32.1 Case Presentation

A 9-month-old, former 30-week premature male patient, presents with a history of mosaic tetrasomy 22q (cat eye syndrome). No spine-related symptoms or signs were found at physical examination (PE).

32.2 Imaging Analysis

Sagittal short tau inversion recovery (STIR) image of the lumbar spine from a 9-month-old infant (▶ Fig. 32.1). The conus medullaris tip is located at mid L3 level (arrow), without any other associated cord, thecal sac, bone, or filum abnormality.

32.3 Differential Diagnosis

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  Low-lying conus medullaris:

  
  
  
  
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    It refers to a low position of a normal-appearing conus medullaris with respect to the vertebral level.

    
    
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    It is usually located between the T12–L1 and L1–L2 disk level; however, in 6.4% of population it can be found between the upper and middle third of L2. ¹

  
  
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  Tethered spinal cord:

  
  
  
  
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    A low-lying conus medullaris pulled down by a thick filum terminale.

    
    
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    The conus medullaris is located at or below the inferior end plate of L2 and is attached to a thickened filum or filum lipoma.

    
    
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    In 25% of cases, there is central canal dilatation. ²

  
  
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  Open or closed spinal dysraphism:

  
  
  
  
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    This is a wide spectrum of malformations including spinal lipoma, myelomeningocele, meningocele, dermoid, and dermal sinus tract.

32.4 Imaging Pearls

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  Low-lying conus medullaris:

  
  
  
  
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    The normal conus medullaris does not end below the middle third of the L2 body. ³

    
    
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    There is no abnormality in the thecal sac, roots, or filum terminale. ^{3 , 4 , 5}