mri spine normal position conus tethered radiology education asia radedasia

WHAT’S THE NORMAL POSITION OF THE CONUS ?

THE NORMAL CONUS

 

To determine if the cord is low lying or potentially tethered its important to know what is the lowest level you can see a conus and still call it normal.

The radiology literature varies with a conus at the L2/3 disc or L3 level considered within the normal range.

NORMAL DEVELOPMENT
  • At birth the normal conus will most commonly be at the L1/2 level but can also be at the L2/3 level. The thecal sac is at the S2 level
  • This because the cord grows at a slower rate than the vertebral column.
  • By 2/12 the conus usually lies around the L1/2 level.

 

NORMAL LOCATION OF CONUS

This is the statement from the International Society of Paediatric Neurosurgeons.
” Any conus medullaris lying caudal to the mid-body of L2 is considered abnormally low (95% confidence limits) and therefore potentially tethered.” (Link to reference below). spine mri normal position conus tethered radiology education asia

NORMAL: Conus at or above mid L2 is normal at any age (orange).

ABNORMAL: Conus below mid-L2 abnormal (green)

 

 

REFERENCE LINK:
The ISPN Guide to Pediatric Neurosurgery: Ascent of the Conus Medullaris

 

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What’s the Purpose of the Tuesday Tips? Many of the Tuesday Tip posts arise from questions or difficulties that people bring up in the Mini Fellowships. These posts are meant to be short and concise to answer those questions.

 

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