumerary hemivertebra


    • Often cause kyphosis/scoliosis


    • May be isolated but if found look for other malformations



      • Gastrointestinal (20%),


      • Congenital cardiac disease (10%)


      • Renal anomalies also described


    • Evaluate spinal cord carefully for associated tethering or diastematomyelia (split cord)


    • Check for maternal alcohol abuse/medications history (valproate)


Helpful Clues for Less Common Diagnoses



  • Caudal Regression Sequence



    • Strong association with poorly controlled maternal diabetes


    • Due to missing vertebra rather than abnormal vertebra


    • Spine looks “short”


    • Tapers abnormally high, not at sacral tip



      • Assess cervical, thoracic, lumbar, & sacral segments systematically in every fetus


    • Look for vertebral bodies between iliac wings on axial images


    • “Shield sign” describes the appearance of apposed iliac wings when sacral vertebra are absent


    • Lower extremities often held in fixed “Buddha” or “cross-legged tailor” position


  • VACTERL Association




    • Non-random association of anomalies involving multiple organ systems except brain



      • Vertebral anomalies


      • Anal atresia


      • Cardiac anomalies


      • Tracheoesophageal fistula


      • Renal anomalies


      • Limb (radial ray)


    • Three or more associated malformations required for diagnosis


  • Achondrogenesis



    • Hallmark is lack of vertebral ossification



      • Type Ia: Completely unossified, associated with rib but not long bone fractures


      • Type Ib: Pedicles may be ossified


      • Type II: Deficient spine mineralization


    • Severe micromelia


    • Disproportionately large head



      • Ossification may be normal (type II) or deficient (type I)


    • Small thorax with protuberant abdomen


  • Thanatophoric Dysplasia



    • Severe platyspondyly with prominent lumbar kyphosis


    • Associated with severe micromelia with prominent bowing but normal ossification


    • Telephone receiver femur in type I


    • Kleeblattschädel (“cloverleaf”) skull deformity in type II


    • Small, narrow thorax


Helpful Clues for Rare Diagnoses

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Aug 10, 2016 | Posted by in OBSTETRICS | Comments Off on Abnormal Vertebral Column

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